KoritheMan's WunderBlog

Tropical weather analysis - June 30, 2014

By: KoritheMan, 7:52 AM GMT on June 30, 2014

Douglas

Tropical Storm Douglas is moving aimlessly across the Pacific Ocean. As of the 0300Z NHC advisory, the following information was posted on Douglas:

Wind: 40 mph, with higher gusts
Location: 16.4°N 113.0°W
Movement: WNW at 16 mph
Pressure: 1003 mb

Latest satellite data shows an increase in central convection, although scatterometer and satellite data indicate that the radius of maximum winds is still probably about 75 miles, localized within the vigorous convective band orbiting cyclonically around the south side of the center. Interestingly, the prominent rainband that was emanating north from the center earlier has essentially dissipated, which could herald the formative stages of an inner core as the outer circulation becomes less competitive, but we shall see. The 6z satellite estimates certainly haven't convinced me that Douglas is strengthening, and the large size will likely continue to be its own worst enemy.



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

The intensity forecast is tricky. On the positive side, Douglas is located within a region of very weak vertical wind shear, and has a rather impressive outflow pattern for a 35 kt tropical storm. In addition, synoptic data indicate that Douglas is embedded in a very moist airmass, with the latest diagnosis on the SHIPS file showing a relative humidity value of 79% at synoptic time (6z). While these parameters would ordinarily portend intensification, as aforementioned, Douglas has a rather large circulation envelope, resembling monsoon depressions commonly seen in the western Pacific or Bay of Bengal. These types of systems do not tend to strengthen very quickly. So far all of Douglas' attempts to formulate and develop a cohesive inner core have fallen on atmospheric deaf ears, and I currently see no real evidence to make me assume this situation will change. My forecast is for a peak of 50 kt in 36 hours, more or less in line with the 0z LGEM but below the recently published 6z iteration. Even the GFDL and HWRF are not being their usually aggressive selves. The odds of Douglas becoming a hurricane appear slim.

Later in the forecast period, Douglas is expected to weaken over cooler waters even though the vertical wind shear is forecast to remain low. I have now elected to show remnant low status by day five, in general agreement with the majority of the guidance and the National Hurricane Center.

Douglas appeared to move due westward earlier in the evening between 0 and 1z, but recent satellite data suggests that a west-northwest motion has resumed, pretty much in line with the guidance and the latest NHC forecast track. Water vapor imagery shows a narrow weakness exists in the subtropical ridge to the north of the tropical cyclone, which is shunting the subtropical ridge progressively westward ahead of Douglas. This general pattern should result in a continuation of current motion trends, followed by a more westward motion between 72 and 96 hours as Douglas returns closer to the axis of the subtropical ridge. The guidance is in good agreement with this scenario, although there are still significant variations in the latitudinal location of the anticipated westward turn. The GFS is farther north than the ECMWF, taking Douglas above 20N, while the ECMWF only takes the storm to around 18.5N. The ECMWF has generally presented more realistic long-range synoptic expectations, so I will continue to closely emulate that guidance. My forecast track is to the south of the majority of the track guidance. A west-southwest motion is forecast at 120 hours, as both the GFS and ECMWF show Douglas moving west-southwestward as a shallow system by that time.

Intensity forecast

Initial 06/30 0300Z 16.4°N 113.0°W 35 kt 40 mph
12 hour 06/30 1200Z 16.8°N 114.2°W 40 kt 45 mph
24 hour 07/01 0000Z 17.3°N 115.5°W 45 kt 50 mph
36 hour 07/01 1200Z 17.7°N 116.4°W 50 kt 60 mph
48 hour 07/02 0000Z 18.3°N 117.5°W 45 kt 50 mph
72 hour 07/03 0000Z 18.6°N 118.8°W 40 kt 45 mph
96 hour 07/04 0000Z 18.6°N 120.0°W 35 kt 40 mph
120 hour 07/05 0000Z 18.4°N 120.7°W 30 kt 35 mph: post-tropical/remnant low

Track forecast



Figure 2. My forecast track for Douglas.



Invest 97E

A small but persistent area of low pressure located several hundred miles to the east of Douglas continues to produce very deep convection.



Figure 3. Latest infrared satellite image of Invest 97E. Image credit: NOAA's Satellite Services Division (SSD).

While the system is currently experiencing strong northerly to northwesterly shear -- no doubt related to Douglas' outflow, we have seen sheared systems unexpectedly develop in the past, and I get the feeling that will be the case with Invest 97E. As mentioned, satellite images show very deep convection, but shortwave infrared satellite images -- generally a good nighttime substitute for daytime visible imagery -- indicates that the low-level center is about 50 miles west of the convection due to the shear, a situation that was confirmed by several evening microwave passes. Recent satellite data indicates that convection has developed closer to the center, and, while it's not likely to completely succeed in covering the entire center, we have what appears to be a convective band trying to wrap into the northern portion of the circulation, which a 0330Z ASCAT pass suggests is very robust, albeit probably not closed yet. If the banding can increase through the overnight (and given the diurnal convective maximum, it definitely could) sufficiently close to the center, we could have a short-fuse tropical storm today, as the aforementioned ASCAT pass indicates that the low is already producing tropical storm force winds to the north and east of the low center, with even a few likely rain-contaminated vectors of 40 kt occurring not far southeast of the center.

If this system does develop, it will likely not intensify much until around 72 hours, when the GFS and ECMWF unanimously suggest a sharp decrease in shear as Douglas moves westward and weakens.

Although the current BAM guidance and some of the GFS ensemble members suggest a possible threat to the southern coast of Mexico, the mid-level flow from Douglas is likely to cause the system to move more to the west-northwest, rather than northwest, although one cannot totally rule out that motion depending on whether or not Douglas exudes any unforeseen wobbles.

Probability of development in 48 hours: 60%

Probability of development in 120 hours: 80%



Invest 91L

A small area of low pressure is located about 150 miles north-northeast of Freeport in the northwestern Bahamas. Satellite and radar data suggest that thunderstorm activity is currently minimal, and I'll be honest; the system looks rather sickly at the moment.



Figure 4. Latest infrared satellite image of Invest 91L. Image credit: NOAA's Satellite Services Division (SSD).

On the positive side, microwave, satellite, and scatterometer data all indicate a very healthy surface circulation that has become increasingly well-defined throughout the evening. In addition, coastal and inland observing stations over the western Atlantic region show a noticeable downward modulation of the surface pressure signal, likely due to the passage of a shortwave trough over the Ohio Valley region. Pressure are still objectively high in the region, though, and the system certainly has its work cut out for it if it wants to become a tropical cyclone. Observations from NOAA buoy 41010, located at 29N 78W indicate that the center of 91L is likely to pass pretty much directly over the buoy, which recently measured a central pressure of 1013 mb, NNW winds, and 17 kt wind gusts. The central pressure was still falling as of 0650 UTC, which could mean that the pressure is closer to 1012 mb.

Negatively, satellite and radar data suggest that much of the associated shower activity -- and all of the deep convection -- is located well to the south of the center, and is currently affecting the northwestern Bahamas. One possibility I haven't seen mentioned much that I believe warrants one is the potential for a center reformation under the deep convection during the next 24 hours, where there is less shear and subsidence. The convection is not very persistent (although it is rather cold), however, which signals to me that a center reformation is unlikely to occur there. But if it does actually happen, a landfall in Florida would probably become increasingly likelier.

