Karen defeated; new disturbance a threat to the Gulf of Mexico
Wind shear put an end to Tropical Storm Karen yesterday. Karen's remains continue to generate a large area of disturbed weather a few hundred miles east of the northern Lesser Antilles Islands (Figure 1). This morning's QuikSCAT pass showed some rotation still exists near the surface, with winds up to 30 mph. Wind shear has fallen to 20 knots over Karen's remains, and some of the models forecast the shear will fall below 15 knots by Tuesday, which may allow redevelopment of the storm. Both the UKMET and NOGAPS model revive Karen later this week, and show it moving very slowly to the west towards the U.S., but well offshore. The GFS model keeps the shear high, and does not redevelop Karen.
Figure 1. This morning's visible satellite image.
Bahamas tropical disturbance
A potential significant threat area has developed today off the U.S. East Coast along an old frontal boundary. Several areas of heavy thunderstorm activity have started firing up along this old front. Wind shear is about 20 knots over the region today, so only slow development will occur. By Tuesday, the shear is forecast to drop below 15 knots, and most of the computer models are forecasting that a tropical depression will form near Florida or Cuba. This storm is forecast to move westward across the Gulf of Mexico, pushed by a strong ridge of high pressure expected to build in. An upper-level anticyclone aloft is expected to develop as well, providing an environment favorable for intensification. The UKMET model is forecasting a strong tropical storm or weak hurricane by Friday for the Texas/Mexico border region. The other models are not so aggressive, but all see the possibility of a tropical storm impacting the western Gulf of Mexico in Louisiana, Texas, or Mexico sometime Thursday through Saturday. The Hurricane Hunters are on call to fly into this system Tuesday afternoon, if necessary. Texas is at highest risk from this potential storm.
Melissa
Tropical Depression Melissa is not long for this world, thanks to wind shear of 15-20 knots that is expected to increase further as Melissa heads northwest. Melissa is not a threat to any land areas, and will not be around three days from now.
I'll have an update Monday.
Jeff Masters
Reader Comments
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Einstein 1923
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Bahamas: Convection sure makes it hard to see the low-level clouds. There's obviously a mid and/or upper level circulation going on there, but I can't tell from there on down. QuikSCAT was kind enough to miss that area in its last pass, too ;) Radar shows no circulation that I could see. Wonder if the circulation on visible is limited to the upper levels. Wind shear is reminiscent of Karen's -- fairly strong in the upper levels, not too bad in the mid levels, and falling. I agree with Dr. Masters that it appears only slow development should occur.
That was deep.
The Gulf Loop Current is one of the most dynamic ocean currents in the world. Frontal eddy cyclones, regions of vigorous upwelling, develop along its margin in association with current meanders, increasing current speeds and impacting flow even in 3000 m of water. At irregular intervals, large warm eddies separate from the Loop Current and move westward, dissipating over many months along the Texas and Mexican coasts. The Loop Current and its eddies are large reservoirs of heat that have the capability to intensify hurricanes and tropical storms crossing the Gulf. Using infrared measurements from the GOES-East satellite, a "cloud eraser" was developed that has enabled us to track and study the frontal eddy cyclones that move rapidly (35 km/day) around the margin of the Loop Current. More recently we have been integrating GOES sea surface temperature data with satellite sea surface height data (from Dr. Robert Leben, CCAR) to improve our capabilities for studying the complex eddy field in the Gulf. Our funding for this research comes mainly from the Minerals Management Service. Visit the SST/SSH image archives and animation page. Publications of interest include Walker et al. (2003), Walker et al. (2005) , and Walker et al. (2006).
Dynamic Archive Composite Night time view of the Loop Current in Motion
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Great Learning Link on the above.
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Sure looks like Karen wants to stick around with a new center.
According to some on here, I am out of my mind for discussing Karen regenerating.
Care to join me in the looney bin??
Noel
Olga
Pablo
Rebekah
Sebastien
Tanya
Van
Wendy
Thanks.
With La Nina already set in, this may very well extend our hurricane season. I expect a busier than usual October, especially closer to home.
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It's no wonder we drink!
