000
AXNT20 KNHC 201738
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1715 UTC.

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 62W TO THE SOUTH OF 13N MOVING WEST AT 
15 KT. THIS POSITION COINCIDES WITH HIGHER LEVELS OF 
PRECIPITABLE WATER ON THE MIMIC-TPW IMAGERY FROM CIMSS. 
SATELLITE IMAGERY SHOWS THE WAVE TO BE A LEADING EDGE OF A LOW 
LEVEL CLOUD MASS WITH NO SIGNIFICANT INCREASE IN PRECIPITATION.  

...THE ITCZ...
THE ITCZ AXIS EXTENDS FROM SIERRA LEONE AT 9N13W TO THE EQUATOR 
AND 28W TO 2S40W TO NE BRAZIL AT 2S44W. SCATTERED MODERATE TO 
ISOLATED STRONG CONVECTION IS ALONG THE COAST OF WEST AFRICA 
FROM EQ-5N BETWEEN THE PRIME MERIDIAN AND 6W. WIDELY SCATTERED 
MODERATE CONVECTION IS FROM 5N-9N BETWEEN 11W-14W...FROM 5N-3S 
BETWEEN 20W-24W...FROM 1N-3S BETWEEN 29W-35W...AND FROM 37W-46W 
BETWEEN EQ-3S. 

...DISCUSSION...

THE GULF OF MEXICO... 
A 1007 MB LOW IS OVER THE E GULF OF MEXICO NEAR 26N83W. A 
SURFACE TROUGH EXTENDS S FROM THE LOW CENTER TO BEYOND W CUBA. 
BANDS OF SCATTERED MODERATE CONVECTION ARE OVER N FLORIDA FROM 
28N-31N BETWEEN 80W-84W...AND N OF THE FLORIDA KEYS FROM 24N-26N 
BETWEEN 81W-83W. SCATTERED SHOWERS ARE ELSEWHERE OVER THE NE 
GULF N OF 24N AND E OF 90W. A TIGHT PRESSURE GRADIENT OVER THE 
NE GULF IS ALSO PRODUCING GALE FORCE WINDS N OF 27N E OF 88W. 
THE W GULF OF MEXICO W OF 90W HAS HAS FAIR TO PARTLY CLOUDY 
SKIES WITH 10-15 KT NE WINDS. IN THE UPPER LEVELS...AN UPPER 
LEVEL LOW IS CENTERED OVER CENTRAL FLORIDA NEAR 27N81W. THE NE 
GULF AND FLORIDA HAS ABUNDANT UPPER AIR MOISTURE WHILE STRONG 
SUBSIDENCE IS OVER THE REMAINDER OF THE GULF. EXPECT...THE 
SURFACE LOW TO DRIFT W TO THE CENTRAL GULF OF MEXICO OVER THE 
NEXT 24 HOURS WITH CONVECTION MOSTLY E OF THE CENTER.        

THE CARIBBEAN SEA...
A SURFACE TROUGH EXTENDS FROM W CUBA NEAR 23N81W TO THE COAST OF 
NICARAGUA NEAR 14N82W. SCATTERED SHOWERS ARE FROM 12N-16N 
BETWEEN 80W-84W. FURTHER E...SCATTERED MODERATE TO STRONG 
CONVECTION IS OVER HISPANIOLA FROM 16N-20N BETWEEN 71W-76W... 
DUE TO UPPER LEVEL DIFFLUENCE SE OF THE FLORIDA UPPER LEVEL LOW. 
A TROPICAL WAVE HAS ENTERED THE WINDWARD ISLANDS PRODUCING MINOR 
IMPACTS. SEE ABOVE. EXPECT...CONTINUED CONVECTION FROM THE SW TO 
NE CARIBBEAN OVER THE NEXT 24 HOURS. 

THE ATLANTIC OCEAN...
A TIGHT SURFACE PRESSURE GRADIENT IS PRODUCING GALE FORCE WINDS 
ALONG THE COAST OF NE FLORIDA. WIDELY SCATTERED MODERATE 
CONVECTION IS FROM 29N-31N BETWEEN 77W-81W...AND FROM 26N-29N 
BETWEEN 73W-76W. FURTHER E...SCATTERED MODERATE CONVECTION IS N 
OF HISPANIOLA FROM 20N-25N BETWEEN 67W-73W...AGAIN DUE TO UPPER 
LEVEL DIFFLUENCE SE OF THE FLORIDA UPPER LEVEL LOW. A 1014 MB 
LOW IS CENTERED OVER THE CENTRAL ATLANTIC NEAR 30N55W. THE 
REMNANTS OF A FRONTAL TROUGH HAS SCATTERED MODERATE CONVECTION 
FROM 23N-26N BETWEEN 43W-47W...AND FROM 29N-31N BETWEEN 46W-50W. 
THE TAIL END OF A COLD FRONT IS OVER THE E ATLANTIC ALONG 32N24W 
29N30W 29N36W. SCATTERED SHOWERS ARE WITHIN 30 NM OF THE FRONT.  
IN THE UPPER LEVELS...AN UPPER LEVEL TROUGH IS OVER THE W 
ATLANTIC W OF 75W. AN UPPER LEVEL RIDGE IS FURTHER E N OF 20N 
BETWEEN 65W-75W. AN UPPER LEVEL LOW IS OVER THE CENTRAL ATLANTIC 
NEAR 31N51W. ANOTHER UPPER LEVEL LOW IS OVER THE E ATLANTIC NEAR 
35N25W. IN THE TROPICS...UPPER LEVEL HIGHS ARE CENTERED NEAR 
5N45W AND 9N7W. ZONAL FLOW IS OVER THE REMAINDER OF THE AREA. 
EXPECT...CONVECTION TO CONTINUE OVER FLORIDA...THE BAHAMAS...AND 
N OF THE LEEWARD ISLANDS FOR THE NEXT 24 HOURS.         

$$
FORMOSA