The GFS and ECMWF continue to suggest that the shear will decrease over the next day or two as the system moves southward to southwestward toward the Florida east coast. If it verifies, this evolution could allow for an increase in deep convection near the center, which would lead to a tropical depression or tropical storm in short order.

The long-range track of the system is simply too uncertain to meaningfully speculate. The system continues to move erratically in a general southward direction, occasionally moving southwestward to west-southwestward. Recent CIMSS steering data suggest that the ridge off the Louisiana coast has recently regressed eastward at the 850-700 mb level, which could lead to a more uniform southwestward to west-southwestward motion with time. This would be possible as the shortwave trough passes by to the north. The short-term guidance suggests that the system will remain well east of Florida despite the likelihood of a southwestward movement, but with the system this devoid of convection -- coupled with the fact that the global models lack the proper resolution to handle these small systems (remember Alberto in 2012 and its failed genesis prospects by the global models? That.), I am inclined to believe a motion closer to the Florida coast is possible. If this were classified now, I think the National Hurricane Center would at least highlight the potential for requiring tropical storm watches along the east coast of Florida, and residents there should closely monitor this system over the next couple of days. I am fairly confident in the early portion of the forecast track in bringing the system a little bit closer to Florida than the current guidance suggests, and I would expect a southward shift in the model suite today. The longer range track becomes rather hazy, with the GFS showing a track inland toward the North Carolina coast, and the ECMWF suggesting that the system will closely scrape Cape Hatteras. Any long-range threat to the Carolinas upward could also be significantly modulated by potential interaction with or landfall in Florida.

Interests all along the eastern United Coast from Florida to New England should carefully monitor the progress of this system over the next week. It should be noted that the GFS and ECMWF show a very favorable outflow regime setting up for this system as it begins to accelerate northeast toward the Carolinas, with a southwesterly upper-level jet to the west and a northerly upper-level jet to the east, one from the trough and the other from the ridge. Were this to verify, the system could become a minimal hurricane as it makes its closest approach to the Carolinas. We have time to assess the situation, though, and I am only highlighting a possibility if that particular forecast were to verify. I'm not making any explicit predictions right now.

An Air Force reserve hurricane hunter aircraft is scheduled to investigate this disturbance later today, if necessary. I get the feeling they will not.

Probability of development in 48 hours: 60%

Probability of development in 120 hours: 80%

2014 Atlantic hurricane season 2014 Pacific hurricane season Tropical Storm Douglas Invest 97E Invest 91L

Updated: 8:13 AM GMT on June 30, 2014

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Tropical weather analysis - June 29, 2014

By: KoritheMan, 8:21 AM GMT on June 29, 2014

Tropical Depression Four-E

Tropical Depression Four-E is spinning aimlessly in the eastern Pacific. As of the latest (0300Z, new one to be out in about an hour) advisory, the following information was posted on the storm:

Wind: 35 mph, with higher gusts
Location: 14.6°N 107.4°W
Movement: WNW at 14 mph
Pressure: 1006 mb

Satellite images suggest that the depression is getting stronger with the formation of two interlocking hooking bands. While the center is a little difficult to find even with microwave imagery, I assume it is probably located roughly between these two bands, and I anticipate a tropical storm sometime this morning as the bands fully consolidate around the center to form a more cohesive central dense overcast structure. The latest UW-CIMSS Final T numbers using the Advanced Dvorak Technique (ADT) yields 2.4, or pretty much on top of tropical storm strength. SAB came in a little lower, at 2.0, not quite maturing beyond the depression stage.



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

The depression is currently over 29-30C SSTs and in a lower vertical wind shear environment as evidenced by the pronounced outflow signature on water vapor images; there is also no dry air in the vicinity. Having said that, most of the intensity guidance does not take the depression to hurricane strength, with the average consensus of those models near 50 kt. I suspect that the reason for this likely lies in the cooler waters which lie ahead along the forecast track, particularly along and just to the west of 115W, where regional sea surface temperature analyses show the approximate location of 26C isotherm. So in case anybody thought it wasn't obvious, any intensification by the depression will likely have to occur within the next 36-48 hours before sea surface temperatures drop off sharply. My forecast takes the cyclone up to 50 kt in 36 hours, then shows only a slow decay since the environmental shear is forecast to be light, along with the latest run of the SHIPS model showing only a gradual decrease in ambient relative humidity values, but it is of course probably more likely than not that the model is failing to appreciate just how much stable air can exist over the 26C isotherm. The cyclone could weaken faster than what I have indicated if the dry air has its way sooner rather than later. Also, while the continued large size of the depression and the sprawling nature of the central convection precludes rapid intensification, once an inner core becomes established, strengthening could become quick. It remains entirely possible that the depression could attain hurricane status within the next 24-36 hours before leveling off, but this is not being shown by me at this time.

The depression appears to be moving more or less on track, rather quickly to the west-northwest under a strong subtropical ridge to the north, perhaps even anomalously strong. The guidance suggests a continuation of the apparent brisk movement in that direction as the cyclone follows the flow around the ridge. In about two days, the depression is forecast to steadily decelerate and turn westward as the ridge builds westward ahead of the system. My forecast track shows the cyclone moving due west through this period. Interestingly, the GFS shows the cyclone moving very little through the 48 to 72 hour timeframe. My only conclusion based on its sea level pressure output is that it anticipates a likely erroneous and non-eventful binary interaction between the sprawling disturbance to the east. That disturbance appears to be comparatively smaller than the depression, and I have discounted the GFS solution in favor the ECMWF solution, both at shorter ranges and at longer ranges. The GFDL and HWRF still show a recurving system affecting Baja due to a pronounced weakness in the subtropical ridge. However, these models run off the GFS, and with the ECMWF and GFS quite far apart at day five, it is likely that the GFS is falsely inflating synoptic troughing signals within the aforementioned models, giving a biased and unrealistic forecast scenario. The only impact that is likely in Baja will be along the southern and central coast in the form of rough surf due to distant tropical storm force winds. My forecast track is a little faster than the NHC official prediction during the latter portion of the forecast since vertical wind shear is forecast to be nil at that point, diminishing the likelihood of the classical "shear apart and stall" scenario.

Intensity forecast

Initial 06/29 0600Z 15.1°N 108.1°W 30 kt 35 mph
12 hour 06/29 1800Z 15.7°N 110.4°W 35 kt 40 mph
24 hour 06/30 0600Z 16.3°N 112.8°W 45 kt 50 mph
36 hour 06/30 1800Z 16.8°N 114.8°W 50 kt 60 mph
48 hour 07/01 0600Z 17.1°N 115.7°W 50 kt 60 mph
72 hour 07/02 0600Z 17.3°N 117.3°W 45 kt 50 mph
96 hour 07/03 0600Z 17.3°N 118.7°W 40 kt 45 mph
120 hour 07/04 0600Z 17.3°N 120.3°W 35 kt 40 mph

Track forecast



Figure 2. My forecast track for Tropical Depression Four-E.



