KoritheMan's WunderBlog

Tropical weather analysis - July 29, 2014

By: KoritheMan, 3:09 AM GMT on July 30, 2014

Notice: All forecasts presented here are based upon my own knowledge of atmospheric dynamics. They are created using my knowledge of the various computer models, satellite interpretation, and other tools and parameters. These forecasts, while striving to be accurate, are not intended to supersede predictions by the National Hurricane Center. Always follow NWS protocol and forecasts.

Genevieve

Genevieve regenerated today, and is moving across the central Pacific far to the south of Hawaii. As of the 0300Z advisory bulletin from the CPHC, the following information was posted on the storm:

Wind: 35 mph, with higher gusts
Location: 12.9N 148.5W
Movement: W at 5 mph
Pressure: 1008 mb

Latest satellite data shows a slight decrease in central convection, likely a diurnal fluctuation. A large and pronounced curved band is evident to the west of the center, and upper-tropospheric outflow is well-defined in that direction and appears to be becoming better defined to the east, signifying a decrease in environmental easterly shear. Satellite estimates have not changed significantly, and Genevieve does not appear to have regained tropical storm strength just yet.



Figure 1. Latest infrared satellite image of Tropical Depression Genevieve. Image credit: NOAA's Satellite Services Division (SSD).

The intensity forecast is an interesting one this evening. Virtually none of the global models -- and also the dynamical models GFDL and HWRF -- intensify Genevieve in what appears to be a favorable environment characterized by low vertical shear, warm water temperatures, and a moist lower- to mid troposphere. In fact, the GFDL and HWRF dissipate Genevieve in short order. Since these models appeared to initialize too weak a vortex, I am discounting their respective solutions. The SHIPS and LGEM indicate some strengthening, but only to around 40 kt. Again, either the models are seeing something I'm not, or they are going to bust horribly. Since Genevieve appears to be distinct from the ITCZ now, I doubt there will be much in the way of convective competition from any gyres orbiting within that regime. Given the seemingly favorable atmospheric parameters, I have no choice but to go higher than all of the guidance, taking Genevieve up to 50 kt in 48 hours. After that time, westerly shear is likely to increase as suggested by the GFS and water vapor imagery, which shows high cirrus blowing near and to the west of 155W, which should promote a slow weakening trend in spite of SSTs continuing around 27C throughout the forecast period.

Genevieve appears to be moving slowly toward the west. Water vapor and UW-CIMSS steering data indicate that a weakness, associated with a mid- to upper-level trough, lies to the north of Genevieve from 140 to 150W, which is keeping the cyclone in an environment of weak synoptic steering. The track forecast is arguably trickier than the intensity forecast for once. The TVCA model consensus is considerably farther south than either my own track or the one from the Central Pacific Hurricane Center, and shows Genevieve moving west-southwestward. Looking at the UW-CIMSS steering maps and comparing the 850-700 mb average to the 850-500 mb average, this could be due to a weak depiction of the storm in the various global model initializations causing the consensus to exhibit an unrealistic equatorial bias. My forecast track is considerably farther north than that guidance; completely outside of the guidance envelope, actually, which is something I don't do often. I expect Genevieve to be a deeper system than the global models are projecting, which have had convective issues within this currently active phase of eastern Pacific convection for several days now, and not just with Genevieve. It is much closer to the latest CPHC prediction, and is in reasonable agreement with the 12z ECMWF, albeit a little farther north and slower than that model.

Intensity forecast

Initial 07/30 0000Z 12,9°N 148.5°W 30 kt 35 mph
12 hour 07/30 1200Z 12.9°N 149.3°W 35 kt 40 mph
24 hour 07/31 0000Z 13.0°N 150.0°W 40 kt 45 mph
36 hour 07/31 1200Z 13.1°N 151.0°W 45 kt 50 mph
48 hour 08/01 0000Z 13.4°N 152.4°W 50 kt 60 mph
72 hour 08/02 0000Z 13.5°N 153.8°W 45 kt 50 mph
96 hour 08/03 0000Z 13.6°N 155.5°W 40 kt 45 mph
120 hour 08/04 0000Z 13.6°N 157.9°W 35 kt 40 mph

Track forecast



Figure 2. My forecast track for Genevieve.



Invest 93L

A vigorous tropical wave and an associated broad area of low pressure (93L) located in the central Atlantic over 1200 miles east-southeast of the Windward Islands has lost some organization today. Latest satellite data shows an increase in convection, but this is far to the west of the wave axis and is not organizing into bands. We were, however, still able to garner a T number from SAB, which came in 1.5 at 0z.



Figure 3. Latest infrared satellite image of Invest 93L. Image credit: NOAA's Satellite Services Division (SSD).

An ASCAT pass from several hours ago suggested that the low-level center was not as vigorous and well-defined as it was yesterday, with an elongation and very little westerly winds to the south of the center, but low cloud lines on shortwave infrared images portray a somewhat contradictory portrait. UW-CIMSS shows around 20 kt of northerly shear affecting the system, likely associated with the subsident portion of the Atlantic subtropical ridge; this shear is likely also advecting dry air into the system, also from the subsident portion of the high. The GFS and ECMWF continue to indicate that the upper-level winds will relax ahead of the system, although so far they have been unable to resolve the near-term struggles 93L has had. Nevertheless, I'm confident that greater organization will take place between 45 and 50W, which would coincide with the wave escaping the harsh influence along the subsident portion of the ridge. I have seen seemingly decadent systems reinvigorate amidst more favorable environmental parameters downstream from the location where they initially struggled. This wave is still liable to become a tropical depression during the next day or two, and interests in the Lesser Antilles should continue to monitor its progress.

There hasn't been much news to report in the track guidance today, with many of the members still in agreement on a turn to the west-northwest in about 24-36 hours, near or over the northern Leeward Islands, followed by a gentle (not sharp) northwestward movement, then recurvature between 70 and 75W. Right now it is still more likely than not to recurve, but there is enough margin for error that it may be a long-range threat to the United States mid-Atlantic coast. I do not think 93L is a threat to the Gulf of Mexico due to the current trough draped over the western Atlantic, which, while forecast to weaken, should hang around long enough to induce a west-northwest component of motion to the system even if it remains devoid of convection for a while longer. It should be noted, however, that the longer deep convection is absent, the farther west the system will move. Indeed, the motion seems to have been due west for several hours, and the wave is still comfortably straddling under the 10N latitude line.

Probability of development in 48 hours: 70%

Probability of development in 120 hours: 70%

2014 Atlantic hurricane season 2014 Pacific hurricane season Invest 93L Tropical Depression Genevieve

Updated: 3:11 AM GMT on July 30, 2014

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Tropical weather analysis - July 29, 2014

By: KoritheMan, 6:00 AM GMT on July 29, 2014

Notice: All forecasts presented here are based upon my own knowledge of atmospheric dynamics. They are created using my knowledge of the various computer models, satellite interpretation, and other tools and parameters. These forecasts, while striving to be accurate, are not intended to supersede predictions by the National Hurricane Center. Always follow NWS protocol and forecasts.

Hernan

Hernan continues to weaken. As of the latest NHC advisory, the following information was posted on the storm:

Wind: 50 mph, with higher gusts
Location: 22.1°N 118.6°W
Movement: WNW at 17 mph
Pressure: 1004 mb

A new burst of convection occurred near the center of Hernan between 0 and 1z, but that burst has since weakened, with satellite imagery showing the remaining shower activity being thwarted to the east and northeast of the low-level center by 25 kt of south-southwesterly shear. Satellite estimates continue to plummet, and now support only minimal tropical storm strength. In addition, satellite data shows a pronounced band of arc clouds radiating westward from the low-level center, suggesting that Hernan has entered a stable atmosphere associated with cold waters that are currently around 24C.



Figure 1. Latest infrared satellite image of Tropical Storm Hernan. Image credit: NOAA's Satellite Services Division (SSD).

The models suggest that the shear will increase even more after 24 hours while veering to the west. Combined with waters as cold as 22C along the projected track, and the only logical explanation is that Hernan is not long for this world. My forecast shows Hernan decaying into a remnant low in about 36 hours, but it could certainly occur sooner; in fact, the GFDL and HWRF even show the circulation of Hernan completely dissipating by Wednesday afternoon. The GFS and ECWMF show the lower-tropospheric circulation persisting through about 72 hours, so I'll go along with that for now, fully cognizant that Hernan could lose its identity sooner. Any additional bursts of thunderstorms associated with Hernan's weakening vortex from this point should be quite limited, warm, and far-removed from the center, which based on shortwave infrared satellite pictures appears to be elongating.

Hernan appears to still be moving generally toward the west-northwest, although perhaps a little bit to the right of the current NHC prediction. Water vapor imagery still shows a broad mid- to upper-level trough not far west of Hernan, which is likely contributing to the right-of-track motion given that Hernan is still deep enough for now to respond to the mid-level flow associated with that synoptic feature. My forecast track is only a little to the right of the 3z NHC prediction for the first 12-24 hours before merging with it after that. It is also a little south of the aforementioned track forecast scheme at the end of the forecast period, and is close to but also a little to the south of the 0z TCVA model consensus. Perhaps finally recognizing its previously folly, the GFS now shows Hernan moving westward in the low-level flow after a couple of days, and while still north of the ECMWF, is more in line with it than yesterday. The NOGAPS is now the northernmost outlier and shows the cyclone moving mostly northwestward under the false pretense of an unrealistically deep modeled vortex.

Intensity forecast

Initial 07/29 0300Z 22.1°N 118.6°W 45 kt 50 mph
12 hour 07/29 1200Z 22.7°N 120.3°W 30 kt 35 mph
24 hour 07/30 0000Z 23.6°N 122.5°W 25 kt 30 mph
36 hour 07/30 1200Z 24.2°N 124.0°W 20 kt 25 mph: post-tropical/remnant low
48 hour 07/31 0000Z 24.5°N 125.0°W 20 kt 25 mph: post-tropical/remnant low
72 hour 08/01 0000Z 24.5°N 126.9°W 15 kt 15 mph: post-tropical/remnant low
96 hour 08/02 0000Z: dissipated

Track forecast





Invest 93L

A vigorous tropical wave located in the eastern Atlantic approaching 40W (93L) continues to become better organized. Satellite and microwave data suggest that the low-level center is roughly in the middle of the ball of deep convection encapsulating the wave axis, with satellite data indicating numerous banding features to the south and a weaker one to the west. A 0100 UTC ASCAT pass (not shown) indicated that the low-level center is perhaps still somewhat elongated and didn't carry much in the way of strong winds. However, satellite data shows that the low-level center is becoming increasingly better-defined, and it is probably more likely than not that we will see a tropical depression form from this area sometime today (Tuesday).



Figure 3. Latest infrared satellite image of Invest 93L. Image credit: NOAA's Satellite Services Division (SSD).

Upper-level winds are expected to become increasingly favorable, especially beyond 48 hours when the GFS and ECMWF show an upper-level ridge building over the system as it approaches the Lesser Antilles. The long-range threat of the system once it emerges north of the Caribbean Sea is highly uncertain. While there is good run-to-run consistency in the GFS and ECMWF showing the system recurving, both those models show the system getting near or even west of 70W before recurving, a situation that is very different than many of the storms we've had the last few years, signifying a return to a more normal 500 mb height pattern. In addition, the 500 mb geopotential height anomalies in the aforementioned models actually don't show much troughing over the western Atlantic as 93L enters it in the long range. The ECMWF drops a weak and progressive shortwave out of Atlantic Canada in the 180 hour timeframe, which appears to be what ejects the system into the westerlies in spite of the main trough (the one now over the eastern United States, the one bringing the cold air advection) completely fragmenting and migrating westward, while in the GFS the recurvature appears to be under the northern end of a building mid-level ridge over the western Atlantic, not necessarily a trough by itself. Finally, the mean 500 mb pattern so far this year, the last two deep troughs notwithstanding, has been for semipermanent ridging near Bermuda and Atlantic Canada, not troughing (shown below). This is a considerably different synoptic setup than we've seen the last few years, but it of course remains to be seen if the troughing will return in August and September. So far I see no evidence of that happening, and I expect a more normal 500 mb pattern this year. Probably not the mega blocking of 2004 and 2005, but normal enough to get some threats to the US coast.

Again, we shouldn't focus on the track of the system in the western Atlantic right now. Just don't let your guard down if you live in that area. I would currently put the odds of recurvature at 60%.



Figure 4. 500 mb geopotential height anomalies for the period June 1 through July 25. Notice the strong and persistent ridging over the aforementioned regions, with little troughing over the US east coast.

Interests in the Lesser Antilles should carefully monitor the progress of the system over the next few days, as it will impact them first.

Probability of development in 48 hours: 80%

Probability of development in 120 hours: 90%

2014 Atlantic hurricane season 2014 Pacific hurricane season Tropical Storm Hernan Invest 93L

Updated: 6:25 AM GMT on July 29, 2014

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Tropical weather analysis - July 28, 2014

By: KoritheMan, 7:38 AM GMT on July 28, 2014

Notice: All forecasts presented here are based upon my own knowledge of atmospheric dynamics. They are created using my knowledge of the various computer models, satellite interpretation, and other tools and parameters. These forecasts, while striving to be accurate, are not intended to supersede predictions by the National Hurricane Center. Always follow NWS protocol and forecasts.

Hernan

Hernan continues to move across the Pacific well off the coast of the Baja Peninsula. As of the 0300Z NHC advisory bulletin, the following information was posted on the storm:

Wind: 75 mph, with higher gusts
Location: 19.3°N 113.1°W
Movement: NW at 15 mph
Pressure: 992 mb
Category: 1 (Saffir-Simpson Hurricane Wind Scale)

The cloud pattern associated with Hernan has become less impressive over the last several hours, with satellite data showing the coldest cloud tops occurring mainly north and east of the center. The current structure is likely attributable to the western portion of the cyclone being over cooler waters (down to about 27C as of the latest areal sea surface temperature analysis) and some dry air entrainment from the Pacific marine layer attendant to those cooler waters. Also, the cloud pattern suggests some mid-level southwesterly shear undercutting the outflow in the southwestern periphery of the tropical cyclone. Satellite estimates are starting to come down, and the 6z NHC ATCF file lowered the winds to 60 kt. Interestingly, a 0408Z TRMM pass over the cyclone still showed a well-defined low-level eye feature, but this should diminish soon.



Figure 1. Latest infrared satellite image of Tropical Storm Hernan. Image credit: NOAA's Satellite Services Division (SSD).

As mentioned above, Hernan is already moving over cooler waters, and regional sea surface temperature analyses indicate that the waters become quite cold very rapidly in about 24 hours, so a more expedited decay of the cyclone is expected by then as southwesterly shear (eventually switching to westerly) increases and Hernan ingests even stabler air. Most of the guidance does not hold onto a coherent cyclonic circulation beyond 72 hours, and I may be generous in providing a forecast point out to 96 hours, but I will do so for the sake of continuity. The ECMWF shows the shear increasing over Hernan even faster, so if that model has its way, Hernan could dissipate sooner than indicated here.

