[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 191802
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT WED OCT 19 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...SPECIAL FEATURE...

DANGEROUS CATEGORY 5 HURRICANE WILMA IS CENTERED NEAR 17.5N
83.5W...OR 260 NM SE OF COZUMEL MEXICO...AT 19/1800 UTC MOVING
WNW 6 KT. MAXIMUM SUSTAINED WIND SPEEDS HAVE DECREASED SLIGHTLY
TO 140 KT WITH GUSTS TO 175 KT. ESTIMATED MINIMUM CENTRAL
PRESSURE IS 900 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.
WILMA'S SATELLITE REPRESENTATION PEAKED AT AROUND 1200 UTC (WHEN
THE RECORD-LOW PRESSURE OF 882 MB WAS REPORTED BY AIR FORCE
RECONNAISSANCE DROPSONDE DATA) BUT SINCE THEN THE CLOUD TOPS
HAVE COOLED AND THE CONVECTIVE SPIRAL BANDS HAVE BEEN EXPANDING
OUTWARD AWAY FROM THE CENTER. THIS BY NO MEANS INDICATES THAT
WILMA IS WEAKENING. IN FACT...THE HURRICANE MAY BE GOING THROUGH
AN EYEWALL REPLACEMENT CYCLE SINCE VISIBLE IMAGERY SHOWS A SMALL
RING OF DEEP CONVECTION ABOUT 15 NM FROM THE EYE...AND
ADDITIONAL CONVECTION EXTENDING UP TO 75 NM OUT AND COILING
INWARD TOWARDS THE CENTER. A 1359 UTC SSMIS PASS SHOWS A LARGE
RING OF CONVECTION SURROUNDING A MOAT...WHICH ITSELF ENCIRCLES A
SMALL BURST OF CONVECTION AT THE CENTER. NUMEROUS STRONG
CONVECTION EXTENDS ABOUT 100 NM FROM THE CENTER. SCATTERED
MODERATE/STRONG CONVECTION IS LOCATED ELSEWHERE IN SPIRAL BANDS
FROM 13N-22N BETWEEN 78W-88W. THE HEAVIEST CONVECTION IS
CURRENTLY LOCATED OVER THE WATERS OF THE NW CARIBBEAN (INCLUDING
OVER THE CAYMAN ISLANDS)...BUT THIS ACTIVITY IS EXPECTED TO
SPREAD SLOWLY NWD ACROSS CUBA AND THE YUCATAN PENINSULA AS WILMA
LIFTS TO THE N.

...TROPICAL WAVES...

EAST ATLANTIC TROPICAL WAVE IS INTRODUCED ALONG 23W/24W S OF 10N
MOVING W 15 KT. THE WAVE HAS A LOW AMPLITUDE SIGNATURE AND WAS
NOT CAPTURED BY THE UPPER AIR DATA FROM DAKAR BUT WAS SEEN IN
THE DATA FROM BAMAKO AND NIAMEY A LITTLE FARTHER TO THE S. THE
AXIS FOLLOWS A CLUSTER OF CONVECTION 500 NM S OF THE CAPE VERDE
ISLANDS AND THE PLACEMENT IS PARTIALLY BASED ON GFS GUIDANCE.
WIDELY SCATTERED MODERATE CONVECTION FROM 3N-8N BETWEEN 14W-27W.

CENTRAL ATLANTIC TROPICAL WAVE ALONG 48W S OF 16N MOVING W 15
KT. THE WAVE IS BEING OVERTAKEN BY A STRONG E/NE LOW-LEVEL
SURGE...BUT CONVECTION IS FLARING WHERE THIS FLOW IS CONVERGING
WITH THE WEAKER WINDS CLOSER TO THE SOUTH AMERICAN COAST.
SCATTERED MODERATE CONVECTION FROM 8N-12N BETWEEN 46W-50W.

TROPICAL WAVE LOCATED ABOUT 225 NM E OF THE LESSER ANTILLES
ALONG 57W S OF 23N MOVING W 10-15 KT. THE WAVE IS COLLOCATED
WITH A SHARP UPPER LEVEL TROUGH WHICH HAS DISPLACED THE DEEP
CONVECTION TO THE E OF THE AXIS. HOWEVER...DIFFLUENCE ASSOCIATED
WITH THE TROUGH IS ALSO CAUSING THE CONVECTION TO BECOME MORE
WIDESPREAD WITH SCATTERED MODERATE FROM 12N-25N BETWEEN 53W-58W.
SOME OF THIS ACTIVITY IS EXPECTED TO SPREAD ACROSS PORTIONS OF
THE LESSER ANTILLES OVER THE NEXT 24-48 HRS.

CENTRAL CARIBBEAN TROPICAL WAVE ALONG 71W S OF 15N MOVING W
10-15 KT. UPPER AIR DATA FROM CURACAO DOES INDICATE THAT A WAVE
PASSED THE ISLAND WITHIN THE PAST 24 HRS BUT OTHER THAN THAT
THERE IS NO SATELLITE SIGNATURE OR RELATED DEEP CONVECTION.