Invest 97E

An area of disturbed weather with an embedded low pressure area is producing a large area of disorganized showers and thunderstorms several hundred miles east of Tropical Depression Four-E.



Figure 3. Latest infrared satellite image of Invest 97E. Image credit: NOAA's Satellite Services Division (SSD).

Low cloud lines on shortwave infrared satellite pictures indicate that the circulation is broad and not well-defined, a situation which was also validated by a slew of evening microwave passes. There are no real signs of organization with the system for now, although recent satellite data does show convection firing closer to where I presume the center to be. The system is currently being plagued by moderate to strong northerly shear. The guidance suggests this affliction will continue for at least the next three days, likely due to outflow from what is likely to be Tropical Storm Douglas. Beyond that time, the shear is forecast to relax, which could allow for some possible development of the system by that time. Indeed, both the GFS and ECMWF make this system a small tropical storm near the west coast of Mexico in five days. No significant development is expected before then. Current guidance indicates a possible long-range threat to Manzanillo and/or southern Baja, which is entirely possible given current synoptic trends, with the system likely to follow the mid-level cyclonic flow associated with Tropical Depression Four-E.

Probability of development in 48 hours: 40%

Probability of development in 120 hours: 50%



Invest 91L

A small, non-tropical area of low pressure located midway between the Florida east coast and the northern Bahamas (91L) continues to move slowly southward. Latest satellite data show that the thunderstorm activity associated with the depression is fairly weak and disorganized at the moment, with no evidence of spiral banding on the long-range Melbourne, Florida doppler radar. UW-CIMSS analyses reveals about 15 to 20 kt of northerly shear over the system associated with a developing ridge over the eastern United States. The shear also appears to be slugging a bit of dry air into the system, a common scenario for this portion of the Atlantic which is almost uniformly under the influence of the subsident portion of either a ridge or a trough; this time it's the ridge.



Figure 4. Latest infrared satellite image of Invest 91L. Image credit: NOAA's Satellite Services Division (SSD).

The models are split on how the shear pattern will evolve, with the GFS showing a weaker vortex coinciding with stronger shear on that model. Conversely, the ECMWF shows a much more favorable upper-tropospheric wind pattern, with the current northerly flow transitioning to a northeasterly to easterly shearing regime. This pattern, if true, is more conducive for the development of the system. Unfortunately, it's hard to decide which model is presenting the most accurate portrayal and expectation of the vertical shear pattern. The ECMWF tends to resolve mid-latitude weather a bit better than the GFS, which might suggest that it has a firmer grasp on the shear pattern, which is directly tied to the mid-latitude shortwave/longwave pattern. Water vapor imagery shows that a shortwave trough that was passing through the western Atlantic yesterday has passed the longitude of Invest 91L, leaving the system in a region of weak steering currents between a developing ridge over the eastern United States and another over southeastern Canada. It is rare to see the westerlies relegated so far north on a water vapor loop, but there is currently little evidence of large-scale cyclonicity over the United States or western Atlantic region, with rather strong ridging take hold in the east. Given these trends, I am inclined to favor the ECMWF solution, with the expectation that the shear will relax as the upper-level trough moving across the central and southern United States slowly lifts northward. If my forecast on this pans out, we could have a tropical depression or tropical storm on short order within the next two days.

Regarding the potential threat to the United States coast... that's still too early to determine. The guidance -- global and dynamical -- have hardly been consistent, but in general they have shown a tendency for a slow movement toward eastern Florida, followed by a stall. That part of the forecast seems reasonably straightforward, and should be valid for the first 72 hours or so. After that time, the puzzle is losing a piece, with the ECMWF recurving the intensifying system into the westerlies not far off Cape Hatteras, while the GFS dissipates the system as it stalls off the Florida coast. The GFS solution appears unlikely for reasons previously mentioned, so if anything I would go with the ECMWF. For what it's worth, climatology is also firmly on its side, with recurvature a common theme for early season storms in this area.

The system remains buried within a high pressure environment, with many coastal and inland stations reporting pressures between 1018 and 1020 mb. It's worth noting that the global models do not have the proper resolution to deal with small entities like this one, and that further complicates the long-range forecast track.

An Air Force reserve hurricane hunter aircraft is scheduled to investigate the disturbance later today, if necessary.

Probability of development in 48 hours: 50%

Probability of development in 48 hours: 70%

Tropical Depression Four-E Invest 97E Invest 91L 2014 Atlantic hurricane season 2014 Pacific hurricane season

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I don't understand people.

By: KoritheMan, 8:15 AM GMT on June 17, 2014

I was talking to a guy on Facebook about... stuff (I don't even remember now, lol). Eventually we get on the subject of personal boundaries. I haven't thought about it in awhile because I honestly don't care anymore. Why should I?

However, when that particular modal of discussion exhibits a resurgence, I end up invariably thinking about it anyway.

It's as my brother said earlier... it's not that I don't understand people... it's that I don't understand their reasons for doing what they do. I am very hard-pressed to respect an opinion if I deem it as illogical or irrational. Emotions get in the way with certain things. That's objectively true. And I feel that for the most part... boundaries are based solely on emotion, without even a modicum of rationality or logic.

I've discussed this with Trent before, but not everyone here. At this point I just pretend to understand people. I know a couple people here that aren't comfortable discussing certain topics, so I avoid discussing them. I think even socially awkward people (aka me) would agree with that. But every time I respect those boundaries, I find myself having to pretend. I don't like the idea of feigning understanding of a person's delineated barriers, but I can't help it. My background turned me into this overly logical machine.

In the end, if feigning produces the same results as authentic understanding (i.e. it maintains the friendship), does it really matter? I'd say not.

What are you guys' thoughts?

Stories of my life that no one cares about

Updated: 8:17 AM GMT on June 17, 2014

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Tropical weather analysis - June 12, 2014

By: KoritheMan, 2:29 PM GMT on June 12, 2014

Cristina

Hurricane Cristina has continued to rapidly intensify. As of the 1230Z special NHC advisory, the following information was posted on the hurricane:

Wind: 145 mph, with higher gusts
Location: 16.4°N 106.9°W
Movement: WNW at 8 mph
Pressure: 940 mb
Category: 4 (Saffir-Simpson Hurricane Wind Scale)

The satellite presentation of Cristina is, in a word, spectacular. The eye is well-defined, circular, and warm; in addition, the central dense overcast is very symmetrical and well-organized. While cloud tops in the eyewall have recently warmed, this is more than likely just a typical structural cycle. Satellite estimates are running high this morning, with the most recent final t number from UW-CIMSS ADT coming in at 6.7, roughly 130 kt. SAB came in at 6.0, or approximately 115 kt. Also, visible satellite images reveal a classical "stadium effect" feature within the central dense overcast, with overt overshooting tops.