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I have been drinking the Karen punch for over a week now:-)
Tastes good. Also, it adds alpha blockers. Some say it challenges the mind.
I have tried and tried to be civil with Lester for two days. He refuses to drop the attitude. Some people are impervious to change.
ATLANTIC OCEAN...
THERE ARE THREE AREAS OF INTEREST IN THE ATLANTIC FORECAST AREA.
FIRST...T.D. MELISSA. SEE SPECIAL FEATURE. SECOND...THE REMNANTS
OF KAREN...LOCATED A COUPLE HUNDRED EAST OF LEEWARD ISLANDS...
WHICH ARE INTERACTING WITH AN UPPER-LEVEL TROUGH. THIS IS
PRODUCING A LARGE AREA OF DISORGANIZED SHOWERS AND TSTMS. A SFC
TROUGH IS ANALYZED IN THIS AREA AND RUNS FROM THE WINDWARD
ISLANDS ALL THE WAY NE TO 21N51W. A WEAK 1012 MB LOW IS ALONG
THE TROUGH AXIS NEAR 16N58W. VIS SATELLITE IMAGERY SHOWS A SWIRL
OF LOW CLOUDS RELATED TO THIS LOW. UPPER-LEVEL WINDS ARE
CURRENTLY UNFAVORABLE FOR REGENERATION OF THIS SYSTEM...BUT THEY
COULD BECOME A LITTLE MORE FAVORABLE DURING THE NEXT DAY OR TWO
AS THIS SYSTEM MOVES NORTHWESTWARD AT 10 TO 15 MPH.
With this time of year, the synoptic pattern becomes much more difficult with these systems.
I love the challenge though!
000
NOUS42 KNHC 301400
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1000 AM EDT SUN 30 SEPTEMBER 2007
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 01/1100Z TO 02/1100Z OCTOBER 2007
TCPOD NUMBER.....07-128
I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY: POSSIBLE LOW-LEVEL INVEST
NEAR 25.0N 84.0W AT 02/1800Z
National Weather Service Houston/Galveston Texas
1007 am CDT sun Sep 30 2007
Discussion...
very minor tweaks to the current forecast to expand probability of precipitation slightly
farther east. Impressive moisture plume evident on GOES
sounder that has expanded across the entire County Warning Area...yesterdays runs
intruded dry air into the easternmost County Warning Area and this is quite
apparently not the case.
Otherwise no changes.
45/37
&&
Previous discussion... /issued 333 am CDT sun Sep 30 2007/
Discussion...
at 08z...deep moisture remains over most of southeast Texas.
Scattered showers and thunderstorms will continue to develop this
morning in response to divergent 250 mb winds and a weak shortwave near
crp. A diffuse boundary separating moisture rich air from slightly
drier air to the northeast will begin to sag southwest during the
day as an 850 mb ridge of high pressure builds into East Texas.
This will system will usher in lower precipitable water air during the afternoon.
Upper levels winds are also forecast to become more zonal as well.
Think highest rain chances will remain over the SW zones closer to
the weak shortwave and located within the deeper moisture. Rain chances
should drop over the east during the afternoon as the drier air
works into East Texas. Weak high pressure will remain over East
Texas through middle-week with temperatures remaining slightly above normal.
Things get more interesting toward the end of the week. An area of
disturbed weather will develop over the eastern Gulf and move
west. Global models diverge in their respective solutions but
there should be an increase in moisture by Friday with a good
chance of rain on Saturday. The upper low will approach Texas
coincident with an approaching upper level trough. The upper
trough will phase with the upper low as it pushes east. This
allows a cold front to cross the area. If the long range models
are correct...this will be the first significant cold front of the
season. The GFS has teased US before with regard to a cold frontal
passage but there is some colder air beginning to build in Canada
and other long range models support the GFS solution. Whether or
not the front crosses the area...the position of the upper low and
tropical moisture should produce a good chance of rain next Sat
and sun. 43
The GOM Sea Surface Temperature Model from LSU.
Area Specific
Click on Boxed area and run as Model.
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The wunderground Tropical Page has been added to the WAVCIS page. Its on the left Highlighted in RED,Tropical Weather
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