[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 180548
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT TUE OCT 18 2005

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

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...SPECIAL FEATURE...

TROPICAL STORM WILMA IS CENTERED NEAR 15.7N 80.0W AT 18/0600
UTC...OR 225 NM SSE OF GRAND CAYMAN...MOVING W AT 2 KT. MAXIMUM
SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 984 MB. SEE LATEST NHC FORECAST/
ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC AND THE
PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT4/WTNT34 KNHC
FOR MORE DETAILS. DEEPEST CONVECTION ASSOCIATED WITH WILMA IS TO
THE SSE OF THE CENTER. NUMEROUS STRONG CONVECTION IS A 45 NM
RADIUS OF 15.5N80W. SCATTERED MODERATE/STRONG CONVECTION IS FROM
11N-15N BETWEEN 78.5W AND THE COAST OF NICARAGUA. AN UPPER
TROUGH/SHEAR AXIS EXTENDS FROM W/CENTRAL CUBA JUST W OF THE
CAYMAN ISLANDS TO THE GULF OF HONDURAS AND IS PLACING SOME NW
SHEAR OVER WILMA...AS WELL AS INFILTRATING SOME DRIER AIR INTO
THE CIRCULATION. OUTFLOW IS BEST TO THE S AND E DUE TO THE RIDGE
AXIS BEING ORIENTED FROM NICARAGUA TO HISPANIOLA. AS
SUCH...CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION
LIES E OF THE MAIN CORE CONVECTION FROM 11N-20N BETWEEN 71W-78W
EXTENDING OVER PARTS OF JAMAICA...HISPANIOLA...AND E CUBA.

...TROPICAL WAVES...

CENTRAL ATLANTIC TROPICAL WAVE IS FROM 19N45W 13N47W 7N47W
MOVING W 10-15 KT. THE LOW IS NO LONGER DISCERNIBLE. WAVE IS
WEDGED BETWEEN A SMALL UPPER HIGH IN THE W TROPICAL ATLC AND A
BROAD RIDGE EXTENDING FROM OFF AFRICA ACROSS THE REMAINDER OF
THE E TROPICAL ATLC. CLUSTERS OF SCATTERED MODERATE CONVECTION
ARE FROM 12N-18N BETWEEN 42W-47W.

E CARIBBEAN TROPICAL WAVE IS ALONG 63W/64W S OF 15N MOVING W
10-15 KT. WAVE IS BENEATH S OUTFLOW FROM T.S. WILMA WITH NO
ASSOCIATED CONVECTION IN THE CARIBBEAN WATERS. THE ENERGY WITH
THIS WAVE APPEARS TO BE WEAKENING AS IT APPROACHES WILMA.

W CARIBBEAN TROPICAL WAVE IS ALONG 75W S OF 15N MOVING W 10 KT.
DUE TO THE CLOSE PROXIMITY TO T.S. WILMA...THE N PORTION HAS
BEEN ABSORBED BY THE STORM AND THE POSITION IS EXTRAPOLATED...AS
THE S PORTION IS MAINLY OVER COLOMBIA. THIS SCENARIO WILL
PROBABLY CONTINUE UNTIL IT EMERGES IN THE E PACIFIC WATERS.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 8N13W 7N24W 7N34W 7N40W 11N46W THEN
ALONG 13N49W 10N60W. LARGE AREA OF SCATTERED MODERATE/STRONG
CONVECTION IS WITHIN 180 NM S OF THE AXIS AND 250 NM N OF THE
AXIS FROM 37W-45W...WITHIN 75 NM N OF THE AXIS FROM THE COAST OF
AFRICA TO 15W...AND WITHIN 150 NM N OF THE AXIS FROM 28W-35W.
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE
WITHIN 90/120 NM OF THE AXIS FROM 48W-55W AND WITHIN 75/90 NM OF
3N FROM 27W-41W.

...DISCUSSION...

GULF OF MEXICO...
VERY QUIET NIGHT FOR THE GULF STRONG UPPER HIGH ANCHORED OVER
THE SW GULF NEAR 23N96W DOMINATES THE AREA AND IS DRIVING DRY/
STABLE AIR S OVER THE NE GULF...THEN CURLING IT BACK TO THE W
ACROSS THE YUCATAN INTO THE BAY OF CAMPECHE. SKIES ARE MOSTLY
CLEAR...ESPECIALLY N OF 25N...AND ONLY PATCHY CLOUDS WITH
POSSIBLE ISOLATED SHOWERS MOVING S NEAR THE W COAST OF THE
YUCATAN. WEAK SURFACE HIGH PRESSURE EXTENDS INTO THE NW GULF.
THE ATMOSPHERE WILL REMAIN MOSTLY DRY OVER THE AREA FOR THE NEXT
DAY OR TWO BUT WILL GRADUALLY INCREASE OVER THE SE AS T.S. WILMA
APPROACHES FROM THE CARIBBEAN.