Hernan continues moving to the northwest along the southwestern periphery of a mid-level ridge over the southwestern United States. The global models and the HWRF/GFDL show this motion persisting for another day or so before a possible bend a little bit to the west of this motion occurs, presumably in response to the upper-level trough to the north of Hernan lifting out coupled with the cyclone's own weakening over cold water. Near the end of the period, the models show Hernan turning pretty much due westward in the lower-tropospheric flow. The GFS continues to have a strange northward bias with Hernan, and consequently begins to shoot the storm due northward after about 36 hours. This is considered highly unlikely since Hernan will be an increasingly shallow system. Overall, the guidance envelope has shifted northward over the last 24 hours, and my own forecast has been nudged in that direction accordingly. My forecast is similar to the 0z TCVA model consensus initially, but is a tad to the south of that guidance later on.

Intensity forecast

Initial 07/28 0600Z 19.5°N 113.9°W 60 kt 70 mph
12 hour 07/28 1800Z 20.4°N 115.1°W 50 kt 60 mph
24 hour 07/29 0600Z 20.7°N 117.3°W 45 kt 50 mph
36 hour 07/29 1800Z 23.4°N 119.8°W 35 kt 40 mph
48 hour 07/30 0600Z 24.0°N 121.7°W 30 kt 35 mph
72 hour 07/31 0600Z 24.2°N 123.3°W 25 kt 30 mph: post-tropical/remnant low
96 hour 08/01 0600Z 24.2°N 125.3°W 20 kt 25 mph: post-tropical/remnant low
120 hour 08/02 0600Z: dissipated

Track forecast



Figure 2. My forecast track for Hernan.


Invest 93L

A tropical wave in the eastern Atlantic several hundred miles southwest of the Cape Verde Islands was recently designated "Invest 93L" by the National Hurricane Center. Current satellite imagery shows a broad cyclonic circulation associated with the wave that is better defined than yesterday. In addition, infrared satellite data indicates that, while still disorganized, there is more deep convection along the wave axis than yesterday.



Figure 3. Latest infrared satellite image of Invest 93L. Image credit: NOAA's Satellite Services Division (SSD).

Water vapor imagery shows an upper cold low near 27N 49W moving southwestward; this feature appears to be enhancing poleward outflow over the system, and the increasing upper divergence is liable to lead to the formation of a surface low within the wave over the next day or so. By midweek, the GFS and ECMWF build an anticyclone over the disturbance as it approaches the Lesser Antilles, which will relax the upper-level flow even farther, allowing consolidation of the system. The GFS continues to develop this system with much enthrallment. The ECMWF does not, but that model is typically a little slower to catch on with tropical cyclogenesis, or perhaps it's state-of-the-art enough to detect something I don't.

It is too early to speculate on where this disturbance might go if it does develop; while the trough over the southeastern United States is aclimatologically deep (even carrying some semblance of "cold" air advection) and will be hard to move, the models do show the trough beginning to retrograde westward a little bit as 93L enters the western Atlantic beyond seven days. This kind of pattern can favor a hit to the mid-Atlantic, but again, meaningful speculation is hard to glean at these ranges. The best chance for intensification will be to the north of the Caribbean, not in the Caribbean, as both models show a belt of 30 kt westerlies radiating south of the mid-oceanic trough near and south of Hispaniola, a situation that is not as apparent once you go north of the islands. I feel confident this system will become a tropical depression by late week.

Probability of development in 48 hours: 30%

Probability of development in 120 hours: 70%

2014 Atlantic hurricane season 2014 Pacific hurricane season Hurricane Hernan Invest 93L

Updated: 7:49 AM GMT on July 28, 2014

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Tropical weather analysis - July 27, 2014

By: KoritheMan, 8:41 AM GMT on July 27, 2014

Notice: All forecasts presented here are based upon my own knowledge of
atmospheric dynamics. They are created using my knowledge of the various
computer models, satellite interpretation, and other tools and
parameters. These forecasts, while striving to be accurate, are not
intended to supersede predictions by the National Hurricane Center.
Always follow NWS protocol and forecasts.

Genevieve


Genevieve continues to churn aimlessly near the central Pacific. As of the 0300Z NHC advisory, the following information was posted on the storm:

Wind: 35 mph, with higher gusts
Location: 12.5°N 139.5°W
Movement: W at 10 mph
Pressure: 1006 mb

Satellite images aren't impressive this morning, as Genevieve continues to struggle with around 25 kt of westerly shear. Since there doesn't appear to be much large-scale troughing in the current near-cyclone vicinity, this shear is likely more symptomatic of a convectively active Intertropical Convergence Zone. The low-level center appears to be outrunning the convection, and Genevieve appears to be well into the process of becoming a remnant low.



Figure 1. Latest infrared satellite image of Tropical Depression Genevieve. Image credit: NOAA's Satellite Services Division (SSD).

While the GFS and ECMWF decrease the shear over the cyclone in a few days, by then there will likely be little left of Genevieve to be concerned with. Despite the GFS, the CMC, and the NAVGEM showing Genevieve restrengthening in the central Pacific under more favorable environmental conditions -- a solution that is not impossible -- I find the ECMWF/UKMET/HWRF solution of a westward-moving persistent remnant low more believable. While I have shown a forecast point out to five days below, it is probably more likely than not that Genevieve will not survive that long, even as a decadent remnant low.

Genevieve appeared to dive a little south-of-west several hours ago, but has since stabilized with a resumed westward motion. Water vapor imagery shows that the tropical cyclone is on the south of a building low- to mid-level ridge in the wake of a departing upper-level trough, the same trough now influencing the motion of Hernan. As Genevieve enters the central Pacific, the global models show a second trough -- quite evident on water vapor imagery from 150W all the way to near 175W -- moving the system more toward the west-northwest in a couple of days. While the guidance is in good agreement with this scenario, the GFS has shifted considerably northward from the forecast I made yesterday, and now shows Genevieve making a landfall on the Big Island in about 144 hours. This solution is not meteorologically impossible, but given the depth of the cyclone in the GFS sea level pressure fields, appears to be more predicated on a deeper system being more responsive to the upper-level trough near Hawaii. My forecast favors the ECMWF which is well to the south, and is similar to yesterday's forecast.

Intensity forecast

Initial 07/27 0600Z 12.4°N 139.7°W 30 kt 35 mph
12 hour 07/27 1800Z 12,5°N 142.0°W 30 kt 35 mph: post-tropical/remnant low
24 hour 07/28 0600Z 12.6°N 143.8°W 30 kt 35 mph: post-tropical/remnant low
36 hour 07/28 1800Z 12.8°N 145.7°W 30 kt 35 mph: post-tropical/remnant low
48 hour 07/29 0600Z 13.3°N 148.3°W 30 kt 35 mph: post-tropical/remnant low
72 hour 07/30 0600Z 13.6°N 150.0°W 30 kt 35 mph: post-tropical/remnant low
96 hour 07/31 0600Z 13.9°N 151.9°W 30 kt 35 mph: post-tropical/remnant low
120 hour 08/01 0600Z 14.4°N 153.8°W 30 kt 35 mph: post-tropical/remnant low

Track forecast



Figure 2. My forecast track for Genevieve.



Hernan

Hernan is intensifying. As of the 0300Z NHC advisory, the following information was posted on the cyclone:

Wind: 50 mph, with higher gusts
Location: 16.2°N 108.9°W
Movement: NW at 14 mph
Pressure: 1000 mb

While the initial intensity was indeed 45 kt at the 0300Z synoptic time, the 6z ATCF file puts Hernan at 55 kt. While no eye is evident in conventional satellite images, there is considerable deep convection around what appears to be the initial stages of a central dense overcast, and an earlier SSMIS pass around 0230 UTC suggests a formative eye aloft, heralding the formation of an inner core. Upper-level outflow is well-defined to the north, where a nearby upper cold low appears to be enhancing it.



Figure 3. Latest infrared satellite image of Tropical Storm Hernan. Image credit: NOAA's Satellite Services Division (SSD).

Environmental conditions appear quite favorable for additional intensification in the near-term, but the GFS and ECMWF are unanimously projecting an abrupt increase in shear, first from the southwest, then from the west later on; these events will be concurrent with Hernan moving across rapidly cooling water temperatures. Most of the global models do not hold onto a circulation at day five, so I have decided to terminate forecast points for Hernan at that time. In the meantime, while environmental conditions are still favorable, Hernan is likely to become a hurricane, with the SHIPS rapid intensification index affixed to the model still indicating a 27% chance of a 30-kt increase in winds over the next 24 hours, or about 3.1 times the sample mean. My forecast is in best agreement with the 6z LGEM, which takes Hernan up to 70 kt in about 24 hours. Given the apparent environmental hostilities later in the period, it is possible Hernan could weaken even faster than shown below. It is also possible that Hernan could get stronger than I'm suggesting below during the next 12-24 hours.

Like its predecessor, Hernan apparently wants to be a deviant. While the motion has stabilized back to the northwest now, microwave and satellite data from a couple of hours ago showed that the cyclone took an apparent north-northwestward jog; this has prompted me to shift my forecast track a little to the right of what I was originally going to do before the wobble. Water vapor and UW-CIMSS synoptic steering data indicates that Hernan is on the southwest side of a weak mid-level ridge, the weakness being caused by an upper-level trough a few hundred miles to the northwest of the tropical storm. The global models maintain this ridge/trough pattern over the next couple of days with very little differences in forward speed, but some notable divergence begins after 48 hours. Ultimately, all of the global models (save the GFS), along with the GFDL and HWRF, show Hernan turning westward in the low-level flow as it shears apart. However, there is considerable disagreement between the guidance on the approximate latitude at which Hernan begins the turn. The GFS is by far the farthest north, showing Hernan getting to around 27N and never turning westward. The ECMWF is farthest south, showing Hernan moving to around 22-23N before proceeding westward. My forecast will lean closer to the ECMWF solution, as the GFS appears to be suffering from something not immediately obvious but clearly spurious.

Intensity forecast

Initial 07/27 0600Z 16.5°N 109.5°W 55 kt 65 mph
12 hour 07/27 1800Z 17.9°N 110.9°W 65 kt 75 mph
24 hour 07/28 0600Z 18.1°N 112.4°W 70 kt 80 mph
36 hour 07/28 1800Z 20.1°N 113.9°W 60 kt 70 mph
48 hour 07/29 0600Z 21.3°N 115.8°W 50 kt 60 mph
72 hour 07/30 0600Z 22.6°N 118.6°W 35 kt 40 mph
96 hour 07/31 0600Z 23.1°N 120.8°W 25 kt 30 mph: post-tropical/remnant low
120 hour 08/01 0600Z: dissipated

Track forecast



Figure 4. My forecast track for Hernan.



Eastern Atlantic tropical wave

A tropical wave in the eastern Atlantic a few hundred miles south of the Cape Verde Islands is currently producing only disorganized showers and thunderstorms. In addition, satellite data shows that the wave is embedded within a large field of Saharan Dust, indicative of a very dry mid-tropospheric environment. The GFS and ECMWF show upper-level winds initially only being marginally favorable at first (but from the east, which is typical and not prohibitive to at least gradual wave amplification) but ultimately giving way to more favorable winds later on as a broad anticyclone attempts to collocate itself with the tropical wave axis as it begins approaching the Lesser Antilles. Right now it is impossible to tell if this system will develop, but the ECMWF appears to be a little slower in relaxing the shear, which could explain why it fails to develop the system. On the other hand, the GFS has developed this area off and on for the last couple of days, at times showing a tropical storm/possible hurricane moving through the Lesser Antilles. It's too early to reasonably speculate on possibilities, but we should watch this wave as it heads westward and eventually west-northwestward over the next few days and enters a more favorable environment characterized by lighter shear and a somewhat moister airmass.

Probability of development in 48 hours: 0%

Probability of development in 120 hours: 40%



Major steering current shift possible

Over the last week, I have noticed in the global model fields -- specifically the GFS and ECMWF -- that a major synoptic pressure shift has been consistently indicated. The GFS was the first to latch onto the idea, with the ECMWF soon following in its wake. The suggested pattern change is evident on the GFS ensembles as well. The models agree on the current anomalous trough over the southeastern United States slowly (emphasis on slowly; this is a highly amplified feature with even some semblance of aclimatological cold air advection) retrograding westward and weakening over the next 7 - 10 days, subsequently being replaced by a strong upper air ridge. While I doubt we will experience anything akin to the persistent blocking we saw in 2004 and 2005, the large-scale pattern this year has so far been for semipermanent ridging near Bermuda and Atlantic Canada, and in this type of pattern the ridge can sometimes build westward. My guess is we'll finally see this year return to a more normal regime in the upper-level jet stream pattern; that is, neither a blocking trough or a blocking ridge. This pattern is not as conducive to westward-moving hurricanes as was experienced in 2004 and 2005, when the United States took a tremendous battering, but a "normal" pattern is still vastly more dangerous than the persistent troughing pattern we've seen draped over the United States east coast time and time again since 2009.

It remains to be seen if this will verify, of course, but given the tenacity of this solution for almost a week, coupled with how this year has performed so far with the 500 mb height pattern, I am inclined to consider it likely that the trough will erode and become replaced by large-scale ridging. How long this pattern persists is unknown, but if it remains through all of August and September, the United States could take quite a few more hits, even during a possible El Nino year like this one. For what it's worth, the CFS climate model has also been consistent in showing an ASO (August-September-October) 700 mb longwave pattern that is conducive for a ridge to be situated over the east coast and western Atlantic instead of a trough.

2014 Pacific hurricane season Tropical Depression Genevieve Tropical Storm Hernan 2014 Atlantic hurricane season

Updated: 8:41 AM GMT on July 27, 2014

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Tropical weather analysis - July 26, 2014

By: KoritheMan, 8:25 AM GMT on July 26, 2014

Notice: All forecasts presented here are based upon my own knowledge of atmospheric dynamics. They are created using my knowledge of the various computer models, satellite interpretation, and other tools and parameters. These forecasts, while striving to be accurate, are not intended to supersede predictions by the National Hurricane Center. Always follow NWS protocol and forecasts.

Genevieve

Tropical Storm Genevieve is no threat to land. As of the 0300Z NHC advisory bulletin, the following information was posted on the cyclone:

Wind: 45 mph, with higher gusts
Location: 12.2°N 136.1°W
Movement: W at 5 mph
Pressure: 1004 mb

Genevieve appears to be struggling this morning. While deep convection has recently reformed in a small ball, satellite and microwave data still suggest that the low-level center resides along the western end of the circulation due to about 25 kt of westerly shear as denoted on UW-CIMSS. In fact, the latest Dvorak numbers do not quite support tropical storm strength, and the NHC 6z ATCF file actually assigned the intensity at 35 kt, down 5 kt from earlier. Unfortunately, ASCAT has not landed a pass over the center of Genevieve this morning, so it's difficult to assess both the definition of the low-level center and the maximum winds. Recent satellite imagery indicates that the low-level center may be somewhat less-defined than earlier.



Figure 1. Latest infrared satellite image of Tropical Storm Genevieve. Image credit: NOAA's Satellite Services Division (SSD).

