KoritheMan's WunderBlog

Tropical weather analysis - October 29, 2013

By: KoritheMan, 3:18 AM GMT on October 30, 2013

Raymond

Tropical Storm Raymond continues moving over the open Pacific. As of the latest NHC advisory, the following information was available on the cyclone:

Wind: 45 mph, with higher gusts
Location: 19.1°N 116.2°W
Movement: NNE at 7 mph
Pressure: 1005 mb

After a rather healthy burst of convection overnight, Raymond has again taken on a disheveled appearance. The low-level center has become quite ill-defined, with recent microwave and satellite data suggesting there could be multiple embedded low-level vorticity maximums within the broad cyclonic gyre encompassing the decaying cyclone. Satellite estimates have not changed, but that is following the typical Dvorak constraints; given the lack of convection, I suspect the winds are closer to 30 kt, with perhaps a small area of 35 kt winds still remaining in the remnant convection to the north.



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

The SHIPS and UW-CIMSS data suggest that the shear over Raymond may have decreased somewhat over the last 24 hours, which could explain why the cyclone was able to make a comeback this morning. However, water vapor imagery shows the core of strongest shear still awaits Raymond, and the SHIPS model responds to this by forecasting the 200 mb winds to increase to nearly 50 kt during the next 24 hours; these winds should cause the cyclone to shear off quite quickly. Since the shear is expected to get stronger, Raymond is forecast to dissipate as a tropical cyclone in about 24 hours. If convection redevelops overnight like it did last night, Raymond could hang onto tropical cyclone status for a little bit longer; considering the shear will soon increase to levels it hasn't throughout the storm's 10 day life cycle, I am not expecting this to happen, with the shear likely to override the upper diffluence over the storm.

Raymond's center has become quite difficult to locate; in fact, there's very little evidence of a closed circulation using conventional satellite images, and the center isn't even clear cut on microwave images, which is something that doesn't happen particularly often. Regardless of the exact location, Raymond is expected to continue moving north-northeastward with a gradual decrease in forward speed as it enters an area of weak synoptic steering southwest of Baja. The models have come into better agreement on the track, with the GFDL no longer a southern outlier. My forecast track now shows Raymond successfully getting above 20N, but is still not quite as far north as the latest NHC prediction.

Intensity forecast and positions

INITIAL 10/30 0300Z 19.1°N 116.2°W 40 KT 45 MPH
12 hour 10/30 1200Z 19.7°N 115.9°W 30 KT 35 MPH
24 hour 10/31 0000Z 20.3°N 115.7°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
36 hour 10/31 1200Z 20.7°N 115.6°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
48 hour 11/01 0000Z 21.1°N 115.5°W 20 KT 25 MPH...POST-TROPICAL/REMNANT LOW
72 hour 11/02 0000Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Raymond.



Elsewhere

An area of disturbed weather appears to have formed several hundred miles south of Acapulco. Shower activity is currently poorly-organized, upper-level winds are forecast to support gradual development of this disturbance as it heads west-northwest and then northwestward. In about five days, the GFS suggests there could be a tropical storm approaching southern Baja California, and the 500 mb pattern definitely supports this prospect. Interests from Manzanillo to the Cabo San Lucas area should closely monitor the progress of this disturbance over the next several days. Regardless of development, this low is expected to bring locally heavy rainfall to much of the southern and southwest coast of Mexico.

Probability of development in 48 hours: 10%

2013 Pacific hurricane season Tropical Storm Raymond

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Tropical weather analysis - October 28, 2013

By: KoritheMan, 2:30 AM GMT on October 29, 2013

Raymond

Raymond continues to weaken. As of the 2100Z NHC advisory, the following coordinates were given on the cyclone:

Wind: 70 mph, with higher gusts
Location: 16.8°N 116.9°W
Movement: N at 7 mph
Pressure: 993 mb

Satellite estimates have continued to plummet as fast as Dvorak constraints allow, with TAFB and SAB coming in with a mutual 3.0 as of 0z. This suggests that Raymond has weakened since the 21Z NHC advisory, and it will be interesting to see what they assign as the initial intensity during the upcoming 0300Z advisory.



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

Satellite images show that the low-level center is completely exposed to the southwest of the remaining convection which continues to get sheared away due to about 25 kt of southwesterly shear as analyzed by the SHIPS model. The models show the shear increasing further, with water vapor animations continuing to strongly indicate that the winds are more likely to rise to around 35 kt during the next 24 hours. The shear, in combination with sea surface temperatures that are already starting to cool, and increasingly marginal thermodynamic profiles, should act to quickly stop the heartbeat of already half dead Raymond. Given the environment, Raymond is expected to lose its nominal status as a tropical cyclone in roughly 48 hours, but there is of course a decent chance that this will occur in as little as 36 hours. The remnant low is forecast to meander and completely lose its identity over the open Pacific well south of Baja California beyond day four.

With the center now exposed, Raymond's motion is easier to determine, and it appears to be due northward. If not for the lack of convection, there would likely be a more east of north track as of now, but there still appears to be a decent ridge around 850 mb that is preventing Raymond from moving poleward for now. Regardless, Raymond should turn northeastward very soon as the trough appears to be gradually exerting its influence even as far down the troposphere as 850 mb, albeit more slowly than heights above that level. The models continue to agree on this general scenario, with the primary difference being whether or not Raymond makes it above 20N, or remains below that latitudinal line. The GFS ECMWF, and HWRF show Raymond getting above 20N during the next 48 hours, while the GFDL does not indicate Raymond making it quite that far north. Despite the historical reliability of the GFS and ECMWF, I feel the GFDL has a better handle on the situation given the still persistent ridge in the lower troposphere, as well as the hostile conditions that prevail along the forecast track. This leads to my forecast track being a shade south of the current NHC prediction, opting instead to show an eastward drift prior to dissipation in deference to the GFDL.

Intensity forecast and positions

INITIAL 10/29 0300Z 17.1°N 117.0°W 60 KT 70 MPH
12 hour 10/29 1200Z 17.8°N 116.7°W 45 KT 50 MPH
24 hour 10/30 0000Z 18.6°N 116.2°W 35 KT 40 MPH
36 hour 10/30 1200Z 19.3°N 115.7°W 30 KT 35 MPH
48 hour 10/31 0000Z 19.5°N 115.6°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
72 hour 11/01 0000Z 19.5°N 115.4°W 20 KT 25 MPH...POST-TROPICAL/REMNANT LOW
96 hour 11/02 0000Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Raymond.

2013 Pacific hurricane season Tropical Storm Raymond

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Tropical weather analysis - October 28, 2013

By: KoritheMan, 7:09 AM GMT on October 28, 2013

Raymond

Hurricane Raymond continues moving across the open eastern Pacific with no consequence to land. As of the 0300Z NHC advisory, the following information was available on the hurricane:

Wind: 105 mph, with higher gusts
Location: 15.3°N 116.8°W
Movement: NNW at 9 mph
Pressure: 972 mb
Category: 2 (Saffir-Simpson Hurricane Wind Scale)

Satellite estimates have not changed, with the latest TAFB and SAB estimate (6z) coming in at 5.0, or 90 kt. While the convective pattern of Raymond has begun to deteriorate as southwesterly shear increases, recent microwave data does not show that this shear has penetrated the core of the hurricane just yet. However, there is some indication from satellite imagery that the mid-level eye could be exhibiting a bit of a northeastward displacement from the low-level one due to the increasing shear. Oddly enough, a 0444Z AMSU pass indicated that the heaviest rains and convection are occurring in the western eyewall, which is a little puzzling given the shear is coming from that direction.



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

Raymond had a good run, becoming the first major hurricane to form in the Western Hemisphere during 2013 and all, but its legacy is coming to an end. The SHIPS/GFS show the shear increasing to at least 30 kt over the next 24 hours and remaining that way for a few days; in fact, water vapor animations suggest it could get even stronger. A drier airmass and gradually cooling sea surface temperatures await the hurricane farther north during its recurvature as well, and my forecast follows this reasoning by taking the projected intensity just a shade lower than the National Hurricane Center. Raymond is forecast to become a remnant low in about 72 hours, although there is a chance it could occur.

Raymond still appears to be moving north-northwestward, but with the center still under the convection and the lack of any comparable microwave passes other than the AMSU one makes this estimate somewhat difficult to be sure of. Regardless, water vapor imagery shows a large upper-level trough amplifying over the western United States digging southward. Mid-level southwesterly flow radiates quite far south from the axis of this feature, and this is shunting the ridge to the north of the hurricane steadily eastward. This pattern should result in Raymond turning northward very soon, followed by a sharp recurvature around the western periphery of the ridge. A few days ago Raymond would not have gained as much latitude, but its abrupt intensification episode over the last 24 hours makes recurvature prior to dissipation a viable scenario. The guidance continues to be in good agreement that Raymond's low-level vortex will shear apart and stall as the cyclone becomes devoid of convection, with the primary difference being a matter of latitude. The GFS continues to be farther north than the ECMWF, but that model has a historical tendency to overamplify troughs and tropical cyclones' response to them, so I tend to side with the latter.

Intensity forecast and positions

INITIAL 10/28 0600Z 15.8°N 117.1°W 90 KT 105 MPH
12 hour 10/28 1800Z 16.6°N 117.2°W 80 KT 90 MPH
24 hour 10/29 0600Z 17.4°N 117.1°W 55 KT 65 MPH
36 hour 10/29 1800Z 17.8°N 117.0°W 40 KT 45 MPH
48 hour 10/30 0600Z 18.2°N 116.7°W 30 KT 35 MPH
72 hour 10/31 0600Z 18.5°N 116.6°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
96 hour 11/01 0600Z 18.7°N 116.4°W 20 KT 25 MPH...POST-TROPICAL/REMNAN LOW
120 hour 11/02 0600Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Raymond.



Elsewhere

Elsewhere in the tropics, the GFS and ECMWF hint that a broad area of low pressure could form off the coast of southern Mexico during the next few days. Upper-level winds appear diffluent enough for some development of this low if it manifests, although the amount of growth will rest strongly on how close the system parallels the coast of Mexico.

This system is expected to move west-northwest to northwestward, and may threaten southern Baja in a week or so.

2013 Pacific hurricane season Hurricane Raymond

Updated: 7:14 AM GMT on October 28, 2013

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Tropical weather analysis - October 26, 2013

By: KoritheMan, 4:03 AM GMT on October 27, 2013

Raymond

Tropical Storm Raymond is finally intensifying again. As of the 0300Z NHC advisory that was just released, the following information became available on the tropical cyclone:

Wind: 65 mph, with higher gusts
Location: 13.2°N 114.3°W
Movement: W at 10 mph
Pressure: 997 mb

The cloud pattern has become much better organized, with a large curved band wrapping cyclonically into the center; in addition, recent microwave data shows the beginnings of a primitive eyewall, a feature which is also shown on infrared imagery to a degree. Satellite estimates have escalated in response, with the latest estimate from TAFB coming in at 3.5.



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

Since Raymond appears to have finally responded to the favorable environment, we won't look like fools for forecasting intensification. My forecast again calls for Raymond to become a marginal hurricane, although my peak is a little higher than the one from the National Hurricane Center in deference to the impressive inner core seen on microwave images. After about 24 hours, the GFS/SHIPS show southerly to southwesterly shear increasing abruptly and significantly ahead of a large mid- to upper-level trough that water vapor imagery shows is diving southeastward toward Raymond at a faster forward speed than what has been observed over the last several days. The shear is likely to increase to at least 30 kt over Raymond; in addition, the cyclone will be traversing a somewhat more marginal thermodynamic environment characterized by dry air at longer ranges, which should hasten the weakening process. Raymond is forecast to decay into a remnant low in about four days, although there is a chance it could occur sooner if the shear becomes stronger than expected.

Raymond has been moving nearly due westward all day, not gaining much latitude. However, the deep-layer ridge that has been responsible for this motion is steadily shifting eastward as the aforementioned trough amplifies southeastward. This evolution should soon result in a turn to the west-northwest at about the same forward speed over the next day or so. After that time, the global models show Raymond approaching a substantial break in the subtropical ridge near and to the east of 120W. Raymond is likely to recurve into that weakness, probably before complete dissipation as a tropical cyclone. There is less contrast between the GFS and ECMWF than there was yesterday, and both models now agree on the shear apart and stall scenario as Raymond gets stripped of its convection and becomes a vertically shallow system. My forecast track is largely similar to the one just published by the National Hurricane Center, showing a southward drift of Raymond at longer ranges.

Intensity forecast and positions

INITIAL 10/27 0300Z 13.2°N 114.3°W 55 KT 65 MPH
12 hour 10/27 1200Z 13.5°N 115.5°W 60 KT 70 MPH
24 hour 10/28 0000Z 14.4°N 116.6°W 70 KT 80 MPH
36 hour 10/28 1200Z 15.2°N 117.3°W 70 KT 80 MPH
48 hour 10/29 0000Z 16.2°N 117.5°W 60 KT 70 MPH
72 hour 10/30 0000Z 17.3°N 116.9°W 40 KT 45 MPH
96 hour 10/31 0000Z 17.7°N 116.7°W 30 KT 35 MPH...POST-TROPICAL/REMNANT LOW
120 hour 11/01 0000Z 17.4°N 116.6°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW

Track forecast



Figure 2. My forecast track for Raymond.

2013 Pacific hurricane season Tropical Storm Raymond

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Tropical weather analysis - October 26, 2013

By: KoritheMan, 4:59 AM GMT on October 26, 2013

Raymond

Tropical Storm Raymond continues to move over the open Pacific well away from any land areas. As of the latest NHC advisory, the following information was posted on the storm:

Wind: 50 mph, with higher gusts
Location: 12.9°N 110.8°W
Movement: WSW at 10 mph
Pressure: 1000 mb

Raymond has mysteriously not strengthened in what I would deem as a favorable environment. A blend of the various satellite estimates suggests that the NHC's operational intensity of 45 kt is probably a decent one, A 1630Z ASCAT pass captured the circulation of Raymond and indicates that it has become less-defined, and that the winds may not even be 40 kt, much less 45 kt.



