Wxchaser97's Tropical Weather Blog

Tropical Storm Raymond degenerates into a remnant low, new EPAC storm possible

By: wxchaser97, 5:53 PM GMT on October 30, 2013

Post-tropical Storm Raymond
Raymond has became a remnant low hundreds of miles off the Mexican coast. The circulation has become less defined on satellite images and is void of deep convection. Since my last blog update, Raymond had reintensified into a category 2 hurricane. Once it entered favorable atmospheric conditions, it was able to RI, developing a defined eye and eyewall. As Raymond turned NW, it entered a region of higher vertical shear and less favorable thermodynamic environment. The turn to the NW, and then NE, was in response to an incoming trough from the north. The continuation of an unfavorable environment led to the deterioration of the convective structure. Raymond was declared post-tropical this morning since it no longer fit the criteria of a tropical cyclone. The remnant circulation should slowly dissipate over the next couple days as it moves slowly over the open waters of the Epac. Remnant mid-level moister from Raymond is getting pulled to the north into Mexico and the southern US as Raymond interacts with the trough. Models did fairly well with the evolution of Raymond. The track of Raymond was predicted pretty well, but the rapid intensification episodes where hard to predict. The latest satellite image of Raymond can be seen below.

Epac AOI
An area of disturbed weather is located several hundred miles SW of Manzanillo, Mexico. Satellite images show that the cloud pattern of this system continues to organize. An area of low pressure also looks to be forming in this area. The AOI should have a pretty favorable environment for development for the next several days. Besides being over warm SST's, the AOI should be in the diffluent zone of the trough to the north, enhancing divergence over the system. This trough should also have an influence in the steering of this system, taking a NW path until turning NE around the southern Baja Peninsula. Most models are showing development of this system over the next few days. It is appearing increasingly likely that the Epac should see Sonia in the next few days. This system would bring more rain to areas that have already gotten rain from several tropical systems this year.
Chance of development in the next 48hrs: 30%

Tropical Storm Raymond Epac


Tropical Storm Raymond reorganizing after becoming EPAC's first major

By: wxchaser97, 1:46 PM GMT on October 25, 2013

Tropical Storm Raymond
Tropical Storm Raymond is trying to restrengthen several hundred miles off the Mexican coast. It first developed from a disturbance that originated from near Central America. It slowly organized and acquired an organized surface circulation. Raymond became a tropical depression at 8pm PDT October 19th. It continued to organize and became TS Raymond the next advisory. Under low shear, very warm SST's, and a moist atmosphere, Raymond was able to enter a period of rapid intensification. It quickly strengthened into a category 2 hurricane with a solid ULAC and deep convection surrounding a warming eye. Raymond was able to become, finally, the EPAC's first major hurricane of the season as it stalled just off the Mexican coast. Hurricane warnings were issued as the storm brought high winds and heavy rain to parts of S Mexico. As quickly as it strengthen, Raymond began to weaken. The cause of this weakening is likely the upwelling of cool ocean waters below the surface. This decreased amount of heat energy available, along with a little dry air, looks to have cause the demise of Raymond. It weakened all they way down to a weak tropical storm that was mostly devoid of deep convection. However, Raymond has been able to survive its weakening episode and has entered a more favorable environment. SST's and TCHP have been increasing allow Raymond to reorganize itself. Deep convection has re-fired over the center and some banding features have developed. However, the circulation isn't as strong as it was earlier and the low-level and mid-level centers look to be tilted a little when looking at UW-CIMSS 850-500mb vorticity maps. Still, satellite intensities have been slowly increasing with SAB at T3.0 and ADT near T3.5. The latest advisory information and satellite image can be found below.

2:00 AM PDT Fri Oct 25
Location: 14.2°N 108.5°W
Moving: W at 10 mph
Min pressure: 1000 mb
Max sustained: 50 mph

Forecast for TS Raymond
Tropical Storm Raymond looks like it still should strengthen some over the next few days. Raymond has left the area where it did upwelling and has entered a more favorable region. SHIPS analysis shows SST's remaining 28.0C+ for the next couple days. Also, the upper air profile has been improving around Raymond. More upper-level outflow has become established in all quadrants. UW-CIMSS and GFS upper-level analysis show a more anticyclonic flow than earlier. This is helping ventilate the system and fend off some shear. This should help keep upper-level winds favorable for intensification for the nest couple days. Later in the forecast period, mid and upper-level wind shear should increase in response to an approaching trough from the north. SST's will also be becoming a little more marginal during that period. Raymond will begin its final weakening period during that time. Before then, it looks like Raymond should be able to have enough time to become a hurricane again. Intensity guidance also shows Raymond regaining hurricane status. They also agree the Raymond should begin weakening at about day 4. My forecast is pretty close to the NHC's.

