[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 200547
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU OCT 20 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...

HURRICANE WILMA REMAINS A DANGEROUS CATEGORY 4 HURRICANE
BORDERING ON CATEGORY 5 CENTERED NEAR 18.1N 84.7W...OR 190 NM SE
OF COZUMEL MEXICO...AT 20/0600 UTC MOVING WNW AT 7 KT. MAXIMUM
SUSTAINED WIND SPEED IS 135 KT WITH GUSTS TO 165 KT. ESTIMATED
MINIMUM CENTRAL PRESSURE IS 894 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. THE SATELLITE REPRESENTATION LOOP OF WILMA
REMAINS IMPRESSIVE WITH DEEP CONVECTION WRAPPING AROUND THE
CORE. CLOUD TOPS HAVE COOLED SLIGHTLY AS THE CONVECTIVE SPIRAL
BANDS EXPAND OUTWARD AWAY FROM THE CENTER. ALTHOUGH WILMA HAS
WEAKENED SLIGHTLY IT APPEARS TO BE GOING THROUGH AN EYEWALL
REPLACEMENT CYCLE. SCATTERED/NUMEROUS STRONG CONVECTION EXTENDS
WITHIN 75 NM OF THE CENTER IN THE NW QUADRANT AND WITHIN 120 NM
ELSEWHERE. SCATTERED MODERATE/STRONG CONVECTION IS LOCATED
ELSEWHERE IN SPIRAL BANDS FROM 14N-22N BETWEEN 80W-88W AND
WITHIN 75 NM OF LINE FROM OVER LAKE MARACAIBO ALONG 12N73W
THROUGH JAMAICA TO CUBA NEAR 21N79W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS COVER MOST OF CUBA...HONDURAS AND NICARAGUA.

...TROPICAL WAVES...

E ATLC TROPICAL WAVE IS ALONG 27W S OF 12N MOVING W 10-15 KT.
WAVE HAS A LOW AMPLITUDE SIGNATURE WITH THE AXIS FOLLOWING A
CLUSTER OF CONVECTION JUST N OF THE ITCZ. THIN LINE OF SCATTERED
MODERATE/ISOLATED STRONG CONVECTION WITHIN 30 NM OF 9.5N
26W-30W.

CENTRAL ATLC TROPICAL WAVE IS ALONG 53W/54W S OF 16N MOVING W
10-15 KT. LOW AMPLITUDE WAVE EMBEDDED WITHIN A LARGE AREA OF
CONVECTION WHERE STRONG E LOW-LEVEL FLOW CONVERGES WITH
WEAKER WINDS CLOSE TO THE SOUTH AMERICAN COAST. SCATTERED
MODERATE/STRONG CONVECTION IS FROM 8N-17N BETWEEN 50W-57W.

E CARIBBEAN TROPICAL WAVE IS ALONG 61W/62W S OF 22N MOVING W
10-15 KT. WAVE IS LOCATED ON THE W SIDE OF A SHARP UPPER LEVEL
TROUGH WHICH IS DISPLACING THE DEEP CONVECTION TO THE E OF THE
LESSER ANTILLES. SCATTERED THUNDERSTORMS ARE FROM 12N-21N
BETWEEN 57W AND THE LESSER ANTILLES BUT INCLUDES BARBADOS.

CENTRAL CARIBBEAN TROPICAL WAVE IS ALONG 74W/75W S OF 16N MOVING
W 10-15 KT. WAVE SIGNATURE REMAINS MASKED BY UPPER OUTFLOW FROM
HURRICANE WILMA WITH ANY CONVECTION ASSOCIATED WITH WILMA AND
NOT THE WAVE ITSELF.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 15N17W 9N23W 6N34W 9N47W 10N61W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 60 NM OF
THE AXIS FROM 17W-20W AND FROM 31W-36W...WITHIN 90 NM OF THE
AXIS FROM 24W-29W...AND WITHIN 150 NM OF LINE FROM 7N43W ACROSS
THE AXIS TO 13N51W. SCATTERED THUNDERSTORMS ARE MOVING OFF
AFRICA WITHIN 90 NM ALONG THE COAST OF LIBERIA...SIERRA
LEONE...AND S GUINEA.

...DISCUSSION...