The intensity forecast for Genevieve is riddled with more uncertainty than normal, which says a lot because intensity forecasts are always uncertain. On one hand, all of the global models maintain Genevieve as a tropical cyclone throughout the next five days, even those that initialize a weak and possibly unrepresentative vortex, and those models even show the cyclone gaining a little strength during the next few days as the shear abates. On the other end of the spectrum, the SHIPS and LGEM actually forecast Genevieve to dissipate in about five days. Water vapor imagery still shows westerly shear affecting the circulation as a distant mid- to upper-level trough amplifies off the coast of Baja California. Since the trough is already lifting northward, the shear should theoretically decrease from this point onward, but it is not likely to abate immediately. Considering the small size of Genevieve, it would not take much to annihilate the storm, and I am honestly a bit surprised that the global models maintain such a vigorous circulation. On the positive side, waters will slowly warm from the 96-120 hour period after an initial period of cooling before that, while the shear is forecast to decrease significantly over the next couple of days, particularly once Genevieve enters the central Pacific. These factors argue in favor of the various global model predictions, but my feeling is that the shear will not relax quickly enough to allow for any short-term intensification. If Genevieve can escape the current hostilities as even a rough shell of its former self, it may be able to restrengthen downstream amidst more favorable upper-level conditions, although water vapor imagery shows a substantial tongue of dry air in the central Pacific near and to the north of the projected storm track, which may be an inhibiting factor. My forecast will show weakening to a depression in 12 hours, with the cyclone remaining steady state after that. I don't actually expect that forecast to verify, though, and it's more likely that either extreme will occur over the next few days.

Genevieve continues to move rather slowly as the aforementioned trough maintains a momentary weakness in the synoptic steering currents. The 0z GFS captured the current south-of-west motion (12.1N at the 6z ATCF update compared to 12.2N at the 0300Z advisory) rather nicely, and shows an almost immediate return to a westward motion. Overall, the model suite has shifted southward with the latest cycle. My forecast track follows the same general idea as the National Hurricane Center and the 6z TVCA model consensus, but is weighted a little bit to the south of the TVCA consensus given that most of the models contributing to the consensus strengthen Genevieve, which would likely inflate a poleward bias to the tropical cyclone. The global models show a slight weakness developing in the subtropical ridge near and north of the Hawaiian Islands as Genevieve enters the central Pacific, so I have followed that trend by indicating a west-northwest movement after Genevieve enters the central Pacific.

It does not currently appear that Genevieve is a threat to Hawaii, although the comparatively less reliable CMC and NAVGEM shoot the storm toward the Big Island, presumably in response to a weaker subtropical ridge. My forecast remains closer to the GFS and ECMWF for now, which show Genevieve passing well to the south of the archipelago.

Intensity forecast

Initial 07/26 12.1°N 136.4°W 0600Z 35 kt 40 mph
12 hour 07/26 12.1°N 137.4°W 1800Z 35 kt 40 mph
24 hour 07/27 12.1°N 138.7°W 0600Z 30 kt 35 mph
36 hour 07/27 12.1°N 139.9°W 1800Z 30 kt 35 mph
48 hour 07/28 12.4°N 141.6°W 0600Z 30 kt 35 mph
72 hour 07/29 12.8°N 144.6°W 0600Z 30 kt 35 mph
96 hour 07/30 13.3°N 147.5°W 0600Z 30 kt 35 mph
120 hour 07/31 14.6°N 150.7°W 0600Z 30 kt 35 mph

Track forecast



Figure 2. My forecast track for Genevieve.

Tropical Storm Genevieve 2014 Pacific hurricane season

Updated: 8:25 AM GMT on July 26, 2014

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Tropical weather analysis - July 23, 2014

By: KoritheMan, 5:19 AM GMT on July 23, 2014

Notice: All forecasts presented here are based upon my own knowledge of atmospheric dynamics. They are created using my knowledge of the various computer models, satellite interpretation, and other tools and parameters. These forecasts, while striving to be accurate, are not intended to supersede predictions by the National Hurricane Center. Always follow NWS protocol and forecasts.

Tropical Depression Two

Tropical Depression Two continues to move westward across the central Atlantic. As of the 0300Z NHC advisory bulletin, the following information was available on the depression:

Wind: 35 mph, with higher gusts
Location: 13.4°N 51.4°W
Movement: WNW at 18 mph
Pressure: 1012 mb

The depression is sending mixed signals this evening. On one hand, the 0z SAB classification was only 1.5, solidly under tropical storm strength, and even 5 kt below the current operational intensity estimate from the NHC. On the other hand, recent T numbers from the UW-CIMSS Advanced Dvorak Technique (ADT) suggests that the depression could be a tropical storm. Realistically, it is probably safe to assume the winds haven't increased lacking any data other than the CIMSS estimates. ASCAT conveniently missed the cyclone, and I am reminded of how difficult it is to glean the intensity of tiny tropical cyclones sans the assistance of a reconnaissance aircraft. This situation reminds me of Tropical Storm Marco in 2008, where the Dvorak numbers were suggestive of a weaker system than the aircraft data showed, which was 55 kt. It's not impossible that the winds are now at the bottom of tropical storm force since the convection has persisted for several hours in a situation that was different to yesterday, when it was producing less convection during the diurnal convective maximum. The location of the low-level center is also quite ambiguous, even with the assistance of the normally reliable microwave satellite data. This is likely because it is quite small. I presume it is near or under the deepest convection, but I shouldn't pretend to be certain.



Figure 1. Latest infrared satellite image of Tropical Depression Two. Image credit: NOAA's Satellite Services Division (SSD).

Having said these things, and even assuming the depression does become a tropical storm, the large-scale environment still does not favor intensification. Water vapor imagery and UW-CIMSS analyses indicate that the depression remains embedded within a very hostile thermodynamic environment characterized by very dry air, with water vapor imagery showing westerly winds blowing toward the eastern Caribbean from the mid-oceanic trough. The global models forecast an abrupt increase in shear in as little as 24 hours, at which point an abrupt weakening trend is anticipated. I expect the cyclone to dissipate in about 48 hours, although I would not be surprised to see this occur even sooner than that. None of the global models hold onto the tropical cyclone for any longer than about 24 hours. The SHIPS and LGEM still insist on a little strengthening, but are much less aggressive than yesterday, finally recognizing what kind of an environment the depression is in.

The cyclone appears to have turned toward the west-northwest as the NHC estimates, although a resumption of the previously observed westward track cannot be ruled out since the ridge appears to be stronger than what I was expecting this time yesterday. The guidance has not changed significantly since my last forecast, and still agrees on the system moving west-northwestward into the Caribbean over the next day or so. After that time, even assuming the depression unexpectedly survives, the guidance shows it running into Hispaniola, which would quickly destroy the already tiny circulation of the sprawling depression.

The depression could still spread locally heavy rains and gusty winds over portions of the Lesser Antilles over the next couple of days, particularly to the right of the storm track in response to the fast forward speed and westerly shear keeping the convection to the east of the lower-tropospheric vortex.

Intensity forecast

Initial 07/23 0300Z 13.4°N 51.4°W 30 kt 35 mph
12 hour 07/23 1200Z 13.8°N 54.1°W 30 kt 35 mph
24 hour 07/24 0000Z 14.6°N 57.7°W 30 kt 35 mph
36 hour 07/24 1200Z 15.3°N 61.9°W 25 kt 30 mph
48 hour 07/25 0000Z: dissipated

Track forecast



Figure 2. My forecast track for Tropical Depression Two.

2014 Atlantic hurricane season Tropical Depression Two

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Tropical weather analysis - July 21, 2014

By: KoritheMan, 3:43 AM GMT on July 22, 2014

Notice: All forecasts presented here are based upon my own knowledge of atmospheric dynamics. They are created using my knowledge of the various computer models, satellite interpretation, and other tools and parameters. These forecasts, while striving to be accurate, are not intended to supersede predictions by the National Hurricane Center. Always follow NWS protocol and forecasts.

Tropical Depression Two

The tropical wave that has marched through the Atlantic over the last few days became a tropical depression today. As of the 0300Z NHC advisory, the following information was posted on the storm:

Wind: 35 mph, with higher gusts
Location: 12.0°N 45.1°W
Movement: W at 16 mph
Pressure: 1012 mb

The satellite signature of this small depression is certainly not impressive. There is a small area of deep convection near the apparent center, with microwave data throughout the evening showing some weak fragmented curved bands to the north and south of the center. Satellite estimates do not currently support tropical storm strength. A recent partial ASCAT pass raises some doubt if the circulation is closed, but there is a frequent inhibition with that instrument to capture closed circulations in small depressions.



Figure 1. Latest infrared satellite image of Tropical Depression Two. Image credit: NOAA's Satellite Services Division (SSD).

The prospects for future intensification appear low, although there is still a chance for the system to become a tropical storm over the next 12-24 hours as it heads westward into progressively warmer waters. That possibility notwithstanding, the cyclone is experiencing ample mid-level dry air on the subsident portion of the Atlantic subtropical ridge. In addition, satellite data shows arc clouds emanating westward ahead of the low-level center, signifying subsident flow creating stable sinking air. Despite the seemingly clear cut synoptic picture, the models are split, with the statistical-dynamical LGEM/SHIPS models showing the depression becoming a moderate to strong tropical storm (indeed, the 0z SHIPS without land factored in takes the depression to hurricane strength in four days), while all of the global models dissipate the tropical cyclone as it nears the Caribbean Sea. Given the increasing shear in the eastern Caribbean associated with the mid-oceanic trough -- which is very apparent on evening water vapor analyses -- coupled with the very meager thermodynamic environment, suggests that the global models likely have a better prediction. My forecast follows the NHC prediction of the cyclone dissipating after 72 hours, although it could occur sooner. Although the GFS and ECMWF show the 200 mb flow possibly relaxing as the depression moves north of the Caribbean later on, there will likely be little to be concerned with at that point.

Satellite data suggests that the depression is moving north of the 2100Z NHC forecast track, and the 0300Z track corrected this accordingly. The depression is currently south of a rather strong low- to mid-tropospheric ridge, with UW-CIMSS steering indicating the ridge building westward ahead of the cyclone between 850 and 700 mb. This should promote a continued west to west-northwestward over the next few days. In about 72 hours, the GFS and ECMWF show a mid-level trough developing over the eastern United States, which is likely to cause the depression to slow down and move more toward the northwestward if it survives beyond the expectation I have delineated below. While there is a nonzero chance of a threat to the United States east coast next week if the depression survives, this is an extremely big if, and dissipation in short order is on today's dollar menu. My forecast track is similar to the current NHC track, but to the south of the latest TVCA model consensus.

The depression could spread locally heavy rains and gusty winds to portions of the Lesser Antilles over the next few days, even if it dissipates as a tropical cyclone.

Intensity forecast

Initial 07/22 0300Z 12.0°N 45.1°W 30 kt 35 mph
12 hour 07/22 1200Z 12.3°N 47.0°W 30 kt 35 mph
24 hour 07/23 0000Z 12.7°N 50.0°W 30 kt 35 mph
36 hour 07/23 1200Z 13.4°N 53.6°W 30 kt 35 mph
48 hour 07/24 0000Z 14.5°N 57.2°W 30 kt 35 mph
72 hour 07/25 0000Z 17.2°N 64.1°W 25 kt 30 mph
96 hour 07/26 0000Z: dissipated

Track forecast



Figure 2. My forecast track for Tropical Depression Two.

2014 Atlantic hurricane season Tropical Depression Two

Updated: 3:48 AM GMT on July 22, 2014

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Introversion

By: KoritheMan, 7:08 AM GMT on July 17, 2014

I'm starting to think I'm decently introverted for a voluntary reason which is really quite simple: people as a whole bore me. I prefer esoteric topics and most people don't. The superficiality I find in most people can only hold me over so long before I get bored.I also like controversial topics. Most people aren't looking to stir the pot. I am. Pacifism is about the last thing ever occupying my mind.

Can anyone relate?

Updated: 7:08 AM GMT on July 17, 2014

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Tropical weather analysis - July 8, 2014

By: KoritheMan, 2:53 AM GMT on July 09, 2014

Fausto

Tropical Storm Fausto continues spinning in the open waters of the eastern Pacific. As of the most recent NHC advisory bulletin, the following was posted on Fausto:

Wind: 40 mph, with higher gusts
Location: 11.0°N 126.5°W
Movement: WNW at 18 mph
Pressure: 1006 mb

It appears that the global models may have been correct all along with the lack of strengthening. The cloud pattern is very disorganized, with a recent SSMIS microwave pass showing a low-level wind flow more resembling of a sharp inverted trough, rather than a tropical cyclone with a well-defined center. An earlier ASCAT pass (not shown) near 17Z suggested that Fausto only had a couple of tropical storm force wind vectors. While these were believable at the time, even considering the well-documented low bias of the instrument, I can only reasonably adjust a slew of 30 kt vectors to 35 kt; this suggests that Fausto was possibly weaker than advertised at the 21Z NHC advisory.



Figure 1. Latest infrared satellite image of Tropical Storm Fausto. Image credit: NOAA's Satellite Services Division (SSD).

I cannot immediately explain the apparent lack of intensification in a seemingly favorable environment. Water vapor analyses still suggests that Fausto has a well-developed outflow pattern, implying good ventilation/divergence aloft. However, ever since its inception, the low-level center has always been straddling the northern edge of the convection, a characteristic found in sheared cyclones. In addition, satellite data shows arc clouds radiating north from the center of Fausto, implying downdrafts are hitting the ocean surface and signifying a subsident flow aloft creating stable sinking air. My best presumption for the disheveled appearance of the tropical cyclone despite the very favorable outflow pattern and warm sea surface temperatures is mid-level northerly to north-northwesterly shear, which is helping to push dry air into the system. It is also possible that Fausto is competing for convergence within another disturbance in the ITCZ a few hundred miles to the east; or perhaps Fausto is actually losing convergence as it steadily exits the ITCZ. Whatever the case, I do not anticipate a significant amelioration of the ongoing situation, and my new forecast is reduced substantially from the previous one, and no longer shows Fausto becoming a hurricane. Instead it shows the tropical storm decaying into a remnant low at day four, and subsequently dissipating by day five. I must congratulate the global models who all along had shown Fausto weakening. I recall a similar evolution with Tropical Storm Bonnie in 2010, when the global models were not calling for significant development over the Gulf of Mexico while most of the statistical guidance was. It is possible that Fausto could dissipate even sooner than I have indicated below. An alternative but less likely scenario is that Fausto restrengthens a little during the next 12-24 hours as it gains latitude and detaches from the ITCZ and the aforementioned convective competition; even so, that would hardly eliminate the ongoing presumed mid-level shear. My forecast will compromise between the above scenarios by not immediately killing Fausto off. After about 48 hours, the models show an increase in shear, with the GFS showing a sharper and faster increase than the ECMWF.

The low-level center of Fausto has become so diffuse to the point where it is not easy to locate, even with last light visible images and recent microwave data. However, the overall cyclonic gyre in which Fausto is embedded is moving west-northwest, and this general motion is expected to continue over the next few days, in agreement with the global model output. My forecast is similar to but south of the latest TVCE model consensus, under the assumption that Fausto will shear apart faster than that guidance is indicating, and also under the presumption that the lower- to mid-tropospheric ridge will be stronger than forecast at longer ranges, in agreement with climatology. Most of the guidance shows Fausto getting very close to the Big Island Sunday into Monday, with a few of the members even showing a landfall. Even if this were to verify, there is likely to be little left of Fausto to be concerned about. A gentle turn back toward the west is expected at the end of the period as the synoptic weakness near 130W weakens and retrogrades northward over the central Pacific, allowing ridging to rebuild to the south of the trough.