CARIBBEAN...
THE CIRCULATION OF T.S. WILMA ENCOMPASSES THE ENTIRE W HALF OF
THE CARIBBEAN...AND BROAD E/SE FLOW FEEDING INTO THE CIRCULATION
COVERS THE REST OF THE AREA. THE UPPER LEVEL HIGH OVER WILMA IS
NOT WELL-DEFINED AT THE MOMENT BUT THE RIDGE AXIS EXTENDS FROM
15N77W NE PAST HISPANIOLA IS PRODUCING EXCELLENT OUTFLOW OVER
THE CONVECTION LOCATED FROM JAMAICA TO HISPANIOLA. A SIGNIFICANT
AREA OF DRY AIR AND STRONG SUBSIDENCE EXTENDS NW OF AN UPPER
LEVEL TROUGH/SHEAR AXIS WHICH STRETCHES FROM W/CENTRAL CUBA SW
INTO THE GULF OF HONDURAS...AND THIS FEATURE APPEARS TO BE AT
LEAST TEMPORARILY AFFECTING WILMA WITH SOME NW SHEAR. FARTHER
E...THE WEATHER IS A LITTLE LESS CONVECTIVE E OF 70W WITH THE
EXCEPTION OF ISOLATED SHOWERS N OF 15N FROM THE VIRGIN ISLANDS
WESTWARD INCLUDING PUERTO RICO. DRIER AIR IS EXPECTED TO BEGIN
MOVING INTO THE AREA FROM THE E OVER THE NEXT 24 HRS...HANGING
AROUND OVER THE E CARIBBEAN AS WILMA BEGINS ITS TRACK NW THEN BY
THU/FRI THE ARRIVAL OF THE NEXT TROPICAL WAVE WILL MOVE ANOTHER
ROUND OF MOISTURE ACROSS THE LESSER ANTILLES.

ATLANTIC...
AN DEEP LAYERED TROUGH REMAINS OVER THE NW ATLC N OF 27N W OF
60W WITH A RAPIDLY WEAKENING COLD FRONT EXTENDS FROM SE OF
BERMUDA NEAR 32N61W SW TO 28N74W...MARKED BY A DISSIPATING ROPE
CLOUD. A SURFACE TROUGH MARKED BY A NE/SE WIND SHIFT EXTENDS
FROM N OF T.S. WILMA OVER CENTRAL CUBA THROUGH THE N BAHAMAS TO
27N70W WITH MOISTURE S OF THE TROUGH PRODUCING SCATTERED
SHOWERS/THUNDERSTORMS S OF 25N BETWEEN 66W-79W. THE N PORTION OF
THE SURFACE TROUGH IS BEGINNING TO SHIFT EASTWARD WHILE THE S
PORTION IS MOVING WESTWARD. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION IS N OF THE SURFACE TROUGH WITHIN 75 NM OF 26.5N FROM
65W-71W. A CUT-OFF UPPER LOW E OF THE LESSER ANTILLES HAS
ELONGATED OVER THE PAST 24 HOURS EXTENDING A TROUGH ALONG 58W
FROM JUST NE OF BARBADOS TO 25N. A SECOND CUT-OFF UPPER LOW IS
OVER THE CENTRAL ATLC NEAR 21N39W WITH AN ASSOCIATED WEAK 1018
MB SURFACE LOW NEAR 24N41W. A BROAD UPPER HIGH IS LOCATED NEAR
32N43W DIPPING DOWN INTO THE REGION N OF THE CUT-OFF LOW IN THE
CENTRAL ATLC BETWEEN 30W-55W. OVER THE NE ATLC...AN UPPER TROUGH
IS N OF 23N E OF 25W WITH THE UPPER LOW MOVING OVER MOROCCO. TO
THE S IS A BROAD RIDGE EXTENDING OFF AFRICA ALONG 8N/9N E OF 45W
AND THE ASSOCIATED DIFFLUENCE ALOFT HAS INITIATED THE LARGE AREA
OF ITCZ CONVECTION. THE UPPER TROUGH IS ALSO PUSHING THIS AIR S
OVER THE E ATLC...FORCING A LARGE AREA OF AFRICAN DUST S OF 22N
AND E OF 42W.

$$
WALLACE


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