GULF OF MEXICO...
TRANQUIL WEATHER TONIGHT OVER THE GULF IS DECEIVINGLY COVERING
UP THE APPROACHING HURRICANE THAT LOOMS IN THE NW CARIBBEAN. THE
UPPER RIDGE THAT HAS DOMINATED THE GULF OVER THE PAST FEW DAYS
IS BEGINNING TO GIVE WAY TO HURRICANE WILMA AND THE DEEP LAYERED
TROUGH OVER THE CENTRAL UNITED STATES. RIDGE AXIS EXTENDS INTO
THE W GULF NEAR THE TEXAS/MEXICO BORDER TO NEAR 26N90W IN THE
CENTRAL GULF CONTINUES PRODUCING STRONG SUBSIDENCE OVER THE
ENTIRE AREA...EXCEPT OVER THE SE GULF WHERE CIRRUS CLOUDS FROM
WILMA ARE SPREADING S OF 26N E OF 89W. AS SUCH...THE WEATHER
REMAINS MOSTLY DRY EXCEPT FOR SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS JUST N OF CUBA AND THE YUCATAN CHANNEL ASSOCIATED
WITH THE OUTER MOST RAINBANDS OF WILMA. CONDITIONS WILL CONTINUE
TO DETERIORATE FROM CUBA TO THE YUCATAN PENINSULA AND THE
FLORIDA STRAITS SPREADING NE AS WILMA CONTINUES ITS TREK TOWARDS
THE GULF. THE WORST CONDITIONS ARE EXPECTED FROM THE YUCATAN NE
TO FLORIDA THROUGH THE WEEKEND DUE TO WILMA WHILE THE REMAINDER
OF THE GULF SHOULD HAVE A NICE DRY WEEKEND.

CARIBBEAN...
SEE SPECIAL FEATURES FOR DISCUSSION ON WILMA. THE BROAD OUTFLOW
CANOPY OF WILMA SPREADS AWAY FROM THE STORM NE INTO THE W
ATLC...SE ACROSS THE ENTIRE W/CENTRAL CARIBBEAN...AND SW ACROSS
CENTRAL AMERICA. FARTHER E...DRIER AIR CONTINUES TO INFILTRATE
INTO THE CENTRAL CARIBBEAN TO ABOUT 73W PRODUCING FAIR SKIES.
SHOWERS/THUNDERSTORMS WILL MOVE INTO THE E CARIBBEAN ACROSS THE
LESSER ANTILLES TONIGHT INTO THU FROM THE TROPICAL OVER THE FAR
E CARIBBEAN.

WEST ATLANTIC...
UPPER TROUGH HAS MOVED ACROSS N FLORIDA INTO THE FAR W ATLC
ALONG 32N74W TO 27N78W WITH THE SUBTROPICAL JET EXTENDING FROM S
FLORIDA E ALONG 26N72W THEN NE TO BEYOND 32N63W WITH WINDS OF
70-90 KT S OF 30N INCREASING TO OVER 100 KTS N OF 30N. A SURFACE
TROUGH EXTENDS BENEATH THE JET FROM A COLD FRONT NEAR 31N64W TO
26N70W WITH SCATTERED SHOWERS/THUNDERSTORMS WITHIN 300/350 NM S
OF THIS BOUNDARY.

EAST/CENTRAL ATLANTIC...
A SHARP NARROW UPPER TROUGH LIES JUST E OF THE LESSER ANTILLES
ALONG 22N57W TO 11N61W AND DOWNSTREAM UPPER DIFFLUENCE IS
TRIGGERING SCATTERED THUNDERSTORMS E OF THE TROPICAL WAVE IN THE
E CARIBBEAN. LARGE UPPER HIGH IS CENTERED OVER THE SUBTROPICS
NEAR 28N40W AND IS SUPPORTING BROAD HIGH PRESSURE AT THE SURFACE
WITH A 1024 MB CENTERED NEAR 31N36W. A VERY WEAK 1017 MB LOW IS
NEAR 28N44W BUT LACKS ANY SHOWERS AND IS EXPECTED TO CONTINUE
DISSIPATING. BROAD UPPER TROUGH EXTENDS FROM JUST INLAND OVER
MOROCCO/WESTERN SAHARA INTO THE E ATLC NEAR 24N16W TO OVER THE
CAPE VERDE ISLANDS NEAR 16N25W AND SHEAR AXIS CONTINUES WNW TO
23N47W.  WIDESPREAD SAHARAN DUST EXTENDS ACROSS A GOOD PORTION
OF THE ATLC FROM 7N-22N E OF 50W.

$$
WALLACE


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