Intensity forecast

Initial 07/09 0300Z 11.0°N 126.5°W 35 kt 40 mph
12 hour 07/09 1200Z 11.3°N 127.9°W 35 kt 40 mph
24 hour 07/10 0000Z 12.0°N 130.6°W 35 kt 40 mph
36 hour 07/10 1200Z 12.7°N 133.2°W 35 kt 40 mph
48 hour 07/11 0000Z 13.6°N 136.6°W 35 kt 40 mph
72 hour 07/12 0000Z 14.9°N 141.1°W 30 kt 35 mph
96 hour 07/13 0000Z 16.3°N 147.4°W 25 kt 30 mph: post-tropical/remnant low
120 hour 07/14 0000Z: dissipated

Track forecast



Figure 2. My forecast track for Fausto.

2014 Pacific hurricane season Tropical Storm Fausto

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Tropical weather analysis - July 7, 2014

By: KoritheMan, 3:07 AM GMT on July 08, 2014

Notice: All forecasts presented here are based upon my own knowledge of atmospheric dynamics. They are created using my knowledge of the various computer models, satellite interpretation, and other tools and parameters. These forecasts, while striving to be accurate, are not intended to supersede predictions by the National Hurricane Center. Always follow NWS protocol and forecasts.

Tropical Storm Fausto rapidly developed from an area of disturbed weather that has been tracked over the last several days well to the southwest of the southern tip of Baja California, roughly midway between that peninsula and the Hawaiian Islands. Actually, I would have expected 98E to develop before this system did, but now it appears that the situation has become more or less the opposite. As of the 0300Z NHC advisory, the following information was posted on Fausto:

Fausto

Wind: 45 mph, with higher gusts
Location: 9.6°N 120.7°W
Movement: W at 12 mph
Pressure: 1004 mb

Satellite images still show an expansive area of deep convection, with formative curved bands to the east and south. Upper-level outflow is well-defined, implying that there is little overall shear afflicting Fausto at this time. Microwave and satellite data suggest that the low-level center of Fausto is located a couple tenths degrees to the west of the eastern curved band, which could suggest some weak mid-level shear affecting Fausto below the outflow layer, or it could just be a typical tropical cyclone structural fluctuation. We shall see.



Figure 1. Latest infrared satellite image of Tropical Storm Fausto. Image credit: NOAA's Satellite Services Division (SSD).

The intensity forecast is a little tricky, and depends on a couple factors. The SHIPS SST assimilation appears to be valid based on a more objective analyses of sea surface temperatures in the region. However, that model only takes Fausto up to 57 kt in 48 hours, then levels off the intensity as the cyclone heads into progressively cooler water and increasing vertical shear. This forecast was based off Fausto taking a more northern track, which would shoot it across the 26C isotherm much sooner. My forecast track is a little south of the models, but ends up fairly similar to the 12z ECMWF near the end of the period. For this reason, and partially because waters appear reasonably warm up through at least 72 hours anyway, my intensity forecast shows Fausto peaking as a hurricane, which is a little higher than most of the guidance, save the HWRF, which takes Fausto up to 75 kt in 72 hours. It should be noted that with such a marked anticyclonic outflow signature currently being observed on water vapor loops, Fausto could get even stronger than forecast below, with the SHIPS rapid intensification parameter indicating a 41% chance of a 25-kt increase in wind speed during the next 24 hours, and 28% chance of a 30-kt increase during the same period. There is some very dry air several hundred miles to the northwest of Fausto, but CIMSS Total Precipitable Water (TPW) imagery and water vapor analyses shows the dry air is moving in tandem with Fausto, which may actually even be moving a little slower than the dry air. In addition, Fausto still lies in close proximity to a convectively active ITCZ, including another disturbance to the east. Coupled with the small size of the tropical storm, I do not anticipate dry air to be a significant problem for Fausto, and certainly not enough to stifle steady intensification. Beyond 72 hours, even if Fausto takes a more southern track and ends up over warmer waters, the GFS and ECMWF show an increase in westerly shear as Fausto comes under the influence of the mid-oceanic trough near Hawaii.

Current UW-CIMSS steering data suggests that Fausto is embedded in a somewhat weak steering regime, and may end up moving a little slower than the guidance suggests, at least initially; satellite images actually suggest a possible south of west motion, but earlier scatterometer data and visible imagery indicated that the low-level center is rather small, which makes gauging the storm movement a little difficult. It is also possible that this apparent south-of-west motion could be due to the modulation of convection within Fausto's circulation, since this assumption appears most strongly in infrared data. This also doesn't coincide with the latest NHC position estimate. Since a south-of-west steering flow does not appear especially realistic at this angle, I have chosen to instead show a due westward motion for the next 12 hours out of respect for the CIMSS data showing a stronger ridge driving a theoretical south-of-west component of motion, but in deference to the guidance and water vapor imagery favoring a track somewhat farther to the north. Fausto is expected to gradually turn west-northwestward and gain latitude over the next few days as it comes under the influence of a weakness in the subtropical ridge forecast to develop around 135W in the global models fields. The GFS has a somewhat stronger trough, which could be influencing the GFDL to be well to the north of the other models, taking Fausto above 20N by day five. My forecast track is fairly similar to but a little south of the current NHC prediction, and as previously mentioned, is also not far from the 12z solution of the ECMWF. It should be noted that most of the guidance, with the exception of the HWRF, did not initialize the Fausto vortex all that auspiciously for the 12-18z cycles. The upcoming 0z models should show a stronger and better placed cyclone, and it will be interesting to see what implications this has on their respective forecast tracks. If Fausto rapidly intensifies, it will likely end up farther north than what I have indicated below, and could very well be one of those quickly spin up and then just as quickly spin down cyclones if that happens, since the shear would be stronger and the waters cooler.

It does not currently appear that Hawaii is at appreciable risk from Fausto as a tropical cyclone, but it may cause some disruption of the local trade wind regime across the islands early next week as it moves west to west-northwestward to the south of islands a weakening tropical cyclone or possibly remnant low.

Intensity forecast

Initial 07/08 0300Z 9.6°N 120.7°W 40 kt 45 mph
12 hour 07/08 1200Z 9.5°N 122.3°W 45 kt 50 mph
24 hour 07/09 0000Z 9.8°N 124.8°W 50 kt 60 mph
36 hour 07/09 1200Z 10.4°N 127.1°W 55 kt 65 mph
48 hour 07/10 0000Z 12.4°N 130.3°W 65 kt 75 mph
72 hour 07/11 0000Z 13.2°N 137.1°W 70 kt 80 mph
96 hour 07/12 0000Z 14.6°N 143.6°W 50 kt 60 mph
120 hour 07/13 0000Z 15.8°N 148.6°W 40 kt 45 mph

Track forecast



Figure 2. My forecast track for Fausto. Note that my track forecast was map was based on the initial position inferred from the 0z ATCF file, and obviously differs a bit from the current NHC operational position estimate. I am not actually showing a southward component of motion to the cyclone from now through 12 hours.

2014 Pacific hurricane season Tropical Storm Fausto

Updated: 3:08 AM GMT on July 08, 2014

Permalink

Tropical weather analysis - July 5, 2014

By: KoritheMan, 7:42 AM GMT on July 05, 2014

Arthur

Arthur remains a hurricane as of the 0600Z NHC intermediate advisory bulletin:

Wind: 75 mph, with higher gusts
Location: 42.3°N 67.6°W
Movement: NE at 31 mph
Pressure: 981 mb
Category: 1 (Saffir-Simpson Hurricane Wind Scale)

Arthur is quickly becoming an extratropical cyclone. Satellite and radar data from Portland, Maine show a sizable area of rain to the north of the center, but little apparent precipitation near the center. In addition, 0z upper air soundings from Portland along with manual analysis of water vapor imagery show a pronounced tongue of cooler and drier air becoming rapidly entrained into the circulation as a cold front approaches and overtakes the cyclone from the west. Satellite estimates are beginning to fall rather abruptly, and Arthur will likely be downgraded to a tropical storm on the forthcoming NHC 0900Z full advisory package. While Arthur is still producing an area of fairly cold convection, satellite data suggest that this convection is occurring well ahead of the center over southwestern Nova Scotia.



Figure 1. Latest infrared satellite image of Hurricane Arthur. Image credit: NOAA's Satellite Services Division (SSD).

While Arthur is probably not quite extratropical yet, it should get there within the next few hours. Although the last AMSU temperature profiles still showed a respectable warm core, the most recent of those assessments were near 2000Z, nearly nine hours ago at the time of this writing, and it is likely that the column has cooled significantly within Arthur since that time as the rapidly transforming tropical cyclones heads over cold water and encounters westerly shear. While a gradual decay of the circulation is forecast throughout the forecast period, Arthur is still expected to make landfall over Atlantic Canada with near hurricane-force winds, especially in gusts. The global models do not suggest baroclinic reintensification of Arthur as an extratropical cyclone, but instead signify a gradual elongation of the circulation and a steady decrease in storm-relative wind speeds as post-tropical cyclone Arthur rotates around a larger extratropical gyre over the north Atlantic.

Arthur is accelerating to the northeast embedded in mid-latitude southwesterly flow connected to the aforementioned cold front. Arthur or more likely its extratropical remnants are expected to make landfall along the southwestern coast of Nova Scotia near Yarmouth within the next several hours. After landfall, most of the guidance shows Arthur briefly moving into the Bay of Fundy before turning to the east-northeast as it rounds the northern periphery of the Atlantic subtropical ridge and begins to also feel the counterclockwise circulation associated with a larger extratropical cyclone over the north Atlantic. The model consensus has shifted a little to the left on the latest cycle, but my forecast remains a little to the right of that guidance, and is fairly close to the current National Hurricane Center forecast track. While a forecast point is not provided out to five days here due to the limitations of the map I use to make the track forecasts, the models show extratropical Arthur ending up near southern Greenland by that time, where it is likely to be significantly weaker.

Earlier scatterometer data indicates that Arthur has a rather expansive wind field, and recent offshore buoy data indicate that sustained tropical storm force winds are not far offshore the coast of Maine (Station M1SM1 located at 43.7°N 68.8°W). While a tropical storm warning has not been issued for that area with the expectation that the strongest winds will arrive behind the cold front, the overall impact will be the same, and interests there should follow the products issued by their local National Weather Service forecast office.

Tropical storm force sustained winds with possible embedded hurricane force gusts are likely over much of Nova Scotia before the circulation begins to wind down in about 24 hours. Residents there should anticipate the likelihood of tree and power line damage. Rainfall should be fairly minimal since Arthur will be moving quickly through the region.

The tropical storm warning for Nantucket and Cape Cod will likely be discontinued by the National Hurricane Center with the next advisory, as surface observations show westerly winds that are well below tropical storm force. A tropical storm warning remains in effect for all of Nova Scotia, and a wide swath of tropical storm force winds is expected to occur here.

Intensity forecast

Initial 07/05 0600Z 42.3°N 67.6°W 65 kt 75 mph
12 hour 07/05 1800Z 44.7°N 65.1°W 50 kt 60 mph: extratropical
24 hour 07/06 0600Z 47.8°N 60.8°W 45 kt 50 mph: extratropical
36 hour 07/06 1800Z 49.8°N 57.8°W 40 kt 45 mph: extratropical

Track forecast



Figure 2. My forecast track for Arthur.

NHC storm information


000
WTNT31 KNHC 050549
TCPAT1

BULLETIN
HURRICANE ARTHUR INTERMEDIATE ADVISORY NUMBER 17A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014
200 AM EDT SAT JUL 05 2014

...ARTHUR RACING TOWARD NOVA SCOTIA...


SUMMARY OF 200 AM EDT...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...42.3N 67.6W
ABOUT 130 MI...210 KM SW OF YARMOUTH NOVA SCOTIA
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...NE OR 45 DEGREES AT 31 MPH...50 KM/H
MINIMUM CENTRAL PRESSURE...981 MB...28.97 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* NANTUCKET
* CAPE COD FROM PROVINCETOWN TO WOODS HOLE
* NOVA SCOTIA INCLUDING CAPE BRETON ISLAND
* PRINCE EDWARD ISLAND
* NEW BRUNSWICK FROM THE U.S./CANADA BORDER TO GRAND-ANSE

IN ADDITION...HIGH WIND WARNINGS...FOR WINDS IN EXCESS OF 40 MPH...
ARE IN EFFECT FOR PORTIONS OF EASTERN MAINE.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 200 AM EDT...0600 UTC...THE CENTER OF HURRICANE ARTHUR WAS
LOCATED BY AN AIR FORCE RECONNAISSANCE PLANE NEAR LATITUDE 42.3
NORTH...LONGITUDE 67.6 WEST. ARTHUR IS MOVING TOWARD THE NORTHEAST
NEAR 31 MPH...50 KM/H...AND THIS MOTION IS EXPECTED TO CONTINUE WITH
SOME DECREASE IN FORWARD SPEED DURING THE NEXT DAY OR SO. ON THE
FORECAST TRACK...THE CENTER OF ARTHUR WILL BE NEAR OR OVER WESTERN
NOVA SCOTIA IN THE NEXT FEW HOURS...AND OVER THE GULF OF ST.
LAWRENCE TONIGHT.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 75 MPH...120 KM/H...WITH HIGHER
GUSTS. WEAKENING IS FORECAST DURING THE NEXT 48 HOURS...AND ARTHUR
IS EXPECTED TO BECOME A POST-TROPICAL CYCLONE LATER THIS
MORNING.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
160 MILES...260 KM.

THE MINIMUM CENTRAL PRESSURE RECENTLY REPORTED BY AN AIR FORCE
HURRICANE HUNTER PLANE WAS 981 MB...28.97 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE SPREADING ACROSS PORTIONS THE
WARNING AREA IN NEW ENGLAND. THESE WINDS SHOULD GRADUALLY SUBSIDE
IN THE NEXT FEW HOURS. TROPICAL STORM CONDITIONS ARE
EXPECTED TO REACH THE WARNING AREA IN CANADA DURING THE NEXT
FEW HOURS AND SPREAD NORTHWARD LATER TODAY. IN ADDITION...WINDS IN
EXCESS OF 40 MPH ARE EXPECTED OVER PORTIONS OF EASTERN MAINE
TODAY...BEHIND A COLD FRONT OVERTAKING THE CIRCULATION OF ARTHUR.

STORM SURGE...COASTAL FLOODING IS POSSIBLE ALONG CAPE COD
TODAY. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE SEE PRODUCTS
ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE.

RAINFALL...RAINFALL ACCUMULATIONS OF 2 TO 4 INCHES ARE EXPECTED
OVER EASTERN MASSACHUSETTS...COASTAL MAINE...NOVA SCOTIA...
NEWFOUNDLAND...AND NEW BRUNSWICK...WITH ISOLATED MAXIMUM AMOUNTS OF
6 INCHES POSSIBLE OVER DOWNEAST MAINE AND INTO NEW BRUNSWICK CANADA.

