[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 250540
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT 25 SEP 2004

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN
SECTIONS OF SOUTH AMERICA...AND ATLC 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
0315 UTC.

...SPECIAL FEATURES...

HURRICANE JEANNE IS CENTERED NEAR 26.5N 75.6W OR ABOUT 100
MILES...160 KM...EAST OF GREAT ABACO ISLAND OR ABOUT 270
MILES...435 KM...EAST OF SE FLORIDA AT 25/0600 UTC MOVING W AT
10 KT. MAXIMUM SUSTAINED WIND SPEED REPORTED BY AIR FORCE
RESERVE HURRICANE HUNTER AIRCRAFT IS 90 KT WITH GUSTS TO 110 KT
AND THE MINIMUM CENTRAL PRESSURE IS 962 MB. SEE LATEST NHC
PUBLIC ADVISORY OR NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCPAT1/WTNT31 KNHC OR MIATCMAT1/WTNT21 KNHC FOR MORE DETAILS.
WELL DEFINED LARGE EYE REMAINS WITH THE ASSOCIATED DEEP
CONVECTION MAINLY TO THE S OF THE CENTER. STRONG UPPER LEVEL
HIGH IS NOW CENTERED OVER JEANNE WITH RIDGE EXTENDING N TO OVER
E CANADA. THIS HIGH IS NOW PUSHING JEANNE TO THE WEST
APPROACHING THE BAHAMAS AND FLORIDA. THE OUTFLOW STILL REMAINS
GOOD IN ALL BUT THE SE QUADRANT. MODERATE SUBSIDENCE/DRY AIR
SURROUNDS JEANNE IN ALL BUT THE E QUADRANT. AS JEANNE MOVES OVER
THE WARMER WATER OF THE GULF STREAM FURTHER INTENSIFICATION IS
POSSIBLE. SCATTERED MODERATE/STRONG CONVECTION IS WITHIN 75 NM
OF THE CENTER IN THE W QUADRANT AND WITHIN 120/150 NM OF THE
CENTER IN THE REMAINDER OF THE QUADRANTS.

TROPICAL DEPRESSION LISA IS CENTERED NEAR 14.3N 44.7W OR ABOUT
950 NM EAST OF THE OUTER LESSER ANTILLES OR ABOUT 1225 NM WEST
OF THE CAPE VERDE ISLANDS AT 25/0300 UTC MOVING NW AT 7 KT.
MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT AND
ESTIMATED MINIMUM CENTRAL PRESSURE IS 1002 MB. SEE LATEST NHC
FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT3/WTNT23 KNHC
FOR MORE DETAILS. THE LOW LEVEL CENTER REMAINS EXPOSED TO THE N
OF THE ASSOCIATED DEEP CONVECTION. LISA CONTINUES TO EXPERIENCE
NORTHEASTERLY SHEAR WHICH ACCOUNTS FOR THE DISPLACEMENT OF THE
DEEP CONVECTION. NUMEROUS STRONG CONVECTION IS WITHIN 45/60 NM
OF 14N FROM 42W-45W. SCATTERED MODERATE/ISOLATED STRONG
CONVECTION COVERS THE REMAINDER OF THE AREA FROM 7N-13N BETWEEN
41.5W-47W.

...TROPICAL WAVES...
TROPICAL WAVE IS W OF THE CAPE VERDE ISLANDS ALONG 27W/28W S OF
17N MOVING W 10-15 KT. A BROAD LOW/MID LEVEL CIRCULATION IS
OBSERVED ALONG THE WAVE ABOUT 14N. CLASSIC SATELLITE SIGNATURE
IS OBSERVED ON INFRARED SATELLITE IMAGERY. SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS ARE WITHIN 75 NM OF 16.5N FROM 23W-28W
INCLUDING SOME OF THE CAPE VERDE ISLANDS.

...ITCZ...

ITCZ EXTENDS ALONG 18N10W 13N26W 15N42W 11N51W 12N70W. OTHER
THAN THE TROPICAL WAVE AND T.D. LISA...LARGE CLUSTERS OF
SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE FROM 2N-9N
BETWEEN 21W-34W.

...DISCUSSION...

GULF OF MEXICO...
BROAD DEEP LAYERED TROUGH EXTENDS FROM THE NORTH-CENTRAL UNTIED
STATES S OVER THE MID WEST OF THE UNITED STATES INCLUDING THE
STATE OF TEXAS. A SHORTWAVE TROUGH AXIS EXTENDS FROM CENTRAL
COAST OF TEXAS INTO THE GULF THROUGH A UPPER LEVEL LOW CENTERED
NEAR 26N94W CONTINUING S INTO THE BAY OF CAMPECHE NEAR 20N92W.
THIS SHORTWAVE TROUGH IS A RESULT OF THE MID/UPPER LEVEL HIGH
OVER THE E PACIFIC AND THE MID/UPPER LEVEL HIGH CENTERED JUST N
OF THE YUCATAN CHANNEL NEAR 23N87W. THE RIDGE AXIS FROM THE
YUCATAN HIGH IS BEING NARROWED BY THE APPROACH OF THE UPPER
LEVEL HIGH OVER HURRICANE JEANNE. AN INDUCED INVERTED TROUGH
OVER THE FAR E GULF IS A RESULT OF THE ABOVE UPPER HIGHS. STRONG
SUBSIDENCE/DRY AIR IS OVER THE E GULF E OF 86W TO OVER THE
FLORIDA PENINSULA. THIS DRY AIR WILL GIVE WAY AS JEANNE
CONTINUES TO MOVE WESTWARD. ONLY SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS REMAIN IN THE NW GULF WHICH IS A RESULT OF THE
REMNANTS OF IVAN THAT IS CURRENTLY INLAND OVER E TEXAS.

