000
AXNT20 KNHC 112355
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN JAN 11 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
2330 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 6N10W 3N25W 2N35W CROSSING THE EQUATOR 
NEAR 44W AND INTO NE BRAZIL NEAR 1S47W. SCATTERED MODERATE 
CONVECTION IS WITHIN 40 NM OF THE AXIS BETWEEN 
17W-29W.

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYER TROUGH OVER THE CENTRAL CONUS IS SUPPORTING A 
STRONG COLD FRONT IN THE GULF OF MEXICO. AS OF 2100 UTC...THE 
FRONT EXTENDS ACROSS THE FLORIDA BIG BEND AREA AND ENTERS THE 
GULF NEAR 30N84W THEN CONTINUES ALONG 26N90W THROUGH THE BAY OF 
CAMPECHE AND INLAND OVER MEXICO NEAR 19N95W. MULTI-LAYERED 
CLOUDS...SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS  ARE 
WITHIN 100 NM OF THE FRONT. INCREASED NORTHERLY WINDS...AS WELL 
AS COOLER AND DRIER CONDITIONS...ARE OBSERVED IN THE WAKE OF THE 
FRONT WITH THE STRONGEST WINDS IN THE BAY OF CAMPECHE WHERE A 
GALE WARNING IS CURRENTLY IN EFFECT SOUTH OF 25N AND WEST OF 93W.
AHEAD OF THE FRONT...RETURN FLOW AROUND A RIDGE EXTENDING FROM 
THE W ATLC IS RESULTING IN SOUTHERLY WINDS OF 15-20 KT. DEEP 
LAYER DRY AIR IS INHIBITING DEEP CONVECTION ACROSS THE SE GULF. 

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE REMAINS SITUATED OVER THE CARIBBEAN SEA. 
STRONG SUBSIDENCE EAST OF 80W IS PREVENTING THE FORMATION OF 
DEEP CONVECTION IN THE REGION RESULTING IN GENERALLY FAIR 
WEATHER. A SFC RIDGE OVER THE W ATLC IS MAINTAINING STRONG TRADE 
WINDS ACROSS THE BASIN...USHERING ISOLATED LOW-LEVEL SHOWERS 
INTO THE NW CARIBBEAN. THE STRONGEST WINDS...UP TO 30 KT...ARE 
OBSERVED ALONG THE COAST OF COLOMBIA. A STRONG GULF OF MEXICO 
COLD FRONT IS FORECAST TO MOVE ACROSS THE YUCATAN CHANNEL AND 
INTO THE NW CARIBBEAN WED AND THU. 

ATLANTIC OCEAN...
A DEEP LAYER TROUGH IN THE CENTRAL ATLC SUPPORTS A COLD FRONT 
THAT ENTERS THE DISCUSSION AREA NEAR 31N43W AND EXTENDS TO 
27N53W WHERE IT WEAKENS AND CONTINUES AS A SFC TROUGH TO 25N63W. 
SCATTERED SHOWERS ARE WITHIN 40 NM OF THE BOUNDARY. TO THE W OF 
THESE FRONTS...DEEP LAYER DRY AIR AND SUBSIDENCE ARE RESULTING 
IN GENERALLY FAIR WEATHER ACROSS MUCH OF THE W ATLC. EXPECT THE 
COLD FRONT CURRENTLY OVER THE GULF OF MEXICO TO MOVE OFF THE 
FLORIDA COAST LATE TONIGHT. FARTHER TO THE E...AN UPPER TROUGH 
IS PRESENT WITH AXIS EXTENDING FROM 20N28W TO 30N40W. 
ATMOSPHERIC INSTABILITY ASSOCIATED WITH THIS UPPER TROUGH IS 
RESULTING IN SCATTERED SHOWERS FROM 20N-32N BETWEEN 20W-34W. 
UPPER DIFFLUENCE POSITIONED TO THE NE OF THE TROUGH AXIS IN 
SOUTHWESTERLY FLOW ALOFT IS ENHANCING THE SCATTERED SHOWERS. 
OTHERWISE...A SFC RIDGE COVERS THE EAST ATLC AHEAD OF THE FRONT. 

$$
WADDINGTON