[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 211209
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT FRI OCT 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURE...

DANGEROUS CATEGORY FOUR HURRICANE WILMA IS CENTERED NEAR
20.1N 86.3W OR ABOUT 44 NM/80 KM SOUTHEAST OF COZUMEL MEXICO
AT 21/1200 UTC MOVING NNW 5 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 930 MB. MAXIMUM SUSTAINED WIND SPEED IS 130 KT
WITH GUSTS TO 160 KT. 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.
WILMA COMPLETED AN EYEWALL REPLACEMENT CYCLE YESTERDAY AND THE
NEW EYE GREW OVERNIGHT TO A DIAMETER OF 40 NM OR SO...BUT
RECENTLY SATELLITE IMAGERY SHOWS IT SHRINKING AGAING TO ABOUT
30 NM WIDE. STRONG CONVECTION WITH CLOUD TOPS TO -82C HAS BEEN
MAINTAINED OVERNIGHT ESPECIALLY OVER THE SRN SEMICIRCLE AND
WATER VAPOR IMAGERY INDICATES EXCELLENT OUTFLOW TO THE N/NE OF
THE SYSTEM...BUT SOMEWHAT MORE MODEST TO THE S AND NON-EXISTENT
TO THE W. NUMEROUS MODERATE/STRONG CONVECTION IS WITHIN 250 NM
E SEMICIRCLE AND 150 NM W SEMICIRCLE (THE RAINBANDS ARE NOT
PENETRATING THAT FAR INLAND OVER THE YUCATAN PENINSULA). RADAR
IMAGERY FROM CANCUN SHOWS AN IMPRESSIVE CIRCULAR EYE WITH HEAVY
RAINBANDS SPREADING ACROSS THE YUCATAN CHANNEL AND THE NE PART
OF THE MEXICAN STATE OF QUINTANA ROO...INCLUDING AREAS SUCH AS
CANCUN...COZUMEL...AND TULUM. CONDITIONS WILL ONLY WORSEN IN
THESE AREAS AS THE CORE OF WILMA APPROACHES THE COAST DURING
THE DAY.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE ALONG 34W S OF 16N MOVING W 15 KT.
THE WAVE IS LOW IN AMPLITUDE BUT HAS A WEAK INVERTED-V SIGNATURE
EMBEDDED WITHIN THE ITCZ. SCATTERED MODERATE/STRONG CONVECTION
FROM 7N-13N BETWEEN 28W-40W.

STRONG TROPICAL WAVE OVER THE LESSER ANTILLES ALONG 61W S OF 20N
MOVING W 15 KT. THE WAVE IS PRODUCING AN AREA OF SCATTERED
MODERATE CONVECTION FROM 11N-16N BETWEEN 55W-64W WHICH HAS
ALREADY SPREAD ACROSS BARBADOS AND PARTS OF THE WINDWARD ISLANDS
BETWEEN GRENADA AND MARTINIQUE. ADDITIONAL ISOLATED SHOWERS/
TSTMS ARE ALSO FORMING OVER THE NRN LEEWARD ISLANDS FROM 16N-20N
BETWEEN 60W-68W. THE WINDS AT BARBADOS AND ST. LUCIA HAVE BEEN
SUSTAINED AT 28 KT AND 23 KT (WITH A GUST TO 34 KT AT ST. LUCIA)
RESPECTIVELY OVER THE PAST FEW HOURS. MOISTURE ASSOCIATED WITH
THE WAVE IS EXPECTED TO SPREAD NW ACROSS THE REMAINDER OF THE
LESSER ANTILLES TOWARDS HISPANIOLA OVER THE NEXT 48 HRS...AND
SHOULD LINGER OVER THE AREA SUPPORTING A THREAT FOR WIDELY
SCATTERED SHOWERS/TSTMS AT ANY TIME OVER THE WEEKEND.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 69W S OF 19N MOVING W 15
KT. THE MOST PRONOUNCED PART OF THE WAVE IS ASSOCIATED WITH A
SURFACE TROUGH N OF PUERTO RICO WHICH HAS SPLIT OFF FROM THE
MAIN AXIS AND IS MOVING NW ALONG 21N68W 25N62W. THE SECTION OF
THE WAVE OVER THE CARIBBEAN IS WEAK AND NOT ASSOCIATED WITH ANY
DEEP CONVECTION.

WEST CARIBBEAN TROPICAL WAVE ALONG 81W S OF 15N MOVING W 10-15
KT. THE WAVE IS EMBEDDED IN BROAD SOUTHERLY FLOW FEEDING INTO
HURRICANE WILMA...SO IT DOES NOT HAVE A DISTINGUISHABLE
SIGNATURE. WIDELY SCATTERED MODERATE CONVECTION IS E OF THE AXIS
FROM 11N-17N BETWEEN 74W-80W.

...ITCZ...

ITCZ IS CENTERED ALONG 9N10W 5N18W 10N32W 8N43W 13N59W.
SCATTERED MODERATE CONVECTION FROM 4N-7N BETWEEN 8W-12W.
SCATTERED MODERATE/STRONG FROM 8N-13N BETWEEN 27W-41W. WIDELY
SCATTERED MODERATE WITHIN 110 NM OF THE AXIS BETWEEN 43W-53W.
NUMEROUS MODERATE ASSOCIATED WITH THE TROPICAL WAVE ALONG 61W
FROM 11N-16N BETWEEN 56W-64W.