THE CARIBBEAN SEA AND W TROPICAL ATLANTIC...
THE MID/UPPER LEVEL HIGH N OF THE YUCATAN CHANNEL COVERS THE W
CARIBBEAN WITH ANTICYCLONIC FLOW W OF 84W. A MID/UPPER LEVEL
HIGH CENTERED OVER NW VENEZUELA IS BRINGING ANTICYCLONIC FLOW
OVER THE CENTRAL CARIBBEAN FROM 64W-81W. AN INDUCED MID/UPPER
LEVEL LOW IS A RESULT OVER THE UPPER HIGH OVER VENEZUELA AND THE
HIGH OVER JEANNE IN THE W ATLC. THIS LOW IS CENTERED OVER SE
CUBA NEAR 20N77W. THIS IS PRODUCING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS FROM 19N85W ACROSS JAMAICA TO OVER HAITI. A
MID/UPPER LEVEL HIGH OVER THE W TROPICAL ATLC ABOUT 500 NM W OF
THE LEEWARD ISLANDS NEAR 18N53W. ANTICYCLONIC FLOW COVERS THE
AREA FROM 40W-63W INCLUDING THE OUTER LESSER ANTILLES. MODERATE
TO STRONG SUBSIDENCE/DRY AIR COVERS THE FAR W CARIBBEAN KEEPING
SHOWER/THUNDERSTORM ACTIVITY INLAND OVER THE YUCATAN PENINSULA
AND CENTRAL AMERICA...AND OVER FAR E CARIBBEAN INTO THE TROPICAL
ATLC FROM 50W-70W. SCATTERED LOW LEVEL SHOWERS/THUNDERSTORMS ARE
OVER THE LESSER ANTILLES S OF 16N INCLUDING TRINIDAD AND TOBAGO.

SUBTROPICAL ATLANTIC AND THE E TROPICAL
HURRICANE JEANNE AND THE UPPER LEVEL HIGH OVER HER DOMINATE THE
W ATLC. THE LARGE DEEP LAYERED TROUGH OVER THE CENTRAL ATLC IS
NOW N OF 25N BETWEEN 38W-64W WITH A LARGE UPPER LEVEL LOW
CENTERED NEAR 40N49W. THIS TROUGH WILL REMAIN NEARLY STATIONARY
OVER THE NEXT 24 HOURS BEFORE IT BEGINS TO LIFT NE AGAIN.
ELSEWHERE OVER THE CENTRAL ATLC...A MID/UPPER LEVEL HIGH IS
CENTERED NEAR 18N53W IN THE TROPICAL ATLC WITH ANTICYCLONIC FLOW
S OF 24N FROM 40W-63W. THIS UPPER LEVEL HIGH IS PRODUCING
NORTHEASTERLY SHEAR OVER T.D. LISA. A RIDGE AXIS EXTENDS FROM
NEAR 24N40W NE TO WELL BEYOND 32N34W. MID/UPPER LEVEL LOW IS
OVER THE E ATLANTIC NEAR 30N27W WITH A TROUGH EXTENDING S TO
12N31W. THE ABOVE UPPER HIGH AND LOW HAVE BEEN NEAR STATIONARY
FOR ALMOST 24 HOURS AND WILL REMAIN SO FOR AT LEAST THE NEXT 24.
LARGE MID/UPPER LEVEL HIGH IS INLAND OVER W AFRICA NEAR 20N9W
WITH ANTICYCLONIC FLOW COVERING THE E ATLC E OF 22W. AT THE
SURFACE...A COLD FRONT ENTERS THE CENTRAL ATLC NEAR 32N51W
EXTENDING W TO 31N59W. A SURFACE TROUGH EXTENDS ACROSS THE
CENTRAL ATLC SE OF THE ABOVE FRONT NEAR 30N43W SW TO 26N50W THEN
W TO 26N56W. THE SUBTROPICAL RIDGE EXTENDS JUST E OF THE AZORES
THROUGH 32N24W SW TO 20N40W. CLUSTERS OF SHOWERS/THUNDERSTORMS
ARE WITHIN 90 NM OF LINE FROM 27N64W 26N48W TO BEYOND 32N37W.

$$
WALLACE




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