SURF...SWELLS GENERATED BY ARTHUR ARE STILL AFFECTING PORTIONS OF
THE COAST OF NORTH CAROLINA...THE MID-ATLANTIC...AND NORTHEAST
UNITED STATES. SWELLS WILL BEGIN AFFECTING PORTIONS OF SOUTHEASTERN
CANADA SOON. THESE SWELLS ARE EXPECTED TO CAUSE LIFE-THREATENING
SURF AND RIP CURRENTS. FOR MORE INFORMATION...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST
OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM EDT.

$$
FORECASTER AVILA

2014 Atlantic hurricane season Hurricane Arthur

Updated: 9:05 AM GMT on July 05, 2014

Permalink

Tropical weather analysis - July 4, 2014

By: KoritheMan, 7:34 AM GMT on July 04, 2014

Arthur

Arthur is a dangerous Category 2 hurricane as it made a second landfall in eastern North Carolina. As of the latest NHC position/intensity estimate, the following information was available on Arthur:

Wind: 100 mph, with higher gusts
Location: 35.6°N 75.9°W
Movement: NE at 22 mph
Pressure: 973 mb
Category: 2 (Saffir-Simpson Hurricane Wind Scale)

Satellite and coastal radar data indicate that Arthur is holding its own. Deep convection has been increasing the eastern and northern eyewall, which is not surprising with a northeastward-moving hurricane that's still largely over water. The radar data suggests that Arthur has closed off its eye, although the eyewall convection remains a little weak to the southwest. A pronounced outflow channel has opened up to the north and east of the hurricane in response to increasing upper divergence from an approaching shortwave trough in the westerlies. There is also a lesser outflow channel to the south.



Figure 1. Latest infrared satellite image of Hurricane Arthur. Image credit: NOAA's Satellite Services Division (SSD).

Although much of the circulation is overland, some modest intensification remains possible once Arthur gets a little farther away from the coast. The LGEM forecasts about a 5 kt increase in wind speeds over the next 6 hours before leveling off. The atmospheric vertical shear is still momentarily light, and nearby surface observations indicate that the near-storm environment is rather moist. Arthur has moved north of the Gulf Stream, so rapid intensification is not anticipated. But as a reminder, Hurricane Alex intensified in a similar location in 2004 under similar atmospheric processes, and unexpectedly strengthened into a 105 kt major hurricane. Coastal and offshore buoy data indicates that the underlying water temperatures are still around 27C in this area, a little bit warmer than normal for this time of year. This portion of the North Carolina coastal area is rather marshy, which is why Arthur has not weakened; in fact, the radar and satellite signature have improved since the 0300Z NHC advisory several hours ago. Any intensification is likely to occur within the next 6-12 hours, after which time the hurricane will encounter quickly cooling waters, drier air, and a substantial increase in southwesterly to westerly shear. A rather abrupt pace of weakening is forecast subsequent to the 12 hour forecast point, and Arthur is likely to become extratropical in about 36 hours, if not sooner. Forecast points are only provided out to 48 hours due to the limitations of the map I used to create the track forecasts. The global models show Arthur possibly becoming absorbed within a larger extratropical cyclone over the North Atlantic by day five.

There is an outside chance that Arthur briefly reaches Category 3 status after it pulls away from North Carolina. This could occur as baroclinic forcing attendant to the approaching shortwave and associated frontal boundary contribute to additional divergence and forcing. Arthur's expected further acceleration could also assist the strengthening process, or at least maintaining the cyclone at its current intensity for a little while longer.

Arthur has been moving somewhat wobbly this morning, but the general direction has been toward the northeast. Water vapor and UW-CIMSS steering data indicate that Arthur is well-embedded in the mid-latitude westerly flow associated with an approaching shortwave trough and attendant frontal system. A comparison of the 12z and 0z upper air data at Bermuda indicate that heights rose a little on the island during that 12 hour period, which likely contributed to Arthur following the western edge of the cone of uncertainty and making an unexpected landfall on the mainland. Because of this, the 6z guidance suite has jumped to the left, and my forecast has followed suit, fairly close to the latest TVCN/TVCE model consensus forecasts. The model guidance is unanimous in showing Arthur making a landfall in Nova Scotia on Saturday morning, likely as a gradually winding down extatropical cyclone. However, Arthur will likely still contain winds in the 45 to 50 kt range as it makes landfall there, and residents there should anticipate the possibility of tree and power line damage. For this reason, a tropical storm watch has been issued for all of the coast of Nova Scotia by the National Hurricane Center. Some deceleration is forecast at the end of the forecast period as the hurricane orbits around a larger extratropical cyclone over the north Atlantic.

So far, the highest reported sustained winds from land stations were 77 mph gusting to 101 mph at Cape Lookout a few hours ago. In addition, Okracoke Island reported a wind gust to 99 mph, also reported several hours ago. Doppler radar indicates that the eyewall and strongest winds are over northern Dare County in far eastern North Carolina. As Arthur pulls away, winds will shift around to the west and gradually diminish.

A tornado watch remains in effect for eastern North Carolina and adjacent coastal waters until 8:00 AM local time as per the Storm Prediction Center. There has so far been one tornado report, occurring at Rose Hill in Duplin County; this is located in central North Carolina at a location that's well inland. The evening hodograph at Morehead City wasn't the most favorable I've seen, although there could be enough curvature to generate a couple more tornadoes along immediate coastal areas experiencing the northern eyewall or the rainbands emanting north from the center, but with Arthur's right-front quadrant just offshore, the overall tornado threat appears to be marginal.

Heavy rainfall has already fallen, with doppler radar estimates of 2 to 5 inches across much of southern and eastern North Carolina. This is not surprising since the northern portion of Arthur is already interacting with an approaching cold front.

Storm surge flooding should slowly subside after Arthur completely moves away from the coast. Much of the coast is already experiencing offshore flow as the eye steadily moves away.

Residents still under the hurricane warning area should not venture outside. Even though Arthur is quickly pulling away from the coast as it gets captured by the trough, strong and damaging winds will linger for several more hours. Interests in Cape Cod should also monitor the hurricane as it accelerates northeast; a tropical storm warning has been issued there as well.

Of note, Arthur is the strongest hurricane to make landfall on the mainland United States since Hurricane Ike of 2008. It is also the earliest hurricane landfall for North Carolina.

Intensity forecast

Initial 07/04 0700Z 35,6°N 75.9°W 85 kt 100 mph: inland
12 hour 07/04 1800Z 37.6°N 73.5°W 90 kt 105 mph
24 hour 07/05 0600Z 41.3°N 69.6°W 75 kt 85 mph
36 hour 07/05 1800Z 44.1°N 65.9°W 60 kt 70 mph: extratropical
48 hour 07/06 0600Z 47.1°N 61.1°W 50 kt 60 mph: extratropical

Track forecast



Figure 2. My forecast track for Arthur.

NHC storm information


000
WTNT31 KNHC 040659
TCPAT1

BULLETIN
HURRICANE ARTHUR INTERMEDIATE ADVISORY NUMBER 13B
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014
300 AM EDT FRI JUL 04 2014

...EYE OF ARTHUR MOVING NEAR MAINLAND DARE COUNTY AND NORTHERN
PAMLICO SOUND...
...HURRICANE CONDITIONS SPREADING NORTHWARD ALONG THE OUTER BANKS...


SUMMARY OF 300 AM EDT...0700 UTC...INFORMATION
----------------------------------------------
LOCATION...35.6N 75.9W
ABOUT 25 MI...40 KM SSW OF MANTEO NORTH CAROLINA
ABOUT 35 MI...55 KM NW OF CAPE HATTERAS NORTH CAROLINA
MAXIMUM SUSTAINED WINDS...100 MPH...155 KM/H
PRESENT MOVEMENT...NE OR 40 DEGREES AT 22 MPH...35 KM/H
MINIMUM CENTRAL PRESSURE...973 MB...28.73 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

THE HURRICANE WARNING FROM SOUTH OF BOGUE INLET NORTH CAROLINA HAS
BEEN DISCONTINUED.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* BOGUE INLET NORTH CAROLINA TO THE NORTH CAROLINA/VIRGINIA BORDER
* PAMLICO SOUND
* EASTERN ALBEMARLE SOUND

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* THE NORTH CAROLINA/VIRGINIA BORDER TO CAPE CHARLES LIGHT
VIRGINIA...INCLUDING THE MOUTH OF THE CHESAPEAKE BAY
* WESTERN ALBEMARLE SOUND
* NANTUCKET
* CAPE COD FROM PROVINCETOWN TO CHATHAM

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* NEW BRUNSWICK FROM THE U. S./CANADA BORDER TO GRAND-ANSE
* ALL OF NOVA SCOTIA INCLUDING CAPE BRETON ISLAND
* ALL OF PRINCE EDWARD ISLAND

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. PREPARATIONS TO PROTECT LIFE
AND PROPERTY SHOULD HAVE ALREADY BEEN COMPLETED.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA.

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA.

INTERESTS ELSEWHERE IN COASTAL PORTIONS OF NEW ENGLAND...NEW
BRUNSWICK...AND NEWFOUNDLAND SHOULD MONITOR THE PROGRESS OF ARTHUR.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE
THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 300 AM EDT...0700 UTC...THE EYE OF HURRICANE ARTHUR WAS LOCATED
BY NOAA DOPPLER RADAR NEAR LATITUDE 35.6 NORTH...LONGITUDE 75.9
WEST. ARTHUR IS MOVING TOWARD THE NORTHEAST NEAR 22 MPH...35
KM/H...AND THIS MOTION IS EXPECTED TO CONTINUE WITH AN INCREASE IN
FORWARD SPEED DURING THE NEXT COUPLE OF DAYS. ON THE FORECAST
TRACK...THE CENTER OF ARTHUR WILL MOVE OVER THE NORTHERN OUTER
BANKS AND THEN MOVE OFFSHORE DURING THE NEXT FEW HOURS. ARTHUR WILL
PASS SOUTHEAST OF NEW ENGLAND LATER TODAY OR TONIGHT...AND BE NEAR
OR OVER WESTERN NOVA SCOTIA EARLY SATURDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 100 MPH...155 KM/H...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS EXPECTED DURING THE NEXT FEW
HOURS. HOWEVER...ARTHUR IS EXPECTED TO BEGIN WEAKENING LATER TODAY
AND BECOME A POST-TROPICAL CYCLONE TONIGHT OR SATURDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 40 MILES...65 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 150
MILES...240 KM. A WEATHERFLOW STATION LOCATED NEAR AVON RECENTLY
REPORTED A SUSTAINED WIND OF 73 MPH...117 KM/H...AND A WIND GUST OF
84 MPH...135 KM/H. A U.S. COAST GUARD STATION JUST WEST OF CAPE
HATTERAS RECENTLY REPORTED A WIND GUST OF 89 MPH...145 KM/H.

THE MINIMUM CENTRAL PRESSURE BASED ON DATA FROM AN AIR FORCE
RESERVE HURRICANE HUNTER AIRCRAFT IS 973 MB...28.73 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS WILL CONTINUE SPREADING INTO
PORTIONS OF THE TROPICAL STORM WARNING AREA IN VIRGINIA THIS
MORNING. HURRICANE CONDITIONS WILL CONTINUE SPREADING NORTHWARD
THROUGH PORTIONS OF THE HURRICANE WARNING AREA DURING THE NEXT FEW
HOURS. TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE NEW
ENGLAND WARNING AREA BY TONIGHT.

STORM SURGE...THE COMBINATION OF A DANGEROUS STORM SURGE AND THE
TIDE WILL CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY
RISING WATERS. THE WATER COULD REACH THE FOLLOWING HEIGHTS ABOVE
GROUND IF THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE...

NORTH CAROLINA WITHIN THE HURRICANE WARNING AREA...3 TO 5 FT
PAMLICO AND ALBEMARLE SOUNDS...2 TO 4 FT
SOUTHERN NORTH CAROLINA WITHIN THE TROPICAL STORM WARNING AREA...1
TO 3 FT
EXTREME SOUTHEASTERN VIRGINIA...1 TO 3 FT

COASTAL FLOODING IS ALSO POSSIBLE ALONG CAPE COD.

THE HIGHEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF
ONSHORE FLOW. THE SURGE WILL BE ACCOMPANIED BY LARGE AND DAMAGING
WAVES. SURGE-RELATED FLOODING DEPENDS ON THE RELATIVE TIMING OF THE
SURGE AND THE TIDAL CYCLE...AND CAN VARY GREATLY OVER SHORT
DISTANCES. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE SEE
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE AND
THE NEW EXPERIMENTAL POTENTIAL STORM SURGE FLOODING MAP FOR MORE
DETAILS.

RAINFALL...RAINFALL ACCUMULATIONS OF 4 TO 6 INCHES...WITH ISOLATED
MAXIMUM AMOUNTS OF 8 INCHES...ARE EXPECTED OVER COASTAL AREAS OF
NORTH CAROLINA THROUGH TODAY. RAINFALL ACCUMULATIONS OF 2 TO 4
INCHES ARE EXPECTED OVER PORTIONS OF EASTERN MASSACHUSETTS AND RHODE
ISLAND.

TORNADOES...ISOLATED TORNADOES ARE POSSIBLE OVER PORTIONS OF
COASTAL NORTH CAROLINA AND SOUTHEASTERN VIRGINIA THROUGH THIS
MORNING.

SURF...SWELLS GENERATED BY ARTHUR ARE AFFECTING AREAS ALONG THE
COAST OF NORTH CAROLINA. THESE SWELLS ARE EXPECTED TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENTS. FOR MORE INFORMATION...
PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER
SERVICE FORECAST OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM EDT.

$$
FORECASTER BRENNAN/LANDSEA

2014 Atlantic hurricane season Hurricane Arthur

Updated: 10:03 AM GMT on July 04, 2014

Permalink

Tropical weather analysis - July 3, 2014

By: KoritheMan, 6:56 AM GMT on July 03, 2014

Notice: All information contained herein is purely a product of my own interpretation of the available data. It is not intended to supersede or replace the directive or forecasts of the National Hurricane Center. Regardless of how well I can identify a trough and a ridge on water vapor imagery, the ultimate go to source should always be the National Weather Service and its affiliates.

Arthur

Arthur remains just under hurricane strength as of the latest NHC advisory package:

Wind: 70 mph, with higher gusts
Location: 30.9°N 79.1°W
Movement: N at 8 mph
Pressure: 988 mb

Satellite images have shown periodic hints of an eye, which recent microwave and radar data confirms is fairly strong aloft. Satellite estimates from TAFB and UW-CIMSS ADT support hurricane strength, but this has been the case since about 0z. Pending investigation from an en route aircraft, they decided to conservatively hold the intensity at 60 kt given some discrepancies in the observed flight-level and SFMR winds. However, with the central pressure already down to 988 mb and likely to continue to slowly fall, it is likely we will have a hurricane sometime this morning. Upper-tropospheric outflow is not particularly well-defined to the west, but that appears to be more a direct symptom of continued dry air than a large-scale increase in shear.



Figure 1. Latest infrared satellite image of Tropical Storm Arthur. Image credit: NOAA's Satellite Services Division (SSD).