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

Raymond's cloud pattern is a little amorphous-looking, with microwave data suggesting the center lies along the northern edge of the small area of central convection. In addition, the orientation of the large and linear convective band to the south kind of gives the hint that Raymond may be caught up in the ITCZ. While there's not a ton of evidence to support this assertion, it is a possibility; additionally, northeasterly shear appears to be affecting the cyclone due to a deep-layer ridge over the Gulf of Mexico. Since there does not appear to be enough dry air in the near storm environment to cause the disheveled appearance of the cyclone, and since the waters are warm, the aforementioned factors are the best in situ explanations I can infer; perhaps a post-season analysis by the National Hurricane Center and yours truly will shed some light on the situation.

The above factors notwithstanding, all known meteorological parameters appear conducive for strengthening, and Raymond is still forecast to regain hurricane strength in a couple of days. After that time, the SHIPS and GFS show southerly shear increasing significantly as a mid- to upper-level trough currently off the coast of California digs southward over the subtropical Pacific. In addition, waters will gradually cool and the air will become less buoyant, both of which should aid the shear in what should be a rather quick decapitation of Raymond at longer ranges. Raymond is anticipated to become a remnant low on day five, but it could occur as much as 24 hours sooner.

Based on a couple of microwave passes over the last few hours, Raymond appears to have continued to move west-southwest. However, Raymond is about to encounter a steering change that goes from southeasterly to easterly as the ridge stabilizes and the cyclone moves underneath its southern periphery. This should cause Raymond to assume a due westward motion over the next 24-36 hours. Subsequent to that period, Raymond is expected to encounter a well-established break in the subtropical ridge near 120W and turn northward and northeastward. The GFS continues to be significantly faster than the ECMWF, taking Raymond to a landfall in southern Baja in five days as Raymond follows the trough. The ECMWF shows a somewhat weaker Raymond at those time ranges that appears more reasonable given current and expected forecast trends, and my forecast is close to the National Hurricane Center prediction, and leans more strongly to the ECMWF scenario of a shear apart and stall situation.

Raymond is not very likely to make landfall in Baja as a tropical cyclone, much less reach the latitude and longitude of that peninsula.

Intensity forecast and positions

INITIAL 10/26 0300Z 12.7°N 111.0°W 45 KT 50 MPH
12 hour 10/25 1200Z 12.7°N 112.7°W 45 KT 50 MPH
24 hour 10/27 0000Z 12.7°N 114.6°W 50 KT 60 MPH
36 hour 10/26 1200Z 12.9°N 116.0°W 55 KT 65 MPH
48 hour 10/28 0000Z 14.1°N 117.2°W 65 KT 75 MPH
72 hour 10/29 0000Z 16.7°N 116.7°W 55 KT 65 MPH
96 hour 10/30 0000Z 18.2°N 115.8°W 40 KT 45 MPH
120hour 10/31 0000Z 19.0°N 114.8°W 30 KT 35 MPH...POST-TROPICAL/REMNANT LOW

Track forecast



Figure 2. My forecast track for Raymond.

2013 Pacific hurricane season Tropical Storm Raymond

Updated: 8:24 AM GMT on October 26, 2013

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Tropical weather analysis - October 23, 2013

By: KoritheMan, 6:10 AM GMT on October 25, 2013

Raymond

Tropical Storm Raymond is intensifying again. As of the latest NHC advisory, the following information was posted on the storm:

Wind: 60 mph, with higher gusts
Location: 14.6°N 107.7°W
Movement: W at 10 mph
Pressure: 998 mb

After its rather abrupt weakening episode the other day, Raymond has made a significant comeback this evening. Although the cloud pattern is still a little ragged, there is a somewhat broken curved band to the west. Satellite estimates range from 3.5 from TAFB to 3.0 with SAB, and an objective UW-CIMSS ADT estimate gave 55 kt. Based on the cloud pattern and the lack of a distinct inner core in the latest microwave images, I prefer the lower end of the satellite estimates.



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

Upper-level outflow has expanded significantly to the west, indicating that the upper flow has transitioned from southwesterly to a more favorable southeasterly. While the upper air environment seen on the GFS model is not the most anticyclonic I've seen, it does appear to at least be diffluent and of fairly light shear. This pattern should allow Raymond to reintensify, and my forecast calls for the cyclone to regain hurricane strength in about 48 hours, although there is a chance it could occur a little sooner. By day four, southerly shear is forecast to increase ahead of a large upper-level trough digging over the eastern Pacific west of Baja California, and Raymond is anticipated to respond by weakening; the environmental airmass will also become drier at that point as sea surface temperatures begin to cool.

Raymond's center has been very difficult to find, and my personal position (shown below) was based heavily on extrapolation of the position given from the 0300Z NHC advisory. It has been equally hard to determine which direction Raymond is moving, but based on the environmental steering flow seen on UW-CIMSS steering data, a south of west motion may be the best estimate. The global models show the rather strong subtropical ridge anchored to the north of Raymond expanding westward ahead of the storm over the next few days, which should cause Raymond to move west-southwestward and then westward as the ridge stabilizes. Guidance is in good agreement on the track out to three days. While there remains some divergence thereafter, in general the guidance continues to trend toward the trough being strong enough to capture Raymond. My forecast will do the same, although will be a little more conservative in pulling Raymond up into the southwesterly flow connected to that trough until I can more confidently determine how strong the trough is going to be at those large timeframes.

It is unlikely Raymond will be a tropical cyclone of any kind if the trough somehow captures it and sends it to Baja.

Intensity forecast and positions

INITIAL 10/25 0600Z 14.5°N 107.8°W 50 KT 60 MPH
12 hour 10/25 1800Z 14.3°N 109.6°W 50 KT 60 MPH
24 hour 10/26 0600Z 14.1°N 111.1°W 55 KT 65 MPH
36 hour 10/26 1800Z 13.8°N 112.8°W 60 KT 70 MPH
48 hour 10/27 0600Z 13.6°N 115.2°W 65 KT 75 MPH
72 hour 10/28 0600Z 13.9°N 118.3°W 75 KT 85 MPH
96 hour 10/29 0600Z 14.7°N 119.7°W 75 KT 85 MPH
120hour 10/30 0600Z 16.3°N 119.9°W 60 KT 70 MPH

Track forecast



Figure 2. My forecast track for Raymond.

2013 Pacific hurricane season Tropical Storm Raymond

Updated: 6:22 AM GMT on October 25, 2013

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Tropical weather analysis - October 22, 2013

By: KoritheMan, 4:10 AM GMT on October 23, 2013

Lorenzo

Tropical Storm Lorenzo continues to march inconsequentially across the central Atlantic. As of the latest NHC advisory, the following information was posted on this system:

Wind: 50 mph, with higher gusts
Location: 29.6°N 50.0°W
Movement: E at 9 mph
Pressure: 1003 mb

The center has been a little difficult to locate this evening, but it appears to be exposed to the west of the convection once again due to rapidly increasing northwesterly vertical wind shear, analyzed at 25 kt by UW-CIMSS. The convection has become rather elongated, and consists of little to no banding. Satellite estimates still support an intensity of 45 kt for now, but these winds will likely decline soon.



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

The SHIPS and GFS show the shear increasing to nearly 40 kt over the next 24 hours, which is likely to cause a quick demise of this tropical cyclone. My forecast is a little lower than the latest NHC prediction, but I agree that Lorenzo is going to lose its identity by 72 hours. There still does not appear to be enough baroclinicity in the environment to cause Lorenzo to become extratropical later in the period, so remnant low status is still my preference.

Lorenzo appears to be moving generally eastward to the north of a rather flat mid-level ridge over the central Atlantic. The guidance suggests that Lorenzo will turn east-northeast and northeastward soon as broad troughing develops to the north. The trough doesn't appear especially sharp, however, and my feeling is that Lorenzo will stay a little to the south of the guidance.

Intensity forecast and positions

INITIAL 10/23 0300Z 29.6°N 50.0°W 45 KT 50 MPH
12 hour 10/23 1200Z 29.7°N 49.2°W 40 KT 45 MPH
24 hour 10/24 0000Z 30.2°N 48.0°W 30 KT 35 MPH
36 hour 10/24 1200Z 30.9°N 46.8°W 25 KT 30 MPH
48 hour 10/25 0000Z 31.9°N 45.2°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
72 hour 10/26 0000Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Tropical Storm Lorenzo. Image credit: NOAA's Satellite Services Division (SSD).



Raymond

Raymond continues to meander as a hurricane just off the southern Mexican coast. As of the latest NHC advisory, the following information was posted on the hurricane:

Wind: 75 mph, with higher gusts
Location: 16.2°N 101.8°W
Movement: Stationary
Pressure: 987 mb
Category: 1 (Saffir-Simpson Hurricane Wind Scale)

Raymond's satellite appearance has degraded a little this evening. There has been a reduction of the central dense overcast, and the small eye is no longer apparent using conventional satellite images. In addition, recent microwave data suggests that the inner core is slowly becoming less defined, with the fragmenting eye open to the southwest due to persistent southwesterly shear. A 0z satellite classification from TAFB suggests that Raymond is still a minimal hurricane, which seems reasonable.



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

In addition to the shear, it is likely that Raymond's rather abrupt weakening over the last 24 hours is due to cold water upwelling to the slow motion of the tropical cyclone. While Raymond should soon move westward away from the cold water upwelling it has likely created, water vapor and TPW imagery show a rather dry airmass not far to the west of the hurricane. This is likely to bring about slow weakening, even though the waters will remain quite warm and the shear could decrease a little. My forecast is a little lower than the NHC prediction, taking Raymond to 50 kt in 36 hours, and holding it steady thereafter. I have no idea how Raymond is going to respond to the dry environment, but I'm confident the warm SSTs will continue to support sustained convection even amidst the marginal thermodynamics. However, this forecast is of low confidence, and restrengthening or further weakening is possible at longer ranges.

Raymond appears to be lounging around again, with little net motion apparent other than a small southeastward drift. The hurricane is still locked firmly in a well-defined col region, but water vapor imagery shows the beginnings of the much advertised mid-level ridging, which should cause the hurricane to bend southwest to west-southwest soon. Later in the period, Raymond's motion is expected to bend more poleward as the hurricane encounters a break in the subtropical ridge. It is too early to determine the precise details of the poleward turn, and whether Raymond will continue toward Baja or move south under a blocking high, as the guidance currently suggests.

Intensity forecast and positions

INITIAL 10/23 0300Z 16.2°N 101.8°W 65 KT 75 MPH
12 hour 10/23 1200Z 16.0°N 102.1°W 60 KT 70 MPH
24 hour 10/24 0000Z 16.8°N 103.0°W 55 KT 65 MPH
36 hour 10/24 1200Z 16.5°N 104.5°W 50 KT 60 MPH
48 hour 10/25 0000Z 16.2°N 106.2°W 50 KT 60 MPH
72 hour 10/26 0000Z 15.9°N 109.3°W 50 KT 60 MPH
96 hour 10/27 0000Z 15.7°N 113.1°W 50 KT 60 MPH
120hour 10/28 0000Z 16.2°N 116.8°W 50 KT 60 MPH

Track forecast



Figure 4. My forecast track for Raymond.

NHC storm information


000
WTPZ32 KNHC 230243
TCPEP2

BULLETIN
HURRICANE RAYMOND ADVISORY NUMBER 13
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172013
800 PM PDT TUE OCT 22 2013

...RAYMOND EXPECTED TO BEGIN MOVING AWAY FROM THE COAST OF MEXICO ON
WEDNESDAY...
...HEAVY RAIN THREAT TO CONTINUE...

SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...16.2N 101.8W
ABOUT 105 MI...170 KM S OF ZIHUATANEJO MEXICO
ABOUT 135 MI...215 KM WSW OF ACAPULCO MEXICO
MAXIMUM SUSTAINED WINDS...75 MPH...120 KM/H
PRESENT MOVEMENT...STATIONARY
MINIMUM CENTRAL PRESSURE...987 MB...29.15 INCHES


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

THE GOVERNMENT OF MEXICO HAS REPLACED THE HURRICANE WARNING
FROM TECPAN DE GALEANA TO LAZARO CARDENAS WITH A TROPICAL
STORM WARNING. THE HURRICANE WATCH FROM ACAPULCO TO TECPAN
DE GALEANA HAS BEEN DISCONTINUED.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

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

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 HURRICANE RAYMOND WAS
LOCATED NEAR LATITUDE 16.2 NORTH...LONGITUDE 101.8 WEST. RAYMOND
REMAINS NEARLY STATIONARY...AND LITTLE MOTION IS EXPECTED OVERNIGHT.
A SLOW MOTION TOWARD THE WEST-SOUTHWEST IS EXPECTED TO BEGIN EARLY
WEDNESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 75 MPH...120 KM/H...WITH HIGHER
GUSTS. SOME WEAKENING IS FORECAST DURING THE NEXT DAY OR TWO...AND
RAYMOND IS EXPECTED TO WEAKEN TO A TROPICAL STORM ON WEDNESDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 25 MILES...35 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 80
MILES...130 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 987 MB...29.15 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...RAYMOND IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 5 TO
10 INCHES WITH ISOLATED AMOUNTS OF UP TO 15 INCHES OVER THE MEXICAN
STATES OF GUERRERO AND MICHOACAN. THESE RAINS COULD PRODUCE LIFE-
THREATENING FLASH FLOODS AND MUD SLIDES.

WIND...TROPICAL STORM CONDITIONS ARE EXPECTED IN SQUALLS ALONG
PORTIONS OF THE COAST WITHIN THE WARNING AREA TONIGHT AND WEDNESDAY.

STORM SURGE...SOME COASTAL FLOODING IS STILL POSSIBLE IN AREAS OF
ONSHORE WINDS WITHIN THE WARNING AREA.