Raymond is moving west at about 10mph. The low-level center is pretty hard to locate on conventional satellite images. Luckily, ASCAT passes and microwave images have been able to get a better center fix. I'd put the center at around 14.3N and moving W-WSW based on extrapolated ASCAT passes. Raymond should turn to the WSW soon in response to the mid-level ridge to its north. This ridge should continue sending Raymond to the WSW for the next couple days. The continued WSW motion is shown on UW-CIMSS steering maps Models are in good agreement of the track of Raymond in the short term. After that time, Raymond should turn NW in response to the trough to the north. The trough should then turn Raymond to the N and then NE over the next several days after that. Models are in decent agreement, though not as much as in the short term, for the track of Raymond. My forecast track is pretty similar to the NHC's. Raymond won't affect any land areas in the next 5 days.

Forecast Intensity

INIT 25/1300Z 45 KT 50 MPH
12H 26/0000Z 50 KT 60 MPH
24H 26/1200Z 55 KT 65 MPH
36H 27/0000Z 65 KT 75 MPH
48H 27/1200Z 65 KT 75 MPH
72H 28/1200Z 65 KT 75 MPH
96H 29/1200Z 55 KT 65 MPH
120H 30/1200Z 45 KT 50 MPH


EPAC Tropical Storm Raymond


Two weak EPAC tropical cyclones

By: wxchaser97, 11:27 AM GMT on October 15, 2013

Tropical Depression Octave
Octave is a sheared, decoupled tropical cyclone. Octave developed from a disturbance of the SW Mexican coast that slowly acquired a pronounced surface circulation with organized convection. TD-15E formed at 0300Z on Sunday the 12th. As the depression continued to organize, it was quickly upgraded to tropical storm strength. While Octave was forecast to only remain a weak tropical storm, it was able to strengthen into a strong tropical storm several hundred miles off the Mexican coast. As southwesterly wind shear increased, Octave began to weaken. This same shear is what has caused the decoupling of the low and mid level centers. Microwave and satellite imagery show pretty clearly that this decoupling event has happened. The weakening low-level center is located on the southern Baja Peninsula while the convection is located over the Gulf of California and the Mexican mainland. ASCAT and OSCAT passes from a few hours ago, along with current surface obs, still show that the low-level circulation still is pretty well-defined, but is weakening. The latest NHC advisory information and satellite image can be found below.

2:00 AM PDT Tue Oct 15
Location: 25.5°N 112.0°W
Moving: NNE at 5 mph
Min pressure: 1004 mb
Max sustained: 35 mph

Forecast for Octave
Not much can be said about Octave's future besides "no bueno". Octave is interacting with land which is disrupting the low-level circulation. The strong southwesterly wind shear is not decreasing and will continue to adversely impact the depression. To add to this, dry air is also entrained into the system and should further suppress the redevelopment of convection. Looking at current satellite trends and the continuation of an unfavorable environment, Octave should become a remnant low later today. The circulation should continue to lift northeast in response to a strong trough to the northeast. Steering currents are weak, however, and whatever is left of Octave should move slowly into Mexico's mainland over the next 1-2 days. Models are in agreement of the track and intensity of Octave. Moisture from Octave should continue to enhance precipitation over Texas in the next couple days. This is good for the drought situation but some flash flooding has occurred in spots. There will also be locally heavy rain over Northern Mexico.

Forecast Intensity
INIT 15/0900Z 30 KT 35 MPH
12H 15/1800Z 25 KT 30 MPH...POST-TROP/REMNT LOW
24H 16/0600Z 20 KT 25 MPH...POST-TROP/REMNT LOW
36H 16/1800Z...DISSIPATED

All tropical storm warnings have been discontinued.

Tropical Storm Priscilla
TS Priscilla is a weak tropical storm over the open waters of the East Pacific. Deep convection has been mostly confined to the western side of Priscilla due to vertical wind shear from Octave. There has been a developing burst of deep convection over the center over the past couple hours. It will be interesting to see how long this are of convection is able to persist under the unfavorable conditions. Satellite intensity estimates still support Priscilla being a tropical storm. While the satellite appearance is rather poor, I have seen multiple worse looking tropical storms than Priscilla. The latest NHC advisory info and satellite image can be found below.

