[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 122347
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT THU 12 AUG 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2315 UTC.

...SPECIAL FEATURES...

HURRICANE CHARLEY CENTERED NEAR 21.7N 82.3W...OR JUST EAST OF
THE ISLE OF YOUTH CUBA...AT 13/0000 UTC MOVING NNW 15 KT.
MINIMUM CENTRAL PRESSURE REPORTED BY AIR FORCE RECONNAISSANCE IS
976 MB. MAXIMUM SUSTAINED WIND SPEED IS 90 KT WITH GUSTS TO 110
KT. SEE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT3/WTNT33 KNHC AND THE FULL FORECAST/ADVISORY
UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC FOR MORE DETAILS.
THE LAST FEW FRAMES OF VISIBLE IMAGERY SHOW A WELL-DEVELOPED
HURRICANE WITH A 15 NM WIDE EYE JUST NOW PASSING ACROSS THE
ARCHIPELAGO DE LOS CANERREOS...JUST E OF THE ISLE OF YOUTH...OFF
THE SW COAST OF CUBA. CONVECTION HAS WOUND TIGHTLY AROUND THE
CENTER...WITH 40-70 NM OF THE CENTER...WITH A PRIMARY BAND
EXTENDING OVER THE ERN SEMICIRCLE FROM CENTRAL CUBA SWD TO THE
CAYMAN ISLANDS. GIVEN THE CURRENT PATTERN...IT IS POSSIBLE THAT
A BIT OF DRY AIR IS BEING ENTRAINED INTO THE SYSTEM BETWEEN THE
CENTRAL CORE AND THE BAND. UPPER LEVEL OUTFLOW HAS BEEN
EXCELLENT OVER THE NORTHERN AND EASTERN SEMICIRCLES FOR MUCH OF
THE DAY...AND IT APPEARS THE CANOPY IS NOW BEGINNING TO EXTEND
MORE TO THE SOUTH AS WELL. AN UPPER TROF LOCATED OVER THE GULF
OF HONDURAS IS LIMITING SOME OF THE OUTFLOW OVER THE SW
QUADRANT. RADAR IMAGERY FROM W CUBA AND KEY WEST REVEAL A BAND
OF VERY HEAVY RAINFALL EXTENDING ACROSS MUCH OF W CUBA AND NOW
FILTERING OVER INTO THE FLORIDA STRAITS...APPROACHING THE LOWER
KEYS. SCATTERED/NUMEROUS MODERATE CONVECTION IS FROM 21N-24N
BETWEEN 79W-84W AND WIDELY SCATTERED MODERATE FARTHER S FROM
19N-21N BETWEEN 79W-81W.

TROPICAL DEPRESSION BONNIE CENTERED INLAND NEAR 31.1N 83.0W...OR
ABOUT 30 MILES NE OF VALDOSTA GEORGIA...AT 12/2100 UTC MOVING NE
23 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1006 MB. MAXIMUM
SUSTAINED WIND SPEED HAS DECREASED TO 30 KT WITH GUSTS TO 40
KT...DOWNGRADING BONNIE FROM A TROPICAL STORM TO A DEPRESSION.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADER
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. BONNIE HAS ESSENTIALLY
BECOME EXTRATROPICAL AND IS MERGING WITH A FRONTAL BOUNDARY THAT
EXTENDS FROM THE MID-ATLC STATES INTO THE SOUTHEAST. THE
CIRCULATION HAS BECOME EXTREMELY DISORGANIZED AND IS MOVING
ACROSS SE GEORGIA WITH WIDELY SCATTERED MODERATE CONVECTION
EXTENDING FROM 31N-33N BETWEEN 80W-83W ACROSS PARTS OF N
FLORIDA...SE GEORGIA...SE SOUTH CAROLINA...AND ADJACENT COASTAL
WATERS. ADDITIONAL CONVECTION IS LOCATED N AND E OF THE CENTER
BUT IS NOT DIRECTLY ASSOCIATED WITH THE SYSTEM. THIS IS THE LAST
ADVISORY ISSUED BY THE NATIONAL HURRICANE CENTER. FUTURE
INFORMATION CAN BE FOUND IN PUBLIC ADVISORIES ISSUED BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER UNDER AWIPS/WMO HEADERS
TCPAT2/WTNT32 KWNH.

...TROPICAL WAVES...

