000
AXNT20 KNHC 131107
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT WED MAY 13 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 1045 UTC.

...THE ITCZ...

FROM 8N11 TO THE EQUATOR ALONG 19W...TO 3S30W INTO NORTHEASTERN 
BRAZIL NEAR 6S43W. WIDELY SCATTERED MODERATE SHOWERS TO LOCALLY 
STRONG THUNDERSTORMS ARE FROM THE EQUATOR TO 6N BETWEEN 9W AND 
46W.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL RIDGE IS ALONG 100W FROM 14N IN THE EASTERN 
PACIFIC OCEAN TO 30N IN SOUTH CENTRAL TEXAS. THE ANTICYCLONIC 
FLOW AROUND THE 100W RIDGE REACHES TO AT LEAST 90W. THE MIDDLE 
LEVEL TO UPPER LEVEL FLOW THAT IS TO THE EAST OF 90W IS 
NORTHWESTERLY...RELATED TO A TROUGH FROM CUBA TO THE BAHAMA
ISLANDS. WEAK SOUTHEASTERLY RETURN FLOW COVERS THE AREA.
BROAD SURFACE LOW PRESSURE EXTENDS FROM JUST WEST OF THE ISTHMUS 
OF TEHUANTEPEC TO CENTRAL MEXICO TO THE TEXAS BIG BEND. REMNANT 
SHOWERS AND HIGH CLOUDS IN MEXICO ARE BEING SHEARED FROM 17N TO 
27N BETWEEN 99W AND 103W. A SURFACE TROUGH IS ALONG 85W/86W FROM 
23N TO 29N. THIS FEATURE SHOWS UP QUITE WELL IN THE SHORTWAVE 
INFRARED IMAGERY WITH BROAD CYCLONIC FLOW IN THE CLOUD FIELD.

THE CARIBBEAN SEA...
MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY WIND FLOW MOVES FROM 
THE GULF OF MEXICO TO THE EAST OF 90W...INTO THE NORTHWESTERN 
CARIBBEAN SEA. THIS FLOW REGIME MEETS A SEPARATE AREA OF BROAD 
UPPER LEVEL FLOW ALONG THE LINE FROM THE SOUTHEASTERN DOMINICAN 
REPUBLIC TO 15N80W TO SOUTHEASTERN NICARAGUA. A MIDDLE LEVEL
TO UPPER LEVEL TROUGH SPANS THE AREA FROM CUBA TO THE BAHAMA 
ISLANDS. THE STRONG CONVECTIVE PRECIPITATION THAT COVERED THE 
AREA FROM 7N TO 10N BETWEEN 74W AND 79W ABOUT 6 HOURS AGO HAS 
WEAKENED AT THIS TIME. WARMING CLOUD TOP TEMPERATURES AND 
POSSIBLY REMNANT SHOWERS ARE THERE NOW. BROAD SURFACE LOW 
PRESSURE AND THE POSSIBLE PRESENCE OF THE ITCZ STILL COVER
THE AREA. A SURFACE TROUGH IS ALONG THE LINE FROM 21N69W TO
CENTRAL PUERTO RICO TO 13N68W. SHOWERS ARE POSSIBLE FROM
14N TO 22N BETWEEN 60W AND 71W.

THE ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH IS MOVING AWAY FROM THE U.S.A.
EAST COAST TO THE NORTH OF 32N/33N. A REMNANT MIDDLE TO UPPER 
LEVEL TROUGH THAT MOST PROBABLY CAME BEFORE THE 32N/33N FEATURE 
SUPPORTS THE COLD FRONT THAT PASSES THROUGH 32N62W TO 31N69W...
AND THE STATIONARY FRONT THAT CONTINUES FROM 31N69W TO 30N79W TO 
FLORIDA NEAR 27N82W. A MIDDLE LEVEL TO UPPER LEVEL TROUGH SPANS 
THE AREA FROM CUBA TO THE BAHAMA ISLANDS...RELATED TO THE 
STATIONARY FRONT. SHOWERS ARE POSSIBLE FROM 25N TO 32N BETWEEN 
70W AND 81W...OVER THE ATLANTIC WATERS AND PARTS OF FLORIDA.
A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS 
NEAR 22N45W. CYCLONIC FLOW EXISTS FROM 12N TO 30N BETWEEN 35W 
AND 61W.

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