000
AXNT20 KNHC 290530
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST THU JAN 29 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

...THE ITCZ...
ITCZ AXIS IS CENTERED ALONG 6N10W 2N18W 1N25W EXTENDING ALONG 
THE EQUATOR TO N BRAZIL NEAR 50W. ISOLATED MODERATE CONVECTION 
IS S OF 3N BETWEEN 17W-20W.  
 
...DISCUSSION...

GULF OF MEXICO...
A DEEP TROUGH OVER MUCH OF THE E CONUS AND THE N GULF IS 
SUPPORTING A SFC COLD FRONT THAT EXTENDS FROM THE FLORIDA BIG 
BEND NEAR 30N85W TO 25N92W AND HAS SURGED SOUTHWARD ACROSS THE W 
GULF INTO THE BAY OF CAMPECHE TO THE MEXICO COAST NEAR 19N96W. 
IN THE WAKE OF THE FRONT...A RELATIVELY COOLER AND DRIER AIRMASS 
IS IN PLACE ADVECTED BY N-NE 15-20 KT WINDS...WITH THE STRONGEST 
FLOW ALONG THE COAST OF MEXICO. LOW LEVEL CONVERGENCE ASSOCIATED 
WITH THIS FRONT IS SUPPORTING SCATTERED SHOWERS WITHIN 90 NM 
EITHER SIDE OF THIS FRONT N OF 25N. THIS ACTIVITY IS BEING 
ENHANCED BY UPPER LEVEL DIVERGENCE ASSOCIATED WITH AN UPPER JET 
MAXIMUM OVER THE SE CONUS. ACROSS THE SE GULF...DEEP LAYER DRY 
AIR AND ATMOSPHERIC STABILITY ASSOCIATED WITH AN UPPER RIDGE IS 
INHIBITING DEEP CONVECTION...WITH SE 10-15 KT SFC WINDS IN 
PLACE. THE AFOREMENTIONED FRONT IS TEMPORARILY SLOWING ITS SE 
PROGRESSION...BUT IS FORECAST TO SURGE SWD ON FRIDAY AS AN UPPER 
TROUGH OVER THE W CONUS IS EJECTED EASTWARD AND A SFC HIGH 
BUILDS OVER THE SE CONUS. WINDS WILL INCREASE IN THE WAKE 
OF THE COLD FRONT ON FRI IN RESPONSE TO THE TIGHTENING PRESSURE 
GRADIENT...WITH GALE FORCE WINDS EXPECTED S OF 22N W OF 95W ON 
FRI.

CARIBBEAN SEA...
MODERATE TO FRESH TRADE WINDS CONTINUE ACROSS THE CARIBBEAN 
ASSOCIATED WITH THE INCREASED PRESSURE GRADIENT SW OF A 1029 MB 
SURFACE HIGH OVER THE W ATLC NEAR 32N54W. THESE WINDS ARE 
FORECAST TO DECREASE ON FRI AS THE HIGH MOVES NE AND A COLD 
FRONT OVER THE GULF MOVES INTO THE NW CARIBBEAN. THIS FRONT IS 
EXPECTED TO ENTER THE NW CARIBBEAN LATE FRI...FOLLOWED BY NE TO 
E 20-25 KT WINDS AND RELATIVELY COOLER AND DRIER CONDITIONS IN 
THE WAKE OF THE FRONT. IN THE MEANTIME...GENERALLY FAIR WEATHER 
CONDITIONS PERSIST ACROSS MUCH OF THE CARIBBEAN REGION WITH DEEP 
LAYER DRY AIR IN PLACE. HOWEVER...TYPICAL ISOLATED SHOWERS ARE 
BEING CARRIED BY THE TRADE WINDS ACROSS THE E CARIBBEAN...WHERE 
SOME UPPER LEVEL MOISTURE IS BEING ADVECTED BY SW 
FLOW ALOFT.
 
ATLANTIC OCEAN...
THE ATLC DISCUSSION REMAINS TRANQUIL TONIGHT AS SFC HIGH PRES 
ALONG 32N/33N DOMINATES THE REGION. THE ASSOCIATED PRESSURE 
GRADIENT ON ITS SRN PERIPHERY IS PRODUCING A LARGE AREA OF NE/E 
20-25 KT TRADES S OF 24N E OF THE BAHAMAS. THE RIDGE HAS BEEN 
ERODED OVER THE FAR NW PART DUE TO A COLD FRONT THAT HAS MOVED 
OFF THE SE U.S. COAST. STRONG SLY WINDS ARE BLOWING OFF THE NE 
FLORIDA COAST AHEAD OF THE FRONT. THE UPPER PATTERN CONSISTS OF 
A FAIRLY FLAT LONGWAVE RIDGE/TROUGH WITH ABUNDANT DRY STABLE AIR 
NOTED IN WATER VAPOR IMAGERY. THIS STABLE ATMOSPHERE IS CAPPING 
THE TYPICAL PATCHES OF LOW CLOUDS AND EMBEDDED SHOWERS WITHIN 
THE TRADE WIND FLOW.

$$
COHEN/CANGIALOSI