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

UW-CIMSS TPW and water vapor imagery shows that the hurricane has created another dry slot in the eastern semicircle which may halt any additional strengthening. However, if Cristina can thwart its desires, the storm still has room for a little more intensification, with most of the guidance showing at least a 5 kt additional increase in wind speeds over the next 12 hours. Indeed, the Maximum Potential Intensity (shown below) for a storm in this region is still supportive of a Category 5 hurricane for a good bit longer, and there is an outside chance that Cristina could attain this intensity before beginning its weakening trend if possible short-term inner core fluctuations, common of intense hurricanes but not evident quite yet, don't mitigate that potential. In about 24 hours, sea surface temperatures are forecast to cool to around the bottom point of 28C, which, while still warm, is still a considerable heat/energy reduction for the hurricane. That, coupled with at least gradually increasing westerly to southwesterly shear should combine with quickly cooling sea surface temperatures and the associated dry stable marine layer accompanying them should hasten the demise of the currently powerful hurricane. The weakening should be especially poignant near the end of the forecast period, when the GFDL, HWRF, and GFS all show very marginal 700-500 mb relative humidity values, possibly decreasing to even below 50% at times. Given the apparent hostilities, and even considering that the GFS has trended lower with the 850-200 mb averaged vertical shear forecast as of 6z, I have officially decided to show a decadent Cristina flaunting her status a remnant low at the five day mark. We'll see.



Figure 2. Maximum Potential Intensity (MPI) for eastern Pacific tropical cyclones valid as of June 12. In simplest terms, a hurricane's MPI is the theoretical upper limit of the hurricane's intensity when atmospheric and oceanic parameters -- including low vertical shear, ambient moisture, adequate upper divergence, and high sea surface temperatures/deep oceanic heat content, are present. The top image expresses this maxim in pressure (mb), while the bottom image expresses theoretical wind speed (kt). As you can see, both images show that the environment is still theoretically supportive of a Category 5 hurricane, leaving the possibility that Cristina could still reach that intensity. I don't, however, consider this the most likely option. Image credit: wxmaps

Cristina continues moving to the west-northwest. It appeared over the last two hours that the hurricane had jogged toward a somewhat more northwesterly heading, and the storm was decidedly to the right of the NHC forecast points at that time. The motion has since stabilized, however, and Cristina now appears to have restarted its desire to follow the NHC forecast points. The GFS appears to be a little farther to the right on the 6z run, and my forecast was nudged in that direction as well since Cristina is now a much stronger system. Near the end of the period, the models still show the cyclone decelerating and turning westward as it relinquishes its vertical integrity and the lower-tropospheric easterlies become influential toward its trajectory. My forecast isn't too much different from the previous one or the NHC forecast, albeit it's a little farther north than my last one, again to account for current trends dictating that a stronger storm should move a shade more poleward. The GFS and ECMWF are both in better agreement on the longer-term track of the then deceased hurricane, with both models eventually anticipating some kind of southwestward to west-southwestward turn. I favor the ECMWF solution at that time, which shows a slower southwestward turn, well after the 120 hour mark.

A 0300Z ASCAT pass suggests that the hurricane-force wind radii remains very small.

While Cristina is not a direct threat to land, large swells will be generated by the hurricane's persistent onshore winds in areas of southwestern Mexico and the southern Baja Peninsula. These conditions will produce life-threatening rip currents for another day or so, even as Cristina weakens.

When Cristina was upgraded operationally to a major hurricane at the 0900Z advisory, it became the earliest formation of the second major hurricane in the eastern north Pacific since reliable records began in 1966. The previous record was held by Hurricane Darby in 2010, which reached Category 3 strength on June 25.

Intensity forecast

Initial 06/12 1230Z 16.4°N 106.9°W 125 kt 145 mph
12 hour 06/13 0000Z 16.8°N 107.8°W 130 kt 150 mph
24 hour 06/13 1200Z 17.6°N 108.8°W 120 kt 140 mph
36 hour 06/14 0000Z 18.4°N 110.2°W 105 kt 120 mph
48 hour 06/14 1200Z 19.2°N 111.3°W 85 kt 100 mph
72 hour 06/15 0000Z 20.0°N 112.6°W 60 kt 70 mph
96 hour 06/16 0000Z 20.4°N 113.9°W 40 kt 45 mph
120 hour 06/17 0000Z 20.4°N 114.7°W 25 kt 30 mph...post-tropical/remnant low

Track forecast



Figure 3. My forecast track for Cristina.

2014 Pacific hurricane season Hurricane Cristina

Updated: 2:38 PM GMT on June 12, 2014

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Tropical weather analysis - June 11, 2014

By: KoritheMan, 3:34 AM GMT on June 12, 2014

Cristina

Cristina has become a Category 2 hurricane. As of the latest NHC advisory, the following information was posted on the hurricane:

Wind: 100 mph, with higher gusts
Location: 16.0°N 105.8°W
Movement: WNW at 6 mph
Pressure: 975 mb
Category: 2 (Saffir-Simpson Hurricane Wind Scale)

Cristina is becoming organized in a hurry. Satellite estimates have come up from all agencies, but they appear to actually be lagging the satellite signature, and the NHC went above the Dvorak estimates at the 0300Z advisory. Expressing how remarkable Cristina looks from a cursory glance of the available satellite data, the most recent UW-CIMSS ADT raw t numbers are up to 6.0, which translates to roughly 115 kt using the Dvorak table. However, I only pointed that out to show how well Cristina looks without a thorough examination, and the CIMSS-ADT raw numbers are estimates that are not adjusted to match actual organization trends. Upper-tropospheric outflow remains exceptionally well-defined, signifying an environment of continued low shear... with the outflow actually being enhanced in the western semicircle by a large thunderstorm complex spanning the monsoon trough to the south of the hurricane.



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

Cristina is sitting over 29-30C SSTs and the depth of the warm water remains vast. The only inhibiting factor to strengthening continues to be a relatively meager thermodynamic environment characterized by only marginal relative humidity values, a situation which is evident on water vapor, satellite data, and UW-CIMSS TPW imagery. However, the aforementioned data slew indicates that Cristina has eliminated much of the dry air which became entrained into the southern portion of the circulation between 1200 and 1800 UTC, and the hurricane may be strong enough now to be largely resilient to the dry air. On the other hand, intensifying hurricanes in weak shear environments can sometimes entrain these subsident flows into their respective circulations as the horizontal extent of the vortex becomes larger, so I am faced with a somewhat tenuous intensity forecast challenge tonight. Having said all of that, my forecast is much higher than all of the guidance this cycle, but is closest to the SHIPS which takes Cristina up to 91 kt in 24 hours. I should note still that if Cristina manages to ward off the dry air as it has been, then the hurricane could get even stronger than I have indicated below, possibly making a run at Category 4 strength.

In about 36-48 hours, waters along the projected path of the hurricane cool abruptly, the thermodynamic environment becomes even more unfavorable, and the GFS shows westerly shear increasing... presumably in response to a distant and quickly amplifying upper-level trough off the coast of the Pacific northwest which the global models show diving southeastward and then eastward into the United States mainland. Current water vapor images, however, have not completely evinced that the shear will be as strong as the GFS suggests, and the SHIPS actually only shows an increase to 11 kt at 120 hours. Even if the shear does not increase as projected, the hostile thermodynamics should promote a quick weakening of Cristina. In deference to the possibility of a somewhat less hostile 200 mb wind flow than the GFS shows, along with the fact that the some of the guidance suggests a somewhat stronger system persisting through the forecast period, I have not elected to show dissipation as a tropical cyclone by day five quite yet, although it could certainly happen.

