000
AXNT20 KNHC 121136
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST THU FEB 12 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 
1115 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 8N10W 3N20W CROSSING THE EQUATOR NEAR 
38W...AND INTO NE BRAZIL NEAR 2S45W. A CLUSTER OF SCATTERED 
MODERATE TO STRONG CONVECTION IS S OF 3N BETWEEN 20W-30W.
 
...DISCUSSION...

GULF OF MEXICO...
STRONG WESTERLY FLOW ALOFT IS PRESENT ACROSS THE N GULF IN THE 
BASE OF A VIGOROUS DEEP LAYER TROUGH MOVING NEWD ACROSS THE ERN 
CONUS. THIS UPPER TROUGH SUPPORTS A SURFACE COLD FRONT THAT 
CROSSES NE FLORIDA AND ENTERS THE GULF NEAR THE BIG BEND AREA  
EXTENDING SW TO NEAR 28N88W WHERE IT CONTINUES AS A STATIONARY 
FRONT ALONG 24N95W 19N95W TO INLAND OVER SRN MEXICO. N-NE WINDS 
AND A RELATIVELY COOLER AND DRIER AIRMASS ARE OBSERVED N OF THIS 
FRONT. A SURFACE TROUGH IS ALSO ANALYZED FROM 25N90W SW TO 
ACROSS THE CENTRAL BAY OF CAMPECHE TO NEAR 18N93W. LOW-LEVEL 
CONVERGENCE IS SUPPORTING SCATTERED SHOWERS WITHIN 75 NM E OF 
THE COLD FRONT AND WITHIN 90 NM ON EITHER SIDE OF THE SURFACE 
TROUGH. ELSEWHERE...A SURFACE RIDGE EXTENDS FROM A 1027 MB HIGH 
ANCHORED IN THE W ATLC ACROSS SRN FLORIDA AND THE SE GULF. 
SUBSIDENCE ASSOCIATED WITH THIS RIDGE IS COMBINING WITH DRY AIR 
AND A STABLE ATMOSPHERE ALOFT TO INHIBIT DEEP CONVECTION.

CARIBBEAN SEA...
GENERALLY FAIR WEATHER IS PRESENT ACROSS THE WRN CARIBBEAN... 
WHERE DEEP LAYER DRY AIR AND CONFLUENT WESTERLY FLOW ARE 
OBSERVED. UPPER LEVEL MOISTURE CONTINUES TO BE ADVECTED NEWD 
INTO THE ERN CARIBBEAN...WITH SCATTERED SHOWERS BEING USHERED IN 
ON STRONG TRADE WINDS E OF 74W. THESE STRONG TRADE WINDS...S OF 
A 1027 MB SURFACE HIGH IN THE W ATLC NEAR 28N60W ARE FORECAST TO 
CONTINUE ACROSS MUCH OF THE CARIBBEAN THROUGH THURSDAY.

ATLANTIC OCEAN...
STRONG WESTERLY FLOW ALOFT CONTINUES ACROSS THE SW NORTH ATLC AS 
A VIGOROUS DEEP LAYER TROUGH OVER THE ERN CONUS MOVES NEWD. A 
SURFACE COLD FRONT ASSOCIATED WITH THIS TROUGH IS FORECAST TO 
ENTER THE SW NORTH ATLC LATER TODAY...FOLLOWED BY W TO NW WINDS 
AND RELATIVELY COOLER AND DRIER CONDITIONS. FARTHER TO THE E... 
DEEP LAYER DRY AIR AND SUBSIDENCE ARE PRESENT IN THE VICINITY OF 
A 1027 MB SURFACE HIGH NEAR 28N60W. ACROSS THE E/CENTRAL ATLC... 
A DEEP LAYER TROUGH IS PRESENT WITH AN ASSOCIATED WEAK SURFACE 
TROUGH EXTENDING FROM 31N30W SW TO 23N41W. LOW-LEVEL CONVERGENCE 
IN THE VICINITY OF THIS BOUNDARY IS SUPPORTING ISOLATED SHOWERS 
WITHIN 90 NM ON EITHER SIDE OF THE TROUGH. ACROSS THE TROPICAL 
ATLC...AN UPPER HIGH IS PRESENT NEAR 5N39W. UPPER LEVEL 
DIVERGENCE ASSOCIATED WITH THIS HIGH IS ENHANCING THE CONVECTION 
ASSOCIATED WITH THE ITCZ.

$$
HUFFMAN