SURF...SWELLS GENERATED BY RAYMOND ARE PRODUCING LARGE AND DANGEROUS
WAVES ALONG PORTIONS OF THE SOUTH-CENTRAL COAST OF MEXICO...WHICH
COULD CAUSE LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. FOR
MORE INFORMATION...PLEASE CONSULT PRODUCTS FROM YOUR NATIONAL
METEOROLOGICAL SERVICE.


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

$$
FORECASTER BROWN

2013 Atlantic hurricane season 2013 Pacific hurricane season Tropical Storm Lorenzo Hurricane Raymond

Permalink

Tropical weather analysis - October 22, 2013

By: KoritheMan, 7:03 AM GMT on October 22, 2013

Lorenzo

Tropical Storm Lorenzo continues to move across the central Atlantic well southeast of Bermuda. As of the latest NHC advisory, the following information was posted on the cyclone:

Wind: 40 mph, with higher gusts
Location: 29.3°N 53.8°W
Movement: NE at 9 mph
Pressure: 1008 mb

There are no indications from recent scatterometer data or satellite estimates that Lorenzo has become any stronger since the 0300Z NHC advisory. Satellite and microwave imagery suggest that the low-level center remains exposed to the west of the deep convection due to moderate westerly shear. However, the banding to the east has been rather persistent, and Lorenzo is carrying a large area of thunderstorms with it.



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

There is evidence on water vapor imagery that the upper flow may be switching to northwesterly a little sooner than forecast by the GFS. In this situation, a northwesterly shear is probably more detrimental than a westerly one, although there is a short window for Lorenzo to gain a little bit of strength before the shear becomes prohibitively strong in the next 24 hours. After that time, weakening is forecast, with Lorenzo expected to completely dissipate by 96 hours, although the global models suggest this could occur sooner. There does not appear that there will be enough baroclinic forcing associated with the trough moving into the western Atlantic to cause Lorenzo to become extratropical, so I will instead indicate remnant low status at 72 hours to reflect that likelihood.

Lorenzo has been moving essentially in obedience with recent model projections, and the steering pattern appears fairly straightforward. The tropical storm is forecast to accelerate toward the east-northeast over the next couple of days as large-scale southwesterly flow increases ahead of the aforementioned trough. The guidance remains in good agreement with this general evolution, although I would not be surprised if Lorenzo ended up tracking south of my forecast in the end, as the upper flow to the north of the system is still not quite suggestive of Lorenzo immediately accelerating.

Intensity forecast and positions

INITIAL 10/22 0600Z 29.4°N 53.5°W 35 KT 40 MPH
12 hour 10/22 1800Z 29.8°N 52.2°W 35 KT 40 MPH
24 hour 10/23 0600Z 30.0°N 51.0°W 35 KT 40 MPH
36 hour 10/23 1800Z 30.5°N 49.5°W 35 KT 40 MPH
48 hour 10/24 0600Z 30.9°N 48.4°W 30 KT 35 MPH
72 hour 10/25 0600Z 32.3°N 45.7°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
96 hour 10/26 0600Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Lorenzo.


Raymond

Hurricane Raymond continues to meander just off the south coast of Mexico. As of the latest NHC advisory, the following information was available on the hurricane:

Wind: 120 mph, with higher gusts
Location: 16.5°N 101.9°W
Movement: N at 2 mph
Pressure: 954 mb

The brief weakening episode that occurred Monday evening was likely the result of an eyewall replacement cycle. Recent microwave data implies that this cycle has culminated. The hurricane has changed little over the last several hours, with the ragged eye occasionally escaping from beneath the high cloud canopy. It should be noted that the small eye remains very well-defined in microwave imagery.



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

The likely completion of the concentric eyewall cycle notwithstanding, Raymond has presumably peaked in intensity. For one thing, the hurricane has been meandering within miles of itself over the last 24 hours; even the impenetrable Pacific basin, which normally supports deep warm water, cannot withstand a beating from such a brutal hurricane for long. For another, there appears to be some southerly shear affecting Raymond, and the GFS has not picked up on this shear particularly well. I don't think the shear is strong enough to permeate the core and cause a hasty demise, but it's anything but positive considering that the cyclone is likely mixing cooler waters to the surface. Lastly, although the core itself is rather small, at least a portion of the outer circulation associated with Raymond is interacting with the coast. In their totality, these factors will likely arrest any restrengthening. Later in the period, although waters only cool very gradually, dry air and increasing westerly shear are likely to cause slow weakening. Nevertheless, Raymond is expected to remain a hurricane throughout the next five days.

Raymond has been meandering again, with an eastward jog apparent several hours ago in microwave and satellite data, but the motion appears to have stabilized again, with Raymond now moving northward at a snail's pace. Raymond is caught between mid-level ridges to the east and west, and a distant trough over the southern United States. This col environment is not going to allow the hurricane to move anywhere anytime soon, and my forecast shows no movement for the first 24 hours, but there will of course likely be wobbles. It no longer appears likely that Raymond will make a landfall or come within arm's reach of the coast, and even the GFDL and HWRF have backed off on taking the system inland. Subsequent to the first 24 hours of the forecast, Raymond is expected to gradually pick up speed as a rather strong mid-tropospheric ridge manifests to the north of the hurricane. The guidance remains in good agreement on the synoptic evolution, and my forecast track closely follows them. Some of the models suggest that Raymond could start to move northward again beyond day five as it comes under the influence of another trough, but it is far too early to determine the extent, or even the existence, of that turn.

Hurricane warnings remain in effect for a portion of the coast of southern Mexico. Although Raymond now appears unlikely to make a landfall, little net motion of the hurricane is anticipated over the next 24 hours, which will prolong the threat of torrential rains, flash flooding and mudslides, and strong winds. Sustained tropical storm force winds are likely to remain just off the coast also, but any continual northward deviations to the forecast track may bring these winds onshore.

Intensity forecast and positions

INITIAL 10/23 0600Z 16.6°N 101.9°W 105 KT 120 MPH
12 hour 10/23 1800Z 16.6°N 101.9°W 105 KT 120 MPH
24 hour 10/24 0600Z 16.5°N 101.9°W 100 KT 115 MPH
36 hour 10/24 1800Z 16.5°N 101.4°W 90 KT 105 MPH
48 hour 10/25 0600Z 16.4°N 103.0°W 85 KT 100 MPH
72 hour 10/26 0600Z 16.3°N 104.9°W 80 KT 90 MPH
96 hour 10/27 0600Z 16.3°N 106.5°W 70 KT 80 MPH
120hour 10/28 0600Z 16.1°N 108.9°W 65 KT 75 MPH

Track forecast



Figure 4. My forecast track for Raymond.

NHC storm information

000
WTPZ32 KNHC 220533
TCPEP2

BULLETIN
HURRICANE RAYMOND INTERMEDIATE ADVISORY NUMBER 9A
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172013
1100 PM PDT MON OCT 21 2013

...RAYMOND DRIFTING ERRATICALLY WHILE CONTINUING TO CAUSE HEAVY
RAINS OVER PORTIONS OF SOUTH-CENTRAL MEXICO...


SUMMARY OF 1100 PM PDT...0600 UTC...INFORMATION
-----------------------------------------------
LOCATION...16.5N 101.9W
ABOUT 85 MI...135 KM SSW OF ZIHUATANEJO MEXICO
ABOUT 135 MI...220 KM WSW OF ACAPULCO MEXICO
MAXIMUM SUSTAINED WINDS...120 MPH...195 KM/H
PRESENT MOVEMENT...N OR 360 DEGREES AT 2 MPH...4 KM/H
MINIMUM CENTRAL PRESSURE...954 MB...28.17 INCHES


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

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* TECPAN DE GALEANA TO LAZARO CARDENAS

A HURRICANE WATCH IS IN EFFECT FOR...
* ACAPULCO TO TECPAN DE GALEANA

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* ACAPULCO TO TECPAN DE GALEANA

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 HURRICANE RAYMOND WAS
LOCATED NEAR LATITUDE 16.5 NORTH...LONGITUDE 101.9 WEST. RAYMOND
HAS BEEN DRIFTING NORTHWARD AT 2 MPH...4 KM/H...OVER THE PAST FEW
HOURS. A SLOW AND ERRATIC MOTION IS EXPECTED DURING THE NEXT DAY
OR SO...AND RAYMOND COULD MOVE CLOSER TO THE COAST OF MEXICO WITHIN
THE HURRICANE WARNING AREA ON TUESDAY. A SLOW MOTION TOWARD THE
WEST IS EXPECTED TO BEGIN ON WEDNESDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 120 MPH...195 KM/H...WITH HIGHER
GUSTS. RAYMOND IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON
HURRICANE WIND SCALE. GRADUAL WEAKENING IS EXPECTED DURING THE NEXT
COUPLE OF DAYS...HOWEVER RAYMOND IS FORECAST TO REMAIN A STRONG
HURRICANE THROUGH WEDNESDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 25 MILES...35 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 80
MILES...130 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 954 MB...28.17 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...RAYMOND IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 4 TO 8
INCHES WITH ISOLATED AMOUNTS OF UP TO 12 INCHES OVER THE MEXICAN
STATES OF GUERRERO AND MICHOACAN. THESE RAINS COULD PRODUCE LIFE-
THREATENING FLASH FLOODS AND MUD SLIDES.

WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO BEGIN IN PORTIONS
OF THE WARNING AREA BY EARLY TUESDAY. HURRICANE CONDITIONS
MAY OCCUR IN PORTIONS OF THE HURRICANE WARNING AREA ON TUESDAY IF
THE CENTER OF RAYMOND MOVES CLOSER TO THE COAST THAN CURRENTLY
FORECAST.

STORM SURGE...A STORM SURGE IS EXPECTED TO PRODUCE SIGNIFICANT
COASTAL FLOODING IN AREAS OF ONSHORE WINDS WITHIN THE WARNING AREAS.
NEAR THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND
DESTRUCTIVE WAVES.

SURF...SWELLS GENERATED BY RAYMOND ARE AFFECTING PORTIONS OF THE
SOUTH-CENTRAL COAST OF MEXICO. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. FOR MORE
INFORMATION...PLEASE CONSULT PRODUCTS FROM YOUR NATIONAL
METEOROLOGICAL SERVICE.


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

$$
FORECASTER PASCH

2013 Atlantic hurricane season 2013 Pacific hurricane season Tropical Storm Lorenzo Hurricane Raymond

Updated: 7:10 AM GMT on October 22, 2013

Permalink

Tropical weather analysis - October 21, 2013

By: KoritheMan, 5:40 AM GMT on October 21, 2013

Raymond

Potentially dangerous Hurricane Raymond is intensifying not too far off the southern coast of Mexico. As of the latest NHC advisory, the following information was posted on the hurricane:

Wind: 100 mph, with higher gusts
Location: 15.9°N 102.0°W
Movement: N at 6 mph
Pressure: 975 mb
Category: 2 (Saffir-Simpson Hurricane Wind Scale)

While the 06z satellite estimates from TAFB and SAB have yet to be released, a recent CIMSS ADT estimate gave an intensity of 100 kt using the raw numbers, or the bottom of major hurricane strength. The satellite presentation of Raymond is impressive, with a 15 to 20 mile wide eye surrounded by a ring of deep convection. Upper-tropospheric outflow is well-defined with the hurricane, particularly to the west and north, where the subtropical jet appears to be energizing and amplifying the poleward outflow. A 0348 UTC AMSU microwave pass suggests that the tight inner core continues to become better defined.



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

Raymond appears to be undergoing a classic rapid intensification episode, and the hurricane is likely to get stronger; I am certainly not going to deify myself and assert with any certainty just how strong, however. Since ocean temperatures are around 30°C and the vertical shear is low, there should be nothing to deter or prevent this episode from continuing. My forecast is well above the intensity consensus, explicitly showing Raymond becoming a Category 4 hurricane in about 36 hours. Given current trends, there exists the possibility that Raymond could actually get a little stronger than even this. Beyond that time, while the waters will stay quite warm along the projected path of the hurricane, interaction with the mountains of southern Mexico and possible inner core fluctuations will likely cause Raymond to weaken. In addition, water vapor imagery shows increasing westerly shear near the longitude Raymond is expected to be by days four and five, which, while not quite shown in the GFS as of now, could cut a sizable chunk of Raymond's health. There is also a drier airmass to the west of the hurricane, and Raymond will likely ingest this subsident flow once it begins to accelerate westward at longer ranges. I should note that I don't have much confidence in my intensity forecast, particularly during the weakening portion.

Recent satellite fixes suggest that Raymond has jogged a little west of due north, but the general motion has been, for the most part, nearly due northward. Water vapor imagery shows a gradually amplifying trough along the southern United States, which is expected to pick up Raymond and turn it toward the coast. Although the models agree with the actual scenario, there are considerable differences in regards to the timing and sharpness of the northeastward turn, as well as how far to the right Raymond gets before a mid-level ridge builds to the north behind the departing trough and forces a westward motion. The ECMWF and GFS continue to keep Raymond offshore, but the latter has trended toward the right between 18z and 0z, bringing Raymond within just miles of the coast before the westward turn commences. The GFDL and HWRF continue to exhibit a more northward-moving hurricane, which runs into the coast and ultimately dissipates over the mountains. CIMSS real-time steering data suggests that the trough is a little stronger the higher you get in the troposphere, which is typical. Hence, Raymond's ultimate track depends largely on its intensification. Since the degree of intensification appears to be quite sizable at the moment, I am going to go to the right of the current NHC forecast during the first 48 hours, but slowly blend in thereafter. My forecast takes the core of a dangerous Category 4 hurricane within miles of the coast; if that were to verify, the northern eyewall may lash the immediate coastal areas, delivering sustained winds of 115 to 135 mph to the region.