...DISCUSSION...

GULF OF MEXICO...
THE OUTERMOST RAIN BANDS OF HURRICANE WILMA HAVE BEGUN TO SPREAD
THROUGH THE YUCATAN CHANNEL INTO THE SE GULF AND WESTERN FLORIDA
STRAITS...AS OBSERVED IN SATELLITE IMAGERY AND CUBAN RADAR. IN
ADDITION...CIRRUS OUTFLOW FROM THE STORM IS TRAPPED E OF A LINE
FROM THE N COAST OF THE YUCATAN PENINSULA NEWD TO THE BIG BEND
OF FLORIDA...BOUNDED TO THE W BY A LARGE AREA OF DRY AIR AND
MODERATE/STRONG SUBSIDENCE. THIS DRY AIR IS BEING BROUGHT ACROSS
THE W GULF BY NORTHERLY FLOW ON THE E SIDE OF A MID/UPPER LEVEL
HIGH CENTERED OVER CNTRL MEXICO. ALSO...A BROAD UPPER LEVEL
TROUGH IS SWINGING EWD ALONG THE N GULF COAST AND MAY BE THE
CULPRIT FOR WILMA'S SHORT-TERM JOG TO THE NORTH...BUT IT IS A
LITTLE UNCERTAIN AT THIS TIME IF THIS IS ONLY TEMPORARY.
SHOWER/TSTMS ARE EXPECTED TO BECOME MORE SCATTERED OVER THE SE
GULF AS WILMA CONTINUES TO SLOWLY LIFT N...AND THEN THE
STRONGEST WINDS AND HEAVIEST RAINS WILL MOVE INTO THE AREA
WITHIN THE NEXT 24-36 HRS AS PER THE LATEST NHC FORECAST TRACK.
ELSEWHERE...A COLD FRONT OVER S/E TEXAS AND NORTHERN MEXICO IS
EXPECTED TO MOVE OFF THE COAST LATER TODAY.

CARIBBEAN...
SEE SPECIAL FEATURES FOR DISCUSSION ON WILMA. SATELLITE-DERIVED
UPPER LEVEL WINDS INDICATE THAT AN UPPER LEVEL ANTICYCLONE HAS
DEVELOPED SE OF WILMA NEAR 16N76W...OR JUST SE OF JAMAICA. A
SMALL AREA OF SUBSIDENCE IS LOCATED NEAR THE CENTER OF THE
ANTICYCLONE BUT UPPER LEVEL CIRRUS MOSTLY FROM WILMA COMPLETELY
ENSHROUDS THIS AREA FROM THE N AND W. AN UPPER LOW IS MOVING W
ACROSS NRN VENEZUELA NEAR 8N68W WITH AN INVERTED TROUGH
EXTENDING N TO THE NRN LEEWARD ISLANDS. UPPER DIFFLUENCE E OF
THE TROUGH IS INTERACTING WITH THE TROPICAL WAVE APPROACHING THE
LESSER ANTILLES TO PRODUCE AN AREA OF TSTMS SPREADING ACROSS
BARBADOS TO PARTS OF THE WINDWARD ISLANDS. CONVERSELY...
SUBSIDENCE AHEAD OF THE UPPER LOW IS SUPPORTING A NICE
CONVECTION-FREE MORNING OVER MUCH OF VENEZUELA AND NRN COLOMBIA.

ATLANTIC...
THE UPPER LEVEL ANTICYCLONE OVER THE CNTRL CARIBBEAN STRETCHES
NWD ACROSS THE GREATER ANTILLES TO OVER FLORIDA AND THE BAHAMAS
WITH OUTFLOW FROM WILMA EXTENDING EWD INTO THE ATLC S OF 28N. AN
UPPER LEVEL SHORTWAVE TROUGH IS ALONG 66W N OF 24N AND
DIFFLUENCE ALOFT IS SUPPORTING SCATTERED MODERATE CONVECTION
FROM 25N-32N BETWEEN 50W-62W...POSSIBLY ALSO FOCUSED ALONG A
WEAK SURFACE TROUGH IN THE AREA. HOWEVER...A LARGE SUBTROPICAL
HIGH OVERWHELMINGLY COVERS MOST OF THE ATLC WITH A MEAN CENTER
NEAR 30N39W AND PRES OF 1022 MB. A SECOND LARGE UPPER LEVEL HIGH
IS CENTERED OVER THE CENTRAL ATLC NEAR 26N41W AND HAS PUSHED THE
SUBTROPICAL JET N OF THE AREA TOWARDS THE AZORES. A NARROW
MID-OCEANIC TROUGH LIES S OF THE HIGH FROM THE COAST OF
MAURITANIA WWD ACROSS THE CAPE VERDE ISLANDS TO 16N40W 20N50W
WITH THE SOUTHERN STREAM OF THE SUBTROPICAL JET DIPPING DOWN TO
ABOUT 13N/14N. THERE IS JUST ENOUGH DIFFLUENCE ASSOCIATED WITH
THE TROUGH TO ENHANCE CONVECTION ALONG THE TROPICAL WAVE NEAR
34W. FARTHER E...AN UPPER TROUGH IS DIGGING SWD FROM S/CNTRL
SPAIN TO THE CANARY ISLANDS...MOVING INTO MOROCCO...BUT THE
ASSOCIATED COLD FRONT REMAINS N OF THE AREA.

$$
BERG



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