000
AXNT20 KNHC 201107
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED MAY 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 58W TO THE SOUTH OF 9N MOVING WEST 
ABOUT 10 KT MOVING THROUGH GUYANA. THIS POSITION COINCIDES
WITH HIGHER LEVELS OF PRECIPITABLE WATER ON THE MIMIC-TPW CHART 
FROM CIMSS AS LATE AS 20/1040 UTC. THE WAVE IS MOVING UNDER
AN AREA OF MIDDLE TO UPPER LEVEL ANTICYCLONIC FLOW. EXPECT 
SCATTERED SHOWER ACTIVITY OVER THE GUYANAS AND EASTERN
VENEZUELA DURING THE NEXT FEW DAYS. THE CONVECTIVE
PRECIPITATION WITH THE WAVE FROM 6 HOURS AGO HAS DISSIPATED.

...THE ITCZ...

FROM LIBERIA NEAR 6N10W...CROSSING THE EQUATOR ALONG 20W...
TO 3S30W TO 5S44W. ISOLATED MODERATE TO STRONG SHOWERS AND 
POSSIBLE THUNDERSTORMS ARE FROM THE EQUATOR TO 7N TO THE
EAST OF 22W. ISOLATED MODERATE SHOWERS ARE TO THE SOUTH
OF 4N BETWEEN 22W AND 50W.

...DISCUSSION...

THE GULF OF MEXICO...THE NORTHWESTERN CARIBBEAN SEA...AND
THE ATLANTIC OCEAN TO THE WEST OF 70W...
THE DEEP LAYER TROUGH FROM 24 HOURS AGO THAT WAS SUPPORTING THE 
COLD FRONT HAS IT MOVED ACROSS THE AREA HAS INTENSIFIED TO THE 
SOUTH...EXTENDING ITSELF INTO THE NORTHWESTERN CORNER OF THE 
CARIBBEAN SEA. THE TROUGH NOW IS ALONG THE LINE FROM 
SOUTHEASTERN GEORGIA TO A CYCLONIC CIRCULATION CENTER THAT IS
ABOUT 50 NM TO THE NORTHWEST OF KEY WEST FLORIDA...TO THE COAST
OF HONDURAS NEAR 85W. MIDDLE LEVEL TO UPPER LEVEL DRY AIR IS
MOVING ACROSS THE GULF OF MEXICO FROM TEXAS TO THE EAST OF 100W
AND LOUISIANA...THROUGH THE NORTHWESTERN CORNER OF THE AREA...
ACROSS THE CENTRAL GULF WATERS AND THROUGH THE YUCATAN CHANNEL
INTO THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA TO THE NORTH 
OF HONDURAS TO THE WEST OF 80W. HIGH CLOUDS ARE BEING PUSHED
INTO THE WESTERN GULF OF MEXICO UNDER THE INFLUENCE OF AN UPPER 
LEVEL RIDGE THAT IS IN CENTRAL MEXICO. BROAD LARGE-SCALE 
CYCLONIC FLOW ON THE WATER VAPOR SATELLITE IMAGERY COVERS THE 
AREA FROM 15N TO 33N BETWEEN 70W AND 91W...COVERING PARTS OF THE 
ATLANTIC OCEAN...THE GULF OF MEXICO...AND THE CARIBBEAN SEA. 
STRONG SHOWERS AND THUNDERSTORMS ARE IN INDIVIDUAL CELLS...
IN SOUTHWESTERN HAITI AND NEARBY COASTAL WATERS...JUST TO THE 
EAST OF THE TURKS ISLANDS...FROM 27N TO 28N BETWEEN 74W AND 
75W...AND ALONG THE NORTHEASTERN FLORIDA COAST FROM 28N TO 30N
BETWEEN 80W AND 82W. ISOLATED MODERATE SHOWERS ALSO ARE IN THE 
GULF OF MEXICO FROM 25N TO 30N BETWEEN 80W AND 86W. A 1007 MB 
LOW PRESSURE CENTER IS OVER WATER ABOUT 80 NM TO THE WEST OF THE 
EVERGLADES IN SOUTHWESTERN FLORIDA. A TROUGH EXTENDS FROM THIS 
LOW CENTER...ACROSS CUBA AND GRAND CAYMAN TO 18N82W IN THE 
NORTHWESTERN CARIBBEAN SEA.

THE REST OF THE CARIBBEAN SEA...
BROAD AND GENERAL WESTERLY WIND FLOW COVERS THE AREA.
AN UPPER LEVEL TROUGH CUTS THROUGH THE EASTERN CARIBBEAN SEA 
ALONG 63W/64W REACHING ITS BASE IN NORTHERN VENEZUELA. UPPER 
LEVEL ANTICYCLONIC FLOW MOVES AWAY FROM VENEZUELA...ACROSS THE
EXTREME SOUTHEASTERN CORNER OF THE AREA...INTO THE OPEN WATERS 
OF THE ATLANTIC OCEAN BEYOND 23N48W.

THE ATLANTIC OCEAN TO THE EAST OF 70W...
A PERSISTENT DEEP LAYER CYCLONIC CIRCULATION CENTER IS NEAR 
31N52W ON WATER VAPOR SATELLITE IMAGERY. A 1014 MB LOW PRESSURE 
CENTER IS NEAR 30N55W AT THE SURFACE. BROAD CYCLONIC FLOW ON
WATER VAPOR IMAGERY COVERS THE ATLANTIC OCEAN FROM 23N TO 37N 
BETWEEN 40W AND 65W. A SURFACE TROUGH EXTENDS FROM THE 1014 MB
LOW PRESSURE CENTER TO 32N48W TO 30N44W 25N46W 22N54W 21N62W.
ISOLATED MODERATE SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF
THE TROUGH TO 29N...AND THEN FROM 29N TO 34N BETWEEN 43W AND 
54W. A MIDDLE LEVEL TO UPPER LEVEL TROUGH PASSES THROUGH 32N25W
TO 28N29W. THIS TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH 
32N25W TO 31N30W TO 33N37W.

$$
MT