Although Raymond still appears to be a fairly small hurricane, scatterometer data over the last 24 hours suggest that the wind field has steadily increased. If Raymond intensifies, the wind field is likely to increase further. Because of this possibility, hurricane warnings have been issued for a portion of the coast by the government of Mexico. Interests in the warned area should carefully monitor the progress of Raymond, which has the potential to be a very dangerous hurricane for the area.

Intensity forecast and positions

INITIAL 10/21 0600Z 16.0°N 102.1°W 85 KT 100 MPH
12 hour 10/21 1800Z 16.4°N 102.0°W 100 KT 115 MPH
24 hour 10/22 0600Z 16.7°N 101.9°W 105 KT 120 MPH
36 hour 10/22 1800Z 17.1°N 101.8°W 115 KT 135 MPH
48 hour 10/23 0600Z 17.5°N 101.7°W 105 KT 120 MPH
72 hour 10/24 0600Z 17.3°N 103.5°W 85 KT 100 MPH
96 hour 10/25 0600Z 17.1°N 106.1°W 75 KT 85 MPH
120hour 10/26 0600Z 16.8°N 109.7°W 70 KT 80 MPH

NOTE: The initial position given above is my estimate of where the center is. Initial time was rounded off to 6z.

Track forecast



Figure 2. My forecast track for Raymond.

NHC storm information


000
WTPZ32 KNHC 210254
TCPEP2

BULLETIN
HURRICANE RAYMOND ADVISORY NUMBER 5
NWS NATIONAL HURRICANE CENTER MIAMI FL EP172013
800 PM PDT SUN OCT 20 2013

...RAYMOND CONTINUES TO RAPIDLY STRENGTHEN...
...HURRICANE WARNING ISSUED FOR A PORTION OF SOUTH-CENTRAL MEXICO...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...15.9N 102.0W
ABOUT 125 MI...205 KM SSW OF ZIHUATANEJO MEXICO
ABOUT 155 MI...250 KM WSW OF ACAPULCO MEXICO
MAXIMUM SUSTAINED WINDS...100 MPH...160 KM/H
PRESENT MOVEMENT...N OR 350 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...975 MB...28.79 INCHES


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

THE GOVERNMENT OF MEXICO HAS ISSUED A HURRICANE WARNING FROM TECPAN
DE GALEANA WESTWARD TO LAZARO CARDENAS.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WARNING IS IN EFFECT FOR...
* TECPAN DE GALEANA TO LAZARO CARDENAS

A HURRICANE WATCH IS IN EFFECT FOR...
* ACAPULCO TO TECPAN DE GALEANA

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* ACAPULCO TO TECPAN DE GALEANA

A HURRICANE WARNING MEANS THAT HURRICANE CONDITIONS ARE EXPECTED
SOMEWHERE WITHIN THE WARNING AREA. A WARNING IS TYPICALLY ISSUED
36 HOURS BEFORE THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-
STORM-FORCE WINDS...CONDITIONS THAT MAKE OUTSIDE PREPARATIONS
DIFFICULT OR DANGEROUS. 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 48 HOURS.

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 HURRICANE RAYMOND WAS
LOCATED NEAR LATITUDE 15.9 NORTH...LONGITUDE 102.0 WEST. RAYMOND IS
MOVING TOWARD THE NORTH NEAR 6 MPH...9 KM/H. A GENERAL NORTHWARD
MOTION WITH A DECREASE IN FORWARD SPEED IS EXPECTED TONIGHT AND
EARLY MONDAY...FOLLOWED BY A SLOW AND ERRATIC MOTION ON TUESDAY. ON
THE FORECAST TRACK...RAYMOND IS EXPECTED TO APPROACH THE COAST OF
MEXICO WITHIN THE HURRICANE WARNING AREA LATE MONDAY OR TUESDAY.

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 100 MPH...160 KM/H...
WITH HIGHER GUSTS. ADDITIONAL STRENGTHENING IS EXPECTED DURING THE
NEXT DAY OR SO...AND RAYMOND IS FORECAST TO BECOME A MAJOR
HURRICANE LATER TONIGHT OR MONDAY.

RAYMOND IS A SMALL HURRICANE. HURRICANE FORCE WINDS EXTEND OUTWARD
UP TO 15 MILES...30 KM...FROM THE CENTER...AND TROPICAL STORM FORCE
WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 975 MB...28.79 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED TO BEGIN IN PORTIONS
OF THE WARNING AREA BY LATE MONDAY. HURRICANE CONDITIONS ARE
EXPECTED IN PORTIONS OF THE HURRICANE WARNING AREA BY LATE MONDAY
NIGHT OR EARLY TUESDAY. HURRICANE CONDITIONS ARE POSSIBLE IN THE
WATCH AREA BY LATE MONDAY NIGHT OR TUESDAY.

STORM SURGE...A STORM SURGE IS EXPECTED TO PRODUCE SIGNIFICANT
COASTAL FLOODING IN AREAS OF ONSHORE WIND WITHIN THE WARNING AREAS.
NEAR THE COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND
DESTRUCTIVE WAVES.

RAINFALL...RAYMOND IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 2 TO 4
INCHES WITH ISOLATED AMOUNTS UP TO 8 INCHES OVER THE MEXICAN STATE
OF GUERRERO. RAINFALL AMOUNTS OF 1 TO 3 INCHES WITH ISOLATED AMOUNTS
UP TO 5 INCHES WILL BE POSSIBLE IN THE ADJACENT BORDERING STATES OF
OAXACA AND MICHOACAN.

SURF...SWELLS GENERATED BY RAYMOND ARE AFFECTING PORTIONS OF
THE SOUTH-CENTRAL COAST OF MEXICO. THESE SWELLS ARE LIKELY TO CAUSE
LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. FOR MORE
INFORMATION...PLEASE CONSULT PRODUCTS FROM YOUR LOCAL WEATHER
OFFICE.


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

$$
FORECASTER BROWN/BERG

Hurricane Raymond 2013 Pacific hurricane season

Updated: 5:49 AM GMT on October 21, 2013

Permalink

Tropical weather analysis - October 14, 2013

By: KoritheMan, 2:46 AM GMT on October 15, 2013

Octave

Tropical Storm Octave continues to move toward the coast of Baja California. As of the latest NHC advisory, the following information was available on Octave:

Wind: 40 mph, with higher gusts
Location: 25.1°N 112.5°W
Movement: NNE at 12 mph
Pressure: 1002 mb

Octave is a highly sheared tropical cyclone. Satellite images show the majority of precipitation is located well northeast of the center over Baja California del Sur and adjoining mainland Mexico. There are some indications that satellite classifications are beginning to drop, which would make sense given the decadent appearance of Octave on satellite imagery.



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

Octave continues to experience southwesterly vertical shear in connection with a broad upstream upper-level trough. This general regime is expected to persist during the next couple of days; in addition, CIMSS TPW imagery shows that Octave has continued to ingest an extremely dry airmass from the Pacific marine layer to its west. In combination with increasing land interaction, Octave should lose its status a tropical cyclone within about 24 hours, if not sooner if orographic lifting does not continue to support convection.

Octave is moving north-northeast, and is now centered just off the coast. Now that Octave has been captured by the trough, a continuation of this general motion is expected to persist. After landfall, the cyclone is forecast to shear apart and stall over the rugged terrain of the southern peninsula, while the mid-level center continues northeastward into the westerlies, enhancing rainfall over northwestern Mexico and the southwestern United States.

Intensity forecast and positions

INITIAL 10/14 2100Z 24.6°N 113.0°W 35 KT 40 MPH
12 hour 10/15 0600Z 25.5°N 113.5°W 30 KT 35 MPH
24 hour 10/15 1800Z 26.2°N 113.3°W 30 KT 35 MPH...INLAND
36 hour 10/16 0600Z 26.3°N 113.2°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
48 hour 10/16 1800Z 26.1°N 113.1°W 20 KT 25 MPH...POST-TROPICAL/REMNANT LOW

Track forecast



Figure 2. My forecast track for Octave. Keep in mind that the initial position on my forecast track was based on the 2100Z NHC advisory, so there are naturally going to be some discrepancies, but the general philosophy is still the same. Also, my intensity forecast has been amended to reflect the initial intensity of Octave as of 0300Z.

NHC storm information

000
WTPZ35 KNHC 150234
TCPEP5

BULLETIN
TROPICAL STORM OCTAVE ADVISORY NUMBER 9
NWS NATIONAL HURRICANE CENTER MIAMI FL EP152013
800 PM PDT MON OCT 14 2013

...OCTAVE WEAKENING AS IT APPROACHES THE BAJA CALIFORNIA
PENINSULA...
...HEAVY RAINFALL THE MAIN THREAT...


SUMMARY OF 800 PM PDT...0300 UTC...INFORMATION
----------------------------------------------
LOCATION...25.1N 112.5W
ABOUT 40 MI...60 KM WNW OF CABO SAN LAZARO MEXICO
MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H
PRESENT MOVEMENT...NNE OR 25 DEGREES AT 12 MPH...19 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES


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

NONE.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* SANTA FE TO PUNTA ABREOJOS

A TROPICAL STORM WARNING MEANS THAT TROPICAL STORM CONDITIONS ARE
EXPECTED SOMEWHERE WITHIN THE WARNING AREA...IN THIS CASE WITHIN
THE NEXT 12 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 STORM OCTAVE WAS
LOCATED NEAR LATITUDE 25.1 NORTH...LONGITUDE 112.5 WEST. OCTAVE IS
MOVING TOWARD THE NORTH-NORTHEAST NEAR 12 MPH...19 KM/H...AND THIS
MOTION IS EXPECTED TO CONTINUE THROUGH TONIGHT. ON THE FORECAST
TRACK...THE CENTER OF OCTAVE WILL BE NEAR THE COAST WITHIN THE
WARNING AREA TONIGHT AND EARLY TUESDAY. LITTLE OR NO MOTION IS
EXPECTED LATE TUESDAY OR WEDNESDAY AS THE SYSTEM WEAKENS.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 40 MPH...65 KM/H...
WITH HIGHER GUSTS. ADDITIONAL WEAKENING IS FORECAST...AND OCTAVE IS
EXPECTED TO WEAKEN TO A TROPICAL DEPRESSION ON TUESDAY AND BECOME A
REMNANT LOW BY TUESDAY NIGHT.

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

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB...29.59 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...OCTAVE IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF
3 TO 6 INCHES...WITH ISOLATED MAXIMUM AMOUNTS OF 8 INCHES
POSSIBLE...OVER THE MAINLAND MEXICO STATE OF SONORA. ADDITIONAL
RAIN ACCUMULATIONS OF 1 TO 2 INCHES ARE POSSIBLE WITH OCTAVE OVER
THE CENTRAL AND SOUTHERN BAJA CALIFORNIA PENINSULA...WITH MAXIMUM
STORM TOTAL AMOUNTS OF 8 INCHES.

WIND...TROPICAL STORM CONDITIONS ARE EXPECTED IN PORTIONS OF THE
WARNING AREA THROUGH TONIGHT.

STORM SURGE...A STORM SURGE IS EXPECTED TO PRODUCE COASTAL FLOODING
NEAR AND TO THE EAST OF WHERE THE CENTER MAKES LANDFALL. NEAR THE
COAST...THE SURGE WILL BE ACCOMPANIED BY LARGE AND DANGEROUS WAVES.

SURF...SWELLS GENERATED WILL CONTINUE AFFECT THE WEST COAST OF BAJA
CALIFORNIA SUR INTO TUESDAY. THESE SWELLS ARE LIKELY TO CAUSE LIFE-
THREATENING SURF AND RIP CURRENT CONDITIONS.


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

$$
FORECASTER BRENNAN



Priscilla

Tropical Storm Priscilla is moving over the open Pacific ocean without threat to land. As of the latest NHC advisory, the following information was given on Priscilla:

Wind: 40 mph, with higher gusts
Location: 16.2°N 115.8°W
Movement: N at 9 mph
Pressure: 1003 mb

Priscilla remains a sheared tropical cyclone, with satellite and microwave imagery identifying the low-level center along the northeastern edge of the convective canopy. Satellite estimates still support tropical storm intensity, and earlier ASCAT data does not look as impressive in terms of winds as the one from 6z Monday.



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

As Octave continues to weaken and move overland, the easterly to east-northeasterly shear that has been persistently afflicting Priscilla should diminish, providing the cyclone with a 24-36 hour window for intensification. Although the GFS shows a decent anticyclone forming at 200 mb over the storm during that period, water vapor imagery and CIMSS TPW data show a rather substantial drying in the airmass to the west of Priscilla. In all likelihood, this subsident airmass will prevent Priscilla from becoming a hurricane; dry air entrainment would be further supported by a relaxation of the shear, which would allow for the cyclone to tighten and consolidate its convection and circulation, allowing dry air to more easily permeate the core. Hence, only a modest strengthening is shown, and Priscilla is expected to peak near 45 kt. There is a chance the cyclone could become stronger if the dry air is not as treacherous is forecast, and small cyclones like Priscilla tend to behave rather erratically in terms of intensity. Beyond 48 hours, southwesterly shear is expected to increase again, and that mechanism should combine with cooler waters and dry air to cause Priscilla to become a remnant low in about four days.

Satellite data suggests that Priscilla is still moving toward the north, but with a more westerly component beginning to ensue. This suggests that low- to mid-level ridging is already returning to the north of the tropical cyclone as Octave exits stage right. The global models show the ridge expanding westward over the next few days, allowing Priscilla to move northwest, then take an abrupt dive to the southwest as the ridge gets even stronger. My forecast track will follow that reasoning, but is not as far south or as sharp with the southwestward turn as some of the recent guidance is.

Intensity forecast and positions

INITIAL 10/14 2100Z 15.7°N 115.8°W 35 KT 40 MPH
12 hour 10/15 0600Z 16.3°N 116.2°W 35 KT 40 MPH
24 hour 10/15 1800Z 16.9°N 117.1°W 40 KT 45 MPH
36 hour 10/16 0600Z 17.5°N 118.1°W 45 KT 50 MPH
48 hour 10/16 1800Z 18.1°N 119.2°W 40 KT 45 MPH
72 hour 10/17 1800Z 19.2°N 120.6°W 35 KT 40 MPH
96 hour 10/18 1800Z 18.7°N 121.7°W 30 KT 35 MPH...POST-TROPICAL/REMNANT LOW
120 hour 10/19 1800Z 17.6°N 123.7°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW

Track forecast



Figure 4. My forecast track for Priscilla.