Arthur is once again presenting a difficult intensity forecast challenge. On one hand, the cyclone appears to have a solid inner core now, as evidenced by the occasional appearance of an eye in infrared satellite data. On the other hand, evening upper air data from Jacksonville and Charleston still show a fairly pronounced pocket of dry air in the middle troposphere, and there has been some hints on long-range doppler radar that the eye has been unable to close off, remaining largely open on the southwestern side. The center has been easy to follow on both the long-range Jacksonville and Charleston radar. The former is closer to the center of Arthur, suggesting that it has a better sample on the low-levels of the storm. The data from that site indicates that precipitation is attempting to consolidate around the relatively vacuous southwestern side. Should this trend continue, Arthur would be able to intensify. Small circulations generally fare better with warding off dry air entrainment than do comparatively larger ones, and although Arthur is likely to grow as it accelerates northeastward, any possible dry air intrusions should not be enough to eliminate at least gradual intensification. My forecast is largely the same one as the I published yesterday, and shows Arthur becoming a hurricane soon, followed by a peak of 75 kt as the cyclone approaches the Outer Banks. It should be noted that several coastal and offshore buoys indicate that ocean temperatures along the path of Arthur are about .5C warmer than the SHIPS integration thinks they are, even all the way up to the Outer Banks. If the cyclone can thwart the dry air from its core, there is a remote possibility of Arthur attaining Category 2 status. Arthur is forecast to weaken rather quickly after passing the Outer Banks as shear and cold waters induce baroclinicity and cause extratropical transition. Although no forecast point is provided out to 120 hours, it's merely due to a limitation of the map I use to create the track forecasts; Arthur is likely to linger around for at least a day longer than indicated below.

Arthur has stubbornly refused to make the anticipated poleward turn this evening, as several radar and satellite fixes show. Indeed, the National Hurricane Center just released the 6z intermediate advisory, and shows a due north (360°) motion during the past three hours. Having said that, water vapor imagery shows that the mid- to upper-level trough expected to recurve the cyclone is progressively amplifying southward, and as a result the tropical storm is likely to begin turning very soon. My forecast track continues to be along the western edge of the model consensus, if not a shade to the west. It should be noted that if Arthur continues moving northward and delays the onset of recurvature, there could be significant implications for the North Carolina coast. While I cannot rule out a possible landfall on the mainland, the odds of this happening appear low at this time. Interests in the hurricane warning area should closely monitor the progress of Arthur. Sustained hurricane-force winds could still affect the Outer Banks in Arthur's northern eyewall, during which time the cyclone is expected to be an intensifying hurricane. The National Hurricane Center wind speed probability product indicates a 30% chance that Cape Hatteras will experience sustained hurricane-force winds as Arthur makes its closest approach to the Outer Banks between late Thursday night and Friday morning.

Heavy rainfall is possible north of the storm track once Arthur interacts more fully with the approaching frontal system. Most of this rain is likely to fall along immediate coastal areas of North Carolina, but it is not out of the question they could affect portions of the South Carolina coast. The tornado risk appears minimal, as Arthur's right-front quadrant will likely remain offshore.

The latest NHC storm surge inundation map shows that a storm on Arthur's track and intensity could produce a storm surge of up to 3 feet along the Outer Banks and immediate coastal areas of the state.

After passing the Outer Banks, Arthur is forecast to accelerate further until the end of the forecast period, when the guidance suggests it could slow as it orbits around a larger extratropical cyclone over the north Atlantic.

A tropical storm warning remains in effect from South Santee River, South Carolina to south of Surf City. Tropical storm force sustained winds will probably stay offshore if Arthur follows the current track, but interests in the warning area should monitor any significant westward deviations from Arthur.

Intensity forecast

Initial 07/03 0300Z 30.6°N 79.1°W 60 kt 70 mph
12 hour 07/03 1200Z 31.7°N 78.7°W 65 kt 75 mph
24 hour 07/04 0000Z 33.3°N 77.3°W 75 kt 85 mph
36 hour 07/04 1200Z 35.4°N 75.1°W 75 kt 85 mph
48 hour 07/05 0000Z 38.6°N 71.1°W 70 kt 80 mph
72 hour 07/06 0000Z 44.9°N 63.1°W 60 kt 70 mph: extratropical
96 hour 07/07 0000Z 50.6°N 54.7°W 45 kt 50 mph: extratropical

Track forecast



Figure 2. My forecast track for Arthur. The track was made using the 3z coordinates, but for all intents and purposes this will not make a large difference.

NHC storm information

000
WTNT31 KNHC 030549
TCPAT1

BULLETIN
TROPICAL STORM ARTHUR INTERMEDIATE ADVISORY NUMBER 9A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014
200 AM EDT THU JUL 03 2014

...ARTHUR NEAR HURRICANE STRENGTH...
...AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INVESTIGATING...


SUMMARY OF 200 AM EDT...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...30.9N 79.1W
ABOUT 365 MI...585 KM SW OF CAPE HATTERAS NORTH CAROLINA
ABOUT 140 MI...230 KM SSE OF CHARLESTON SOUTH CAROLINA
MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 8 MPH...13 KM/H
MINIMUM CENTRAL PRESSURE...988 MB...29.18 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* SURF CITY NORTHWARD TO DUCK
* PAMLICO SOUND
* EASTERN ALBEMARLE SOUND

A HURRICANE WATCH IS IN EFFECT FOR...
* LITTLE RIVER INLET TO SOUTH OF SURF CITY

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* SOUTH SANTEE RIVER SOUTH CAROLINA TO SOUTH OF SURF CITY
* NORTH OF DUCK TO CAPE CHARLES LIGHT VIRGINIA...NOT INCLUDING
CHEASEPEAKE BAY
* WESTERN ALBEMARLE SOUND

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. PREPARATIONS TO PROTECT LIFE
AND PROPERTY SHOULD BE RUSHED TO COMPLETION.

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA...IN THIS CASE WITHIN THE NEXT 24 HOURS. ANY
DEVIATION OF THE FORECAST TRACK TO THE LEFT...OR AN INCREASE IN THE
FORECAST SIZE OF ARTHUR WOULD LIKELY REQUIRE THE ISSUANCE OF
HURRICANE WARNINGS FOR ALL OR PART OF THE HURRICANE WATCH AREA.

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA.

INTERESTS ALONG THE UNITED STATES EAST COAST NORTH OF THE WARNING
AREA...PRIMARILY IN SOUTHEASTERN NEW ENGLAND...SHOULD MONITOR THE
PROGRESS OF ARTHUR.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY YOUR
LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 200 AM EDT...0600 UTC...THE CENTER OF TROPICAL STORM ARTHUR WAS
LOCATED BY NOAA DOPPLER RADARS NEAR LATITUDE 30.9 NORTH...LONGITUDE
79.1 WEST. ARTHUR IS MOVING TOWARD THE NORTH NEAR 8 MPH...13 KM/H. A
TURN TOWARD THE NORTH-NORTHEAST IS EXPECTED TODAY...FOLLOWED BY A
TURN TOWARD THE NORTHEAST WITH AN INCREASE IN FORWARD SPEED TONIGHT.
ON THE FORECAST TRACK...THE CORE OF ARTHUR IS EXPECTED TO APPROACH
THE COAST IN THE HURRICANE WARNING AREA TONIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 70 MPH...110 KM/H...WITH HIGHER
GUSTS. STRENGTHENING IS FORECAST...AND ARTHUR IS EXPECTED TO BECOME
A HURRICANE SOON. AIR FORCE AND NOAA HURRICANE HUNTER AIRCRAFT
WILL BE INVESTIGATING ARTHUR THIS MORNING.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 90 MILES...150 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB...29.18 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE TROPICAL
STORM WATCH AREA BY THIS AFTERNOON...AND ARE EXPECTED TO SPREAD
NORTHWARD WITHIN THE TROPICAL STORM WARNING AND HURRICANE WARNING
AREAS LATER TODAY AND TONIGHT. HURRICANE CONDITIONS ARE EXPECTED
WITHIN THE HURRICANE WARNING AREA BY TONIGHT.

STORM SURGE...THE COMBINATION OF A DANGEROUS STORM SURGE AND THE
TIDE WILL CAUSE NORMALLY DRY AREAS NEAR THE COAST TO BE FLOODED BY
RISING WATERS. THE WATER COULD REACH THE FOLLOWING HEIGHTS ABOVE
GROUND IF THE PEAK SURGE OCCURS AT THE TIME OF HIGH TIDE...

NORTH CAROLINA OUTER BANKS...2 TO 4 FT
PAMLICO AND ALBEMARLE SOUNDS...2 TO 4 FT
SOUTHERN NORTH CAROLINA AND NORTHEASTERN SOUTH CAROLINA...1 TO 3 FT
EXTREME SOUTHEASTERN VIRGINIA...1 TO 2 FT

THE HIGHEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST IN AREAS OF
ONSHORE FLOW. THE SURGE WILL BE ACCOMPANIED BY LARGE AND DAMAGING
WAVES. SURGE-RELATED FLOODING DEPENDS ON THE RELATIVE TIMING OF THE
SURGE AND THE TIDAL CYCLE...AND CAN VARY GREATLY OVER SHORT
DISTANCES. FOR INFORMATION SPECIFIC TO YOUR AREA...PLEASE SEE
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE AND
THE NEW EXPERIMENTAL POTENTIAL STORM SURGE FLOODING MAP FOR MORE
DETAILS.

RAINFALL...RAINFALL ACCUMULATIONS OF 2 TO 4 INCHES...WITH ISOLATED
MAXIMUM AMOUNTS OF 6 INCHES...ARE EXPECTED OVER COASTAL AREAS OF
NORTH CAROLINA THROUGH FRIDAY. RAINFALL AMOUNTS NEAR AN INCH ARE
POSSIBLE ON THE EAST COAST OF FLORIDA.

SURF...SWELLS GENERATED BY ARTHUR ARE AFFECTING AREAS FROM THE
EAST-CENTRAL COAST OF FLORIDA NORTHWARD TO SOUTH CAROLINA. THESE
SWELLS ARE EXPECTED TO CAUSE LIFE-THREATENING SURF AND RIP CURRENTS.
FOR MORE INFORMATION...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL
NATIONAL WEATHER SERVICE FORECAST OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM EDT.

$$
FORECASTER BRENNAN/STEWART


Douglas

Tenacious Douglas holds on as a tropical storm. As of the 3Z NHC advisory, the following information was available on Douglas:

Wind: 40 mph, with higher gusts
Location: 20.2°N 116.3°W
Movement: NNW at 2 mph
Pressure: 1004 mb

Douglas is still producing some fairly deep convection for a mid-latitude system over sub-26C waters, but as soon as the tropical storm begins to accelerate, it will not be long for this world. Earlier scatterometer data suggest that Douglas continues to possess an unusually large wind field.



Figure 3. Latest infrared satellite image of Tropical Storm Douglas. Image credit: NOAA's Satellite Services Division (SSD).

The cyclone remains embedded in an environment of weak vertical shear, and this is likely to continue for several more days, so even though Douglas will be moving across progressively cooler water after it accelerates, only a gradual spin down is expected of this rather large circulation. There isn't much new to say on Douglas except that the GFS now shows the system losing its identity in the trade wind belt in less than 120 hours. Given that this seems reasonable, I have chosen to terminate a 120 hour forecast position from this forecast package. The ECMWF remains a little stronger, so it's not completely out of the question that Douglas or its remnants could persist a little longer.

Douglas continues to meander very slowly north-northwestward, and doesn't appear to have gained much... if any... forward momentum over the last few hours. Water vapor and UW-CIMSS analyses indicate that Douglas is embedded in a region of very weak steering as broad downstream troughing continues to push against the subtropical ridge. The model guidance indicates a restrengthening of the ridge to the north of Douglas over the next couple of days, which is expected to result in a gradual acceleration to the west-northwest and then west if it persists beyond day four. My forecast track is similar to the current National Hurricane Center prediction except noticeably east at longer ranges because I terminate the track after day four.

Intensity forecast

Initial 07/03 0300Z 20.2°N 116.3°W 35 kt 40 mph
12 hour 07/03 1200Z 20.4°N 116.5°W 35 kt 40 mph
24 hour 07/04 0000Z 20.6°N 116.9°W 30 kt 35 mph
36 hour 07/04 1200Z 20.9°N 117.7°W 30 kt 35 mph: post-tropical/remnant low
48 hour 07/05 0000Z 21.5°N 119.2°W 25 kt 30 mph: post-tropical/remnant low
72 hour 07/06 0000Z 22.7°N 121.6°W 20 kt 25 mph: post-tropical/remnant low
96 hour 07/07 0000Z 24.1°N 125.1°W 20 kt 25 mph: post-tropical/remnant low
120 hour 07/08: dissipated

Track forecast



Figure 4. My forecast track for Douglas.

2014 Atlantic hurricane season 2014 Pacific hurricane season Tropical Storm Arthur Tropical Storm Douglas

Updated: 7:00 AM GMT on July 03, 2014

Permalink

Tropical weather analysis - July 2, 2014

By: KoritheMan, 7:38 AM GMT on July 02, 2014

Arthur

Tropical Storm Arthur is intensifying just off the Florida coast. As of the just released 0600Z NHC intermediate advisory bulletin, the following information was posted on the storm:

Wind: 60 mph, with higher gusts
Location: 28.0°N 79.1°W
Movement: N at 4 mph
Pressure: 1001 mb

Arthur is presenting an interesting structure this morning. Satellite and radar data suggest a formative eye feature with convection attempting to consolidate around this feature, with long-range doppler radar from Melbourne showing this evolution nicely. Recent aircraft fixes indicate that the low-level center has now become aligned with the eye feature observed in the satellite and radar data.



Figure 1. Latest infrared satellite image of Tropical Storm Arthur. Image credit: NOAA's Satellite Services Division (SSD).

The intensity forecast this morning is certainly a complex one for me. While the radar and satellite presentation show a low- to mid-level eye, water vapor imagery and UW-CIMSS Total Precipitable Water (TPW) analyses show substantial mid-level dry air has become entrained into the southern half of Arthur's circulation, and the eye is open to the south and west on infrared satellite data. Indeed, the 0z upper air soundings at Miami and Jacksonville showed a substantial inversion between 700 and 500 mb, with isolated segments of relative humidity values of less than 40% within specific locations of the delineated levels. Since Arthur's convection is extremely meager to the south and west, it could have a difficult time warding off the dry air, at least in the near term. On the positive side, the upper tropospheric shear over the cyclone appears to have decreased some, as denoted by an expansion of the cirrus outflow in the northern semicircle, but the GFS and ECMWF do not show the most favorable upper flow occurring until the system accelerates toward North Carolina, with the ECMWF showing somewhat less anticyclonicity in the near-term. While the development of a formative eye is respectable for intensification purposes, Arthur cannot intensify in the midst of dry air coming off the Gulf of Mexico and the Florida peninsula. My guess is that it will take another 24 hours or so -- Arthur gaining some speed, actually -- before any significant intensification can occur and we have to worry about the system becoming a hurricane. My forecast doesn't show Arthur becoming a hurricane until Thursday afternoon, but this is of course uncertain and subject to how favorably or unfavorably the upper pattern evolves over the next 24 hours. It remains possible, although unlikely, that dry air will afflict the system continually enough over the next few days to prevent intensification to hurricane status, and instead we end up with a messy and wet tropical storm. I will forecast a peak of 75 kt as the system makes its closest approach to the Outer Banks, which is essentially a careful blend of the 0z LGEM and decay SHIPS model (DSHIPS). After passing the Outer Banks, water temperatures drop off sharply, and the guidance suggests that the shear will increase as a fast-moving upper-level trough envelops Arthur. The global model guidance continues to show Arthur remaining a potent extratropical cyclone as it races toward Atlantic Canada in the latter portion of the forecast period. It remains possible that Arthur could end up 5 or 10 kt stronger than forecast as it makes it closest approach to the Outer Banks. Alternatively, it could end up weaker if dry air works its way into the cyclone as it moves north of 30N, a common scenario in this portion of the Atlantic.

