000
AXNT20 KNHC 090530
TWDAT 

TROPICAL WEATHER DISCUSSION 
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 AM EDT THU APR 09 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 0515 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 5N7W 2N17W CROSSING THE EQUATOR NEAR 
23W AND EXTENDING TO 2N34W INTO NE BRAZIL NEAR 3S43W. SCATTERED 
MODERATE CONVECTION IS S OF 4N BETWEEN 3W-11W. SIMILAR 
CONVECTION IS S OF 3N BETWEEN 17W-20W.

...DISCUSSION...

GULF OF MEXICO...
SFC HIGH PRES CONTINUES TO SHIFT E NOW CENTERED OVER THE FAR SE 
WATERS JUST W OF THE DRY TORTUGAS. SLY RETURN FLOW TO THE W OF 
THE HIGH HAS MODIFIED THE COOL AIRMASS THAT WAS IN PLACE EARLIER 
THIS WEEK. WINDS ARE STRONGEST OVER THE NW WATERS IN RESPONSE 
TO BROAD LOW PRES OVER THE PLAINS AND ROCKIES. THIS LOW PRESSURE 
SYSTEM WILL BE DRAGGING A COLD FRONT NEAR OR OVER THE NW GULF 
FRI. ALOFT...STRONG W TO NW FLOW LIES OVER THE REGION...BETWEEN 
RIDGING OVER THE CENTRAL CONUS AND LARGE SCALE TROUGHING OVER 
THE W ATLC...ADVECTING SOME PACIFIC HIGH LEVEL CLOUDINESS INTO 
THE WRN GULF. 

CARIBBEAN SEA...
A STATIONARY FRONT IS DISSIPATING FROM THE WINDWARD PASSAGE TO 
NICARAGUA. PATCHY LOW-MID LEVEL CLOUDS AND EMBEDDED ISOLATED 
SHOWERS ARE WITHIN 180 NM W OF THE FRONT. NLY WINDS HAVE 
DIMINISHED BELOW 20 KT NEAR THE FRONT. IN FACT...THE ONLY AREA 
OF 20 KT WINDS ARE NEAR THE COAST OF COLOMBIA. A WEAK INVERTED 
SFC TROUGH HAS MOVED ACROSS THE LESSER ANTILLES ALONG 63W FROM 
13N-17N. LOW-LEVEL CLOUDS AND EMBEDDED SCATTERED SHOWERS ARE 
WITHIN 180 NM E OF THE TROUGH AXIS. SIMILAR ACTIVITY IS 
OCCURRING OVER THE ISLAND OF HISPANIOLA ASSOCIATED WITH REMNANT 
TROUGHING AND LOCAL UPSLOPE CONDITIONS. ALL OF THE AREAS 
OUTLINED ARE SHALLOW IN NATURE CAPPED BY DRY AIR IN THE MID AND 
UPPER LEVELS.   

ATLANTIC OCEAN...
A LARGE SCALE MID-UPPER TROUGH OVER THE W ATLC IS PROVIDING 
SUPPORT FOR A COLD FRONT EXTENDING FROM 32N60W TO 24N67W THROUGH 
THE WINDWARD PASSAGE. LOW-LEVEL CONVERGENCE AND UPPER DIFFLUENCE 
IS PRODUCING SCATTERED SHOWERS WITHIN 180 NM E OF THE FRONT N OF 
26N AND ISOLATED ACTIVITY WITHIN 180 NM S OF 26N. THIS FRONT IS 
EXPECTED TO STALL AND GRADUALLY DISSIPATE OVER THE NEXT DAY OR 
TWO. A WEAK SFC RIDGE IS BUILDING E OVER THE W ATLC BEHIND THE 
FRONT. DESPITE THE DECREASE IN WINDS OVER THE W ATLC...SEAS 
REMAIN QUITE ELEVATED N OF THE BAHAMAS IN NW SWELL. FARTHER 
E...AN UPPER LOW CENTERED NEAR 23N40W IS PRODUCING MULTILAYER 
CLOUDINESS AND EMBEDDED ISOLATED SHOWERS FROM 20N-24N BETWEEN 
38W-43W. AN ASSOCIATED WEAK LOW-LEVEL TROUGH ALONG 50W FROM 
20N-26N IS PRODUCING LITTLE SENSIBLE WEATHER. A SW TO W UPPER 
JET WITH CORE WINDS NEAR 100 KT ORIGINATES JUST E OF THE BASE OF 
THE UPPER TROUGH FROM 15N61W TO 14N40W TO 23N31W TO 26N15W 
GENERATING AND ADVECTING MID-HIGH LEVEL CLOUDINESS WITHIN 300 NM 
SE OF THE JET AXIS. 

$$
CANGIALOSI