TROPICAL WAVE LOCATED JUST OFF THE AFRICAN COAST...ABOUT 260 NM
E OF THE EASTERNMOST CAPE VERDE ISLANDS...ALONG 18W S OF 19N
MOVING W AT AN AVERAGE SPEED OF 10 KT OVER THE PAST 12 HOURS.
THE WAVE IS EMBEDDED WITHIN A BROAD AREA OF LOW PRES THAT
EXTENDS W OF SENEGAL TO THE CAPE VERDES...BUT A WELL-DEFINED
CIRCULATION IS LOCATED FARTHER S WITH A 1010 MB LOW CENTERED
NEAR 12N18W. THE LOW HAS FAIRLY IMPRESSIVE BANDING OVER ITS SRN
SEMICIRCLE...WITH SCATTERED MODERATE CONVECTION FROM 8N-12N
BETWEEN 16W-22W.

EAST ATLANTIC TROPICAL WAVE ALONG 36W S OF 17N MOVING W ABOUT 20
KT. A CLUSTER OF TSTMS HAS BEEN RACING WWD ACROSS THE TRPCL
ATLC...AND IT APPEARS THAT THE CURRENT WAVE POSITION MAY
ACTUALLY BE A BIT TOO SLOW GIVEN THAT WIDELY SCATTERED MODERATE
CONVECTION IS FROM 8N-12N BETWEEN 40W-45W.

TROPICAL WAVE LOCATED ABOUT 430 NM E OF BARBADOS ALONG 52W S OF
17N MOVING W A LITTLE OVER 15 KT. ALTHOUGH THE WAVE IS NOT VERY
WELL-DEFINED...A CLUSTER OF SHOWERS/TSTMS HAS DEVELOPED N OF
FRENCH GUIANA AND SURINAME DUE TO WEAK LOW-LEVEL CONVERGENCE AND
TURNING. THIS PUTS A LITTLE MORE CONFIDENCE IN THE WAVE'S
CURRENT LOCATION. ISOLATED SHOWERS/TSTMS FROM 10N-13N BETWEEN
52W-58W.

TROPICAL WAVE LOCATED OVER S MEXICO JUST W OF THE ISTHMUS OF
TEHUANTEPEC ALONG 96W S OF 19N MOVING W 10-15 KT. THERE ARE NO
ASSOCIATED CLOUDS/CONVECTION WITH THIS WAVE.

...ITCZ...

ITCZ AXIS IS ALONG 8N18W 5N30W 6N50W...THEN ALONG 3N53W 8N67W
6N80W. ISOLATED SHOWERS/TSTMS 150 NM N OF THE AXIS BETWEEN
35W-41W. WIDELY SCATTERED MODERATE 230 NM S OF THE AXIS BETWEEN
52W-60W OVER PARTS OF BRAZIL...FRENCH GUIANA...SURINAME...AND
GUYANA. SCATTERED MODERATE WITHIN 150 NM OF THE AXIS BETWEEN
61W-67W OVER NE VENEZUELA.

...DISCUSSION...

GULF OF MEXICO...
A STRONG MID-LATITUDE TROF CONTINUES TO DIG SWD OFF THE TEXAS
AND LOUISIANA COAST INTO THE NW GULF...AND WILL BE THE ULTIMATE
PLAYER IN THE FORECAST TRACKS OF HURRICANE CHARLEY AND TROPICAL
DEPRESSION BONNIE. THE TROF IS SUPPORTING THE SWD MOVEMENT OF AN
UNUSUALLY STRONG COLD FRONT WHICH NOW EXTENDS JUST W OF BONNIE
FROM NEAR PANAMA CITY FLORIDA TO 27N90W 24N97W. A PRE-FRONTAL
TROF IS LOCATED ABOUT 150 NM SE OF THE FRONT EXTENDING FROM
BONNIE SWWD TO 23.5N90W. WIDELY SCATTERED SHOWERS/TSTMS ARE
LOCATED ACROSS MUCH OF THE NE GULF FROM 25N-30N BETWEEN
83W-92W...BUT IS IT HARD TO SAY WHETHER THIS ACTIVITY IS FOCUSED
SOLELY BY THE FRONT OR TROF. HURRICANE CHARLEY IS CURRENTLY
MOVING IN A NNW DIRECTION AROUND THE WRN PERIPHERY OF A STRONG
UPPER HIGH OVER THE WRN BAHAMAS...AND WILL SOON BE CROSSING THE
WESTERN PART OF CUBA DURING THE NIGHT. THE TRACK WILL BEGIN TO
TURN MORE TO THE N AND NNE AS THE HURRICANE GETS PICKED UP BY
THE SWLY FLOW AHEAD OF THE UPPER LEVEL TROF...AND MUCH OF W
FLORIDA WILL HAVE A ROUGH GO OF IT ON FRI AS STRONG
WINDS...HEAVY RAINFALL...AND DANGEROUS STORM SURGE SPREAD FROM
SW FLORIDA NWD THROUGH THE DAY. ELSEWHERE...BROAD NLY FLOW WILL
BRING DRIER CONDITIONS ACROSS THE NW GULF WITH PWAT VALUES
ALREADY FALLING TO NEAR 1.0-1.25" ALONG THE TEXAS COAST.

