[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 261747
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SUN APR 26 2009

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...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N9W 3N16W CROSSING THE EQUATOR NEAR
20W EXTENDING TO 2S24W 2S33W AND INTO NE BRAZIL NEAR 3S40W.
CLUSTERS OF SCATTERED MODERATE CONVECTION IS S OF 6N E OF 22W.
ELSEWHERE...A SMALL CLUSTER OF SCATTERED MODERATE CONVECTION IS
FROM THE EQUATOR TO 2N BETWEEN 43W-48W.

...DISCUSSION...

GULF OF MEXICO...
AN UPPER LEVEL TROUGH IS PRESENT ACROSS THE GULF REGION WITH THE
AXIS EXTENDING FROM THE FLORIDA BIG BEND THROUGH THE ERN BAY OF
CAMPECHE. TO THE W OF THE TROUGH AXIS...UPPER LEVEL MOISTURE IS
EVIDENT ON WATER VAPOR IMAGERY AS HIGH LEVEL CLOUDS ARE OBSERVED
W OF 95W. ALSO...UPPER LEVEL DIVERGENCE E OF THE TROUGH AXIS IS
SUPPORTING INCREASED CLOUDINESS AND POSSIBLE SCATTERED SHOWERS
FROM 23N-27N BETWEEN 83W-87W. HOWEVER...SUBSIDENCE ASSOCIATED
WITH A SURFACE RIDGE EXTENDING WESTWARD INTO THE SE CONUS FROM A
1031 MB SURFACE HIGH OVER THE W ATLC NEAR 33N70W IS RESULTING IN
GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF THE GULF THIS
AFTERNOON. THE FLOW AROUND THE SURFACE RIDGE IS RESULTING IN E
TO SE WINDS OF 20 TO 25 KT ACROSS PORTIONS OF THE GULF...WITH E
WINDS UP TO 30 KT THROUGH THE STRAITS OF FLORIDA. THESE
CONDITIONS ARE EXPECTED TO PERSIST THROUGH LATE MONDAY WHEN THE
PRESSURE GRADIENT RELAXES ACROSS THE GULF.

CARIBBEAN SEA...
A 1031 MB SURFACE HIGH OVER THE W ATLC NEAR 33N70W IS
MAINTAINING FRESH TO STRONG TRADE WINDS ACROSS THE CARIBBEAN
SEA. THE STRONGEST WINDS ARE FOUND NEAR THE COAST OF COLOMBIA...
WHERE NE TO E SURFACE WINDS UP TO 30 KT ARE OCCURRING. A BROAD
UPPER LEVEL RIDGE COVERS THE CARIBBEAN SEA WHERE ATMOSPHERIC
STABILITY IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS.
HOWEVER...THE TRADE WINDS ARE ADVECTING POCKETS OF LOW LEVEL
MOISTURE WITH ISOLATED SHOWERS WESTWARD ACROSS THE CARIBBEAN.
THE GREATEST CONCENTRATION OF THESE SHOWERS IS ACROSS THE
WINDWARD ISLANDS S OF 15N...SOUTH OF HISPANIOLA FROM 16N-19N
BETWEEN 70W-73W...AND OVER JAMAICA. ALSO...UPPER LEVEL MOISTURE
AND HIGH LEVEL CLOUDS CONTINUE TO STREAM NORTHEASTWARD ACROSS
THE WRN CARIBBEAN.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH OVER THE CENTRAL ATLC IS ASSOCIATED WITH A
SURFACE STATIONARY FRONT THAT EXTENDS FROM 24N65W TO 27N56W TO
31N53W AND NE BEYOND THE DISCUSSION AREA. LOW LEVEL CONVERGENCE
IS SUPPORTING SCATTERED SHOWERS AND ISOLATED TSTMS WITHIN 120 NM
E OF THE FRONT N OF 27N. ELSEWHERE ALONG THE BOUNDARY...ISOLATED
SHOWERS ARE WITHIN 50 NM. THIS ACTIVITY IS ALSO BEING SUPPORTED
BY UPPER LEVEL DIVERGENCE IN THE NE QUADRANT OF AN 80-90 KT
UPPER LEVEL WIND SPEED MAXIMUM LOCATED SE OF THE STATIONARY
SURFACE FRONT. TO THE NW OF THE BOUNDARY...DEEP LAYER DRY AIR
AND SUBSIDENCE ASSOCIATED WITH A 1031 MB SURFACE HIGH NEAR
33N70W ARE RESULTING IN GENERALLY FAIR WEATHER CONDITIONS. THIS
HIGH PRESSURE RIDGE IS FORECAST TO REMAIN QUASI-STATIONARY OVER
THE NEXT 24 HOURS. FARTHER TO THE E...SUBSIDENCE IN THE
VICINITY OF A SURFACE RIDGE IS RESULTING IN GENERALLY FAIR
WEATHER CONDITIONS ACROSS MUCH OF THE CENTRAL AND E ATLC.
HOWEVER...AN UPPER TROUGH IS LOCATED OVER THE FAR NE ATLC NW OF
THE CANARY ISLANDS WITH AN UPPER LOW CENTERED NEAR 30N20W.
ATMOSPHERIC INSTABILITY AND UPPER LEVEL DIVERGENCE IN THE
VICINITY OF THIS UPPER LOW ARE RESULTING IN SCATTERED SHOWERS N
OF 24N E OF 21W. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL
ANTICYCLONE CENTERED OVER W AFRICA EXTENDS A RIDGE ALONG 9N14W
1N37W. UPPER LEVEL DIVERGENCE ON THE SRN PERIPHERY OF THE RIDGE
IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ.

$$
HUFFMAN



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