2:00 AM PDT Tue Oct 15
Location: 17.1°N 116.0°W
Moving: N at 8 mph
Min pressure: 1004 mb
Max sustained: 40 mph

Forecast for Priscilla
There are some mixed signals for whether Priscilla will be able to strengthen in the short term before conditions become unfavorable overall. Easterly wind shear is decreasing over the storm and is expected to decrease further over the next day. This is good for Priscilla as it can then try and develop deep convection fully over the low-level center without it being sheared away while further tightening up said circulation. The decrease in easterly shear is due to the weakening of Octave and its outflow. In theory, this should give Priscilla a 36hr window to organize before shear increases to unfavorable levels. However, there are other forces that will be working against Priscilla. Large amounts of dry, stable air are surrounding the system, especially to the west. SHIPS analysis shows the mid-levels only getting drier as time goes on. This dry air could easily interact with Priscilla and slow the organization of Priscilla. Also, SST's will be decreasing to marginal levels in about 24hrs. With a more marginal thermodynamic environment, there will be less energy available to help sustain the tropical cyclone. After about 48hrs, the atmosphere becomes increasingly unfavorable and any organization would be halted and reversed. Models aren't showing much in the way of strengthening over the short term either. The majority of the models slowly weaken Priscilla from here on out. Giving her the benefit of the doubt, I will forecast her to retain TS strength for the next 12hrs followed by weakening. Priscilla should become a post-tropical cyclone in about 4 days.

Priscilla is moving to the north at 8mph. This is in response to a weakness to its NNE. This weakness is due to Octave, though it is more shallow now, and a strong trough over the US. As Octave dissipates and the trough moves farther to the east, mid to upper level ridging should build over the Eastern Pacific. This would turn Octave to the NW. As the ridge amplifies more in 3-4 days, Priscilla should turn more to the west. The majority of dynamical, statistical, and global models take Priscilla off to the west. There are a few models that diverge late in the forecast period, but they won't verify. Priscilla should remain far from land and bring no significant impacts to any landmasses.

Forecast Intensity
INIT 15/0900Z 35 KT 40 MPH
12H 15/1800Z 35 KT 40 MPH
24H 16/0600Z 30 KT 35 MPH
36H 16/1800Z 30 KT 35 MPH
48H 17/0600Z 25 KT 30 MPH
72H 18/0600Z 20 KT 25 MPH...POST-TROP/REMNT LOW
96H 19/0600Z...DISSIPATED


Tropical Storm Octave Tropical Storm Priscilla Epac


Powerful Cyclone Phailin threatning India, developement of Invest 98L possible

By: wxchaser97, 4:21 AM GMT on October 12, 2013

Cyclone Phailin
A powerful cyclones is bearing down on the eastern sections of India. This cyclone is named Phailin and is one of the strongest cyclones on record in the Indian Ocean basin since their satellite era began. After moving generally WNW in the Bay of Bengal for a few days, Phailin was named on October 9th in about the middle of the Bay of Bengal. As it moved a little father NW, it encountered very favorable conditions for strengthening. Since it had a relatively moist environment, low shear, and warm SST's, Phailin was able to intensify quickly. It became a category 1 hurricane-equivalent cyclone on October 10th. After that, Phailin rapidly intensified into a category 4-equivalent cyclone. A solid ULAC had developed and a strong eyewall had taken shape around the eye. This eyewall was relatively small to begin with, which increased the chances for an Eyewall Replacement Cycle(EWRC). Later that evening, Phailin underwent an EWRC and weakened slightly as the new, outer eyewall contracted inwards and became dominate. The EWRC was quick and was completed in about 7hrs. Since atmospheric conditions remained very favorable for strengthening, Phailin was able to intensify into a category 5-equivalent cyclone in the Northern Bay of Bengal. Currently, Phailin is beginning to undergo another EWRC. Another eyewall has developed away from the inner eyewall and should begin to become the dominate eyewall. Phailin still looks impressive on satellite with a warm eye surrounded by very cold cloud tops and a nice upper level outflow channel. Satellite intensity estimates are still around T7.0/135kts, but they are beginning to drop as Phailin begins the EWRC. The current JTWC advisory info, satellite image, and microwave imagery can be found below.

