[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 252355
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 PM EDT SUN SEP 25 2011

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...

TROPICAL STORM OPHELIA WAS DOWNGRADED TO A REMNANT AREA OF
DISORGANIZED CONVECTION CENTERED NEAR 18.5N 60.9W AT 25/2100Z
OR ABOUT 145 MI...235 KM E OF THE NORTHERN LEEWARD ISLANDS...
MOVING W-NW AT 7 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1010
MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT.
PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT1/ WTNT21 KNHC FOR MORE DETAILS. SCATTERED MODERATE TO
ISOLATED STRONG CONVECTION IS FROM 16N-22N BETWEEN 54W-69W.

TROPICAL STORM PHILIPPE IS CENTERED NEAR 13.2N 31.7W AT 25/2100Z
OR ABOUT 500 MI...805 KM WSW OF THE SOUTHERNMOST CAPE VERDE
ISLANDS MOVING NW AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE
IS 997 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT WITH GUSTS TO
60 KT. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO
HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. SCATTERED
MODERATE/STRONG CONVECTION IS AROUND THE WRN SEMI-CIRCLE FROM
10N-15N BETWEEN 31W-35W. PHILIPPE IS MOVING TOWARD A WEAKNESS IN
THE SUBTROPICAL RIDGE. THIS MOTION IS EXPECTED TO CONTINUE FOR
THE NEXT COUPLE OF DAYS.

...TROPICAL WAVES...

TROPICAL WAVE IS IN THE CENTRAL ATLC ANALYZED FROM 17N43W TO
8N42W MOVING W 10-15 KT. LOW LEVEL SATELLITE DERIVED WINDS
INDICATE WEAK CYCLONIC TURNING AROUND THE WAVE AXIS. THE WAVE IS
BETTER DEPICTED ON TOTAL PRECIPITABLE WATER IMAGERY SHOWING A
SURGE OF DEEP LAYER OF MOISTURE IN THE VICINITY OF THE WAVE
AXIS. CURRENTLY NO DEEP CONVECTION ACCOMPANIES THE WAVE.

...ITCZ/MONSOON TROUGH...

DUE TO THE LARGE SCALE CIRCULATION OF T.S. PHILIPPE...THE
CENTRAL ATLC TROPICAL WAVE AND T.S. OPHELIA...THE OCEANIC
MONSOON TROUGH ONLY EXTENDS FROM THE COAST OF WEST AFRICA NEAR
19N16W TO 16N19W. THE ITCZ IS NOT PRESENT. HOWEVER...SCATTERED
MODERATE TO ISOLATED STRONG CONVECTION IS E OF 22W FROM 4N-17N
DUE TO A MID-UPPER CYCLONIC CIRCULATION MOVING OFF THE COAST OF
WEST AFRICA. AS PHILIPPE MOVES TOWARDS THE WNW...THE MONSOON
TROUGH WILL SLOWLY BUILD BACK IN BEHIND IT.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY CONTINUES TO SHOW A BROAD UPPER TROUGH/CUT
OFF LOW CENTERED OVER ERN IOWA. THE CYCLONIC FLOW ASSOCIATED TO
THIS FEATURE PUSHES A LONGWAVE THAT SWINGS OVER THE NRN GULF...
SUPPORTING A PAIR OF SURFACE TROUGHS OVER THE FLORIDA PENINSULA
AND THE ERN GULF. THE MAIN ONE EXTENDS ACROSS THE SE CONUS
SEABOARD...ENTERING THE FLORIDA PENINSULA ACROSS DAYTONA BEACH
SW TO THE FLORIDA KEYS NEAR KEY WEST. THESE TWO FEATURES ARE
GENERATING SCATTERED MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS
OVER THE FAR ERN GULF...ESPECIALLY NEAR THE COASTAL WATERS OF
THE WRN FLORIDA PENINSULA N OF 24N E OF 85W. FAIR WEATHER
CONDITIONS ARE OBSERVED ELSEWHERE ACROSS THE BASIN THIS EVENING.
EXPECT CONTINUED PRECIPITATION OVER FLORIDA...THE SE GULF...AND
THE YUCATAN PENINSULA OVER THE NEXT 24 HOURS.

CARIBBEAN SEA...
MOSTLY FAIR WEATHER CONDITIONS WITH 10-15 KT ELY TRADE WIND FLOW
ARE OBSERVED OVER MOST OF THE CARIBBEAN SEA THIS EVENING...WITH
ISOLATED SHOWERS AND POSSIBLE THUNDERSTORMS ARE EMBEDDED IN THE
FLOW. A WEAK UPPER CYCLONIC CIRCULATION IS OVER THE NW CARIBBEAN
AND IS LIKELY ENHANCING THE ISOLATED CONVECTION IN THIS REGION.
STRONGER SCATTERED CONVECTION IS OBSERVED IN THE FAR SW BASIN.
LAST SATELLITE VISIBLE PICTURES OF THE DAY SHOWED CLUSTERS OF
MODERATE TO HEAVY SHOWERS AND THUNDERSTORMS S OF 13N W OF 67W...
ASSOCIATED TO THE MONSOON TROUGH EXTENDING ACROSS SRN NICARAGUA
INTO NRN COLOMBIA. COMPUTER MODELS SUGGEST THE CONVECTION WILL
LIFT N OVER THE NEXT 24 HOURS AFFECTING THE CENTRAL CARIBBEAN.
THE REMNANTS OF TROPICAL STORM OPHELIA ARE CURRENTLY E AND N OF
THE LESSER ANTILLES AND HISPANIOLA. THIS CONVECTION IS EXPECTED
TO REMAIN OUT OF THE DISCUSSION AREA.

ATLANTIC OCEAN...
WATER VAPOR IMAGERY CONTINUES TO SHOW A BROAD UPPER TROUGH/CUT
OFF LOW CENTERED OVER ERN IOWA. THE CYCLONIC FLOW ASSOCIATED TO
THIS FEATURE PUSHES A LONGWAVE THAT SWINGS OVER THE ESE CONUS...
SUPPORTING A SURFACE TROUGH EXTENDING SSE ACROSS THE SEABOARD
WITHIN 30-90 NM OFF THE COAST...ENTERING THE FLORIDA PENINSULA
ACROSS DAYTONA BEACH. SCATTERED MODERATE TO HEAVY SHOWERS AND
THUNDERSTORMS ARE WITHIN THE SAME DISTANCE AS THE SURFACE TROUGH
AXIS. AN UPPER RIDGE IS AHEAD OF THIS AREA OF CONVECTION
SUPPORTING A NEARLY STATIONARY 1022 MB HIGH CENTERED OVER
BERMUDA AND PROVIDING FAIR/STABLE CONDITIONS TO A GREAT PART OF
THE WRN ATLC N OF 22N BETWEEN 45W-77W. A WEAK UPPER LOW IS N OF
HISPANIOLA. THIS FEATURE ALONG WITH THE REMNANTS OF OPHELIA IS
GENERATING SCATTERED MODERATE TO STRONG CONVECTION ACROSS THE
NRN COASTAL WATERS OF THE LESSER ANTILLES...PUERTO RICO...AND
DOMINICAN REPUBLIC S OF 22N W OF 54W. A BROAD UPPER TROUGH
COVERS THE ERN AND CENTRAL NORTH ATLC SUPPORTING AN AREA OF
SCATTERED MODERATE CONVECTION N OF 27N BETWEEN 34W-42W. A 1020
MB HIGH IS E MADEIRA ISLANDS PROVIDING MOSTLY FAIR WEATHER
ACROSS THE SE ATLC.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

GARCIA



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