The hurricane appears to have turned toward the west-northwest as large-scale cyclonicity slowly increases to the north and the western periphery of the subtropical ridge erodes. The guidance remains in good agreement on the evolution of the synoptic pattern over the next few days, with a continued west-northwestward motion forecast around the southern periphery of the broad ridge, with the potential for a northwestward motion at times. The GFS and ECMWF remain in excellent agreement with their respective tracks, showing the hurricane passing near or over Socorro Island in about 48 hours, followed by an abrupt deceleration at the end of the forecast period as Cristina becomes unraveled and more responsive to the low-level flow. While some of the outlying guidance suggests a northward motion -- particularly the GFDL and HWRF -- in general the entire slew of models, including the aforementioned, show Cristina turning westward at the end of the period, with the only differences being the sharpness and timing of the turn. The GFS still shows the cyclone moving northward as a stagnating system, while the ECMWF shows a continued westward motion. Since the GFS could be overamplifying the western United States trough, and more likely keeping an unrealistically strong vortex amidst the apparent environmental hostilities, my forecast blends the two models at first, but leans closer to the ECMWF solution at days four and five. It is possible that Cristina could actually move a little bit faster than shown at the end of the forecast period if the cyclone unwinds fast enough to not be influenced by the distant trough.

Satellite data throughout the day suggests that Cristina's wind field could be expanding, particularly the hurricane-force wind radii.

Intensity forecast

Initial 06/12 0300Z 16.0°N 105.8°W 85 kt 100 mph
12 hour 06/12 1200Z 16.4°N 106.7°W 95 kt 110 mph
24 hour 06/13 0000Z 16.8°N 107.8°W 105 kt 120 mph
36 hour 06/13 1200Z 17.5°N 109.0°W 105 kt 120 mph
48 hour 06/14 0000Z 18.3°N 110.3°W 90 kt 105 mph
72 hour 06/15 0000Z 19.4°N 112.2°W 65 kt 75 mph
96 hour 06/16 0000Z 20.0°N 113.4°W 40 kt 45 mph
120 hour 06/17 000Z 20.2°N 114.9°W 30 kt 35 mph

Track forecast



Figure 2. My forecast track for Cristina.

2014 Pacific hurricane season Hurricane Cristina

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Tropical weather analysis - June 10, 2014

By: KoritheMan, 3:52 AM GMT on June 11, 2014

Cristina

Tropical Storm Cristina is intensifying. As of the latest NHC advisory, here was the information provided on the tropical storm:

Wind: 65 mph, with higher gusts
Location: 15.2N 103.9W
Movement: W at 6 mph
Pressure: 996 mb

Visible and infrared satellite images have shown periodic hints of a ragged eye, with the latest imagery suggesting that this feature could be getting more persistent. Satellite estimates are a unanimous 3.5/55 kt from TAFB, SAB, and UW-CIMSS ADT, and that is the intensity that was recently assigned to the system by the National Hurricane Center attendant to the release of the latest advisory. Having said, that Cristina is still experiencing subsident flow, which is generating sinking air into the cyclone circulation and collapsing the thunderstorms. Indeed, visible satellite images earlier in the day showed a pronounced swath of arc clouds emanating northwestward away from the tropical cyclone in the western quadrant, which is a visible effect of downdrafts hitting the ocean surface. Subsequent to Cristina mixing out that dry air, another surge has managed to sneak its way into the southern quadrant, with a 2138Z SSMI microwave pass showing what appears to be a primitive eyewall open to the southeast in the area where conventional satellite and CIMSS-TPW signify the apparent dry slot.



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

As long as the dry air continues to choke Cristina, the cyclone will not rapidly intensify. The 0z SHIPS file continues to articulate a very high chance for rapid intensification, with a purported 42% chance of an increase of 40 kt during the next 24 hours. While this model seems to be ignoring the marginal thermodynamics, vertical shear over the system is very weak, and that degree of intensification is certainly possible if the tropical storm can overcome its present hurdles. On the positive side, as the recent National Hurricane Center discussion pointed out, recent lightning data (shown below) reveal pronounced lightning returns in the convective band southwest of the center; lightning typically presages rapid intensification in tropical cyclones. Additionally, the central dense overcast has become more focused while the outer banding seen earlier has contracted to meet the central gyre, which is also typically a sign of intensification.



Figure 2. Map of the latest lightning returns. The approximate center of Tropical Storm Cristina is in the far left part of the image, between Manzanillo, Mexico and Cabo San Lucas, located on the southern tip of the Baja California Peninsula. The blue dots denote estimated lightning returns.

Cristina is expected to become a hurricane by tomorrow given current trends. My forecast is higher than the National Hurricane Center intensity prediction based on current convective trends, but held firmly below what could happen if Cristina fully overcomes the thermodynamic environment, in which case a major hurricane would be possible. My intensity forecast takes the cyclone up to 85 kt in 48 hours, or the bottom of Category 2 intensity. This is above all of the 0z intensity guidance, but still fairly close to the LGEM throughout the entire forecast period. Beyond that time, increasing southwesterly shear, even drier mid-level air, and progressively cooler ocean temperatures should promote weakening, especially when the cyclone gets west of 110W, where regional SST analyses show the approximate location of the 26C isotherm. It is entirely possible that the anticipated weakening during those longer ranges could very well be more rapid than even what I have indicated below, which in itself is already a very swift decay. Indeed, the ECMWF dissipates Cristina by day five.

Cristina has moved south of the advertised NHC forecast points today, and this was reflected in the 0300Z advisory that was just released. A lot of this apparent south-of-west motion could be ascribed to small-scale inner core fluctuations inducing erratic track wobbles. Water vapor imagery and UW-CIMSS synoptic steering data indicate that the low- to mid-level ridge to the north of Cristina is beginning to weaken as forecast; this is due to a broad downstream upper-level trough between 125 and 130W. Hence, it is unclear how much longer the apparent south-of-forecast-points westward motion can persist. In about 24 hours, Cristina is likely to turn west-northwestward as it moves into an increasing weakness as the western end of the subtropical ridge. The guidance continues to be split with regards to the magnitude and timing of the turn, with the GFDL and HWRF forecasting Cristina to turn northward into Mexico. Given that the GFS is significantly farther north than the ECMWF after 120 hours despite the likelihood of Cristina being a much weaker system by that time -- not to mention the notorious convective feedback issue with that model when it comes to adequate heat transport to mid-latitude troughs -- it is possible that the GFDL and HWRF synoptic fields are contaminated by an exaggerated trough earlier in the period, since those models are based on the GFS parameters. Interestingly, this does not show up on the operational GFS, which shows a very believable track through 120 hours. The above was pure speculation on my part, and may not fully explain the discrepancies between the GFS and the GFDL/HWRF. Back to the models... the ECMWF shows a weaker cyclone turning Cristina westward beyond 120 hours as it becomes a vertically shallow system, and the more westward motion appears to be more likely than the continued northward motion shown by the GFS at those ranges, again likely due to an exaggerated trough.

My forecast is a blend of the GFS/ECMWF models, both of which present a believable synoptic representation and Cristina's anticipated response to that pattern. It is possible that Cristina could move slowly and erratically near the end of the period as it encounters a developing col region between an anticyclone to the west and upper-level trough to the east, over the western United States. For now though, only a slight deceleration is shown in my forecast at day five until I become more cognizant of how Cristina might respond to the col pattern, which appears to be largely a function of its intensity by that time.