120000Z --- NEAR 17.4N 86.5E

Forecast For Phailin
The forecast is bleak for India over the coming days. There is nothing that looks to significantly weaken Phailin before it slams into the Eastern Indian coastline. With the solid ULAC over Phailin, any vertical wind shear would be kept to a minimum while over water. It should also help to continue to ventilate the cyclone and promote the continuation of thunderstorm development. The warm waters of the Bay of Bengal should provide sufficient fuel for Phailin to continue to strengthen. There is also moderate amounts of TCHP which means Phailin won't have to worry about upwelling and/or weakening due to decreased amounts of heat. Dry air also isn't any problem as Phailin has a large moisture field surrounding the center. The only thing that will negatively effect Phailin's intensity is the ongoing EWRC. As the inner eyewall diminishes and the outer eyewall becomes established, the central pressure will rise some with a decrease in the maximum winds. With Phailin have about 135kt maximum winds right now, per satellite estimates, they may be brought down to around 130-125kts for a brief time. If Phailin completes this EWRC as fast as it did the first one, then it should have enough time to restrengthen back to the intensity before the replacement cycle and then some. However, if this EWRC lasts longer than the other one, Phailin will run out of time before it makes landfall and begins interacting with land causing weakening. Going with how good environmental conditions are and Phailin's past history, I think the cyclone should have enough time to restrengthen. Since EWRC aren't always predictable, there is the possibility that Phailin doesn't strengthen. No matter what, Phailin should make landfall as a strong category 4 to category 5 equivalent cyclone. Phailin should continue to be steered by a mid-upper level ridge to its NE. This should bring Phailin inland in about 12hrs coming in from the SE. As Phailin gets farther inland, it should be turned more to the north in response to the steering flow turning more to the S/SW. Models are in pretty good agreement in the track of Phailin and there is little reason to diverge from the limited model support. My forecast track is pretty similar to the JTWC one. Since that is the case, and the fact I can't get a good tracking map of the Indian Ocean, I'm not doing a forecast graphic for Phailin. No matter on where the exact landfall location is, Phailin will bring devastating impacts to much of NE India. A large storm surge will be felt along the coast extending into vulnerable areas. The IMD predicts a maximum storm surge of about 3m (9-10ft) near the center. I find this to be too low and think a storm surge of 20ft+ is possible in some areas due to the large size and strong winds of Phailin. Also near the center, destructive hurricane-force winds will whip the coast, and nearby inland areas, downing trees and damaging structures. Very heavy rains will cause flash flooding and mudslides, especially in more mountainous areas. This is an extremely dangerous situation for the areas that are going to be impacted. The last storm of similar magnitude was the 1999 Odisha Cyclone that killed thousands of people. While the death toll hopefully shouldn't be that high, there will still be devastating impacts.

My forecast intensity:
INT 12/00Z MAX WINDS 140kts
12HR 12/12Z MAX WINDS 140kts ...LANDFALL...
24HR 13/00Z MAX WINDS 95kts ...INLAND...
36HR 13/12Z MAX WINDS 60kts ...INLAND...
48HR 14/00Z MAX WINDS 30kts ...INLAND...

Invest 98L
A low pressure system, dubbed invest 98L, embedded in the ITCZ/monsoon trough is producing numerous showers and thunderstorms in the central Atlantic. While the convection is pretty deep, it is being partly feed by the monsoon trough and is getting sheared by moderate vertical wind shear. A recent ASCAT pass showed a defined low pressure system with 30kt wind barbs. However, since ASCAT only caught 1/2 of the circulation, it is unclear whether the circulation is closed or not. This is important to determine whether a tropical depression has formed or if it remains an open low. Microwave imagery doesn't give a conclusive picture either of if the circulation is closed or not. Since there isn't enough evidence to show a tropical cyclone exists, the NHC has not started advisories on invest 98L. Environmental conditions have been deteriorating around 98L for the past day. Wind shear has been on the increase which has not allowed the thunderstorms to get very organized. However, overall, 98L has somewhat improved in organization from the past few days and still remains a threat to develop into a tropical cyclone. Models aren't showing much improvement in the environment over the next 5 days with wind shear remaining at moderate values. Not many of the global, dynamical, or statistical models show 98L developing into a tropical cyclone. If 98L is able to develop into a TC over the next day or so, it won't survive to long in a sheared environment with the atmosphere becoming dry in the mid-levels. Invest 98L would follow the theme of sheared tropical storms in 2013. A subtropcial ridge over the central Atlantic should steer 98L to the W/WNW over the next couple days before being pulled more to the NW in response to an incoming trough. Whatever is left of 98L may bring some rain to the Lesser Antilles in a few days. The current ATCF info and satellite image can be found below.