2013 Pacific hurricane season Tropical Storm Octave Tropical Storm Priscilla

Updated: 8:42 AM GMT on October 15, 2013

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Tropical weather analysis - October 13, 2013

By: KoritheMan, 2:20 AM GMT on October 14, 2013

Octave

Tropical Storm Octave continues to move toward the central Baja Peninsula. As of the 2100Z NHC advisory (new advisory comes out momentarily), the following information was available on the cyclone:

Wind: 65 mph, with higher gusts
Location: 19.2°N 112.7°W
Movement: NNW at 13 mph
Pressure: 995 mb

Octave's satellite presentation has not changed much over the last several hours, although I do see evidence of the upper flow turning from southerly to southwesterly in advance of an upper-level trough, which could explain the somewhat south to north elongation of the convection. Satellite estimates have not changed appreciably, and Octave has probably not lost strength yet.



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

While a couple of microwave passes from several hours ago showed evidence of a low- and mid-level eye, the same data also showed a small northward displacement between the mid- and low-level eye features, likely due to about 25 kt of southerly shear. The inner core does not appear to have been affected by the shear for now, but since it is beginning to increase, Octave should begin to steadily weaken, with the possibility of rapid weakening beyond 24 hours. In addition to the shear, Octave will soon cross a sharp sea surface temperature gradient, and will also have to deal with an increasingly dry airmass. I expect Octave to become a remnant low in 72 hours, and dissipate completely the very next day. Given the hostilities, Octave is not likely to make landfall in Baja as a tropical cyclone, and even when the residual vorticity lobe reaches the area, most of the associated weather will be connected with the mid-level center. The low-level center will likely get stuck over the rugged terrain of the peninsular proper.

The large-scale steering pattern surrounding Octave has not changed. The tropical storm remains situated on the southwest side of a decaying mid-tropospheric ridge as an upper-level trough amplifies over the western United States. This pattern is expected to turn the cyclone northward over the next 12-18 hours, followed by a gradual turn to the east-northeast toward central Baja. The track guidance remains in good agreement on the overall scenario, with only small differences apparent between the GFS and ECMWF. My forecast track is similar to, but a little faster than the NHC 2100Z forecast for the first 24 hours; in addition, the anticipated recurvature of Octave in my forecast is a little faster than some of the guidance, under the assumption that Octave will feel more influence from the trough than predicted while it remains at least somewhat vertically respectable over the next 24 hours.

Intensity forecast and positions

INITIAL 10/13 2100Z 19.2°N 112.7°W 55 KT 65 MPH
12 hour 10/14 0600Z 20.4°N 113.1°W 50 KT 60 MPH
24 hour 10/14 1800Z 22.0°N 112.8°W 45 KT 50 MPH
36 hour 10/15 0600Z 22.9°N 112.6°W 35 KT 40 MPH
48 hour 10/15 1800Z 23.6°N 112.3°W 30 KT 35 MPH
72 hour 10/16 1800Z 24.0°N 111.9°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
96 hour 10/17 1800Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Octave.



Invest 95E

An area of low pressure located a few hundred miles southwest of Tropical Storm Octave is showing signs of organization. Visible satellite images from earlier in the day suggested that a small low-level circulation likely exists. Convection has persistently been trying to wrap around this feature, only to be cut off by easterly shear associated with the southern outflow jet of Tropical Storm Octave. Although the large-scale shear is unlikely to decrease much, the system has been persistent enough that it may get a designation as a tropical depression by the National Hurricane Center overnight.

The GFS suggests the system could find itself in a somewhat more favorable environment during the 36-48 hour period as Octave moves away. After that, southwesterly shear is expected to increase, and the system will be moving over cooler water, which should stifle additional development at that time.

This low should initially move northeastward to northward in tandem with Octave's cyclonic circulation, but a building low- to mid-level ridge in the wake of the western United States trough should steer the low toward the northwest and west-northwest with time, away from Baja.



Figure 3. Latest infrared satellite image of Invest 95E. Image credit: NOAA's Satellite Services Division (SSD).

Probability of development in 48 hours: 60%

2013 Pacific hurricane season Tropical Storm Octave Invest 95E

Updated: 2:29 AM GMT on October 14, 2013

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Tropical weather analysis - October 13, 2013

By: KoritheMan, 6:45 AM GMT on October 13, 2013

Tropical Depression Fifteen-E

Tropical Depression Fifteen-E formed well south of Baja California a few hours ago. As of the first (and so far only) NHC advisory, the following information was available on the cyclone:

Wind: 35 mph, with higher gusts
Location: 16.1°N 110.2°W
Movement: NW at 12 mph
Pressure: 1005 mb

A 0454Z AMSUB microwave pass captured the circulation of the depression, and suggests that the center is embedded between two convective bands, and a 06z satellite classification from SAB suggests the depression has become a tropical storm.



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

While there have been no recent scatterometer passes, increasing Dvorak numbers and the satellite presentation suggest that the cyclone has likely become a tropical storm, and is likely to be named 'Octave' at the next advisory. A significant burst of convection to the south suggests that the winds may temporarily be strongest in that particular quadrant.

The depression is experiencing some moderate southeasterly shear as denoted by observed high cloud motion vectors on water vapor imagery, but the cyclone is moving essentially in tandem with the upper flow, and this shear should not be enough to prohibit gradual strengthening. The GFS retains a relatively favorable environment over the cyclone, and some intensification seems probable over the next 24 hours; it is possible the depression could intensify more than forecast during this period. Subsequent to that time, objective SST data and the SHIPS model suggest that the cyclone will cross the 26C isotherm; concurrent with a steady increase in southwesterly shear and an increasingly marginal thermodynamic environment, the cyclone should steadily decay. I expect the depression to become a remnant low in about four days while still over central Baja, but it is not completely out of the question that it could occur sooner. My particular dissipation regime is a day faster than the NHC, when I terminate the system completely in 120 hours.

Synoptic data suggests that the depression is situated on the southwest side of a mid-level ridge over the Gulf of Mexico. Water vapor animations show the steady progression of an upper-level trough over the western United States, which is anticipated to gradually erode what's left of the ridge and allow the depression to turn northward and northeastward toward central or southern Baja. The model guidance is fairly clustered on central Baja for a landfall point, and I will go along with that solution as well. After landfall, it seems likely that the low-level circulation will shear apart and stall over the peninsula proper, so some slow and possibly erratic motion is expected after the cyclone moves inland.

Although there are currently no watches and warnings in effect, the National Hurricane Center maintained the possibility that they could be issued for portions of Baja later today. However, given the harsh conditions that lie ahead, I would be surprised if the cyclone were stronger than a 35 kt storm, and more likely it will be a weakening depression.

Intensity forecast and positions

INITIAL 10/13 0300Z 16.1°N 110.2°W 30 KT 35 MPH
12 hour 10/13 1200Z 16.9°N 111.0°W 35 KT 40 MPH
24 hour 10/14 0000Z 18.3°N 112.1°W 40 KT 45 MPH
36 hour 10/14 1200Z 19.6°N 112.1°W 35 KT 40 MPH
48 hour 10/15 0000Z 21.3°N 111.7°W 30 KT 35 MPH
72 hour 10/16 0000Z 23.7°N 111.4°W 25 KT 30 MPH
96 hour 10/17 0000Z 24.4°N 111.2°W 20 KT 25 MPH...POST-TROPICAL/REMNANT LOW
120 hour 10/18 0000Z...DISSIPATED

Track forecast



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

2013 Pacific hurricane season Tropical Depression Fifteen-E

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Tropical weather analysis - October 12, 2013

By: KoritheMan, 8:51 AM GMT on October 12, 2013

Phailin

Extremely dangerous Cyclone Phallin continues to approach the coast of eastern India. As of the 0900Z JTWC advisory, the following information was available on the cyclone:

Wind: 150 mph, with higher gusts
Location: 18.0°N 85.8°E
Movement: NW at 10 mph
Category: 4 (Saffir-Simpson Hurricane Wind Scale)

Perhaps in a stroke of perfect coincidental timing, Phailin has weakened a little over the last six hours, falling from 140 kt, the bottom of Category 5 (Saffir-Simpson Hurricane Wind Scale), to 130 kt, the upper end of Category 4. There has been a noticeable warming of the cloud tops, and an overall shrinkage of the central dense overcast. Satellite estimates have begun to fall, although the latest Dvorak numbers still support an intensity within the 130 kt range. That kind of intensity is still nothing to sneeze at, and there is little categorical difference a 130 kt storm and a 140 kt one. The outflow pattern remains excellent, and any additional intensity fluctuations are not going to come from large-scale increases in vertical shear.



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

Recent microwave and satellite data suggests that Phailin is experiencing another concentric eyewall cycle, which is common in intense hurricanes. Since the cyclone is so close to the coast, this process is unlikely to be complete by the time landfall occurs within the next 6-12 hours. Internal core fluctuations are both deceiving and extremely difficult to anticipate, and these small but important changes will be crucial to determining how strong Phailin is when it makes landfall later this evening (India local time). As it were, said inner core fluctuations could also play a pivotal role in the exact location the eye crosses the coast, as cyclones this intense sometimes "wobble" around the modulating convection. That too, however, is a process that is equally difficult to pinpoint.

Water vapor and upper air data from Calcutta, India indicate that Phailin is on the southwest side of a mid-level ridge over northeastern India. A secondary ridge is building over western India in the wake of the progressing shortwave trough; this pattern favors a continuation of the general northwestward movement observed within the cyclone over the last several hours. I do not know where to find a reliable track map for the northern Indian Ocean/Bay of Bengal region, but my forecast track is pretty similar to the 0900Z one from the Joint Typhoon Warning Center, which I will show below. My forecast is essentially on top of the one from the JTWC.

It should be noted that satellite images showed a definitive northward jog over the last couple of hours, but recent images suggest that the cyclone has turned back to the northwest.

Although Phailin is likely to continue to slowly weaken up until landfall due to the ongoing current eyewall cycle and land interaction, the cycle, if it culminates fast enough (which is more a possibility than a likelihood at this point, but worth mentioning given the excruciating circumstances surrounding the cyclone), the outer wind field could expand significantly, increasing the storm surge and freshwater flood threat over a wider area.

The primary hazard associated with even the most powerful cyclones is flooding, either from storm surge or freshwater flooding from heavy rainfall. A significant storm surge is likely near and to the east of where the eye crosses the coast, and even interests well away from the cyclone center should pay close attention to local storm surge threats from the cyclone's large outer wind field. I liken the size and intensity of Phailin to Hurricane Katrina when it was approaching New Orleans in August 2005.

Extreme wind damage is likely to occur near where the eye crosses the coast, particularly to the north and east, where the wind threat should be most focused, coincident with the general movement of the cyclone.

After landfall, Phailin should quickly dissipate; although I indicate a forecast point out to 48 hours as a decaying remnant low, it is probably more likely that Phailin kicks the bucket before then.

Although no reliable surface observations exist within the coastal region where Phailin is expected to make landfall, it is likely that sustained tropical storm force winds have already moved ashore, and if not, are very close to doing so.

Intensity forecast and positions

INITIAL 10/12 0600Z 130 KT 150 MPH
12 hour 10/12 1800Z 90 KT 105 MPH...INLAND
24 hour 10/13 0600Z 45 KT 50 MPH...INLAND
36 hour 10/13 1800Z 30 KT 35 MPH...INLAND
48 hour 10/14 0600Z 20 KT 25 MPH...POST-TROPICAL/REMNANT LOW
72 hour 10/15 0600Z...DISSIPATED

JTWC track forecast (0900Z)



Figure 2. Latest JTWC forecast track for Cyclone Phailin. Forecast track valid as of 0900Z.