CARIBBEAN SEA...
WITH HURRICANE CHARLEY NOW APPROACHING THE S COAST OF CUBA...AND
FORECAST TO MOVE INTO THE SE GULF OF MEXICO BY TOMORROW
MORNING...CONDITIONS WILL RAPIDLY IMPROVE OVER MUCH OF THE NW
CARIBBEAN AS DRIER CONDITIONS PUSH FROM E TO W ACROSS THE BASIN.
A WEAK LOW-LEVEL TROF IS SKIRTING THROUGH THE NORTHERN LEEWARD
ISLANDS ALONG 16N63W 20N62W AND IS SPREADING ONLY A FEW ISOLATED
SHOWERS FROM DOMINICA NWD TO THE VIRGIN ISLANDS/PUERTO RICO.
WATER VAPOR IMAGERY DEPICTS A STRONG UPPER LEVEL HIGH CENTERED
OVER THE WRN BAHAMAS WITH MOSTLY EASTERLY FLOW EXTENDING FROM
THE LEEWARD/WINDWARD ISLANDS TO CENTRAL AMERICA...EXCEPT FOR
SOME NLY FLOW STREAMING ACROSS THE WINDWARD PASSAGE INTO THE W
CARIBBEAN. THE ATMOSPHERE E OF ABOUT JAMAICA IS MODERATELY DRY
AND THESE CONDITIONS WILL SPREAD ACROSS THE REST OF THE BASIN
TOMORROW...WITH THE NEXT BEST CHANCE OF WIDESPREAD RAIN
APPROACHING THE LESSER ANTILLES ON MON ALONG A TROPICAL WAVE.

SUBTROPICAL ATLANTIC...
WITH THE BULK OF THE INCLEMENT WEATHER FOCUSED OVER THE
CARIBBEAN AND GULF OF MEXICO...THE SUBTROPICS ARE SURPRISINGLY
QUIET WITH VERY LITTLE WIDESPREAD CONVECTION. STRONG SUBTROPICAL
RIDGING EXTENDS ACROSS THE AREA FROM A 1024 MB HIGH NEAR 33N29W
SWWD TO 27N50W THEN TO A 1022 MB HIGH NEAR 26N67W. DEEP RIDGING
EXTENDS OVER MUCH OF THE W ATLC...EXTENDING NE OF CHARLEY...AND
BROAD UPPER LEVEL DIVERGENCE E OF FLORIDA HAS ALLOWED SCATTERED
MODERATE CONVECTION TO DEVELOP AHEAD OF THE APPROACHING UPPER
TROF N OF 25N BETWEEN 77W-81W. FARTHER E...A WEAK 1020 LOW AND
DISSIPATING FRONT ARE DRAPED ALONG 31N/32N OVER THE CNTRL
ATLC...AND A SFC TROF EXTENDS ALONG 25N59W 31N55W INTERRUPTING
THE RIDGE JUST A BIT. WIDELY SCATTERED SHOWERS/TSTMS EXTEND S OF
THE FRONT AND E OF THE TROF FROM 28N-32N BETWEEN
47W-55W...ENHANCED BY A MID/UPPER LOW MOVING N NEAR 26N50W.
ELSEWHERE...BROAD WLY FLOW COVERS THE REMAINDER OF THE AREA E OF
45W...WITH ONLY A WEAK MID/UPPER LEVEL LOW DAWDLING NEAR THE
CANARY ISLANDS.

TROPICAL ATLANTIC...
SEVERAL TROPICAL WAVES ARE MOVING WWD ACROSS THE BASIN...BUT THE
TSTM ACTIVITY BETWEEN ABOUT 25W AND THE LESSER ANTILLES IS NOT
WIDESPREAD NOR VERY ORGANIZED. THE WAVE JUST NOW COMING OFF THE
COAST OF AFRICA APPEARS MOST PROMISING WITH AT LEAST A GOOD
MID-LEVEL CIRCULATION AND A HINT OF SOME BANDING FEATURES. WITH
A STRONG UPPER LEVEL HIGH CENTERED NEAR 23N36W AND DEEP ELY FLOW
EXTENDING S OF 20N...THE ENVIRONMENT ACROSS MUCH OF THE AREA IS
UNDER LOW VERTICAL SHEAR AND SO TROPICAL DEVELOPMENT IS NOT OUT
OF THE QUESTION OVER THE NEXT SEVERAL DAYS.

$$
BERG






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