Satellite and radar data suggest that Arthur has made the anticipated northward turn as a broad downstream mid- to upper-level trough over the Ohio Valley digs southward. The model guidance continues to be in excellent agreement on this scenario, and shows Arthur accelerating from this point forward as it becomes captured by the flow around the trough. Although the guidance shifted eastward a bit today compared to when I made my last forecast some 24 hours ago, I have elected to stay a little bit to the west of the 0z TVCN and TCVE model consensus, taking Arthur very close to the Outer Banks on Friday morning. This forecast is also in good agreement with the ECMWF, which has performed well with Arthur so far. The guidance is in good agreement on the evolution of the pattern and Arthur's anticipated response to it, but there are still some differences in forward speed, especially after the system passes the Outer Banks. The GFS is quite a bit faster than the ECMWF, presumably in response to a somewhat stronger trough digging southward. Since the trough doesn't look as deep as some of the troughs of recent years in this area, I have based the forward speed more on the ECMWF. Arthur is likely to affect Atlantic Canada as a powerful extratropical cyclone over the weekend.

If Arthur tracks close enough to the coast, hurricane-force sustained winds cannot be ruled out in the northern eyewall along the Outer Banks. Right now it appears that the odds of Arthur making a landfall on the mainland are low, but the mainland is still in the cone of uncertainty, and residents there should carefully follow the progress of Arthur over the next couple of days. Heavy rainfall may also train north of the storm track along coastal and possibly inland sections of the mid-Atlantic as Arthur interacts more strongly with the aforementioned frontal boundary.

The National Hurricane Center has discussed the possibility of issuing tropical storm or hurricane watches today (Wednesday) for portions of the North Carolina coast in the 0300Z forecast discussion. If you are put under a tropical storm or hurricane watch/warning, take the appropriate precautions. Non-perishable foods, flashlights/batteries, bottled water will assist if there are any prolonged power outages. Also, freezing water bottles will aid in keeping your freezer cold for longer in the event of a power outage.

A tropical storm watch remains in effect for portions of the eastern Florida peninsula, and gusty winds and locally heavy rainfall in squalls remain possible through tonight into tomorrow morning.

Intensity forecast

Initial 07/02 0600Z 28.0°N 79.1°W 50 kt 60 mph
12 hour 07/02 1800Z 28.5°N 79.2°W 50 kt 60 mph
24 hour 07/03 0600Z 30.0°N 79.2°W 60 kt 70 mph
36 hour 07/03 1800Z 31.9°N 78.3°W 65 kt 75 mph
48 hour 07/04 0600Z 34.8°N 76.5°W 75 kt 85 mph
72 hour 07/05 0600Z 37.8°N 71.8°W 70 kt 80 mph
96 hour 07/06 0600Z 41.7°N 66.6°W 60 kt 70 mph: extratropical
120 hour 07/07 0600Z 47.9°N 58.7°W 50 kt 60 mph: extratropical

Track forecast



Figure 2. My forecast track for Arthur.

NHC storm information

000
WTNT31 KNHC 020543
TCPAT1

BULLETIN
TROPICAL STORM ARTHUR INTERMEDIATE ADVISORY NUMBER 5A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014
200 AM EDT WED JUL 02 2014

...ARTHUR A LITTLE STRONGER AS IT MOVES SLOWLY NORTHWARD...


SUMMARY OF 200 AM EDT...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...28.0N 79.1W
ABOUT 95 MI...155 KM ESE OF CAPE CANAVERAL FLORIDA
ABOUT 105 MI...170 KM N OF FREEPORT GRAND BAHAMA ISLAND
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 4 MPH...6 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* EAST COAST OF FLORIDA FROM FORT PIERCE TO FLAGLER BEACH

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...IN THIS CASE WITHIN THE NEXT 24
HOURS.

INTERESTS ALONG THE UNITED STATES EAST COAST NORTH OF THE WATCH
AREA THROUGH SOUTHEASTERN VIRGINIA SHOULD MONITOR THE PROGRESS OF
TROPICAL STORM ARTHUR. TROPICAL STORM AND HURRICANE WATCHES WILL
LIKELY BE REQUIRED LATER THIS MORNING FOR PORTIONS OF THIS AREA.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED STATES...
INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE FORECAST
OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA OUTSIDE THE
UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED BY YOUR NATIONAL
METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 200 AM EDT...0600 UTC...THE CENTER OF TROPICAL STORM ARTHUR WAS
LOCATED NEAR LATITUDE 28.0 NORTH...LONGITUDE 79.1 WEST. ARTHUR IS
MOVING TOWARD THE NORTH NEAR 4 MPH...6 KM/H. A GRADUAL INCREASE IN
FORWARD SPEED IS EXPECTED TODAY...FOLLOWED BY A TURN TOWARD THE
NORTHEAST BY THURSDAY. ON THE FORECAST TRACK...THE CENTER OF ARTHUR
IS EXPECTED TO REMAIN JUST OFFSHORE AND MOVE EAST OF THE EAST-
CENTRAL COAST OF FLORIDA TODAY...PASS EAST OF NORTHEASTERN FLORIDA
TONIGHT...AND MOVE PARALLEL TO THE SOUTHEASTERN COAST OF THE UNITED
STATES ON THURSDAY.

SATELLITE DATA INDICATE THAT MAXIMUM SUSTAINED WINDS ARE NEAR 60
MPH...95 KM/H...WITH HIGHER GUSTS. STRENGTHENING IS FORECAST DURING
THE NEXT 48 HOURS....AND ARTHUR IS EXPECTED TO BECOME A HURRICANE BY
THURSDAY. AIR FORCE RESERVE AND NOAA HURRICANE HUNTER AIRCRAFT WILL
BE INVESTIGATING ARTHUR IN THE NEXT FEW HOURS.

TROPICAL-STORM-FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1001 MB...29.56 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH AREA
TODAY. IN ADDITION...WINDS TO TROPICAL STORM FORCE ARE OCCURRING
INTERMITTENTLY ON ON GRAND BAHAMA ISLAND...AND ARE LIKELY TO
CONTINUE THERE FOR A FEW MORE HOURS.

RAINFALL...ARTHUR IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 1 TO 2 INCHES...MAINLY ACROSS THE EASTERN FLORIDA
PENINSULA. ISOLATED MAXIMUM AMOUNTS OF 4 INCHES ARE POSSIBLE THROUGH
TODAY. RAINFALL AMOUNTS OF 2 TO 4 INCHES WITH ISOLATED MAXIMUM
AMOUNTS OF 6 INCHES ARE POSSIBLE OVER THE NORTHWESTERN BAHAMAS
THROUGH TODAY.

SURF...SWELLS GENERATED BY ARTHUR ARE AFFECTING PORTIONS OF THE
EAST-CENTRAL COAST OF FLORIDA. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENTS...ESPECIALLY ALONG PIERS AND
JETTIES. THESE HAZARDOUS CONDITIONS WILL GRADUALLY SPREAD NORTHWARD
ALONG THE COASTS OF NORTHEAST FLORIDA AND GEORGIA TODAY. FOR MORE
INFORMATION...PLEASE MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL
WEATHER SERVICE FORECAST OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM EDT.

$$
FORECASTER BRENNAN



Douglas

Tropical Storm Douglas continues to move across the open Pacific Ocean well away from land. As of the 0300Z NHC (which will be replaced in an hour), the following information was posted on the storm:

Wind: 45 mph, with higher gusts
Location: 19.4°N 115.7°W
Movement: NNW at 2 mph
Pressure: 1001 mb

Satellite images show an increase in deep convection near the center; in fact, this is the first time I recall seeing such intense convection within 50 miles of the center. However, the SHIPS SST analysis suggests that Douglas has crossed the 26C isotherm and will be moving into progressively cooler water from this point forward. There may be some cool upper-level temperatures assisting in the development of convection, or the waters may be warmer than the SHIPS is suggesting, but in any event this is likely to be Douglas' last hurrah, and the satellite signature will undoubtedly look much worse 24 hours from now. A recent ASCAT pass suggests that the cyclone's radius of maximum winds have decreased considerably, and Douglas now resembles a more classical tropical cyclone. Unfortunately for Douglas, it will simply be too little too late.



Figure 3. Latest infrared satellite image of Tropical Storm Douglas. Image credit: NOAA's Satellite Services Division (SSD).

Douglas remains embedded in an environment of rather weak upper tropospheric vertical shear, with the large-scale outflow pattern continuing to remain very impressive for a weak tropical storm. The shear is not forecast to increase appreciably along the forecast track, so Douglas is likely to spin down very slowly. Satellite data already indicates that the cyclone is ingesting a bit of dry air in the eastern semicircle which may wrap around the center overnight and put an end to the ongoing burst of cold-topped convection. Remnant low status is shown by day three, and while a forecast track is given out to 120 hours, it is certainly possible that Douglas could kick the bucket before then, especially since its overall circulation envelope appears to have decreased a little. The overall cyclone decay process should be much slower than is typical for eastern Pacific cyclones that weaken over cold water due to the expected light environmental wind shear, and Douglas or its remnants will be liable to carry strong winds for a good while longer.

Satellite data suggest that a broad mid- to upper-level trough is amplifying off the western coast of the United States to the north of Douglas. This trough appears stronger than I expected over the last couple of days, and even the ECMWF, which has a had a pronounced southern bias with Douglas so far, now shows the cyclone getting comfortably above 20N. My forecast track is a close emulation of the current National Hurricane Center forecast track, but is weighed a little to the north of the ECMWF and closer to the latest GFS solution.

Intensity forecast

Initial 07/02 0600Z 19.5°N 115.9°W 40 kt 45 mph
12 hour 07/03 1800Z 19.8°N 116.1°W 40 kt 45 mph
24 hour 07/04 0600Z 20.2°N 116.3°W 35 kt 40 mph
36 hour 07/04 1800Z 20.5°N 116.5°W 30 kt 35 mph
48 hour 07/05 0600Z 21.1°N 117.4°W 30 kt 35 mph
72 hour 07/06 0600Z 22.3°N 119.6°W 25 kt 30 mph: post-tropical/remnant low
96 hour 07/07 0600Z 23.1°N 121.9°W 25 kt 30 mph: post-tropical/remnant low
120 hour 07/08 0600Z 23.3°N 125.7°W 20 kt 25 mph: post-tropical/remnant low

Track forecast



Figure 4. My forecast track for Douglas.

2014 Atlantic hurricane season Tropical Storm Arthur Tropical Storm Douglas Tropical Depression Elida 2014 Pacific hurricane season

Updated: 8:48 AM GMT on July 02, 2014

Permalink

Tropical weather analysis - July 1, 2014

By: KoritheMan, 6:51 AM GMT on July 01, 2014

Tropical Depression One

The persistent small area of low pressure that has been meandering in the western Atlantic over the last several days has finally acquired enough organization to be considered a tropical depression, the first of the Atlantic season. As of the 0600Z NHC advisory, the following information was posted on the system:

Wind: 35 mph, with higher gusts
Location: 27.5°N 79.2°W
Movement: SW at 2 mph
Pressure: 1009 mb

Satellite images show a considerable increase in deep convection this evening, with the satellite data, radar echoes, and microwave imagery showing an increase in convective banding to the south and southeast of the center. Having said that, the center still appears to be located on the far northwestern edge of the convective canopy due to residual northwesterly shear. Satellite estimates do not quite support tropical storm strength yet. Upper tropospheric outflow remains quite limited in the northern semicircle due to shear, but is fair to good elsewhere.



Figure 1. Latest infrared satellite image of Tropical Depression One. Image credit: NOAA's Satellite Services Division (SSD).

The intensity forecast is rather tricky this evening. While there is still shear and dry air over the depression, about 10 to 15 kt due to a combination of the subsident portions of a ridge located along the Louisiana coast and along the backside of an eastward-moving upper level trough over the central plains, underlying water temperatures are around 28C and extend to appreciable depth. Also, small cyclones tend to fare better against dry air entrainment than do comparatively larger cyclones. Given these factors, along with the fact that the global models appear to have a decent handle on the current shear pattern -- forecasting a further decrease in shear -- intensification appears probable, and the depression is likely to become a tropical storm over the next 12 hours. The perhaps the more enigmatic portion of the intensity forecast comes in a few days, when the tropical cyclone is forecast to approach the coast of North Carolina. The ECMWF and GFS differ significantly in their respective presentations of the synoptic upper flow at that time, with the former showing a more uniformly southerly upper jet just to the west of the system attendant with the eastward-moving shortwave trough. The latter model forecasts the jet to be more southwesterly, which would likely provide some extra upper divergence to the system and boost its prospects for intensification. This is important, since again, the cyclone is forecast to reach its peak intensity very near the North Carolina coastline. The differences in upper-tropospheric shear values in these models appears to be due to differing representations of the shortwave trough. The GFS solution shows a more positively-tilted trough, while the ECMWF shows a more negative tilt. It is impossible to tell which scenario will verify at this stage, but I am biased toward the ECMWF in deference to how well it has seemed to handle the upper tropospheric shear over the depression in recent days. If the GFS solution verifies, the chances of the cyclone becoming a hurricane in the vicinity of the North Carolina coast increase. My forecast will stay on the conservative side for now, but is still higher than the majority of the guidance. It should be noted that the ECMWF is forecasting a pressure of about 992 mb as the system accelerates across North Carolina. Since global models do not tend to recognize the sharp accompanying pressure drop in a tropical cyclone's center -- much less on a small one like this one -- that would likely correlate more to a Category 1 hurricane than a strong tropical storm.

After moving past the North Carolina coast, most of the global models show some baroclinic reintensification, with the ECMWF showing a stronger cold-core cyclone than the GFS at longer ranges. My forecast will not yet reflect this, and will instead keep the cyclone more or less steady state after its brush with the mid-Atlantic coast.

The depression was moving southwestward a few hours ago, but recent satellite and radar data indicate that it could be moving a little more toward the west, although this is still quite uncertain. The cyclone is forecast to move westward for the next 12-18 hours, followed by a turn to the northwest, north, and then northeast at later periods as it becomes captured by the trough. The guidance agrees with this scenario, but there are some differences in forward speed and precisely how close the cyclone gets to the coast before committing to full recurvature. The GFS was farther west than the ECMWF on the 18z run, and took the cyclone just inland along the North Carolina coast, with the latter suggesting the system will pass near or over the Outer Banks on Thursday. The GFS has since joined the ECMWF at 0z, likely because it represents a more realistically deep system that is more responsive to the mid-level flow. Whether the center tracks over the mainland or not will be determined by the expected amplification and orientation of the central plains trough. A much weaker system would be liable to move closer to the Florida coast, a solution that appears unlikely given current convective trends. My forecast track will lean closer to the NHC solution for now, and is a little to the left of the 0z model consensus TVCE/TVCN. I should note that if the shear does not abate as quickly as anticipated, there could be significant short-term prospects for the impact to the Florida coast, and possibly even influential to the eventual trajectory up to the mid-Atlantic; this would occur if the center were to follow the convection to the south in an area of somewhat lesser shear.

