[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 251150
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
805 AM 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1115 UTC.

...SPECIAL FEATURES...

TROPICAL STORM OPHELIA IS CENTERED NEAR 18.4N 59.5W AT 25/0900
UTC OR ABOUT 205 NM E OF THE NORTHERN LEEWARD ISLANDS MOVING W
AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008 MB. MAXIMUM
SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT. PLEASE SEE
LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT1/
WTNT21 KNHC FOR MORE DETAILS. OPHELIA REMAINS UNDER SW SHEAR.
SCATTERED MODERATE/STRONG CONVECTION IS FROM 15N-19N BETWEEN
52W-55W WITH SCATTERED MODERATE/ISOLATED STRONG CONVECTION
WITHIN 45 NM OF LINE FROM 17N56W TO 19N58W.

TROPICAL STORM PHILIPPE IS CENTERED NEAR 12.0N 29.8W AT 25/0900
UTC OR ABOUT 355 NM W-SW OF THE SOUTHERNMOST CAPE VERDE ISLANDS
MOVING W-NW AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004
MB. MAXIMUM SUSTAINED WIND SPEED IS 40 KT WITH GUSTS TO 50 KT.
PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS
MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS. PHILIPPE HAS BECOME A
BETTER ORGANIZED DURING THE PAST SEVERAL HOURS. SCATTERED STRONG
CONVECTION IS WITHIN 60 NM OF THE CENTER IN THE NW QUADRANT.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION COVERS THE
REMAINDER OF THE AREA FROM 10N-13N BETWEEN 29W-33W.

...TROPICAL WAVES...

TROPICAL WAVE IS ANALYZED 17N41W TO 10N39W MOVING W 5-10 KT.
WAVE REMAINS BETWEEN TROPICAL STORMS OPHELIA AND PHILIPPE AND
WELL DEFINED IN THE UPPER LEVEL SATELLITE WINDS. THERE IS
VIRTUALLY NO CLOUD SIGNATURE ON SATELLITE IMAGERY WITH NO
ASSOCIATED SHOWERS/CONVECTION.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS ACROSS AFRICA BUT DOES NOT ENTER THE
E TROPICAL ATLC. CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG
CONVECTION ARE FROM 5N-10N E OF 16W TO THE COAST OF SW AFRICA...
WITHIN 90 NM ALONG THE COAST OF GUINEA-BISSAU...AND WITHIN 75/90
NM OF LINE FROM 5N33W 7N43W TO 7N50W.

...DISCUSSION...

GULF OF MEXICO...
THE WEAKENING STATIONARY FRONT EXTENDS ACROSS THE FLORIDA
PANHANDLE JUST W OF TALLAHASSEE THEN ACROSS MOBILE BAY ALABAMA
TO SE LOUISIANA SUPPORTED BY A BROAD UPPER TROUGH THAT COVERS E
HALF OF THE US TO THE EASTERN SEABOARD AND INTO THE GULF N OF
23N GIVING THE GULF SE FLOW ALOFT. MOST OF N GULF IS DOMINATED
BY STRONG SUBSIDENCE AND DRY STABLE AIR THUS THE FRONT IS NOT
PRODUCING ANY SHOWERS. A SURFACE TROUGH EXTENDS ACROSS THE SE
GULF FROM 27N85W TO 21N91W GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS SE OF A LINE FROM N OF CEDAR KEY FLORIDA NEAR
30N83W TO 23N92W. THE REMAINDER OF THE GULF REMAINS UNDER
REMARKABLY CLEAR SKIES AGAIN THIS MORNING. THE WEAKENING
STATIONARY FRONT WILL GRADUALLY DISSIPATE LATER TODAY. HIGH
PRESSURE WILL BUILD ALONG 27N THROUGH TUE THEN SHIFT N WED AND
THU.