AL, 98, 2013101200, , BEST, 0, 117N, 398W, 30, 1006, LO, 34, NEQ, 0, 0, 0, 0, 1011, 200, 80, 0, 0, L, 0, , 0, 0, INVEST, M,

Chance of tropical cyclone development in the next 48hrs: 60%


Karen threatening the Gulf Coast

By: wxchaser97, 1:14 AM GMT on October 05, 2013

Tropical Storm Karen
Since this is the 2013 Hurricane Season, Karen remains disorganized. The center remains on the western edge of the convection. While convection tries to refire over Karen's center, it is getting sheared away. This is what happens when you have moderate shear impacting a tropical cyclone with no ULAC over the tropical system. This wind shear has also caused Karen to become decoupled somewhat. This means that the low-level center and the mid-level centers are not vertically aligned, which isn't good for the prospects of intensification. This decoupling is noticeable on CIMSS vorticity maps and microwave imagery. The dry mid-upper levels of the atmosphere aren't helping Karen's cause either. The dry air has been suppressing convection on mostly the western side of Karen. Nevertheless, Karen still has a well-defined low-level circulation. Aircraft reconnaissance flights show Karen having maximum sustained surface winds of about 50mph and a central pressure of 1003mb. TAFB and SAB T#'s also support surface winds up to 50mph. The latest advisory information, satellite image, and microwave image can be found below.

7:00 PM CDT Fri Oct 4
Location: 25.9°N 90.3°W
Moving: Stationary
Min pressure: 1002 mb
Max sustained: 50 mph

Forecast For TS Karen
Tropical Storm Karen won't get as strong as forecast earlier. Moderate wind shear and a dry central GOM have been able to keep Karen at bay. If fact, these unfavorable conditions have been able to weaken Karen as she gets farther north. Luckily for the people along the Gulf Coast, conditions don't look to get favorable for significant intensification. This doesn't mean that Karen couldn't slightly strengthen, but significant intensifying is unexpected. Global models and SHIPS analysis continue to show moderate wind shear over Karen and issues with dry air. Karen is also moving over an area with less TCHP values which means there is a little less energy available for the cyclone. Based on this, it looks like Karen will only be able to maintain strength, at the most, for the next 24hrs. As Karen nears landfall, increased upper level divergence should move over Karen ahead of the approaching trough. This could promote some convective growth and consequently some intensification. Global models are also in decent agreement that there may be some strengthening before landfall. After making landfall, conditions turn very unfavorable for Karen. Besides having its heat source lost, wind shear will sharply increase due to the aforementioned trough. This should, along with the baroclinic energy getting injected into Karen, turn her into a post-tropical storm before getting absorbed into the trough. My forecast shows for the maintained intensity of 45kts for the next 36hrs before slightly increasing to 50kts. It is entirely possible that Karen doesn't strengthen at all and even continue to slowly weaken before making landfall. This is especially true if the system fully decouples and makes a quicker landfall. Also if Karen fully decouples and the low-level circulation stays exposed, then there is a small possibility that Karen degenerates.

Karen has slowed a little from yesterday and is generally moving to the NNW. The center has made some wobbles due to the fluctuations of the convection. Karen is still riding around the periphery of the subtropical ridge to the west. As Karen has remained weaker than previously thought, the ridge has been able to push Karen a little farther west. As the mid to upper level trough gets closer, Karen will feel more of the effects of this trough. Karen has already slowed its forward motion and turned a little farther north than from yesterday and these effects will increase over the next day. As we get past about 24hrs, we should see Karen get turned to the NE and begin to accelerate. The trough will then continue to pull Karen to the NE over the SE US before getting absorbed in about 4 days. Global models have come into a little better agreement in the track of Karen, but there is still differences in timing and how far east/west Karen will get between the GFS and ECMWF. knowing that the ECMWF has done better with Karen, and the fact that the GFS shows a sharper turn, I am more inclined to go with a solution near the Euro. The dynamical/statistical guidance is spread still from LA to FL. Based on all of this, a track into the far western FL panhandle seems likely in about 48-60hrs. Karen should bring gusty winds, moderate rain, and a few tornadoes to the NE Gulf Coast over the weekend. Some minor coastal flooding is also possible due to the increased wave heights and storm surge. This won't be a huge impact storm, but people in Karen's path still need to be prepared for TS conditions.