JTWC storm information

WTIO31 PGTW 120900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE 02B (PHAILIN) WARNING NR 014//
RMKS/
1. TROPICAL CYCLONE 02B (PHAILIN) WARNING NR 014
01 ACTIVE TROPICAL CYCLONE IN NORTHIO
MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE
WIND RADII VALID OVER OPEN WATER ONLY
---
WARNING POSITION:
120600Z --- NEAR 18.0N 85.8E
MOVEMENT PAST SIX HOURS - 310 DEGREES AT 09 KTS
POSITION ACCURATE TO WITHIN 020 NM
POSITION BASED ON CENTER LOCATED BY SATELLITE
PRESENT WIND DISTRIBUTION:
MAX SUSTAINED WINDS - 130 KT, GUSTS 160 KT
WIND RADII VALID OVER OPEN WATER ONLY
RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT
030 NM SOUTHEAST QUADRANT
030 NM SOUTHWEST QUADRANT
030 NM NORTHWEST QUADRANT
RADIUS OF 050 KT WINDS - 060 NM NORTHEAST QUADRANT
055 NM SOUTHEAST QUADRANT
055 NM SOUTHWEST QUADRANT
060 NM NORTHWEST QUADRANT
RADIUS OF 034 KT WINDS - 120 NM NORTHEAST QUADRANT
110 NM SOUTHEAST QUADRANT
110 NM SOUTHWEST QUADRANT
120 NM NORTHWEST QUADRANT
REPEAT POSIT: 18.0N 85.8E
---
FORECASTS:
12 HRS, VALID AT:
121800Z --- 19.4N 84.5E
MAX SUSTAINED WINDS - 095 KT, GUSTS 115 KT
WIND RADII VALID OVER OPEN WATER ONLY
VECTOR TO 24 HR POSIT: 330 DEG/ 09 KTS
---
24 HRS, VALID AT:
130600Z --- 20.9N 83.5E
MAX SUSTAINED WINDS - 060 KT, GUSTS 075 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATING AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
VECTOR TO 36 HR POSIT: 335 DEG/ 09 KTS
---
36 HRS, VALID AT:
131800Z --- 22.6N 82.6E
MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT
WIND RADII VALID OVER OPEN WATER ONLY
DISSIPATED AS A SIGNIFICANT TROPICAL CYCLONE OVER LAND
---
REMARKS:
120900Z POSITION NEAR 18.3N 85.5E.
TROPICAL CYCLONE 02B (PHAILIN), LOCATED APPROXIMATELY 312 NM SOUTH-
SOUTHWEST OF KOLKATA, INDIA, HAS TRACKED NORTHWESTWARD AT 09 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
SHOWS A SLIGHT WEAKENING OF THE DEEP CONVECTION SURROUNDING THE EYE
OF THE SYSTEM. CLOUD TOP TEMPERATURES HAVE BEEN WARMING OVER THE
PAST SIX HOURS AND SUPPORTS THE RECENT DECREASE IN INTENSITY FOR TC
02B. THE SYSTEM REMAINS A STRONG TROPICAL CYCLONE, AND IS EXPECTED
TO REMAIN STRONG AS IT MOVES INTO THE NORTHEASTERN COASTAL REGION OF
INDIA WITHIN THE NEXT 8 TO 10 HOURS. THE EYE REMAINS WELL DEFINED
AND SYMMETRIC, BUT HAS RECENTLY THINNED FROM THE OUTER PERIMETER OF
THE DEEP CONVECTION AND THE CENTRAL EYEWALL. THE SYSTEM APPEARS TO
BE UNDERGOING THE INITIAL PHASE OF AN EYEWALL REPLACEMENT CYCLE, BUT
IS UNLIKELY TO COMPLETE THE PROCESS PRIOR TO LANDFALL. TC 02B IS
TRACKING ALONG THE SOUTHWESTERN PERIPHERY OF THE DEEP-LAYERED
SUBTROPICAL RIDGE (STR) TO THE NORTHEAST AND WILL REMAIN ON A STEADY
TRACK TO THE NORTHWEST FOR THE NEXT 36 HOURS AROUND THE STR. AS THE
SYSTEM APPROACHES THE COAST, THE LOW LEVEL INFLOW WILL ERODE DUE TO
THE FRICTIONAL EFFECTS OF LAND ON THE NORTHWESTERN QUADRANT OF THE
SYSTEM. ONCE THE SYSTEM MAKES LANDFALL, TC 02B IS EXPECTED TO
RAPIDLY WEAKEN DUE TO FRICTIONAL LAND EFFECTS, AND WILL BE FULLY
DISSIPATED BY TAU 36. BASED ON THE TIGHT GROUPING OF MODEL GUIDANCE,
THE CONFIDENCE REMAINS HIGH FOR THE FORECAST TRACK. MAXIMUM
SIGNIFICANT WAVE HEIGHT AT 120600Z IS 45 FEET. NEXT WARNINGS AT
121500Z, 122100Z, 130300Z AND 130900Z.//
NNNN

2013 North Indian Cyclone Season Cyclone Phailin

Updated: 9:20 AM GMT on October 12, 2013

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Tropical weather analysis - October 6, 2013

By: KoritheMan, 4:02 AM GMT on October 07, 2013

Invest 98L

A tropical wave over the eastern Atlantic is accompanied by a broad area of low pressure. Convection has increased with this low significantly over the last several hours, but satellite classifications have not yet been initiated on the disturbance.



Figure 1. Latest infrared satellite image of Invest 98L. Image credit: NOAA's Satellite Services Division (SSD).

The cloud pattern suggests the presence of some westerly shear, but the GFS shows the upper-level environment improving somewhat in the path of the system over the next 24 hours, although my preliminary guess is that the environment will remain marginal. In about 72 hours, the GFS shows 200 mb westerly winds increasing sharply as the wave moves west-northwestward into a sharp upper-level trough over the central Atlantic. This shear could become quite strong by days four and five, possibly leading to an abrupt dissipation of whatever nominal status the system has at those times.

Probability of development in 48 hours: 20%



Narda

Tropical Storm Narda is moving westward across the eastern north Pacific. As of the latest NHC advisory, the following information was available on the storm:

Wind: 40 mph, with higher gusts
Location: 13.2°N 119.8°W
Movement: W at 12 mph
Pressure: 1005 mb

Narda has a healthy cloud pattern, with the center embedded within the eastern portion of some very deep convection; in addition, a large spiral band emanates from the western semicircle of the cyclone. Satellite estimates have climbed accordingly, with all but the generally lower SAB supporting tropical storm strength. Upper-level outflow is particularly well-defined to the west and north, suggesting the potential for some significant intensification.



Figure 2. Latest infrared satellite image of Tropical Storm Narda. Image credit: NOAA's Satellite Services Division (SSD).

With the center not fully locked within the central convection, there still appears to be some easterly shear affecting Narda. As convection builds and the cyclone establishes a ridge aloft, this shear should diminish, and Narda should intensify. While not explicitly stated, it is possible that Narda could rapidly intensify if an inner core can develop, particularly during the first 24 hours of the forecast period when the underlying waters will be warmest. Another supporting factor for the prospect of rapid intensification is a broad mid- to upper-level trough several hundred miles northwest of the tropical storm, which could enhance the poleward outflow channel. My forecast is higher than the National Hurricane Center forecast, as I am not really convinced conditions will become that detrimental until beyond the 72 hour mark. The GFS shows vertical shear increasing beyond day three of the forecast, and Narda is forecast to weaken rapidly at those later times, becoming a remnant low at day five.

Narda is south of a well-established mid-tropospheric ridge. The global models suggest that this ridge will deamplify a little over the next several days, which is expected to lift Narda more toward the west-northwest starting tomorrow. Following the typical progression, a comparison of the various tropospheric altitudes indicates that the stronger Narda becomes, the more poleward it should move. In the latter portion of the forecast period, the track forecast becomes rather mysterious and skewed, with considerable differences amongst the models whether Narda will turn westward or gradually become captured by the trough. The GFDL and HWRF show Narda riding along the trough toward southern Baja, while the GFS and ECMWF show a slowing of the forward speed concurrent with a more westward track at those ranges. The GFDL and HWRF seem to be having issues resolving the large-scale shear pattern at longer ranges, which is likely inflating the model signals. My feeling is that the GFS and ECMWF solution of a shear apart and stall scenario is much more reasonable given the very strong upper tropospheric shear levels shown on the GFS, these winds already being apparent on water vapor imagery near 130W.

As of now, Narda is not expected to threaten Baja, although it will be worth monitoring to see if the cyclone indeed becomes captured by the trough.

Intensity forecast and positions

INITIAL 10/07 0300Z 13.2°N 119.8°W 35 KT 40 MPH
12 hour 10/07 1200Z 13.4°N 120.8°W 40 KT 45 MPH
24 hour 10/08 0000Z 14.0°N 122.4°W 50 KT 60 MPH
36 hour 10/08 1200Z 14.5°N 123.6°W 55 KT 65 MPH
48 hour 10/09 0000Z 15.1°N 124.9°W 65 KT 75 MPH
72 hour 10/10 0000Z 15.5°N 126.3°W 75 KT 85 MPH
96 hour 10/11 0000Z 15.9°N 127.4°W 50 KT 60 MPH
120 hour 10/12 0000Z 15.2°N 128.4°W 35 KT 40 MPH...POST-TROPICAL/REMNANT LOW

Track forecast



Figure 3. My forecast track for Narda.

2013 Atlantic hurricane season 2013 Pacific hurricane season Invest 98L Tropical Storm Narda

Updated: 4:26 AM GMT on October 07, 2013

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Tropical weather analysis - October 4, 2013

By: KoritheMan, 2:31 AM GMT on October 05, 2013

Karen

Tropical Storm Karen continues to struggle against strong vertical shear. As of the 0000Z NHC intermediate advisory (actual 0300Z full advisory is coming up soon), the following information was available on Karen:

Wind: 50 mph, with higher gusts
Location: 25.9°N 90.3°W
Movement: Stationary
Pressure: 1002 mb

There isn't much new to say about Karen, or this pathetic excuse of a hurricane season. Satellite images show the low-level center has become completely exposed once again, after a brief period of reorganization earlier in the day. The deep convection is confined to the vigorous mid-level center located about 125 miles to the east of Karen's actual center.



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

The environment ahead of Karen does not appear particularly promising for intensification, with water vapor images continuing to show strong westerly shear affecting the cyclone in association with a seasonably deep longwave trough moving across the central United States. Upper air soundings over the United States indicate that the environmental airmass to the west of Karen is also exceptionally dry. These factors argue against reintensification of Karen despite the very deep warm water over the northern Gulf of Mexico. Although the GFS, after incorporation of data from the NOAA G-IV surveillance mission conducted earlier shows the 200 mb winds decreasing a little bit as Karen approaches the coast, there does not currently appear to be much evidence of this happening. Under the presumption that increasing upper divergence associated with the right entrance region of the upper-level trough increases over the tropical storm during the next 24-48 hours, Karen should be able to maintain the status quo all the way to landfall, but actual reintensification is unlikely. An alternate scenario is that the cyclone decays into a remnant low before reaching the coast, as happened with Tropical Storm Bonnie in 2010.

Karen's motion has become easy to determine since the center is in plain view once again. The cyclone has been moving somewhat erratically, but the general motion over the last few hours appears to be north-northwest. Karen is between a deep-layer ridge over the eastern United States, and a broad mid-latitude trough over the central United States. This evolution argues against little deviation from current trends, and the cyclone is expected to pass near or over the southeastern Louisiana coast in the next 36 hours. After that time, Karen is forecast to become well-embedded in the high latitude westerlies and accelerate northeastward over the southeastern United States. The guidance is in better agreement on the more westward motion toward Louisiana over the succeeding 36 hours than they were yesterday, and my forecast is largely the same as the one I published this morning, albeit a little farther west of the current NHC prediction and model consensus due to the vertically shallow nature of Karen's vortex. It should be noted that there is some indication in the upper air soundings over the northern Gulf Coast and southeastern United States that large-scale ridging has increased above 850 mb compared to 24 hours ago, and this could keep Karen on a more westward track even if convection redevelops.

Unless the shear decreases before landfall, the main impact from Karen will be to the east of the center, in the form of tropical storm force winds, high surf, minor coastal flooding, isolated tornadoes, and heavy rain.

Intensity forecast and positions

INITIAL 10/05 0000Z 25.9°N 90.3°W 45 KT 50 MPH
12 hour 10/05 1200Z 26.7°N 90.6°W 45 KT 50 MPH
24 hour 10/06 0000Z 27.7°N 90.5°W 45 KT 50 MPH
36 hour 10/06 1200Z 28.9°N 89.7°W 45 KT 50 MPH
48 hour 10/07 0000Z 30.4°N 87.7°W 35 KT 40 MPH...INLAND
72 hour 10/08 0000Z 32.7°N 82.6°W 30 KT 35 MPH...POST-TROPICAL/EXTRATROPICAL
96 hour 10/09 0000Z...ABSORBED

Track forecast



Figure 2. My forecast track for Karen.

NHC storm information

000
WTNT32 KNHC 042337
TCPAT2

BULLETIN
TROPICAL STORM KAREN INTERMEDIATE ADVISORY NUMBER 7A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013
700 PM CDT FRI OCT 04 2013

...KAREN HESITATES IN THE CENTRAL GULF OF MEXICO...


SUMMARY OF 700 PM CDT...0000 UTC...INFORMATION
----------------------------------------------
LOCATION...25.9N 90.3W
ABOUT 235 MI...375 KM SSW OF THE MOUTH OF THE MISSISSIPPI RIVER
ABOUT 270 MI...430 KM SSE OF MORGAN CITY LOUISIANA
MAXIMUM SUSTAINED WINDS...50 MPH...85 KM/H
PRESENT MOVEMENT...STATIONARY
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES


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

NONE

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* MORGAN CITY LOUISIANA TO THE MOUTH OF THE PEARL RIVER

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* METROPOLITAN NEW ORLEANS
* LAKE MAUREPAS
* LAKE PONTCHARTRAIN
* EAST OF THE MOUTH OF THE PEARL RIVER TO INDIAN PASS FLORIDA

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

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

INTERESTS ELSEWHERE ALONG THE NORTHEASTERN COAST OF THE GULF OF
MEXICO SHOULD MONITOR THE PROGRESS OF KAREN.

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 700 PM CDT...0000 UTC...THE CENTER OF TROPICAL STORM KAREN WAS
LOCATED NEAR LATITUDE 25.9 NORTH...LONGITUDE 90.3 WEST. KAREN HAS
BEEN NEARLY STATIONARY DURING THE PAST COUPLE OF HOURS...BUT THE
CYCLONE SHOULD RESUME A NORTH-NORTHWEST TRACK NEAR 7 MPH...11 KM/H
LATER TONIGHT. A TURN TOWARD THE NORTH WITH A DECREASE IN FORWARD
SPEED IS EXPECTED ON SATURDAY...AND A TURN TOWARD THE NORTHEAST
WITH AN INCREASE IN FORWARD SPEED IS EXPECTED ON SUNDAY. ON THE
FORECAST TRACK...THE CENTER OF KAREN IS EXPECTED BE NEAR THE COAST
IN THE TROPICAL STORM WARNING SATURDAY NIGHT.

DATA FROM AN AIR FORCE RESERVE AND NOAA HURRICANE HUNTER AIRCRAFT
INDICATE THAT MAXIMUM SUSTAINED WINDS REMAIN NEAR 50 MPH...85
KM/H...WITH HIGHER GUSTS. LITTLE CHANGE IN STRENGTH IS FORECAST
TONIGHT AND SATURDAY. SLIGHT STRENGTHENING IS POSSIBLE SATURDAY
NIGHT AND SUNDAY.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES...220
KM...MAINLY TO THE NORTH AND EAST OF THE CENTER.

