000
AXNT20 KNHC 211740
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL  
205 PM EDT SAT MAY 21 2011

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...WEATHER OBSERVATIONS...RADAR...AND 
METEOROLOGICAL ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...TROPICAL WAVES...

A TROPICAL WAVE IS ALONG 70W TO THE SOUTH OF 13N MOVING W AT 10 
KT. THE WAVE EXTENDS S OVER W VENEZUELA AND E COLOMBIA TO 4N. IT 
IS EMBEDDED IN A BROAD AREA OF MOISTURE AS DEPICTED ON THE SSMI 
TOTAL PRECIPITABLE WATER IMAGERY. SCATTERED MODERATE/ISOLATED 
STRONG CONVECTION IS E OF THE AXIS FROM 5N-11N 64W-70W. 

...THE ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N11W 4N30W 4N40W 6N50W 6N57W. 
SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS ON THE COAST OF 
W AFRICA FROM 3N-11N BETWEEN 11W-15W...FROM 1N-8N BETWEEN 
17W-26W...AND ON THE COASTS OF FRENCH GUIANA...SURINAME...AND 
GUYANA FROM 4N-8N BETWEEN 51W-60W. ISOLATED MODERATE 
CONVECTION IS FROM 4N-9N BETWEEN 40W-48W

...DISCUSSION...

GULF OF MEXICO...
10-15 KT SE FLOW IS OVER THE EASTERN GULF OF MEXICO. 15-20 KT SE 
FLOW IS OVER THE WESTERN GULF CAUSED BY A TIGHTER SURFACE 
GRADIENT BETWEEN A 1019 MB HIGH CENTERED OVER VIRGINIA NEAR 
37N81W AND LOWER PRESSURES OVER MEXICO. BROKEN TO OVERCAST LOW 
CLOUDS ARE WITHIN 75 NM OF THE TEXAS COAST. VISIBLE SATELLITE 
IMAGERY SHOWS SMOKE OVER S MEXICO...THE YUCATAN PENINSULA...AND 
THE GULF N OF 17N W OF A LINE FROM THE W YUCATAN TO THE FLORIDA 
PANHANDLE. OTHERWISE...FAIR SKIES ARE OVER THE GULF. IN THE 
UPPER LEVELS...AN UPPER LEVEL TROUGH EXTENDS SW FROM THE W ATLC 
INTO THE GULF. N-NW FLOW IS OVER THE GULF WITH STRONG 
SUBSIDENCE...THUS THE AREA IS VOID OF ANY HIGH CLOUD. EXPECT 
LITTLE CHANGE IN THE NEXT 24 HOURS.

CARIBBEAN SEA...
A TROPICAL WAVE IS OVER THE SE CARIBBEAN...SEE ABOVE. UPPER 
LEVEL DIFFLUENCE AROUND THE WESTERN HALF OF AN UPPER RIDGE IS 
OVER THE EASTERN CARIBBEAN. A SURFACE TROUGH EXTENDS N FROM 
COLOMBIA NEAR 10N75W TO HISPANIOLA NEAR 17N71W. DUE TO THE UPPER 
LEVEL DIFFLUENCE...AND THE SURFACE TROUGH...SCATTERED SHOWERS 
AND THUNDERSTORMS ARE FROM 13N-19N BETWEEN A LINE FROM 14N60W TO 
12N69W AND 74W AFFECTING THE DOMINICAN REPUBLIC...PUERTO RICO... 
AND THE LEEWARD ISLANDS. ELSEWHERE...FAIR WEATHER IS NOTED. SW 
UPPER LEVEL FLOW DOMINATES THE CARIBBEAN WITH UPPER LEVEL 
MOISTURE E OF 74W...AND STRONG SUBSIDENCE W OF 74W. EXPECT THE 
TROPICAL WAVE AND TROUGH TO MOVE SLOWLY W WITH CONTINUED SHOWERS 
OVER THE NEXT 24 HOURS.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH COVERS THE W ATLC SUPPORTING A COLD FRONT 
STILL N OF THE DISCUSSION AREA. FARTHER E...A SURFACE TROUGH 
EXTENDS FROM 29N62W TO 20N67W. SCATTERED SHOWERS ARE WITHIN 120 
NM OF THE TROUGH AXIS. ANOTHER SURFACE TROUGH IS OVER THE 
CENTRAL ATLC FROM 30N42W TO 26N42W WITH NO SIGNIFICANT 
PRECIPITATION. A SURFACE RIDGE AXIS IS OVER THE E ATLC N OF 10N 
E OF 41W. UPPER LEVEL DIFFLUENCE BETWEEN THE UPPER LEVEL TROUGH 
OVER THE W ATLC...AND OF AN UPPER RIDGE WITH AN AXIS ALONG 55W 
IS SUPPORTING THE W ATLC SURFACE TROUGH. EXPECT LITTLE CHANGE 
OVER THE NEXT 24 HOURS.

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$
WALTON/MONTALVO