Forecast Intensity
INIT 04/0000Z 45 KT 50 MPH
12H 05/1200Z 45 KT 50 MPH
24H 06/0000Z 45 KT 50 MPH
36H 06/1200Z 45 KT 50 MPH
48H 07/0000Z 50 KT 60 MPH
96H 09/0000Z...ABSORBED

Forecast Track





Tropical Storm Karen

Updated: 2:14 AM GMT on October 05, 2013


TD Jerry Degenerates, TS Karen forms and threatens the US

By: wxchaser97, 1:38 AM GMT on October 04, 2013

Remnants of Jerry
Formerly a tropical storm, Jerry weakened to a depression early today and then degenerated to a remnant low in the Northeast Atlantic. This is due to the abundance of dry air prohibiting thunderstorm activity, and the heat source being lost with SST's at 26C and falling. There is only one area of thunderstorms near the center and the surface circulation looks ragged. Conditions aren't favorable for redevelopment in the next 5 days as the remnants move off to the NE. Shear will be increasing due to the approaching trough, SST's will continue to drop, and dry air will still be sticking around. The remnant low will be steered to the NE by the incoming trough. The low should get absorbed into the front in a few days before going over the Azores. The Azores will see some unsettled weather from the remnants of Jerry and the approaching front. Models are in good agreement in the track of the remnants and the weakening of the system. Since Jerry has degenerated and doesn't look to regenerate, this is likely my last update on the system. The last advisory and satellite image can be found below.

5:00 PM AST Thu Oct 3
Location: 31.8°N 38.7°W
Moving: ENE at 14 mph
Min pressure: 1010 mb
Max sustained: 35 mph

Tropical Storm Karen
Tropical Storm Karen, the 11th storm of the 2013 Atlantic hurricane season, formed this morning near the Yucatan Peninsula. This system was formerly invest 97L, but it was able to develop a well-defined, closed surface circulation and had fit the criteria for a tropical cyclone. Karen is an east-weighted tropical storm, which means that most of the convection and strongest winds are on the eastern side of the system. Southwesterly wind shear, coming from an anticyclone to the south of the storm, and dry air in the central Gulf are not allowing a lot of convective growth on the western side. There is a burst of deep convection over the center, but it will probably get partly sheared off. While Karen is a lopsided tropical cyclone, it is a pretty vigorous one. Aircraft reconnaissance continues to find Karen have a sub-1000mb pressure and 50-55kt surface winds, along with flight level winds at hurricane force. Karen is already bringing wet weather to the NW Caribbean and the northern/eastern Gulf Coast. The current advisory info, satellite image, and microwave image can be found below.

7:00 PM CDT Thu Oct 3
Location: 23.8°N 88.9°W
Moving: NNW at 12 mph
Min pressure: 999 mb
Max sustained: 65 mph

Forecast For TS Karen
Tropical Storm Karen has a rough future ahead. While the storm already has 65mph winds, Karen shouldn't increase that number by too much. There are a couple things going against significant intensification for Karen. The first is wind shear. Southwesterly shear is impacting the system right now and giving it the lopsided appearance. This shear won't abate enough while Karen is in the Gulf to allow for any substantial strengthening. SHIPS analysis shows about 20kts of shear, CIMSS also shows this, and SHIPS believes that shear should remain at around 20kts for the next 2-3 days. It then sharply increases, but Karen will already be over land and weakening so that doesn't matter. Most of the global models have moderate shear sticking with Karen the whole way through. The GFS is the only model that builds upper-level riding over Karen and thus allows it to strengthen into a hurricane. While I currently don't believe the GFS solution will come to fruition, it is possible that if enough deep convection can remain over the center some riding aloft could develop and abate shear a little. No matter what happens in the next day or so, shear will be on the uptick when Karen nears the coast, halting any strengthening before landfall. Issues with wind shear isn't the only problem Karen is facing, dry, stable air is also present in the central gulf. This mid to upper level dry air is limiting convection on the western semicircle. There are no indications of the atmosphere moistening up substantially in the next few days. Implications of this dry air are that Karen won't be able to intensify significantly and that Karen will likely remain an eastern weighted storm. SHIPS analysis shows no improvement in the moister profile over the next few days as well. SST's around Karen are high and Karen shouldn't have much trouble firing convection on the favorable eastern side. TCHP values over the southern GOM are also decent, promoting the continued gradual strengthening. However, as Karen gets closer to the coast, they decrease somewhat. This isn't as substantial as the dry atmosphere or the unfavorable upper air pattern, but it may still inversely impact Karen. Most of the global and dynamical/statistical models show little strengthening due to the marginal conditions. The GFS is the most bullish global model and I do not think it will verify for a hurricane landfall, but it still should be monitored. Karen could become a hurricane tomorrow if enough deep convection can pull down some of the hurricane force flight-level winds to the surface. If Karen becomes a hurricane, it won't be one for long. It is entirely possible that Karen doesn't become a hurricane due to it not being able to pull the strong winds to the surface. My current forecast is to have Karen gradually strengthen for the next 24hrs before slowly, but steadily, weakening.