WEST CARIBBEAN TROPICAL WAVE ALONG 81W/82W S OF 11N MOVING W 10
KT. THE WAVE IS MOVING W BENEATH HURRICANE WILMA...AND THE
WESTERLY FLOW IS PREVENTING ANY IDENTIFIABLE SIGNATURE.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 11N10W 4N30W 4N35W 14N56W.SCATTERED
MODERATE CONVECTION WITHIN 175 NM N OF THE AXIS BETWEEN 15W-19W.
SCATTERED MODERATE WITHIN 120 NM OF THE AXIS BETWEEN 25W-35W.
SCATTERED MODERATE ASSOCIATED WITH TROPICAL WAVES ALONG 48W AND
58W...SEE ABOVE.

...DISCUSSION...

GULF OF MEXICO...
TRANQUIL WEATHER OVER THE GULF IS DECEIVINGLY COVERING UP THE
APPROACHING HURRICANE THAT LOOMS TO THE SE. AN UPPER RIDGE AXIS
EXTENDING FROM PUERTO VALLARTA MEXICO TO 26N90W IN THE CNTRL
GULF...AND A BROAD UPPER TROUGH SWEEPING ACROSS N FLORIDA ARE
BOTH PRODUCING MODERATE/STRONG SUBSIDENCE OVER THE ENTIRE
AREA...EXCEPT THE FLORIDA STRAITS WHERE CIRRUS FROM WILMA IS
SPREADING TO THE NE. AS SUCH...THE WEATHER REMAINS MOSTLY DRY
EXCEPT FOR ISOLATED SHOWERS OVER THE SE GULF NEAR A SURFACE
TROUGH WHICH EXTENDS FROM 25N85W TO NEAR LAKE OKEECHOBEE.
CONDITIONS WILL BEGIN TO GO DOWNHILL FROM W CUBA TO THE YUCATAN
PENINSULA AND THE FLORIDA STRAITS LATE TONIGHT AND ON THU AS THE
OUTERMOST RAINBANDS OF WILMA SPREAD FROM S TO N. THE WORST
CONDITIONS ARE EXPECTED OVER THE SE GULF FRI AND SAT AS WILMA
TREKS FROM NEAR COZUMEL AND CANCUN NEWD TO SOUTH FLORIDA.

CARIBBEAN...
SEE SPECIAL FEATURES FOR DISCUSSION ON WILMA. THE BROAD OUTFLOW
CANOPY OF WILMA SPREADS AWAY FROM THE STORM NEWD INTO THE W
ATLC...SEWD ACROSS THE ENTIRE W/CNTRL CARIBBEAN...AND SWWD
ACROSS CNTRL AMERICA. CONVECTION ASSOCIATED WITH WILMA CONTINUES
TO EXPAND OUTWARD FROM THE CENTER AND THE OUTERMOST SPIRAL BANDS
EXTEND ACROSS PORTIONS OF CUBA...JAMAICA...AND INTO THE WINDWARD
PASSAGE. FARTHER E...DRIER AIR HAS INFILTRATED INTO THE E
CARIBBEAN TO ABOUT 70W PRODUCING FAIR SKIES OVER THE AREA WITH
ONLY OCCASIONAL PASSING SHOWERS. SHOWERS/TSTMS ARE DEVELOPING
ALONG A TROPICAL WAVE LOCATED E OF THE ISLANDS AND ARE EXPECTED
TO SPREAD W INTO THE E CARIBBEAN LATER TONIGHT OR THU.

WEST ATLANTIC...
AN UPPER TROUGH IS SLIDING ACROSS N FLORIDA INTO THE FAR W ATLC
ALONG 32N76W 27N80W WITH THE SUBTROPICAL JET EXTENDING FROM
SOUTH FLORIDA NEWD TO 32N60W AND 200 MB WINDS APPROACHING 100
KT. A SURFACE TROUGH EXTENDS BENEATH THE JET FROM NEAR FT.
LAUDERDALE FLORIDA EWD TO 27N70W 30N60W AND WIDELY SCATTERED
SHOWERS/TSTMS HAVE FORMED WITHIN 250 NM S OF THIS BOUNDARY
BETWEEN 57W-74W.

EAST/CENTRAL ATLANTIC...
A SHARP UPPER TROUGH LIES JUST E AND NE OF THE LESSER ANTILLES
ALONG 27N56W 20N59W 12N58W AND DOWNSTREAM UPPER DIFFLUENCE IS
TRIGGERING SCATTERED MODERATE CONVECTION ALONG THE TROPICAL WAVE
NEAR 57W/58W. A LARGE UPPER HIGH IS CENTERED OVER THE SUBTROPICS
NEAR 29N40W AND IS SUPPORTING BROAD HIGH PRES AT THE
SURFACE...CENTERED NEAR 33N37W WITH A PRESSURE OF 1026 MB. A
WEAKENING 1022 MB LOW NEAR 27N44W IS MOVING NW 5 KT BUT IS
CAUSING NO DEEP CONVECTION AND IS EXPECTED TO CONTINUE
DISSIPATING. A BROAD UPPER LOW IS MOVING TOWARDS THE MOROCCAN
COAST NEAR 34N10W WITH A TROUGH EXTENDING SW ACROSS THE CANARY
ISLANDS TO A SECOND UPPER LOW OVER THE CAPE VERDE ISLANDS NEAR
18N25W. A TROUGH/SHEAR AXIS EXTENDS W OF THIS LOW TO 20N40W WITH
A BAND OF 50 KT UPPER LEVEL WESTERLIES EXTENDING ALONG 15N.
WIDESPREAD SAHARAN DUST EXTENDS ACROSS A GOOD PORTION OF THE
ATLC FROM 7N-24N E OF 55W.

$$
BERG


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