Intensity forecast

Initial 06/11 0300Z 15.2N 103.9W 55 kt 65 mph
12 hour 06/11 1200Z 15.3°N 105.3°W 65 kt 75 mph
24 hour 06/12 0000Z 15.9°N 106.7°W 75 kt 85 mph
36 hour 06/12 1200Z 16.6°N 108.2°W 80 kt 90 mph
48 hour 06/13 0000Z 17.3°N 109.7°W 85 kt 100 mph
72 hour 06/14 0000Z 18.4°N 112.0°W 80 kt 90 mph
96 hour 06/15 0000Z 19.3°N 114.6°W 60 kt 70 mph
120 hour 06/16 0000Z 19.8°N 115.3°W 40 kt 45 mph

Track forecast



Figure 3. My forecast track for Cristina.

2014 Pacific hurricane season Tropical Storm Cristina

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Tropical weather analysis - June 9, 2014

By: KoritheMan, 2:14 AM GMT on June 10, 2014

Tropical Depression Three-E

The tropical disturbance that has paralleled the coast of southern Mexico over the last few days has become a tropical depression. As of the 5 PM EDT NHC advisory, the following information was posted on the depression:

Wind: 35 mph, with higher gusts
Location: 15.4°N 102.0°W
Movement: W at 5 mph
Pressure: 1006 mb

Most of the convection is confined a persistent band to the east of the center, but recent satellite data suggests that it could be forming and becoming more persistent over the center while the outer band slowly contracts. There is currently no hard data suggesting the depression has become a tropical storm, and I expect the National Hurricane Center will keep the winds at 30 kt at the upcoming advisory. Upper-tropospheric outflow is well-defined, implying an environment of light vertical shear.



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

Interestingly, a 1640 UTC ASCAT pass captured the circulation of the tropical depression and showed a few isolated wind vectors of 30 kt within the vigorous convective band to the east of the center; using the low-bias of the ASCAT instrument, that would equate to roughly 35 kt at the surface, or the bottom of tropical storm intensity. However, the pass also showed that the circulation was elongated and in its formative stages at the time it revealed those winds, and it is likely that those estimates were rain-contaminated. Nevertheless, if current trends persist and the convection appearing over the low-level center can maintain itself, we should have a short-fuse tropical storm overnight.

Environmental conditions appear quite conducive for intensification... if the cyclone can manage to mix out the pronounced dry slot wrapping into the southern semicircle, a situation which still appears evident based on recent satellite and microwave data. If the dry air can mix out, the depression could certainly intensify much faster than what I have indicated below. Indeed, the SHIPS rapid intensification is currently indicating a 63% chance of a 25-kt increase in wind speed during the next 24 hours, which is 4.8 times the sample mean. While the SHIPS can sometimes be too aggressive in projecting rapid intensification, I have found that it is usually adequate for delineating rapid intensification potential based on in situ atmospheric and oceanic conditions. Also, the Maximum Potential Intensity (MPI) in the path of the depression is approximately 880 mb/150 kt, or quite comfortably in the Category 5 threshold (shown below). While this scenario has a nearly 0% chance of occurring even if the depression rapidly intensifies, it certainly highlights the distinct possibility that the depression could get much stronger than forecast if a well-defined inner core becomes established. For now, my forecast will remain conservative but will trend upward toward the upper end of the current intensity guidance. It is possible that tomorrow's forecast will be forced to show a much stronger hurricane.

Beyond three days, cooler waters, dry mid-level air, and increasing southwesterly shear will likely induce an abrupt weakening trend.



Figure 2. Eastern Pacific Maximum Potential Intensity (MPI) as of June 9. Put simply, the MPI is a theorized upper intensity limit based on the presumption of idealized atmospheric and oceanic conditions comprised of nil vertical shear, abundant moisture, sea surface temperature/oceanic heat content, and upper divergence. The bottom image indicates theoretical wind speed (kt), while the top image shows a theoretical pressure point (mb).

The depression appears to be moving westward to the south of a well-established subtropical ridge over northern Mexico that is being enhanced by an upper-level trough moving through the Arklatex region extending toward the northern Gulf Coast. The global models suggest this general motion should continue with a fairly constant forward speed being maintained. In about 36-48 hours, the tropical cyclone is expected to begin moving west-northwest as it encounters a pronounced break in the subtropical ridge induced by a slow-moving upper-level trough off the coast of central California. While the general guidance agrees on this scenario, there are some subtleties on precisely where and how sharp the depression is going to turn. The GFDL shoots the system northward toward a landfall in southwestern Mexico, while the GFS shows a continued west-northwest motion past Socorro Island. The ECMWF is similar but somewhat farther south, particularly near the end of the period. The CMC maintains the westward motion longer and consequently has a track a smidgeon farther south than the other guidance. My forecast leans toward a blend of the GFS/ECMWF and is a little south of the current NHC advisory during the first 24-36 hours. As the depression approaches a developing col region between an anticyclone to the west and a mid- to upper-level trough to the east over the western United States near the end of the period, its motion is likely to slow, with some of the guidance suggests some erratic and very slow motion by that time.

Intensity forecast

Initial 06/10 0000Z 15.4°N 102.0°W 30 kt 35 mph
12 hour 06/10 1200Z 15.4°N 103.3°W 40 kt 45 mph
24 hour 06/11 0000Z 15.5°N 104.7°W 50 kt 60 mph
36 hour 06/11 1200Z 16,0°N 106.3°W 60 kt 70 mph
48 hour 06/12 0000Z 16.5°N 108.2°W 75 kt 85 mph
72 hour 06/13 0000Z 17.1°N 110.1°W 75 kt 85 mph
96 hour 06/14 0000Z 18.0°N 112.0°W 60 kt 70 mph
120 hour 06/15 0000Z 19.0°N 114.0°W 45 kt 50 mph

Track forecast



Figure 3. My forecast track for Tropical Depression Three-E.

2014 Pacific hurricane season

Updated: 11:05 AM GMT on June 10, 2014

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Tropical weather analysis - June 3, 2014

By: KoritheMan, 1:41 AM GMT on June 04, 2014

Boris

Tropical Storm Boris continues northward toward the coast of southern Mexico. As of the 8 PM NHC intermediate advisory, the following information was posted on Boris:

Wind: 40 mph, with higher gusts
Location: 15.4°N 94.1°W
Movement: N at 5 mph
Pressure: 1000 mb

I don't know what happened, but Boris is definitely not invincible. Boris is producing some very deep convection, up to -80C in some spots, satellite estimates have recently come down, with recent SAB estimates coming in below tropical storm strength; on the other hand, recent CIMSS-ADT numbers still support an intensity of 35 kt. One positive is that upper-tropospheric outflow has expanded in the southern semicircle yesterday, and the outflow pattern as a whole appears more representative of an upper-level anticyclone hovering aloft, rather than exhibiting a south-to-north shear pattern as occurred yesterday.



