[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 251820
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT TUE SEP 25 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN
SECTIONS OF SOUTH AMERICA...AND THE ATLANTIC OCEAN TO THE
AFRICAN COAST FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION
IS BASED ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...
WEATHER OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1745 UTC.

...SPECIAL FEATURES...
THE CENTER OF TROPICAL STORM KAREN AT 25/1500 UTC WAS NEAR
10.8N 38.7W OR ABOUT 1316 NM/2440 KM EAST OF THE WINDWARD
ISLANDS. KAREN IS MOVING WEST-NORTHWEST 13 KT. THE ESTIMATED
MINIMUM CENTRAL PRESSURE IS 1005 MB. THE MAXIMUM SUSTAINED
WIND SPEEDS ARE 35 KT WITH GUSTS TO 45 KT. PLEASE READ THE
LATEST NHC FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT2/
WTNT22 KNHC AND THE PUBLIC ADVISORY UNDER MIATCPAT2/WTNT32 KNHC
FOR MORE DETAILS. KAREN IS EXHIBITING SOME BANDING FEATURES ON
VISIBLE SATELLITE IMAGERY...BUT THE DEEP CONVECTION IS NOT THAT
STRONG OR CONCENTRATED NEAR THE CENTER. THE ENVIRONMENT TO THE
WEST OF KAREN IS QUESTIONABLE FOR STRENGTHENING. THE UPPER LEVEL
OUTFLOW OF KAREN IS BEING RESTRICTED OVER THE NORTHWESTERN
QUADRANT DUE TO A NEARBY UPPER-LEVEL CYCLONIC SHEAR AXIS.
GLOBAL MODELS DEPICT A COUPLE OF UPPER-LEVEL TROUGHS OVER THE
CENTRAL SUBTROPICAL ATLANTIC DURING THE NEXT FEW DAYS THAT
SHOULD CAUSE INCREASING SOUTHWESTERLY VERTICAL SHEAR OVER KAREN.
SCATTERED STRONG SHOWERS AND THUNDERSTORMS IN A BAND FROM 8N TO
10N BETWEEN 36W AND 38W. SCATTERED MODERATE SHOWERS TO ISOLATED
STRONG THUNDERSTORMS FROM 9N TO 13N BETWEEN 35W AND 41W.

SATELLITE IMAGES INDICATE THAT A TROPICAL DEPRESSION MAY BE
FORMING IN THE SOUTHWESTERN GULF OF MEXICO ABOUT 180 MILES
EAST OF TAMPICO MEXICO. AN AIR FORCE RECONNAISSANCE PLANE IS
SCHEDULED TO INVESTIGATE THE AREA THIS AFTERNOON. THIS SYSTEM
IS EXPECTED TO MOVE LITTLE DURING THE NEXT 24 HOURS. A 1009 MB
LOW PRESSURE CENTER IS NEAR 22.5N95W...ALONG A TROUGH THAT RUNS
FROM MEXICO NEAR 19N91W IN THE SOUTHWESTERN CORNER OF THE GULF
OF MEXICO TO THE LOW CENTER...AND TO 26N96W. SCATTERED TO
NUMEROUS STRONG SHOWERS AND THUNDERSTORMS FROM 20N TO 22N
BETWEEN 94W AND 96W. SCATTERED MODERATE SHOWERS TO ISOLATED
STRONG THUNDERSTORMS ARE ELSEWHERE FROM 20N TO 24N BETWEEN
86W AND 96W. A CONTINUALLY-WEAKENING MIDDLE LEVEL TO UPPER LEVEL
CYCLONIC CIRCULATION CENTER IS IN THE GULF OF MEXICO WATERS JUST
OFF THE UPPER TEXAS COAST. ISOLATED MODERATE SHOWERS ARE FROM
25N TO 30N BETWEEN 90W AND 94W. AN UPPER LEVEL RIDGE IS ON TOP
OF THE AREA OF THE 1009 MB LOW PRESSURE CENTER AND TROUGH.

...TROPICAL WAVES...

AN EASTERN CARIBBEAN SEA TROPICAL WAVE IS ALONG 62W MOVING WEST
10 TO 15 KT. A 1012 MB LOW PRESSURE CENTER IS ALONG THE WAVE
NEAR 17N. NUMEROUS STRONG SHOWERS AND THUNDERSTORMS ARE WITHIN
A 30 NM RADIUS OF 16N63.5W. OTHER STRONG SHOWERS ARE FROM 16N
TO 17N BETWEEN 61W AND 64W. ISOLATED MODERATE SHOWERS FROM 20N
TO 24N BETWEEN 59W AND 62W. THIS SYSTEM HAS CHANGED LITTLE IN
ORGANIZATION DURING THE PAST SEVERAL HOURS AND UPPER-LEVEL WINDS
ARE BECOMING LESS FAVORABLE FOR DEVELOPMENT. THE LOW SHOULD MOVE
TOWARD THE NORTHWEST...BRINGING SQUALLY WEATHER TO THE NORTHERN
LEEWARD ISLANDS...THE BRITISH AND US VIRGIN ISLANDS AND PUERTO
RICO DURING THE NEXT 24 HOURS. RESIDENTS IN THESE AREAS
SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS SYSTEM.

A TROPICAL WAVE IS ALONG 92W SOUTH OF 17N MOVING WEST 10 TO
15 KT. NO DEEP CONVECTIVE PRECIPITATION THAT IS RELATED TO THIS
WAVE IS OCCURRING IN THE GULF OF MEXICO NOR IN MEXICO OR THE
REST OF CENTRAL AMERICA.

