000
AXNT20 KNHC 292345
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST THU DEC 29 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2330 UTC.

...ITCZ/MONSOON TROUGH...
THE MONSOON TROUGH EXTENDS FROM THE COAST OF GUINEA AT 10N14W TO 
4N23W. THE ITCZ AXIS CONTINUES TO N BRAZIL ALONG 4N23W 2N40W 
EQ50W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM S OF THE 
MONSOON TROUGH BETWEEN 14W AND 20W...AND FROM 3N-5N BETWEEN THE 
PRIME MERIDIAN AND 6W. 

...DISCUSSION...

GULF OF MEXICO...
A 1021 MB HIGH IS CENTERED OVER N CENTRAL FLORIDA NEAR 
GAINESVILLE AND GOVERNS THE WEATHER OVER THE GULF OF MEXICO WITH 
LIGHT AND VARIABLE WINDS OF 5 TO 10 KT OVER THE GULF N OF 25N 
AND GENERALLY NE TO E WINDS OF 10 KT OVER THE SOUTHERN GULF. 
CLEAR SKIES PREDOMINATED WITH PATCHES OF LOW AND MID LEVEL 
CLOUDS OVER THE GULF N OF 23N BETWEEN 85W AND 88W AND BROKEN TO 
LOCALLY OVERCAST SKIES WITH SCATTERED SHOWERS OVER THE BAY OF 
CAMPECHE AND S MEXICO S OF 22N. A 1016 MB LOW IS CENTERED JUST 
NE OF GALVESTON TEXAS NEAR 30N95W. IN THE UPPER LEVELS...THE 
FLOW IS GENERALLY ZONAL WITH STRONG UPPER LEVEL SUBSIDENCE 
NOTED. OVER THE NEXT 24 HOURS THE SURFACE HIGH IS FORECAST TO 
REMAIN QUASI-STATIONARY. 

CARIBBEAN SEA...
A 1456 UTC ASCAT SCATTEROMETER PASS CAPTURED SOME OF THE STRONGER
TRADEWINDS OF 20-25 KT ALONG THE COAST OF COLOMBIA AND OVER THE 
SOUTHWEST CARIBBEAN SEA. THE SAME PASS ALSO INDICATED NE TRADES 
OF 20 KT EXTENDED NORTHWARD TO JUST S OF HISPANIOLA. LIGHTER 
NE TO E WINDS OF 10 KT WERE NOTED OVER THE NW CARIBBEAN 
EXTENDING OVER THE GULF OF HONDURAS. NE WINDS INCREASED TO 20 KT 
OVER THE EXTREME NW CARIBBEAN TO THE NW OF A DYING FRONTAL 
BOUNDARY WHICH EXTENDED FROM CENTRAL CUBA TO THE BORDER OF 
YUCATAN AND BELIZE. PATCHES OF BROKEN LOW CLOUDS WITH SCATTERED 
SHOWERS DOTTED THE CARIBBEAN MOVING W WITH THE TRADEWINDS 
ESPECIALLY OVER THE LEEWARD ISLANDS...PUERTO RICO... 
HISPANIOLA...AND THE NW CARIBBEAN WITHIN 60-90 NM OF THE DYING 
FRONTAL BOUNDARY. ADDITIONAL SHOWER ACTIVITY WAS JUST 
INLAND OVER CENTRAL AMERICA FROM PANAMA TO HONDURAS IN AREAS OF 
FAVORED OROGRAPHIC LIFT. IN THE UPPER LEVELS...AN UPPER LEVEL 
RIDGE IS OVER THE EXTREME E CARIBBEAN WITH AXIS ALONG 62W/63W
WITH BROAD SOUTHWESTERLY FLOW ALOFT TO THE W OF THE RIDGE AXIS. 
STRONG SUBSIDENCE PREVAILED OVER THE CARIBBEAN AND CENTRAL 
AMERICA SUPPRESSING ALL DEEP CONVECTION. LITTLE CHANGE IN THE
OVERALL SYNOPTIC PATTERN IS EXPECTED OVER THE NEXT 24 HOURS AS 
THE FRONTAL BOUNDARY OVER THE NW CARIBBEAN DISSIPATES 
ALTOGETHER. 

ATLANTIC OCEAN...
A STATIONARY FRONT IS OVER THE W ATLANTIC FROM 32N58W TO THE 
CENTRAL BAHAMAS NEAR 24N75W TO CENTRAL CUBA NEAR 23N79W. 
OVERCAST LOW CLOUDS ARE WITHIN 120 NM NW OF THE FRONT WITH 
SCATTERED SHOWERS WITHIN 60 NM. ANOTHER STATIONARY FRONT IS OVER 
THE EAST-CENTRAL ATLANTIC FROM 32N39W TO 22N49W. BROKEN TO 
OVERCAST LOW CLOUDS AND SCATTERED SHOWERS ARE WITHIN 60-90 NM W 
OF THE FRONT. A LARGE 1041 MB HIGH IS CENTERED W OF SPAIN NEAR 
43N15W. A STRONG SURFACE RIDGE AXIS EXTENDED S FROM THE HIGH TO 
20N38W. EXPECT LITTLE CHANGE IN THE SYNOPTIC PATTERN OVER THE 
NEXT 24 HOURS.       

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

$$
COBB