[Tropical] Tropical Weather Discussion

[Nashville EMWIN]

AXNT20 KNHC 312351
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT TUE 31 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
2345 UTC.

...SPECIAL FEATURES...

HURRICANE FRANCES IS CENTERED NEAR 20.5N 65.9W...OR  ABOUT 145
MILES... 235 KM... NORTH OF SAN JUAN PUERTO RICO...AT 31/2100
UTC. IT IS MOVING WEST 15 KT AROUND THE SOUTHERN PERIPHERY OF
THE SUBTROPICAL RIDGE. MAXIMUM SUSTAINED WIND SPEED IS MEASURED
BY RECON AT 140 MPH/225 KM/HR WITH HIGHER GUSTS...AND THE RECON
MEASURED MINIMUM CENTRAL PRESSURE IS 939 MB. SEE THE LATEST NHC
PUBLIC ADVISORY OR FORECAST/ADVISORY ISSUED UNDER AWIPS/WMO
HEADERS MIATCPAT1/WTNT31 KNHC OR MIATCMAT1/WTNT21 KNHC FOR MORE
DETAILS AND WARNING INFORMATION. SATELLITE IMAGERY SHOWS
EXCELLENT UPPER OUTFLOW AND LITTLE VERTICAL SHEARING. THE EYE IS
30 NM DIAMETER AT THE MOMENT...AND IS EXPECTED TO UNDERGO THE
NORMAL EYEWALL FLUCTUATIONS... RESULTING IN SLIGHT CHANGES IN
INTENSITY ALONG ITS WESTWARD TRACK...WITH AN OVERALL INCREASE IN
INTENSITY TO 125 KT EXPECTED DURING THE NEXT 24 HOURS...THEN
LITTLE CHANGE IN INTENSITY THROUGH LANDFALL SOMEWHERE ON THE SE
COAST CONUS. NUMEROUS STRONG CONVECTION NOTED WITHIN 115 NM NE
SEMICIRCLE AND WITHIN 90 NM OVER THE SW SEMICIRCLE.  SCATTERED
MODERATE CONVECTION EXTENDS FROM 18N-24N BETWEEN 62W-69W.

TROPICAL STORM GASTON WAS CENTERED NEAR 40.7N 68.6W OR ABOUT  90
MILES...140 KM...EAST-SOUTHEAST OF NANTUCKET MASSACHUSETTS... AT
31/2100 UTC. GASTON IS MOVING TOWARD THE EAST NORTHEAST AT 25
KT. MAXIMUM SUSTAINED WINDS ARE 35 KT WITH GUSTS TO 45 KT AND
THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 999 MB. SEE THE LATEST
NHC ADVISORIES ISSUED UNDER AWIPS/WMO HEADERS MIATCPAT2/WTNT32
KNHC OR MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.  SCATTERED
MODERATE TO STRONG CONVECTION IS CONCENTRATED WITHIN 90 NM OF
CENTER OVER N SEMICIRCLE.

...TROPICAL WAVES...

TROPICAL WAVE IS ALONG 28W S OF 23N MOVING WEST AT 20 KT.  A
1011 MB LOW IS ON THE WAVE AXIS NEAR 19N28W.  THE LOW IS
ACCOMPANIED BY SCATTERED MODERATE TO STRONG CONVECTION WITHIN 90
NM OF CENTER...BUT CURRENTLY LACKS A CONSISTENT BANDING FEATURE
THUS THE UPGRADE TO DEPRESSION STATUS HAS NOT OCCURRED. THE
SURROUNDING ENVIRONMENT REMAINS FAVORABLE FOR DEVELOPMENT AND
TROPICAL DEPRESSION FORMATION IS POSSIBLE DURING THE NEXT 48
HOURS.

CENTRAL ATLANTIC OCEAN TROPICAL WAVE IS APPROXIMATELY 550 NM E
OF BARBADOS ALONG 50W SOUTH OF 17N MOVING WEST 10-15 KT. NO
SIGNIFICANT CONVECTION IS NOTED AT THIS TIME.

...ITCZ...
ITCZ AXIS IS CENTERED ALONG 15N1W 8N15W 13N25W 10N40W 8N50W
12N65W 10N80W.  SCATTERED MODERATE TO ISOLATED STRONG CONVECTION
IS INLAND OVER W AFRICA FROM 12N-15N BETWEEN 13W-17W.  SCATTERED
MODERATE CONVECTION IS ALONG THE COAST OF COSTA RICA FROM 8N-13N
BETWEEN 80W-84W.

...DISCUSSION...

THE GULF OF MEXICO...

AT THE LOW LEVELS A STATIONARY FRONT EXTENDS FROM THE FLORIDA
PANHANDLE TO THE CENTRAL TEXAS COAST ALONG 31N86W 28N92W 30N98W.
A TROUGH EXTENDS S TO THE BAY OF CAMPECHE FROM 28N88W TO 20N95W.
IN THE UPPER LEVELS...NORTHERLY WINDS ARE OVER THE W GULF OF
MEXICO W OF 95W DUE TO AN ANTICYCLONIC CIRCULATION OVER S MEXICO
NEAR 19N105W.  A CYCLONIC CIRCULATION IS CENTERED OVER THE
YUCATAN PENINSULA NEAR 22N88W.  CYCLONIC FLOW IS FROM 16N-25N
BETWEEN 84W-95W.  ANOTHER CYCLONIC CIRCULATION IS NEAR S FLORIDA
AT 25N79W ENHANCING THUNDERSTORM ACTIVITY.  AN ANTICYCLONIC
CIRCULATION IS OVER S GEORGIA NEAR 32N81W.

CARIBBEAN SEA...
HURRICANE FRANCES IS N OF PUERTO RICO MOVING W.  OUTER FEEDER
BANDS ARE OVER PUERTO RICO AND THE VIRGIN ISLANDS.  ITCZ
CONVECTION IS NOTED ALONG THE COAST OF COSTA RICA.  STRONG
EASTERLIES COVER THE REMAINDER OF THE CARIBBEAN SEA.  IN THE
UPPER LEVELS...EASTERLY FLOW IS FROM 60W-70W.  THE CYCLONIC
CIRCULATION AT 25N79W IS PRODUCING CONVECTION OVER W CUBA.

SUBTROPICAL ATLANTIC OCEAN...
SURFACE HIGH IS OVER THE CENTRAL ATLANTIC NEAR 38N54W.  A RIDGE
EXTENDS SW TO FLORIDA NEAR 30N80W.  IN THE UPPER LEVELS...
LARGE ANTICYCLONIC CIRCULATION IS OVER HURRICANE FRANCES FROM
17N-30N BETWEEN 58W-73W.  A LARGE CYCLONIC CIRCULATION IS OVER
THE CENTRAL ATLANTIC NEAR 25N44W.  CYCLONIC FLOW IS FROM 16N-32N
BETWEEN 37W-55W.

TROPICAL ATLANTIC...
ASIDE FROM HURRICANE FRANCES...THE MID ATLC CYCLONIC CIRCULATION
AND UPPER TROUGH EXTENDING S INTO THE TROPICS AND HAS SUPPRESSED
CONVECTION ALONG THE ITCZ TO S OF 11N W OF 35W.  AN ANTICYCLONIC
CIRCULATION IS ALONG THE COAST OF W AFRICA NEAR 17N17W.  A RIDGE
AXIS EXTENDS W TO 30W.


$$
FORMOSA



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