The current motion of Karen is off to the NW at about 12mph. The easy to distinguish center on satellite and recon center fixes make it easy to determine the motion and forward speed of Karen. TS Karen continues to head off in the general NW direction in response to a subtropical ridge to its west. This feature should continue to drive Karen through the Gulf. Karen is on the edge of the ridge and is getting pulled around the periphery. This should turn Karen to the north and then the NE over the next couple days as Karen nears the United States. An approaching mid/upper level trough will make sure Karen continues to the NE. The timing of the trough will dictate how far west Karen could go. If the trough is a little slower than thought, Karen could move farther to the west before feeling the influence of the trough. If the trough is a little faster then Karen would turn to the N and then NE sooner meaning a higher chance of a FL landfall. The ECMWF, UKMET, and CMC are slower with the trough while the GFS is faster with bringing the trough eastward. This has the GFS being the farther east solution with the other global models being the westward solution. The hurricane models (GFDL and HWRF) are leaning toward a path that is closer to the GFS. The dynamical/statistical model guidance does have some spread between LA and FL, but most are focused in on the AL/MS coast. My track forecast is a blend of the solutions and brings Karen into the Alabama coast in 48 to 60hrs. After making landfall, the same trough should accelerate Karen to the northeast.

Tropical Storm Karen will bring a multitude of impacts to the northern Gulf Coast. people on the eastern side of Karen will get worse impacts than on the west side, but that doesn't mean people on the western side should let their guard down. Both sides, especially close to the center, should receive strong, gusty winds. Wind gusts will probably exceed hurricane force in some areas, knocking down trees and powerlines. The saturated ground in the NE Gulf doesn't help with having trees not get uprooted. Storm surge, while no large, will still be seen in the coastal areas. This may cause some coastal flooding. Heavy rain, especially on the western side, may cause inland flooding where multiple inches of rain are possible. Hurricane watches and tropical storm warnings/watches are in effect for parts of LA, MS, AL, and FL. People in these areas need to be preparing for the conditions advised about for their area. The progress of Karen will continue to be closely monitored for changes in potential impacts.

Forecast Track

Forecast Intensity
INIT 04/0100Z 55 KT 65 MPH
12H 04/1200Z 60 KT 70 MPH
24H 05/0000Z 65 KT 75 MPH
36H 05/1200Z 60 KT 70 MPH
48H 06/0000Z 55 KT 65 MPH
72H 07/0000Z 40 KT 45 MPH...INLAND







I'll have a new blog update on Karen, plus on a major winter storm in the N Plains, tomorrow evening.

Tropical Storm Jerry Tropical Storm Karen Atlantic


Tropical Storm Jerry hanging on, Invest 97L approaching tropical strom strength

By: wxchaser97, 1:45 AM GMT on October 03, 2013

Tropical Storm Jerry
Tropical Storm Jerry continues to battle dry air intrusions from an upper level low. The convection isn't as widespread or deep as it was a couple days ago. The circulation also isn't as well-defined as earlier. However, TAFB and SAB remain at T2.5 so Jerry is still a tropical storm, just not a pretty one. The NHC advisory info, satellite, and microwave imagery can be found below for Jerry.

