[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 041141
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SAT 04 SEP 2004

TROPICAL WEATHER DISCUSSION FOR N AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHEASTERN  SECTIONS
OF S 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

HURRICANE FRANCES IS CENTERED NEAR 26.7N 78.4W AT 04/1200 UTC
MOVING NORTHWEST AT 5 KT. MAXIMUM SUSTAINED WIND SPEED IS 90 KT
WITH GUSTS TO 110 KT. MINIMUM CENTRAL PRESSURE IS 960 MB. SEE
LATEST NHC PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPAT1/
WTNT31 KNHC AND THE FORECAST/ADVISORY UNDER HEADERS MIATCMAT1/
WTNT21 KNHC FOR ADDITIONAL INFORMATION. FRANCES REMAINS A STRONG
CAT 2 HURRICANE WITH LESS CONVECTION IN FEEDER BANDS ESPECIALLY
TO THE W OF THE SYSTEM. THE WIND FIELD REMAINS BROAD OVER THE
AREA. OUTFLOW IS MOST PRONOUNCED IN THE NORTHEAST SEMICIRCLE DUE
TO SOUTHWESTERLY SHEAR ALOFT. MODERATE SUBSIDENCE IS ALSO NOTED
ON WATER VAPOR IMAGERY W OF THE CENTER OVER FLORIDA AND THE E
GULF OF MEXICO. SCATTERED STRONG CONVECTION IS WITHIN 50 NM IN
THE NE SEMICIRCLE. SCATTERED MODERATE/ISOLATED STRONG CONVECTION
EXTENDS FROM 24N-30N BETWEEN 73W-79W.

TROPICAL STORM IVAN IS CENTERED NEAR 9.0N 37.4W AT 04/0900 UTC
MOVING W AT 16 KT. THE MAXIMUM SUSTAINED WIND SPEED IS 50 KT
WITH GUSTS TO 60 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 997
MB. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. UPPER LEVEL CONDITIONS
WILL REMAIN FAVORABLE FOR CONTINUED STRENGTHENING OF IVAN TO
HURRICANE STATUS IN 24 TO 36 HOURS. SCATTERED STRONG CONVECTION
IS WITHIN 75 NM OF LINE FROM 7N38W-10N37W AND WITHIN 45/60 NM
RADIUS OF 11N40W. SCATTERED MODERATE CONVECTION COVERS THE AREA
FROM 5N-10N BETWEEN 35W-42W.

...TROPICAL WAVES...
TROPICAL WAVE ALONG 70W/71W S OF 19N MOVING W 10-15 KT. WAVE
AXIS WAS EASIER TO FIND ON THE 0600 UTC ANALYSIS DUE TO SHIP
OBSERVATIONS. SCATTERED SHOWERS/THUNDERSTORMS ARE IN THE E
CARIBBEAN N OF 14N FROM 64W-68W.

...ITCZ...

ITCZ AXIS IS CENTERED ALONG 9N10W 12N27W 7N42W 12N62W. OTHER
THAN T.S. IVAN...SCATTERED MODERATE/ISOLATED STRONG CONVECTION
IS WITHIN 75/90 NM OF LINE FROM 6N24W-8N28W. SCATTERED
THUNDERSTORMS ARE WITHIN 45 NM OF 11.5N FROM 17W-22W.

...DISCUSSION...

GULF OF MEXICO...
WEAK MID/UPPER LOW IN THE W GULF CENTERED NEAR 22N95W. MID/UPPER
LEVEL RIDGE AXIS EXTENDS FROM E TEXAS NEAR 26N98W NE ALONG
31N87W THEN N ACROSS CENTRAL GEORGIA TO BEYOND 32N84W. BROAD
UPPER MODERATE SUBSIDENCE COVERS THE E GULF AND FLORIDA BETWEEN
80W-87W...BUT CONTINUES TO ERODE ALONG THE EASTERN EDGE WITH
THE APPROACH OF THE MOISTURE PLUME ASSOCIATED WITH HURRICANE
FRANCES. AT THE SURFACE...OUTER RAIN BANDS CONTINUES TO
STRENGTHEN OVER FLORIDA WITH STRONG THUNDERSTORMS EXTENDING
ACROSS MELBOURNE TO JUST S OF LAKE OKEECHOBEE.

W ATLANTIC AND CARIBBEAN...
UPPER LEVEL HIGH CONTINUES IN THE STRAITS OF FLORIDA SW OF
HURRICANE FRANCES NEAR 24N82W WITH BROAD FLOW COVERING THE W
ATLC INTO THE CENTRAL/WESTERN CARIBBEAN W OF 67W. THIS IS
CONTRIBUTING TO THE WESTERLY SHEAR THAT FRANCES CONTINUES TO
EXPERIENCE. MODERATE UPPER LEVEL SUBSIDENCE IS SUPPRESSING
SHOWERS AND THUNDERSTORMS OVER THE CARIBBEAN. MID/UPPER LEVEL
LOW IS OVER THE WINDWARD ISLANDS NEAR 14N61W WITH FLOW COVERING
THE E CARIBBEAN AND W TROPICAL ATLC FROM 11N-21N BETWEEN
57W-67W.

REMAINDER OF SUBTROPICAL ATLANTIC...
SMALL WEAK UPPER LEVEL LOW IS IN THE CENTRAL ATLC ABOUT 725 NM
SE OF BERMUDA NEAR 27N53W EMBEDDED WITH MID/UPPER LEVEL STRONG
SUBSIDENCE THAT COVERS THE AREA FROM 23N-30N BETWEEN 50W-62W. AN
UPPER LEVEL HIGH IS CENTERED NEAR 22N39W WITH RIDGE AMPLIFYING
NE BEYOND 32N36W. AT THE SURFACE...A SURFACE TROUGH EXTENDS FROM
19N47W THROUGH A 1014 MB LOW CENTERED NEAR 24N45W TO 32N43W.
ASSOCIATED UPPER DIFFLUENCE IS ENHANCING SCATTERED MODERATE/
ISOLATED STRONG CONVECTION FROM 23N-30N BETWEEN 39W-44W.
IN THE FAR E ATLC...AN UPPER LEVEL TROUGH EXTENDS THROUGH 32N14W
SW TO 19N23W. MID/UPPER LEVEL MODERATE/STRONG SUBSIDENCE COVERS
THE AREA FROM 10N-22N BETWEEN 20W-40W AND WITHIN 150 NM OF LINE
FROM 32N30W TO THE COAST OF AFRICA NEAR 27N13W.

TROPICAL ATLC...
UPPER DIFFLUENCE IS ENHANCING CLUSTERS OF SCATTERED SHOWERS/
ISOLATED THUNDERSTORMS FROM 10N-22N BETWEEN 52W-64W INCLUDING
THE LESSER ANTILLES.

$$
WALLACE



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