Interests along the southeastern United States coast from Florida to the mid-Atlantic should monitor the progress of this system. Interests in the Cape Cod area should also anticipate a possible close brush, even though my own and the official NHC track keeps the center well east of there for now.

Tropical storm force winds are likely to remain just offshore the Florida east coast, but a tropical storm watch has been issued for a portion of that area (see below), and any significant deviation to the left could bring them onshore to immediate coastal areas. Rainfall should be relatively light, since the state will be on the subsident portion of the system.

Intensity forecast

Initial 07/01 0300Z 27.6°N 79.1°W 30 kt 35 mph
12 hour 07/01 1200Z 27.6°N 79.3°W 35 kt 40 mph
24 hour 07/02 0000Z 28.0°N 79.9°W 40 kt 45 mph
36 hour 07/02 1200Z 29.0°N 80.0°W 45 kt 50 mph
48 hour 07/03 0000Z 30.0°N 80.0°W 50 kt 60 mph
72 hour 07/04 0000Z 33.3°N 77.6°W 60 kt 70 mph
96 hour 07/05 0000Z 36.6°N 73.7°W 55 kt 65 mph
120 hour 07/06 0000Z 41.9°N 65.3°W 55 kt 65 mph: extratropical

Track forecast



Figure 2. My forecast track for Tropical Depression One.



NHC storm information

000
WTNT31 KNHC 010540
TCPAT1

BULLETIN
TROPICAL DEPRESSION ONE INTERMEDIATE ADVISORY NUMBER 1A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL012014
200 AM EDT TUE JUL 01 2014

...DEPRESSION DRIFTING SOUTHWESTWARD...


SUMMARY OF 200 AM EDT...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...27.5N 79.2W
ABOUT 105 MI...170 KM SE OF CAPE CANAVERAL FLORIDA
ABOUT 205 MI...330 KM NNW OF THE NORTHWESTERN BAHAMAS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...SW OR 225 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* EAST COAST OF FLORIDA FROM FORT PIERCE TO FLAGLER BEACH

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...IN THIS CASE WITHIN 24 TO 36 HOURS.

INTERESTS ELSEWHERE ALONG THE SOUTHEAST COAST OF THE UNITED STATES
SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...INCLUDING POSSIBLE
INLAND WATCHES AND WARNINGS...PLEASE MONITOR PRODUCTS ISSUED BY YOUR
LOCAL NATIONAL WEATHER SERVICE FORECAST OFFICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 200 AM EDT...0600 UTC...THE CENTER OF TROPICAL DEPRESSION ONE
WAS LOCATED NEAR LATITUDE 27.5 NORTH...LONGITUDE 79.2 WEST. THE
DEPRESSION IS MOVING TOWARD THE SOUTHWEST NEAR 2 MPH...4 KM/H. A
SLOW WEST TO WEST-NORTHWEST MOTION IS FORECAST TO BEGIN TODAY. A
TURN TOWARD THE NORTHWEST AND THEN TOWARD THE NORTH IS FORECAST
BY WEDNESDAY. ON THE FORECAST TRACK...THE CENTER OF THE DEPRESSION
IS EXPECTED TO REMAIN OFFSHORE AND MOVE EAST OF THE EAST-CENTRAL
COAST OF FLORIDA DURING THE NEXT DAY OR SO. THE SYSTEM IS FORECAST
TO PASS EAST OF NORTHEASTERN FLORIDA ON WEDNESDAY AND WEDNESDAY
NIGHT.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/H...WITH HIGHER
GUSTS. GRADUAL STRENGTHENING IS EXPECTED DURING THE NEXT 48
HOURS...AND THE DEPRESSION IS FORECAST TO BECOME A TROPICAL STORM
LATER TODAY.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1009 MB...29.80 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE POSSIBLE WITHIN THE WATCH
AREA BY LATE TODAY.

RAINFALL...THE DEPRESSION IS EXPECTED TO PRODUCE TOTAL RAINFALL
ACCUMULATIONS OF 1 TO 3 INCHES...MAINLY ACROSS EAST-CENTRAL FLORIDA
AND NORTHEASTERN PORTIONS OF THE FLORIDA PENINSULA WITH POSSIBLE
ISOLATED MAXIMUM AMOUNTS OF 5 INCHES THROUGH WEDNESDAY. RAINFALL
AMOUNTS OF 2 TO 4 INCHES WITH ISOLATED MAXIMUM AMOUNTS OF 6 INCHES
ARE POSSIBLE OVER PORTIONS OF THE NORTHERN BAHAMAS THROUGH
WEDNESDAY.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...500 AM EDT.

$$
FORECASTER PASCH



Douglas

Tropical Storm Douglas poses no threat to land. As of the 0300Z NHC advisory, the following information was posted on Douglas:

Wind: 45 mph, with higher gusts
Location: 18.4°N 114.9°W
Movement: NW at 9 mph
Pressure: 1000 mb

The tropical cyclone appears to finally be strengthening. Although earlier scatterometer data still showed a fairly large radius of maximum winds, the general motif on satellite imagery this evening has been for the outer core to slowly contract, with the inner circulation becoming more dominant. Satellite estimates actually support an intensity somewhat higher than 40 kt right now. Upper-tropospheric outflow remains very well-defined and pronounced, implying a substantial lack of storm-centered vertical shear.



Figure 3. Latest infrared satellite image of Tropical Storm Douglas. Image credit: NOAA's Satellite Services Division (SSD).

Douglas still has about 24 more hours to strengthen before crossing the 26C isotherm, and I am not seeing much evidence of dry air entrainment or the fabled stratocumulus cloud deck that's commonly found over the 26C isotherm on the storm-centered satellite images. This suggests Douglas could get a little stronger, and my peak is for 50 kt, although it's possible Douglas could peak at 45 kt if it crosses the 26C isotherm quicker than anticipated. Subsequent to that time, the tropical storm is forecast to track across progressively cooler waters and an accompanying stable airmass. However, the GFS and ECMWF show vertical shear remaining quite weak over the cyclone during the next five days, and this should preclude the typical rapid spin down we often experience with tropical cyclones in the eastern north Pacific crossing cooler waters. Remnant low status is shown by day four, although it is possible it could occur a little sooner, particularly if we get any abrupt increases in shear that the models don't yet identify.

Douglas appears to be moving toward the northwest, pretty much on track. Water vapor imagery shows a broad upper-level trough off the coast of California, along with a westward-moving mid- to upper-level cold low several hundred miles to the west-southwest of Douglas. This synoptic evolution should cause the storm to continue moving northwest with a gradual decrease in forward speed. The model guidance continues to be in excellent agreement with this scenario. During the latter part of the forecast period, Douglas is expected to accelerate westward as it becomes a shallow system and feels the influence of a deepening low- to mid-level ridge. The guidance has come a little north since yesterday, with most members now taking Douglas comfortably north of 20N. I will do the same, but my forecast track is a little to the south of the current NHC prediction, which takes Douglas up to around 21.5N. My forecast remains fairly close to the latest ECMWF prediction, albeit a little farther north than that model.

Intensity forecast

Initial 07/01 0300Z 18.4°N 114.9°W 40 kt 45 mph
12 hour 07/01 1200Z 18.8°N 115.6°W 50 kt 60 mph
24 hour 07/02 0000Z 19.4°N 116.4°W 45 kt 50 mph
36 hour 07/02 1200Z 19.7°N 117.0°W 45 kt 45 mph
48 hour 07/03 0000Z 20.0°N 117.8°W 35 kt 40 mph
72 hour 07/04 0000Z 20.2°N 118.9°W 30 kt 35 mph
96 hour 07/05 0000Z 20.4°N 120.6°W 30 kt 35 mph: post-tropical/remnant low
120 hour 07/06 0000Z 20.7°N 122.9°W 25 kt 30 mph: post-tropical/remnant low

Track forecast



Figure 4. My forecast track for Douglas.



Elida

Tropical Storm Elida formed on Monday from the persistent area of low pressure that was trailing Douglas. As of the latest NHC advisory, the following information was available on the storm:

Wind: 50 mph, with higher gusts
Location: 17.5°N 104.4°W
Movement: WNW at 2 mph
Pressure: 1003 mb

There has been little change to the cloud pattern associated with tenacious Elida. Rather cold-topped convection continues to ignite, with satellite and microwave data suggesting that the strongest thunderstorms are just to the south of the low-level center due to about 25 kt of persistent northwesterly shear associated with outflow from large Douglas.



Figure 5. Latest infrared satellite image of Tropical Storm Elida. Image credit: NOAA's Satellite Services Division (SSD).

Elida is currently over 29-30C SSTs and is embedded in a very moist environment despite being lambasted by the subsident side of Douglas' outflow. The GFS and ECMWF do not show much of a decrease in the shear until around 72 hours, when Douglas moves westward and weakens. Looking at current trends on water vapor imagery, Douglas is in no hurry to relieve Elida of its outflow affliction, and I am inclined to believe the global model forecasts of continued short-term shear. Beyond that time, Elida is forecast to enter a tightly anticyclonic environment characterized by low shear. Since the cyclone will still be over reasonably warm water by that time, some modest intensification is expected. It should be noted that the global models do not intensify Elida during this period, with the GFS actually failing to follow the vortex out to that point. Even the statistical models do not show much intensification during this period, which is a little puzzling. My forecast is higher than all of the guidance and the current National Hurricane Center prediction, and we shall see if I get burned. It is possible that short-term intensity fluctuations could occur at any time during the next few days pending any unexpected increases or decreases in vertical shear occur. Unfortunately, neither the models nor myself are skilled enough to predict these possible changes, which are common in sheared tropical cyclones.

Elida has been moving erratically west-northwestward throughout the evening. The cyclone is currently located in a col region between a broad upper-level trough to the north and an elongated upper ridge to the east. This combination is expected to cause some highly erratic motion near the coast of southwestern Mexico over the next couple days, in agreement with the latest model guidance. Even though Elida is expected to stay well offshore, tropical storm warnings are in effect for a portion of the coast (see below), and interests there should monitor the progress of this tropical cyclone through Wednesday. Beyond that time, Elida is forecast to pick up some forward speed and move westward under a building mid-tropospheric ridge. My forecast track is in good agreement with the current NHC prediction.

Current satellite images suggest that Elida is a rather small tropical cyclone, and tropical storm force winds are likely to remain offshore from the coast of Mexico.

Intensity forecast

Initial 07/01 0600Z 17.5°N 104.4°W 45 kt 50 mph
12 hour 07/01 1800Z 17.5°N 104.5°W 45 kt 50 mph
24 hour 07/02 0600Z 17.5°N 104.6°W 45 kt 50 mph
36 hour 07/02 1800Z 17.4°N 104.6°W 45 kt 50 mph
48 hour 07/03 0600Z 17.4°N 104.6°W 45 kt 50 mph
72 hour 07/04 0600Z 17.3°N 105.1°W 45 kt 50 mph
96 hour 07/05 0600Z 17.4°N 107.0°W 50 kt 60 mph
120 hour 07/06 0600Z 17.5°N 109.9°W 55 kt 65 mph

Track forecast



Figure 6. My forecast track for Elida.



NHC storm information

000
WTPZ35 KNHC 010540
TCPEP5

BULLETIN
TROPICAL STORM ELIDA INTERMEDIATE ADVISORY NUMBER 3A
NWS NATIONAL HURRICANE CENTER MIAMI FL EP052014
1100 PM PDT MON JUN 30 2014

...ELIDA MOVING SLOWLY NEAR THE SOUTHWESTERN COAST OF MEXICO...


SUMMARY OF 1100 PM PDT...0600 UTC...INFORMATION
-----------------------------------------------
LOCATION...17.5N 104.4W
ABOUT 105 MI...165 KM S OF MANZANILLO MEXICO
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...WNW OR 290 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...1003 MB...29.62 INCHES


WATCHES AND WARNINGS
--------------------
CHANGES IN WATCHES AND WARNINGS WITH THIS ADVISORY...

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* LAZARO CARDENAS TO CABO CORRIENTES

FOR STORM INFORMATION SPECIFIC TO YOUR AREA...PLEASE MONITOR
PRODUCTS ISSUED BY YOUR NATIONAL METEOROLOGICAL SERVICE.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM PDT...0600 UTC...THE CENTER OF TROPICAL STORM ELIDA WAS
LOCATED NEAR LATITUDE 17.5 NORTH...LONGITUDE 104.4 WEST. ELIDA IS
MOVING TOWARD THE WEST-NORTHWEST NEAR 2 MPH...4 KM/H...AND A SLOW
WEST-NORTHWESTWARD MOTION IS EXPECTED TO CONTINUE TONIGHT. ELIDA IS
EXPECTED TO BECOME NEARLY STATIONARY ON TUESDAY...AND MEANDER OFF
THE COAST OF SOUTHWESTERN MEXICO THROUGH WEDNESDAY. ON THE FORECAST
TRACK...THE CENTER OF ELIDA AND THE STRONGEST WINDS ARE EXPECTED TO
REMAIN OFFSHORE OF THE COAST OF SOUTHWESTERN MEXICO.

MAXIMUM SUSTAINED WINDS ARE NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST DURING THE NEXT 48
HOURS.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 70 MILES...110 KM
FROM THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1003 MB...29.62 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO AFFECT PORTIONS
OF THE SOUTHWESTERN COAST OF MEXICO WITHIN THE WARNING AREA. THESE
CONDITIONS ARE EXPECTED TO EXPAND NORTHWESTWARD IN THE WARNING AREA
DURING THE NEXT DAY OR TWO.

RAINFALL...ELIDA IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF
3 TO 6 INCHES OVER THE WESTERN PORTIONS OF THE MEXICAN STATES OF
COLIMA AND MICHOACAN...AND OVER THE SOUTHWESTERN PORTION OF JALISCO.
ISOLATED MAXIMUM AMOUNTS OF 8 INCHES ARE POSSIBLE IN THESE AREAS.

SURF...SWELLS GENERATED BY ELIDA ARE AFFECTING PORTIONS OF THE
SOUTHWESTERN COAST OF MEXICO. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENTS. FOR MORE INFORMATION...
PLEASE CONSULT PRODUCTS FROM YOUR NATIONAL METEOROLOGICAL OFFICE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...200 AM PDT.

$$
FORECASTER BRENNAN

2014 Atlantic hurricane season 2014 Pacific hurricane season Tropical Storm Douglas Tropical Storm Elida Invest 91L Tropical Depression One

Updated: 7:13 AM GMT on July 01, 2014

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About KoritheMan

I'm just a 23 year old with an ardent passion for weather. I first became aware of this interest after Tropical Storm Isidore struck my area in 2002.