5:00 PM AST Wed Oct 2
Location: 29.3°N 42.6°W
Moving: NE at 7 mph
Min pressure: 1009 mb
Max sustained: 40 mph

Forecast For TS Jerry
The forecast for Jerry is downhill from here on out. Conditions look to only get less favorable over the next few days before Jerry turns extratropical. For the next day or two, Jerry's biggest limiting factor will be dry air. The dry air will continue to limit convection and slow any reorganization of the storm's circulation. This dry air is expected to persist, even after the ULL gets farther away from Jerry, for the next 5 days. SST's are also on the downturn and will be dropping below the 26.0C isotherm in about 24hrs. This will also cause Jerry to begin to weaken and slowly lose its tropical characteristics. As Jerry progresses into the weekend, SST's will plummet into the low 20C range and thus Jerry will lose it's main heat source. Wind shear should also begin to become a problem again in the next 48hrs or so. The increase in southwesterly shear will be the result of an incoming trough. This should be the final nail in Jerry's coffin and Jerry should really begin weakening during this time. Due to the continued unfavorable conditions and the current state of Jerry, I forecast no strengthening over the next 5 days. I see Jerry maintaining TS intensity for about the next 48-72hrs before weakening to a TD and the shortly after become post-tropical. While this is below the intensity guidance, it is more in line with the global models and the NHC. Jerry has also made the anticipated turn to the northeast, just a little more to the east than I expected. As Jerry gets farther north and east, it should accelerate as it gets more under the influence of the approaching trough and the westerlies. There is good consensus on the models for where Jerry should go and there is little reason to go against them with the pattern in place. Jerry could bring some gusty winds and showers to the southern Azores in about 4 days.

Forecast Intensities
INIT 00/0000Z 35 KT 40 MPH
12H 03/1200Z 35 KT 40 MPH
24H 04/0000Z 35 KT 40 MPH
36H 04/1200Z 35 KT 40 MPH
48H 05/0000Z 30 KT 35 MPH
72H 06/0000Z 30 KT 35 MPH
96H 07/0000Z 30 KT 35 MPH...POST-TROP/REMNT LOW
120H 08/0000Z...DISSIPATED

Forecast Track


Invest 97L
A low pressure system, dubbed invest 97L is located in the Northwest Caribbean. This low is producing gale-force winds and has deep convection near/over the center. However, a recon flight into 97L found that there wasn't enough of a well-defined circulation to upgrade 97L to a tropical cyclone. There is a broad surface circulation, but it lacks the structure of a tropical cyclone. There is a decent burst of convection firing over the center that should aid in the organization of the LLC. An impressive anticyclone over 97L should help keep upper-level divergence strong thus keep the system ventilated and convection firing. The next recon flight is scheduled to leave at 11pm EDT and should reach 97L a couple hours after that. We should get a better idea of the low-level structure when the plane enters. The latest ATFC info, satellite imagery, and microwave imagery can be found below.

Forecast For Invest 97L
Invest 97L has a decent environment to strengthen in for the next couple days. Shear should remain favorable due to the impressive ULAC, 97L has developed a decent moister shield which should help fight against dry air for a while, and 97L is over high SST's and TCHP values. This should help aid in the organization and intensification process. With the current rate of organization and the present atmospheric conditions, it is likely that we have Karen in the next 12hrs. After about 36-48hrs dry air could begin to limit intensification. Even with the amount of moisture 97L currently has, there is an abundance of dry air in the central GOM and this will be a problem for 97L. Also upper level winds will increase as 97L gets closer to the NE Gulf Coast. The increase in shear will be as a result of an approaching trough from the north. Because the environment isn't perfect for significant strengthening, I don't think 97L will become a hurricane. If it is able to get a well-defined circulation going along with developing an inner core then invest 97L could become a hurricane in the C Gulf before conditions become more marginal. The storm will probably make landfall along the MS, AL, FL gulf coast. It is being steered by a ridge to its east and will continue to be influenced by it, along with an approaching trough, over the next several days. After whatever become of 97L makes landfall in the US, it should be pulled to the NE by the trough and bring rain to the eastern US. Strong, gusty winds will be possible along coastal areas of the NE GOM, W Cuba, and the NE Yucatan peninsula. People in these regions need to be ready, especially the NW Caribbean as they are getting impacts right now, for stormy conditions. This is a system that will be with us for several days and will be monitored closely. I'll have a more detailed forecast on this system tomorrow evening.

Chance of development in the next 48hrs: 90%

Tropical Storm Jerry Atlantic

Updated: 2:06 AM GMT on October 03, 2013


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

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I'm a CMU Honors student and love meteorology and extreme weather. I've been fascinated by weather since I was 5, and plan on becoming a meteorologist

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