THE LATEST MINIMUM CENTRAL PRESSURE BASED ON DATA FROM THE AIRCRAFT
IS 1002 MB...29.59 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...TROPICAL STORM CONDITIONS ARE EXPECTED WITHIN PORTIONS OF THE
WARNING AREA BY SATURDAY AFTERNOON. TROPICAL STORM CONDITIONS ARE
POSSIBLE IN PORTIONS OF THE WATCH AREA SATURDAY NIGHT AND SUNDAY.

STORM SURGE...THE COMBINATION OF 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...

WEST OF THE MISSISSIPPI RIVER TO TERREBONNE BAY...1 TO 3 FT
MOUTH OF THE MISSISSIPPI RIVER TO THE PEARL RIVER...3 TO 5 FT
EAST OF THE PEARL RIVER TO WEST OF APALACHEE BAY...1 TO 3 FT
APALACHEE BAY INCLUDING CEDAR KEY...2 TO 4 FT
SOUTH OF APALACHEE BAY TO TAMPA BAY...1 TO 2 FT

THE HIGHEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST...WHERE THE
SURGE WILL BE ACCOMPANIED BY DANGEROUS 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.

RAINFALL...KAREN IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 3 TO 6
INCHES OVER PORTIONS OF THE CENTRAL AND EASTERN GULF COAST THROUGH
SUNDAY NIGHT...MAINLY NEAR AND TO THE RIGHT OF THE PATH OF THE
CENTER. ISOLATED STORM TOTAL AMOUNTS OF 10 INCHES ARE POSSIBLE.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...1000 PM CDT.

$$
FORECASTER AVILA/RAPPAPORT

2013 Atlantic hurricane season Tropical Storm Karen

Permalink

Tropical weather analysis - October 4, 2013

By: KoritheMan, 8:27 AM GMT on October 04, 2013

Karen

Tropical Storm Karen continues to move across the central Gulf of Mexico. As of the 0600z NHC intermediate advisory, the following information was posted on the storm:

Wind: 65 mph, with higher gusts
Location: 24.5°N 89.5°W
Movement: NNW at 10 mph
Pressure: 999 mb

Karen has a rather disheveled satellite appearance this morning due to strong southwesterly shear caused by an upper-level trough to the west. This is typical of October Gulf of Mexico tropical cyclones. A reconnaissance aircraft has been sampling the tropical storm over the last several hours, and the pressure and flight-level wind values from that mission suggest that Karen could be downgraded a bit at the upcoming NHC full advisory. Satellite estimates from TAFB and SAB at 06z were 3.0 and 2.5, respectively, suggesting that Karen is likely weaker.



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

The low-level center is completely exposed well to the west of a rather vigorous burst of deep convection. The GFS does not show this shear relaxing much over the next several days as a deep longwave trough over the Rockies moves eastward. In fact, the shear might actually increase more as Karen approaches the northern Gulf Coast. In addition, water vapor imagery shows a rather large expanse of dry air over the western Gulf of Mexico, and the current wind shear regime afflicting the cyclone will likely help to ingest that airmass into the cyclone circulation. These factors should prevent strengthening, and in fact, I would not be surprised if my forecast below ends up being too generous. After landfall, the models show Karen interacting with a cold front, and the cyclone is likely to become absorbed by this front within about five days, if not perhaps a little sooner.

The center is easily located now that it's exposed. Satellite fixes prior to the exposing showed a more north-northwestward motion, but recent satellite fixes suggest a motion closer to the northwest. In addition, 0z upper air data from the northern Gulf Coast shows that low-level ridging has maintained itself up to about 800 mb at the sounding site in New Orleans, which suggests that Karen is not going to move eastward immediately. Troughing exists above that level, but Karen is disorganized enough that it may not fully appreciate and respond to such a flow.

Tonight's forecast is rather tricky, to say the least. Synoptic data indicate that a rather large trough is moving across the Rockies, while a comparably strong mid-level ridge is parked over the eastern United States. This general pattern favors a continued motion toward the northern Gulf Coast. However, water vapor imagery suggests that the frontal trough intended to recurve Karen is moving somewhat slower than I was expecting, which would theoretically cause a delay in the turn. On the other hand, possibly as an extension of that feature, mid-level southwesterly flow exists across much of Texas, as denoted in upper air soundings and water vapor imagery. This would tend to suggest that the trough will migrate eastward into western Louisiana soon enough, and prevent too much additional westward motion. Further complicating matters is a noticeable eastward shift in the model guidance at 0z. The ECMWF, which previously showed a Louisiana landfall, has come east and now shows a landfall near Pensacola after taking Karen very near southern Louisiana in 48 hours. In addition, the HWRF has come east to a landfall on the Florida panhandle as well. The UKMET has maintained its stubborn westward track, and takes Karen inland near or west of Houma, Louisiana. That model is probably overdoing it, and if Karen does make it into Louisiana, it probably won't come west of Grand Isle.

Further, the exposed circulation of Karen suggests it will follow the low-level flow, which consists of strong ridging more than at the mid-levels. It is difficult and a little dishonest to go westward when the models shifted eastward, however. On the other hand, I surmise that perhaps the 0z guidance suite did not quite initialize Karen with the exposed vortex it has now, which could throw an understandable poleward bias into their respective tracks. The generally reliable TVCN model consensus did not come that far east at 6z, especially at longer ranges, so there is that to consider.

Given the uncertainties in how long Karen will remain devoid of convection, and the eastward shift in the guidance in spite of it, the best I can do is essentially split the predictions down the middle. This turn out to be a little to the west of the model consensus TVCN, and fairly close to the 0z ECMWF model prediction.

If a new center forms under the deep convection to the east, the track would likely be much farther east.

Regardless of where the center of Karen makes landfall, shear associated with the longwave trough suggests the storm will be fairly east-weighted, with the majority of winds and rain occurring to the east of the center in strong rainbands. These bands could pose a threat for isolated tornadoes, tropical storm force winds, and heavy rains. Coastal flooding and storm surge will also be a concern, as well as local power outages.

Watches and warnings are in effect for a large portion of the northern Gulf Coast from Louisiana to Florida. Interests in these areas should closely monitor the progress of Karen over the weekend.

Intensity forecast and positions

INITIAL 10/04 0600Z 24.5°N 89.5°W 55 KT 65 MPH
12 hour 10/04 1800Z 25.3°N 90.3°W 50 KT 60 MPH
24 hour 10/05 0600Z 26.6°N 90.2°W 50 KT 60 MPH
36 hour 10/05 1800Z 28.1°N 89.9°W 45 KT 50 MPH
48 hour 10/06 0600Z 29.2°N 89.2°W 45 KT 50 MPH...INLAND
72 hour 10/07 0600Z 31.0°N 86.6°W 30 KT 35 MPH...INLAND
96 hour 10/08 0600Z 32.9°N 82.3°W 25 KT 30 MPH...POST-TROPICAL/EXTRATROPICAL
120 hour 10/09 0600Z...ABSORBED

Track forecast



Figure 2. My forecast track for Karen.

Watches and warnings


000
WTNT32 KNHC 040545
TCPAT2

BULLETIN
TROPICAL STORM KAREN INTERMEDIATE ADVISORY NUMBER 4A
NWS NATIONAL HURRICANE CENTER MIAMI FL AL122013
100 AM CDT FRI OCT 04 2013

...KAREN CONTINUING NORTH-NORTHWESTWARD OVER THE CENTRAL GULF OF
MEXICO...


SUMMARY OF 100 AM CDT...0600 UTC...INFORMATION
----------------------------------------------
LOCATION...24.5N 89.5W
ABOUT 320 MI...515 KM S OF THE MOUTH OF THE MISSISSIPPI RIVER
MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H
PRESENT MOVEMENT...NNW OR 335 DEGREES AT 10 MPH...17 KM/H
MINIMUM CENTRAL PRESSURE...999 MB...29.50 INCHES


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

NONE

SUMMARY OF WATCHES AND WARNINGS IN EFFECT...

A HURRICANE WATCH IS IN EFFECT FOR...
* GRAND ISLE LOUISIANA TO WEST OF DESTIN FLORIDA

A TROPICAL STORM WARNING IS IN EFFECT FOR...
* GRAND ISLE LOUISIANA TO THE MOUTH OF THE PEARL RIVER

A TROPICAL STORM WATCH IS IN EFFECT FOR...
* WEST OF GRAND ISLE TO EAST OF MORGAN CITY LOUISIANA
* METROPOLITAN NEW ORLEANS
* LAKE MAUREPAS
* LAKE PONTCHARTRAIN
* DESTIN TO INDIAN PASS FLORIDA

A HURRICANE WATCH MEANS THAT HURRICANE CONDITIONS ARE POSSIBLE
WITHIN THE WATCH AREA. A WATCH IS TYPICALLY ISSUED 48 HOURS BEFORE
THE ANTICIPATED FIRST OCCURRENCE OF TROPICAL-STORM-FORCE WINDS...
CONDITIONS THAT MAKE OUTSIDE PREPARATIONS DIFFICULT OR DANGEROUS.

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

A TROPICAL STORM WATCH MEANS THAT TROPICAL STORM CONDITIONS ARE
POSSIBLE WITHIN THE WATCH AREA...GENERALLY WITHIN 48 HOURS.

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.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 100 AM CDT...0600 UTC...THE CENTER OF TROPICAL STORM KAREN WAS
LOCATED NEAR LATITUDE 24.5 NORTH...LONGITUDE 89.5 WEST. KAREN IS
MOVING TOWARD THE NORTH-NORTHWEST NEAR 10 MPH...17 KM/H. A TURN
TOWARD THE NORTH WITH A DECREASE IN FORWARD SPEED IS EXPECTED LATER
TODAY WITH A GRADUAL TURN TO THE NORTHEAST ON SATURDAY. ON THE
FORECAST TRACK...THE CENTER OF KAREN IS EXPECTED TO BE NEAR THE
COAST WITHIN THE TROPICAL STORM WARNING AREA ON SATURDAY.

MAXIMUM SUSTAINED WINDS REMAIN NEAR 65 MPH...100 KM/H...WITH HIGHER
GUSTS. SOME SLIGHT STRENGTHENING IS POSSIBLE DURING THE NEXT DAY OR
TWO...AND KAREN COULD BE NEAR HURRICANE STRENGTH LATE TODAY AND
EARLY SATURDAY. AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT IS
CURRENTLY ENROUTE TO INVESTIGATE KAREN.

TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 140 MILES...220 KM
PRIMARILY TO THE NORTH AND EAST OF THE CENTER.

THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 999 MB...29.50 INCHES.


HAZARDS AFFECTING LAND
----------------------
WIND...HURRICANE CONDITIONS ARE POSSIBLE WITHIN PORTIONS OF THE
HURRICANE WATCH AREA ON SATURDAY. TROPICAL STORM CONDITIONS ARE
EXPECTED WITHIN PORTIONS OF THE TROPICAL STORM WARNING AREA BY
TONIGHT OR SATURDAY MORNING.

STORM SURGE...THE COMBINATION OF 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...

WEST OF THE MISSISSIPPI RIVER TO TERREBONNE BAY...1 TO 3 FT
MOUTH OF THE MISSISSIPPI RIVER TO MOBILE BAY...3 TO 5 FT
EAST OF MOBILE BAY TO WEST OF APALACHEE BAY...1 TO 3 FT
APALACHEE BAY...2 TO 4 FT
SOUTH OF APALACHEE BAY TO TAMPA BAY...1 TO 2 FT

THE HIGHEST WATER WILL OCCUR ALONG THE IMMEDIATE COAST NEAR AND TO
THE EAST OF WHERE LANDFALL OCCURS...WHERE THE SURGE WILL BE
ACCOMPANIED BY DANGEROUS 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.

RAINFALL...KAREN IS EXPECTED TO PRODUCE RAINFALL AMOUNTS OF 4 TO 8
INCHES OVER PORTIONS OF THE CENTRAL AND EASTERN GULF COAST
THROUGH SUNDAY NIGHT...MAINLY NEAR AND TO THE RIGHT OF THE PATH OF
THE CENTER. ISOLATED STORM TOTAL AMOUNTS OF 12 INCHES ARE POSSIBLE.
ADDITIONAL RAINFALL AMOUNTS OF 1 TO 2 INCHES ARE POSSIBLE OVER
PORTIONS OF WESTERN CUBA AND THE NORTHERN YUCATAN PENINSULA.


NEXT ADVISORY
-------------
NEXT COMPLETE ADVISORY...400 AM CDT.

$$
FORECASTER BEVEN

2013 Atlantic hurricane season Tropical Storm Karen

Updated: 8:34 AM GMT on October 04, 2013

Permalink

Tropical weather analysis - October 3, 2013

By: KoritheMan, 7:43 AM GMT on October 03, 2013

Jerry

Jerry is slowly decaying over the central Atlantic. As of the 0300Z NHC advisory, the following information was posted on the storm:

Wind: 35 mph, with higher gusts
Location: 29.7°N 42.0°W
Movement: NE at 7 mph
Pressure: 1010 mb

Satellite estimates have fallen below tropical storm strength, and there is an absence of deep convection near the center. The nearest deep convection is about 100 miles east of the center in a disorganized storm cluster. If present trends continue, Jerry could degenerate into a remnant low sometime today. Given that convection has not returned during the diurnal maximum period, this is a distinct possibility.



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

My forecast generously lets Jerry live for another 48 hours, but it could dissipate before then. The global models are starting to show the storm having less longevity, so I did not draw a forecast point beyond 72 hours with this forecast package.

Jerry is moving northeast as it feels the influence of a deep-layer trough to the west. The models continue to suggest it could pass near or over the Azores in a few days, but there is likely to be very little left of the cyclone by that time. My forecast track is similar to the current NHC prediction.