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

As mentioned above, Boris is not particularly well-organized, and a 1523 ASCAT pass showed an elongated circulation, particularly to the north, which is not surprising considering that's the main portion of the circulation interacting with land. The pass also showed several areas of seemingly uncontaminated tropical storm force winds (which was the justification for the NHC upgrading to a tropical storm this afternoon), and recent satellite data shows that the cyclone is still producing vigorous convection about 50 miles from where the NHC had the center fix as of the recent intermediate advisory.

Upper-level winds have improved considerably over Boris, but it's simply going to be too little too late. Satellite data and microwave data suggest that the low-level center appears to be moving faster toward the coast than earlier predictions, with the center itself remaining diffuse, broad, and ill-defined. In fact, even glancing thoroughly at visible satellite imagery, there is only a hint of a small vortex heading northward, with the imagery suggesting a secondary vorticity maximum within a small burst of convection to the west, and what appears to be a mid-level center moving inland along the coast within the -80C convection. My best guess is that the low-level center is on the far southwest side of the cold cloud tops encompassing the coast of Mexico within the landfall area, but it is possible the center has relocated a bit under the deep convection, which would herald a motion even faster toward the coast.

The global models continue to have trouble resolving the Boris vortex within their respective sea-level pressure and 850 mb vorticity fields, with the GFS and ECMWF just barely taking Boris inland before the energy fractures and the southern portion reenters the Pacific while the northern stream continues northward into the Bay of Campeche. Even so, the model consensus is for Boris to move inland over the next 24 hours and then emerge into the Bay of Campeche thereafter; however, I suspect landfall will occur much sooner, probably within the next 12 hours, and I have decided to reflect this in my forecast for the storm. Given current trends, it is possible that the cyclone could weaken to a tropical depression prior to landfall, if it has not done so already. After landfall, Boris should quickly lose its circulation, and it may not even persist as long as I have indicated below.

No additional intensification is expected since the circulation is broad and already interacting with land. However, Boris is producing very deep convection over southern Mexico, and significant rainfall totals and attendant flash flooding will likely produce mudslides and fatalities across the mountainous regions of this area as Boris continues northward. A large fetch of southerly winds are likely even after the cyclone dissipates, in combination with a persistent area of cyclonicity/rainfall over the Bay of Campeche. Rainfall could approach 20 to 30 inches across the mountains.

Intensity forecast

Initial 06/04 0000Z 15.4°N 94.1°W 35 kt 40 mph
12 hour 06/04 1200Z 16.3°N 94.0°W 30 kt 35 mph: inland
24 hour 06/05 0000Z 16.9°N 94.0°W 25 kt 30 mph: inland/remnant low
36 hour 06/05 1200Z 17.5°N 94.0°W 20 kt 25 mph: inland/remnant low
48 hour 06/06 0000Z: dissipated

Track forecast



Figure 2. My forecast track for Boris.

NHC storm information

000
WTPZ32 KNHC 032333
TCPEP2

BULLETIN
TROPICAL STORM BORIS INTERMEDIATE ADVISORY NUMBER 5A
NWS NATIONAL HURRICANE CENTER MIAMI FL EP022014
500 PM PDT TUE JUN 03 2014

...HEAVY RAINS FROM BORIS CONTINUE TO SPREAD OVER SOUTHEASTERN
MEXICO...


SUMMARY OF 500 PM PDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...15.4N 94.1W
ABOUT 90 MI...150 KM SE OF SALINA CRUZ MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1000 MB...29.53 INCHES


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

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* SALINA CRUZ MEXICO TO MEXICO/GUATEMALA BORDER

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


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 500 PM PDT...0000 UTC...THE CENTER OF TROPICAL STORM BORIS WAS
LOCATED NEAR LATITUDE 15.4 NORTH...LONGITUDE 94.1 WEST. BORIS IS
MOVING TOWARD THE NORTH NEAR 5 MPH...7 KM/H...AND THIS GENERAL
MOTION IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ON THE FORECAST
TRACK...THE CENTER OF BORIS SHOULD BE NEAR THE COAST OF MEXICO
WITHIN THE WARNING AREA BY WEDNESDAY MORNING.

MAXIMUM SUSTAINED WINDS ARE NEAR 40 MPH...65 KM/H...WITH HIGHER
GUSTS. LITTLE CHANGE IS STRENGTH IS EXPECTED WHILE BORIS
APPROACHES THE COAST OF SOUTHERN MEXICO. WEAKENING IS FORECAST
AFTER BORIS MOVES ONSHORE.

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

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1000 MB...29.53 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE AFFECTING THE COAST WITHIN THE
WARNING AREA AND SHOULD CONTINUE INTO TONIGHT.

RAINFALL...THIS SYSTEM IS EXPECTED TO PRODUCE AS MUCH AS 10 TO 20
INCHES OF RAIN OVER A LARGE PART OF SOUTHERN MEXICO THROUGH
SATURDAY...WITH ISOLATED AMOUNTS EXCEEDING 30 INCHES LIKELY OVER THE
MOUNTAINOUS TERRAIN OF THE MEXICAN STATES OF OAXACA AND CHIAPAS.
BORIS IS ALSO EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS OF 5 TO 10
INCHES IN GUATEMALA. THESE RAINS ARE LIKELY TO RESULT IN
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...800 PM PDT.

$$
FORECASTER PASCH



Bay of Campeche disturbance

A large area of disturbed weather is producing widespread cloudiness and thunderstorms over the Bay of Campeche, adjacent Yucatan Peninsula, and even extending southward into southern Mexico where it connects with the low-level center of Boris. Upper-level winds are currently highly unfavorable for development, with the recent UW-CIMSS estimate showing 30 kt of westerly shear encroaching on the disturbance. Satellite pictures show a very impressive area of cyclonic turning, however, and nearby stations suggest that surface pressures in the vicinity are low. The GFS shows upper-tropospheric winds remaining marginal at best, with only a very small area of 15 kt shear enveloping the disturbance, with westerly shear of 30+ kt just to the north anticipated over the next several days. I am not expecting significant development of this disturbance, and it still remains unlikely to ever become Arthur.

The global models suggest it will move little over the next few days, with the GFS eventually shooting the strung out energy toward southwestern Florida, while the ECMWF shows a more gentle northward motion in the central Gulf of Mexico heading toward the central Gulf Coast, again as a very strung out and diffuse system undergoing heavy shear, which is the expected forecast scenario here.

Regardless of development, very heavy rainfall in combination with a decaying Tropical Storm Boris will likely produce significant flash floods and mudslides over portions of southern Mexico over the next several days.



Figure 3. Latest infrared satellite image of the Bay of Campeche disturbance. Image credit: NOAA's Satellite Services Division (SSD).

2014 Pacific hurricane season Tropical Storm Boris 2014 Atlantic hurricane season

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Tropical weather analysis - June 2, 2014

By: KoritheMan, 2:51 AM GMT on June 03, 2014

Tropical Depression Two-E

The area of disturbed weather that has persisted near and south of the Gulf of Tehuantepec for several days has finally become a tropical depression. As of the just released NHC advisory, the following information was available on the storm:

Wind: 35 mph, with higher gusts
Location: 13.8°N 94.2°W
Movement: NNW at 5 mph
Pressure: 1001 mb

While there are a lot of deep and expansive thunderstorms with the depression, satellite and microwave data suggest that the majority of them are located in rainbands about 50-60 miles north of the presumed center; this also suggests that the strongest winds are probably located closer to the coast than a storm in this location would ordinarily portend. Satellite estimates are still below tropical storm strength, and I personally don't see much evidence warranting an upgrade to tropical storm status. Upper-tropospheric outflow is well-defined to the north, although there may be a little bit of southerly shear impacting the system at this time, in conjunction with the subtropical ridge to the east.



