[Tropical] Tropical Weather Discussion

[EMWIN Server]

AXNT20 KNHC 250506
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT SAT APR 25 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0445 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N8W 1N15W CROSSING THE EQUATOR NEAR
21W EXTENDING TO 1S29W 1S36W AND INTO NE BRAZIL NEAR 3S41W.
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 1N-5N
BETWEEN 2W-6W. SCATTERED MODERATE CONVECTION IS FROM 2N-5N
BETWEEN 12W-15W. SCATTERED MODERATE CONVECTION IS ALSO S OF 3N
BETWEEN 17W-28W.

...DISCUSSION...

GULF OF MEXICO...
DEEP LAYER DRY AIR AND SW TO W FLOW ALOFT ARE PRESENT ACROSS
MUCH OF THE GULF REGION. SUBSIDENCE ASSOCIATED WITH A 1025 MB
SURFACE HIGH OVER THE NE GULF NEAR 30N86W AND A SURFACE RIDGE
ACROSS THE N GULF ALONG 29N IS RESULTING IN GENERALLY FAIR
WEATHER CONDITIONS ACROSS MUCH OF THE GULF REGION. HOWEVER...
UPPER LEVEL DIVERGENCE AND INCREASING UPPER LEVEL MOISTURE OVER
THE S AND W GULF ARE RESULTING IN SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS N OF 29N BETWEEN 94W-96W INCLUDING THE SE TEXAS
COAST AND THE S GULF S OF 23N BETWEEN 88W-91W. THE FLOW AROUND
THE AFOREMENTIONED SURFACE HIGH AND SURFACE RIDGE IS RESULTING
IN SE WINDS OF 20 TO 25 KT ACROSS PORTIONS OF THE W GULF WITH E
WINDS OF 20 TO 25 KT ACROSS THE STRAITS OF FLORIDA. DURING THE
NEXT DAY...THE 1025 MB SURFACE HIGH OVER THE NE GULF NEAR 30N86W
IS FORECAST TO DISSIPATE. HOWEVER...THE SURFACE RIDGE ALONG 29N
IS FORECAST TO DRIFT NE OF THE GULF REGION AND STRENGTHEN DURING
THE NEXT DAY...WITH INCREASING EASTERLY SURFACE WINDS ACROSS THE
GULF THROUGH TUESDAY.

CARIBBEAN SEA...
A 1031 MB SURFACE HIGH OVER THE W ATLC NEAR 33N71W 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 IS PRESENT ACROSS THE
CARIBBEAN SEA. ATMOSPHERIC STABILITY ASSOCIATED WITH THIS RIDGE
IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS ACROSS MUCH OF
THE CARIBBEAN. 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 N OF
15N BETWEEN 63W-74W INCLUDING PUERTO RICO AND HISPANIOLA.
ALSO...UPPER LEVEL MOISTURE CONTINUES TO STREAM NORTHEASTWARD
ACROSS THE WESTERN CARIBBEAN...WHERE HIGH LEVEL CLOUD COVERAGE
IS INCREASING.

ATLANTIC OCEAN...
A DEEP LAYER TROUGH OVER THE WESTERN AND CENTRAL ATLC IS
ASSOCIATED WITH A SURFACE COLD FRONT THAT EXTENDS FROM NE OF THE
DISCUSSION AREA TO 32N56W TO 28N60W...A SURFACE STATIONARY FRONT
THAT EXTENDS FROM 28N60W TO 26N70W...AND A SURFACE WARM FRONT
THAT EXTENDS FROM 26N70W TO SW OF THE BAHAMAS NEAR 23N77W. LOW
LEVEL CONVERGENCE IS RESULTING IN SCATTERED SHOWERS WITHIN 60 NM
EITHER SIDE OF THESE FRONTS. THIS ACTIVITY IS ALSO BEING
SUPPORTED BY UPPER LEVEL DIVERGENCE IN THE NE QUADRANT OF A
70-80 KT UPPER LEVEL WIND SPEED MAXIMUM OVER THE SW NORTH ATLC.
TO THE W OF THE FRONTS...DEEP LAYER DRY AIR AND SUBSIDENCE
ASSOCIATED WITH A 1031 MB SURFACE HIGH NEAR 33N71W ARE RESULTING
IN GENERALLY FAIR WEATHER CONDITIONS. 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...ATMOSPHERIC INSTABILITY AND UPPER LEVEL
DIVERGENCE IN THE VICINITY OF A SHARP UPPER LEVEL TROUGH WITH AN
AXIS EXTENDING FROM 8N45W TO 22N36W TO 32N25W TO NE OF THE
DISCUSSION AREA IS RESULTING IN SCATTERED SHOWERS N OF 24N
BETWEEN 21W-33W. ACROSS THE TROPICAL ATLC...AN UPPER LEVEL RIDGE
IS PRESENT WITH AN AXIS EXTENDING FROM 10N14W TO 3N30W TO 1N41W.
UPPER LEVEL DIVERGENCE IN THE VICINITY OF THIS UPPER LEVEL RIDGE
IS ENHANCING THE CONVECTION ASSOCIATED WITH THE ITCZ.

$$
COHEN




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