Intensity forecast and positions

INITIAL 10/03 0300Z 29.7°N 42.0°W 30 KT 35 MPH
12 hour 10/03 1200Z 30.3°N 41.1°W 30 KT 35 MPH
24 hour 10/04 0000Z 31.4°N 38.9°W 30 KT 35 MPH
36 hour 10/04 1200Z 32.5°N 36.3°W 30 KT 35 MPH
48 hour 10/05 0000Z 34.6°N 34.4°W 30 KT 35 MPH
72 hour 10/06 0000Z 35.4°N 31.3°W 25 KT 30 MPH...POST-TROPICAL/REMNANT LOW
96 hour 10/07 0000Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Jerry.



Invest 97L

A well-defined area of low pressure located just east of the northeastern tip of the Yucatan Peninsula has continued to become better organized. It has the look of a developing tropical storm, and the 6z update from ATCF placed the maximum winds at 40 kt; hence, if classification happens overnight, there will be an immediate upgrade to a tropical storm. Surface observations from the Yucatan Peninsula suggest that a broad closed surface circulation may exist.



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

It has not been easy for me to locate the center this evening, but with the help of a fortuitous ASCAT pass, microwave comparisons, and radar data from Cancun, the low-level center appears to be located along the western edge of the convective cloud shield, which suggests the storm is struggling with westerly shear. Given the outflow pattern observed on water vapor imagery, any such shear is likely confined below the outflow layer. This shear is not expected to be enough to prohibit gradual strengthening of the disturbance over at least the next 48 hours. Beyond that time, the GFS suggests that westerly to southwesterly upper shear will increase as the system nears the northern Gulf Coast, which should curb any additional development, and may even cause the system to weaken somewhat before US landfall.

One possibility I was concerned about earlier in the day was that the system may develop an anticyclone before reaching the northern Gulf. If that were to verify, it would likely shunt the strongest shear to the north of the system, and allow it to potentially strengthen more than forecast. The outflow pattern is suggestive that the system has at least a weak anticyclone aloft, but it will remain to be seen how long the system can keep that.

Based on the upper-level wind parameters shown by the GFS, and the subsident airmass seen over the Gulf of Mexico on water vapor images, I am not currently anticipating a hurricane. However, there remains a very small chance, about 10%, that this could occur if the situation I described above with the anticyclone occurs.

Speaking of difficulty, it's been even harder to distinguish and determine the general motion of the system lacking recent reconnaissance observations and a reliable center fix via satellite imagery. With the help of a couple of decent microwave passes, my best guess is that the system is still moving northwestward. Water vapor and upper air data over the southern United States show a broad trough covers much of the central and southern United States, while a mid-level ridge exists downstream over the eastern United States coast and western Atlantic Ocean. This pattern suggests that the disturbance should continue moving northwestward to north-northwestward, followed by an eventual turn to the north as it approaches the northern Gulf Coast. While the models are in general agreement on the northward turn, there are substantial differences on where it will occur. The ECMWF and UKMET, likely at least partially in response to a weaker vortex, show the disturbance making landfall in southeastern Louisiana Saturday evening. On the other hand, the stronger GFS solution shows the system turning toward the Florida panhandle. Given development trends, the GFS solution automatically has more weight, but the ECMWF has been historically reliable. In addition, the majority of GFS ensemble members are considerably west of the operational run, which suggests that the westward turn shown by the ECMWF may not be completely unwarranted.

Looking at it carefully, the biggest differences amongst the models appears to be related to the amplitude of the trough. The UKMET appears to have the flattest trough in relation to the GFS and ECMWF, which allows a predominant south to north flow to not allow for such a quick recurvature.

Even though the ECMWF and UKMET solutions may be more closely related to the strength of the system, I am not completely confident that that is 100% the case, so I am not going to shift my forecast from yesterday, and I still expect a landfall along the coast of Mississippi on Saturday evening, likely closer to the Alabama border than the Louisiana border. There is margin for error on both sides, however, and areas from Houma, Louisiana to Apalachicola, Florida should monitor the progress of this system carefully.

I don't see anything stronger than 50 kt right now.

Probability of development in 48 hours: 90%

2013 Atlantic hurricane season Tropical Depression Jerry Invest 97L

Permalink

Tropical weather analysis - October 2, 2013

By: KoritheMan, 7:47 AM GMT on October 02, 2013

Jerry

Jerry continues as a minimal tropical storm as of the 0300Z NHC advisory:

Wind: 40 mph, with higher gusts
Location: 28.1°N 43.7°W
Movement: W at 1 mph
Pressure: 1008 mb

Jerry has changed little in organization over the last several hours, with the central convection rather thin and nondescript. A newly-formed convective band with cloud tops to about -60C has recently formed in the eastern semicircle, and this convection may attempt to wrap around the central gyre overnight. While this could theoretically keep Jerry as a minimal tropical storm, I have decided to forecast the cyclone to drop down to a tropical depression in about 12 hours, as water vapor imagery and CIMSS TPW show a rather large amount of dry air has become entrained into much of the cyclone circulation.



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

Jerry appears to have temporarily found itself in a less harsh upper tropospheric wind environment, with a narrow upper ridge building over the storm; hence, the primary cause for the decadent state of the cyclone appears to be the very stable troposphere. Arc clouds continue to radiate outward from the center, and there is little reason to assume an improvement in the environment over the next several days. In about three days, cooler waters and increasing southwesterly shear ahead of another upper-level trough are expected to weaken Jerry, and it is entirely possible that the cyclone will become a remnant low much sooner than expected. There does not appear to be enough baroclinic forcing in connection with the upper trough to cause Jerry to transition into an extratropical cyclone through the forecast period, as the distance between the two features is rather great.

Jerry appears to be meandering slowly westward, steered by a weak and narrow mid-level ridge to the north. Water vapor imagery shows an approaching upper-level trough weakening the ridge to the west of the cyclone, which should cause Jerry to turn northward very soon, along with a gradual increase in forward momentum. The global models continue to be in good agreement on the future trajectory of the storm, and my forecast is a little left of the 0300Z NHC one, in part to come into better agreement with the latest model trends.

Although the day four forecast point on my forecast track shown below shows Jerry very near the central Azores, it is entirely possible the cyclone will be dissipated by then. Even if not, there will be little weather in connection with the system at that time.

Intensity forecast and positions

INITIAL 10/02 0300Z 28.1°N 43.7°W 35 KT 40 MPH
12 hour 10/02 1200Z 28.3°N 43.8°W 30 KT 35 MPH
24 hour 10/03 0000Z 29.5°N 43.5°W 30 KT 35 MPH
36 hour 10/03 1200Z 30.7°N 42.3°W 30 KT 35 MPH
48 hour 10/04 0000Z 32.8°N 40.8°W 30 KT 35 MPH
72 hour 10/05 0000Z 35.0°N 35.4°W 30 KT 35 MPH
96 hour 10/06 0000Z 37.8°N 30.1°W 25 KT 30 MPH
120 hour 10/07 0000Z...DISSIPATED

Track forecast



Figure 2. My forecast track for Jerry.



Invest 97L

An area of low pressure over the northwestern Caribbean Sea between the Yucatan Peninsula and the Cayman Islands has become a little better organized this morning. A concentrated burst of convection has become apparent near the low-level center, and earlier microwave data suggested that the overall circulation has become a little better defined. There also appears to be a convective band forming to the east of the center.



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

While the rate of organization is not remarkable, the system does appear to be slowly consolidating, and it should be watched for additional development as it heads toward the Yucatan Peninsula and southern Gulf of Mexico. The motion of this disturbance is a bit difficult to gauge since the center appears to be embedded beneath the convective canopy, but after a careful study of satellite data, it appears the system may be moving more toward the WNW for now, likely because an upper low over northern Louisiana is shifting northward on water vapor images, allowing the ridge over the eastern Gulf to rebuild a little. For this reason, my forecast is a little left of the model consensus, with my current target favoring an eventual landfall along the Mississippi Gulf Coast. The synoptic flow over the western United States is rather flat right now, and it is possible the models are overestimating the speed of the upper trough that is supposed to pull this into the northern Gulf Coast in a few days. A slower-moving trough would allow for a more westward track towards Louisiana, while a more progressive upper trough would allow for a strike east of there, possibly as far east as the Tallahassee, Florida area. Either scenario appears just as likely at this time, so I have essentially split those possibilities with my personal forecast track.

One caveat to development may be a small upper low just inland from the Yucatan Peninsula. The GFS initialized this feature a little too diffusely and farther east than it actually is. If this low sticks around, it may exert more of a shearing influence over the disturbance than the models currently indicate.

Shear is still forecast to increase in the Gulf ahead of the upper trough, but if the system can manage to formulate a decent anticyclone while still in the Caribbean, it may be able to ward off the strongest shear.

Right now, if this develops, I favor a 45 to 50 kt tropical storm.

Probability of development in 48 hours: 40%

2013 Atlantic hurricane season Tropical Storm Jerry Invest 97L

Updated: 8:47 AM GMT on October 02, 2013

Permalink

Tropical weather analysis - October 1, 2013

By: KoritheMan, 6:33 AM GMT on October 01, 2013

Jerry

Wind: 50 mph, with higher gusts
Location: 27.4°N 43.8°W
Movement: E at 8 mph
Pressure: 1005 mb

After a period of increased organization Monday afternoon, the satellite presentation of Jerry has dwindled this morning. Satellite estimates have not increased, and the cyclone's convection has become rather thin, with the deepest convection now confined to a band in the western semicircle. The convection with this band is not very cold, and the vigorous band that was seen encompassing the northern half of the circulation center a few hours ago has largely depleted. A partial ASCAT pass around 0200Z did not detect the entire circulation, regrettably only capturing the western half, but extrapolation of that pass would still lend credence to the NHC's assigned intensity of 45 kt.



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

While Jerry is essentially collocated with an upper low, providing an environment of light vertical shear, water vapor imagery and Total Precipitable Water (TPW) products from the University of Wisconsin-Madison CIMSS group suggest that Jerry has entrained some dry air, and there is evidence of arc clouds emanating away from the system on satellite imagery. There is not much reason to assume the dry air will abate much over the next few days, and there is also evidence of northwesterly upper tropospheric flow approaching the tropical storm from the northwest, behind the shortwave trough that bypassed the system. While these factors should prevent significant strengthening, Jerry could intensify more than currently forecast during the 48-72 hour period, when the GFS predicts the cyclone will become collocated with an upper-level anticyclone, reducing the vertical shear over the system. There is an outside chance that Jerry could become a hurricane during that time, but that is largely contingent on how it survives the current hostilities. Jerry is a small tropical storm, and the ECMWF's forecast of dissipation prior to day five is certainly still a viable one. Near the end of the period, southwesterly shear is forecast to increase ahead of the next upper-level trough now carving out over the western Atlantic; thus, weakening is shown during that time.

I've stared into the abyss, and now I fear the abyss has begun to stare into me. There haven't been any microwave passes to compare, but low cloud lines on shortwave infrared satellite imagery indicate that Jerry may have moved east of the 0300Z NHC forecast track, perhaps by as much as 25 miles while continuing generally eastward. This was a little outside of the model predictions, and so my forecast is a little to the right of the National Hurricane Center in the short-term, but gradually merges into agreement after that. There is still little reason to assume Jerry will not cease the eastward motion and turn westward very soon; the mid-level ridge to the north of the cyclone is clearly building. Jerry is forecast to begin recurving ahead of the next upper trough in a few days. It should be noted that the 0z GFS captured the initial eastward motion rather well, but I did not follow that matter through to its entirety since it seems to unrealistically keep the cyclone vortex moving in a more poleward fashion for longer than seems reasonable, allowing for a quicker recurvature.

Intensity forecast and positions

INITIAL 10/01 0300Z 27.4°N 43.8°W 45 KT 50 MPH
12 hour 10/01 1200Z 27.5°N 43.7°W 45 KT 50 MPH
24 hour 10/02 0000Z 27.5°N 44.4°W 50 KT 60 MPH
36 hour 10/02 1200Z 27.6°N 45.1°W 50 KT 60 MPH
48 hour 10/03 0000Z 27.7°N 46.1°W 50 KT 60 MPH
72 hour 10/04 0000Z 28.8°N 46.2°W 50 KT 60 MPH
96 hour 10/05 0000Z 30.7°N 44.1°W 50 KT 60 MPH
120 hour 10/06 0000Z 34.0°N 39.0°W 45 KT 50 MPH

Track forecast



Figure 2. My forecast track for Jerry.



Invest 97L

A broad area of low pressure located about 125 miles northeast of Puerto Cabezas, Nicaragua, has revived itself from the dead this morning. Shower activity has become more concentrated near the center, and the system looks better now than it ever has. There is still some dry air around, and the convection, while fairly deep, is fragmented and not very organized. Scatterometer and surface data suggest that the trough axis has become a little better-defined in the surface wind field compared to 24 hours ago.



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

Upper-level winds are slowly improving, with water vapor images suggesting the possibility that a small anticyclone may be attempting to build near the estimated center location. The GFS continues to suggest that the upper air environment over the northwestern Caribbean Sea will be characterized by fairly light and diffluent upper-level southwesterlies, but there is also the possibility that the anticyclone may not be completely connected to the center at that point, limiting the chances for significant intensification. Shear should increase a little in the Gulf of Mexico as the disturbance nears an upper-level trough, but there are situations where troughs act to promote convective growth via upper diffluence than they do to primarily shear a system. It is impossible to tell how the upper-level winds will evolve more than about a day or two in advance, and we will just have to watch this disturbance as it heads generally northwestward toward the northwestern Caribbean Sea and southern Gulf of Mexico.

None of the models are still particularly enthusiastic about development, but given the conditions, this area should be watched carefully. I sincerely doubt the prospects of this becoming anything more than a modest tropical storm, however, if it develops at all.

Locally heavy rains will continue to affect portions of Jamaica, the Cayman Islands, and Cuba over the next couple of days.

Probability of development in 48 hours: 30%

2013 Atlantic hurricane season Tropical Storm Jerry Invest 97L

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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.

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