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

With the cyclone sitting under 29C SSTs and ample oceanic heat content along with low vertical wind shear characterized by a building upper ridge (shown below), the depression appears poised to strengthen. The biggest limiting factor to the cyclone attaining hurricane status is the limited time of water that the system appears to have. The 0z model suite has shifted eastward and show a much faster motion toward the coast, which would greatly limit the prospects for strengthening. In addition, satellite data indicates that the depression has a large and sprawling circulation more characteristic of monsoon depressions in the western north Pacific. Given these factors, it is not likely the cyclone will be able to formulate an inner core before reaching the coast in about 36 hours. The GFS shows the ambient near-storm shear remaining very low even after the system moves inland, with even small patches of near zero vertical shear prevailing across the Gulf of Tehuantepec. Hence, if the depression somehow moves slower than forecast, more strengthening could occur under that paradigm.





Figure 2. Latest (0000 UTC) CIMSS mid- to upper-tropospheric wind analyses compared side by side with earlier (1800 UTC) estimates. The light blue wind barbs denote winds at 100-250 mb, more or less at the approximate "outflow layer", so those are obviously most important. Notice the expansion of the upper-tropospheric outflow during the six hour comparison, signifying better upper ventilation, and thus greater prospects for intensification.

Synoptic data indicate that the depression is moving presumably north-northwest -- though this is hard to gauge given the sprawling nature of the cyclone vortex -- between a mid-level ridge over the western Atlantic extending southward into the western Caribbean Sea, and a mid- to upper-level trough over the Gulf of Mexico. The upper low connecting the trough is forecast to move northward and gradually weaken over the next two days, but enough residual mid-level cyclonicity should be sufficient to help pull the depression slowly inland toward the coast of southern Mexico, especially if it becomes an even deeper system, bearing in mind that the mid- and upper-troposphere normally recovers more slowly than the lower-troposphere. As mentioned earlier, the latest set of track models -- including the typically reliable TVCE model consensus -- has shifted eastward and are much faster toward the coast, with most members taking the depression inland within 24-36 hours. To err on the side of being conservative, I have decided to choose the latter timeframe to pull the tropical depression into the coast. The GFS and ECMWF are still quite divided, with the former bringing the depression inland in 36-48 hours, while the latter shows the cyclone meandering offshore, turning west, and weakening through five days. For what it's worth, the GFDL and HWRF also show a much faster motion toward the coast, making the ECMWF an outlier in this particular forecasting scenario. Given the model consensus biased against the ECMWF, current motion, and large-scale synoptic trends, I prefer to side with the GFS side of things. My forecast is similar to but a little slower and slightly farther west than the latest model consensus.

To my knowledge, if the depression makes landfall along my current forecast track, it will be in the top-five most-eastward landfalling eastern Pacific tropical cyclone, with the most recent hurricane to make landfall in the area between 94 and 97W being Hurricane Carlotta in 2012, which made landfall at 96.9°W.

Given the eastward shift in the track and the potential for the storm to track toward the coast faster than anticipated, the National Hurricane Center has issued a tropical storm warning for a portion of the coast of southern Mexico.

Intensity forecast

Initial 06/03 0300Z 13.8°N 94.2°W 30 kt 35 mph
12 hour 06/03 1200Z 14.2°N 94.6°W 35 kt 40 mph
24 hour 06/04 0000Z 14.8°N 94.7°W 40 kt 45 mph
36 hour 06/04 1200Z 15.6°N 95.0°W 45 kt 50 mph
48 hour 06/05 0000Z 16.5°N 95.1°W 30 kt 35 mph: inland
72 hour 06/06 0000Z 17.1°N 95.1°W 20 kt 25 mph: inland/remnant low
96 hour 06/07 0000Z: dissipated

Track forecast



Figure 3. My forecast track for Tropical Depression Two-E.

NHC storm information

000
WTPZ32 KNHC 030238
TCPEP2

BULLETIN
TROPICAL DEPRESSION TWO-E ADVISORY NUMBER 2
NWS NATIONAL HURRICANE CENTER MIAMI FL EP022014
800 PM PDT MON JUN 02 2014

...TROPICAL STORM WARNING ISSUED FOR PORTIONS OF THE SOUTHERN COAST
OF MEXICO...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...13.8N 94.2W
ABOUT 180 MI...285 KM SSE OF SALINA CRUZ MEXICO
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...NNW OR 330 DEGREES AT 5 MPH...7 KM/H
MINIMUM CENTRAL PRESSURE...1001 MB...29.56 INCHES


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

THE GOVERNMENT OF MEXICO HAS CHANGED THE TROPICAL STORM WATCH TO A
TROPICAL STORM WARNING FROM SALINA CRUZ EASTWARD TO THE
MEXICO/GUATEMALA BORDER.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* SALINA CRUZ TO MEXICO/GUATEMALA BORDER

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA WITHIN 36 HOURS.

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


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 800 PM PDT...0300 UTC...THE CENTER OF TROPICAL DEPRESSION TWO-E
WAS LOCATED NEAR LATITUDE 13.8 NORTH...LONGITUDE 94.2 WEST. THE
DEPRESSION IS MOVING TOWARD THE NORTH-NORTHWEST NEAR 5 MPH...7 KM/H
...AND A TURN TOWARD THE NORTH IS EXPECTED ON TUESDAY. ON THE
FORECAST TRACK...THE CENTER OF THE TROPICAL CYCLONE WILL BE NEAR
THE COAST IN THE WARNING AREA BY EARLY WEDNESDAY.

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

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


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED WITHIN PORTIONS OF THE
WARNING AREA BY LATE TUESDAY NIGHT OR WEDNESDAY.

RAINFALL...GIVEN ITS SLOW NORTHWARD PROGRESSION...TROPICAL
DEPRESSION TWO-E IS EXPECTED TO PRODUCE AS MUCH AS 10 TO 20 INCHES
OF RAIN OVER A LARGE PART OF SOUTHERN MEXICO THROUGH SATURDAY...WITH
ISOLATED AMOUNTS EXCEEDING 30 INCHES LIKELY OVER THE MOUNTAINOUS
TERRAIN OF THE MEXICAN STATES OF OAXACA AND CHIAPAS. TROPICAL
DEPRESSION TWO-E IS ALSO EXPECTED TO PRODUCE TOTAL RAINFALL AMOUNTS
OF 5 TO 10 INCHES IN GUATEMALA. THESE RAINS ARE LIKELY TO RESULT IN
LIFE-THREATENING FLASH FLOODS AND MUD SLIDES.


NEXT ADVISORY
-------------
NEXT INTERMEDIATE ADVISORY...1100 PM PDT.
NEXT COMPLETE ADVISORY...200 AM PDT.

$$
FORECASTER PASCH

2014 Pacific hurricane season Tropical Depression Two-E

Updated: 3:51 AM GMT on June 03, 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.