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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.
...JERRY BECOMES A REMNANT LOW... ...THIS IS THE LAST ADVISORY...
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.
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
96H 08/0000Z 25 KT 30 MPH...POST-TROP/EXTRATROP
120H 09/0000Z...ABSORBED BY FRONT
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.
I'll have a new blog update on Karen, plus on a major winter storm in the N Plains, tomorrow evening.
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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