...THE ITCZ...
8N12W 6N16W 10N34W 8N40W 4N50W 6N58W. SCATTERED MODERATE TO
STRONG SHOWERS AND THUNDERSTORMS FROM 4N TO 8N BETWEEN 20W AND
30W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS
FROM 6N TO 10N BETWEEN AFRICA AND 16W.

DISCUSSION...

THE REST OF THE GULF OF MEXICO AWAY FROM THE 1009 MB
LOW PRESSURE CENTER IN THE SOUTHWESTERN CORNER OF THE AREA...
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS JUST OFF
THE COAST OF SOUTHWESTERN FLORIDA. A TROUGH EXTENDS FROM THIS
CYCLONIC CENTER INTO THE NORTHWESTERN CARIBBEAN SEA. SCATTERED
MODERATE SHOWERS TO ISOLATED STRONG THUNDERSTORMS ARE FROM 20N
TO CUBA AND THE YUCATAN CHANNEL BETWEEN 80W AND THE YUCATAN
PENINSULA. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG
THUNDERSTORM ALSO ARE OVER THE BAHAMAS FROM 23N TO 26N BETWEEN
74W AND 81W...INCLUDING IN THE STRAITS OF FLORIDA.

THE CARIBBEAN SEA...
A MIDDLE TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS JUST
SOUTH OF JAMAICA NEAR 17N77W. UPPER LEVEL ANTICYCLONIC NORTHERLY
WIND FLOW MOVES FROM THE GULF OF MEXICO...AND ULTIMATELY BLENDS
INTO THE FLOW ON THE WESTERN SIDE OF THE 17N77W CYCLONIC CENTER.
A TROUGH EXTENDS FROM THE 17N77W CYCLONIC CENTER TO THE COAST OF
COSTA RICA/PANAMA. STRONG SHOWERS AND THUNDERSTORMS HAVE MOVED
OUT OF THE GULF OF URABA AWAY FROM COLOMBIA AND NOW ARE FROM
10N TO 11.5N BETWEEN 76W AND 78W. LINGERING SHOWERS ARE POSSIBLE
IN THE GULF OF URABA. WARMING CLOUD TOP TEMPERATURES AND
DISSIPATING PRECIPITATION ARE ON THE SOUTHERN SIDE OF PANAMA AND
ITS COASTAL WATERS. THE ITCZ PASSES RIGHT ON TOP OF PANAMA.
ISOLATED MODERATE SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF THE
LINE FROM THE MONA PASSAGE TO 15N71W ON THE EASTERN SIDE OF THE
17N77W CYCLONIC CENTER. THIS PRECIPITATION IS OCCURRING IN AN
AREA OF UPPER LEVEL DIFFLUENT FLOW. UPPER LEVEL ANTICYCLONIC
COVERS THE REST OF THE CARIBBEAN SEA TO THE EAST OF THE 17N77W
CYCLONIC CENTER.

THE ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM THE WESTERN ATLANTIC
OCEAN NEAR 29N60W TO A 29N77W CYCLONIC CIRCULATION CENTER...
TO THE CYCLONIC CENTER OFF THE SOUTHWEST FLORIDA COAST IN THE
GULF OF MEXICO. BROAD LARGE-SCALE CYCLONIC FLOW ON WATER VAPOR
IMAGERY COVERS THE ATLANTIC OCEAN NORTH OF 20N WEST OF 60W. THE
SURFACE PRESSURES ARE NOT FALLING AT THIS TIME AND ANY TYPE OF
ADDITIONAL DEVELOPMENT WILL BE SLOW TO OCCUR. IT IS POSSIBLE
THAT THIS SYSTEM MAY BRING LOCALLY HEAVY RAINS TO SOUTH FLORIDA
AND THE FLORIDA KEYS DURING THE NEXT DAY OR TWO. ISOLATED TO
WIDELY SCATTERED MODERATE SHOWERS ARE FROM 24N TO 32N ELSEWHERE
BETWEEN 60W AND 80W. A SURFACE TROUGH IS ALONG 29N66W 27N67W
24N67W. THE BASE OF A DEEP LAYER CENTRAL ATLANTIC OCEAN TROUGH
STILL IS NORTH OF 30N. THIS TROUGH SUPPORTS A COLD FRONT THAT
GOES FROM 32N60W...ACROSS BERMUDA TO 32N68W. A PERSISTENT
SURFACE TROUGH PASSES THROUGH 32N40W 27N50W TO 26N56W. ISOLATED
TO WIDELY SCATTERED MODERATE SHOWERS ARE WITHIN 60 TO 90 NM ON
EITHER SIDE OF 31N38W 28N43W 27N52W 27N57W. A SURFACE TROUGH IS
ALONG 51W/52W FROM 12N TO 18N. THIS TROUGH IS THE REMNANT OF
A SURFACE LOW PRESSURE CENTER FROM 24 HOURS THAT ULTIMATELY
DISSIPATED INTO AN OPEN TROUGH. ISOLATED MODERATE SHOWERS WITHIN
A 15 NM RADIUS OF 14N51.5W. A MIDDLE TO UPPER LEVEL TROUGH
PASSES THROUGH 31N20W 22N22W TO 14N24W NEAR THE CAPE VERDE
ISLANDS. A RIDGE IS ALONG 24N41W BEYOND 32N30W.

$$
MT




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