CARIBBEAN SEA...
AN UPPER LOW IS OVER THE NW CARIBBEAN CENTERED JUST S OF THE
CAYMAN ISLANDS GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS N OF LINE FROM 17N73W ACROSS JAMAICA TO THE
YUCATAN PENINSULA NEAR 20N87W TO INLAND OVER CUBA AND SW HAITI
AND THROUGH THE YUCATAN CHANNEL. AN UPPER RIDGE IS OVER THE SW
CARIBBEAN EXTENDING FROM E PANAMA ACROSS NE NICARAGUA/NE
HONDURAS TO CENTRAL BELIZE PROVIDING A DIFFLUENT ENVIRONMENT TO
GENERATE SCATTERED SHOWERS/ISOLATED THUNDERSTORMS N OF 12N AND S
OF A LINE FROM THE YUCATAN PENINSULA NEAR 20N87W ALONG 16N80W.
AN UPPER LOW LOCATED N OF THE DOMINICAN REPUBLIC EXTENDS S OVER
THE NE CARIBBEAN GENERATING ISOLATED SHOWERS OVER THE N
CARIBBEAN ISLANDS FROM THE VIRGIN ISLANDS TO THE DOMINICAN
REPUBLIC. THE MONSOON TROUGH EXTENDS ACROSS THE SW CARIBBEAN
FROM COLOMBIA NEAR 11N75W INTO THE E PACIFIC REGION ACROSS
NICARAGUA NEAR 12N84W GENERATING SCATTERED SHOWERS/
THUNDERSTORMS S OF 12N BETWEEN 74W-84W. THIS IS LEAVING THE
REMAINDER OF THE CARIBBEAN UNDER CLEAR SKIES AGAIN THIS MORNING.
TROPICAL STORM OPHELIA WILL CONTINUE TO MOVE NE OF THE LEEWARD/
VIRGIN ISLANDS THROUGH MON NIGHT. A WEAK TROPICAL WAVE IS
EXPECTED TO ENTER THE THE E CARIBBEAN THU.

ATLANTIC OCEAN...
A NARROW UPPER RIDGE IS OVER THE FAR W ATLC FROM THE CENTRAL
BAHAMAS TO NEAR 30N78W PROVIDING A DIFFLUENT ENVIRONMENT ALOFT
WITH A SURFACE TROUGH EXTENDING FROM JUST W OF GRAND BAHAMA
ISLAND THROUGH A WEAK 1013 MB LOW ALONG THE FLORIDA COAST NEAR
MELBOURNE TO BEYOND 32N81W. SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS ARE S OF 29N ACROSS THE THE BAHAMA ISLANDS TO OVER
CUBA BETWEEN 76W-80W WITH ISOLATED SHOWERS COVERING THE AREA N
OF 29N BETWEEN 76W-80W. A BROAD UPPER RIDGE DOMINATES THE W ATLC
ANCHORED ABOUT 150 NM NW OF BERMUDA PROVIDING DRY STABLE AIR
OVER THE AREA N OF 25N BETWEEN 45W-75W. AN UPPER TROUGH EXTENDS
FROM AN UPPER LOW IN THE SW ATLC N OF THE DOMINICAN REPUBLIC
NEAR 21N69W TO OVER THE E CARIBBEAN BUT IS ONLY PRODUCING
POSSIBLE ISOLATED SHOWERS S OF 22N TO OVER THE CARIBBEAN ISLANDS
BETWEEN THE VIRGIN ISLANDS AND THE DOMINICAN REPUBLIC. A BROAD
SURFACE RIDGE DOMINATES THE REMAINDER OF W INTO THE CENTRAL ATLC
N OF 23N BETWEEN 45W-75W ANCHORED BY 1024 MB HIGH JUST E OF
BERMUDA. AN UPPER TROUGH DIPS S OVER THE E ATLC N OF 23N BETWEEN
20W-50W SUPPORTING A SURFACE TROUGH THAT ENTERS THE REGION NEAR
32N29W TO 29N33W GENERATING SCATTERED SHOWERS/ISOLATED
THUNDERSTORMS WITHIN 75 NM E OF THE TROUGH. A WEAK SURFACE RIDGE
COVERS THE REMAINDER OF THE E ATLC ANCHORED BY A 1019 MB HIGH
NEAR MADEIRA ISLANDS. THE SURFACE TROUGH/LOW IN THE W ATLC WILL
SLOWLY LIFT N OF THE AREA TODAY. TROPICAL STORM OPHELIA WILL
TRACK NW THROUGH TUE NIGHT THEN TURN MORE NORTHERLY THROUGH THU
EVENING. THE WEAK TROPICAL WAVE IS EXPECTED TO MOVE ACROSS THE W
TROPICAL ATLC REACHING THE E CARIBBEAN THU.

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

$$
PAW






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