000
AXNT20 KNHC 282342
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST WED DEC 28 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 
2315 UTC.

...ITCZ/MONSOON TROUGH...

THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 08N13W TO 
07N17W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
07N17W TO 04N30W TO 01N47W. SCATTERED MODERATE CONVECTION IS 
FROM 02N-12N BETWEEN 17W-31W.

...DISCUSSION...

GULF OF MEXICO...
WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL SHORTWAVE TROUGH IS 
PROGRESSING OVER NORTH TEXAS AND CONTINUES TO ADVECT MIDDLE TO 
UPPER LEVEL MOISTURE ACROSS THE NORTHERN GULF. AT THE SURFACE 
HOWEVER...A 1023 MB HIGH CENTERED OVER THE WESTERN FLORIDA 
PANHANDLE NEAR 30N87W INFLUENCES THE ENTIRE BASIN THIS EVENING 
AND IS PROVIDING RATHER TRANQUIL CONDITIONS WITH LIGHT 
ANTICYCLONIC WINDS AND AN OVERALL STABLE ENVIRONMENT. THE HIGH 
IS FORECAST TO SLIDE EASTWARD THROUGH SATURDAY AND MOVE INTO THE 
SW NORTH ATLC BY SUNDAY. THE NEXT COLD FRONT IS THEN EXPECTED BY 
SUNDAY MORNING TO ENTER THE NW GULF USHERING IN STRONG NORTHERLY 
WINDS THAT WILL SPREAD EASTWARD ACROSS THE GULF THROUGH EARLY 
NEXT WEEK.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE EXTENDS ACROSS THE CARIBBEAN SEA WITH AXIS 
FROM SOUTHERN VENEZUELA NEAR 05N63W N-NW TO OVER HISPANIOLA NEAR 
18N83W. WATER VAPOR IMAGERY INDICATES DRY AIR AND SUBSIDENCE 
OVER MUCH OF THE BASIN THIS EVENING WHICH IS RESULTING IN RATHER 
TRANQUIL CONDITIONS AT THE SURFACE. THE ONLY EXCEPTION TO FAIR 
WEATHER IS A SHEAR LINE ANALYZED FROM CENTRAL CUBA NEAR 22N80W 
TO 18N87W WITH ISOLATED SHOWERS OCCURRING WITHIN 120 NM EITHER 
SIDE OF THE BOUNDARY. ELSEWHERE MODERATE TO FRESH E-NE TRADES 
CONTINUE AND THIS OVERALL PATTERN IS FORECAST TO PERSIST THROUGH 
THE REMAINDER OF THE WEEK INTO THE WEEKEND.

ATLANTIC OCEAN...
AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY THIS 
EVENING ACROSS THE NORTHEAST CONUS AND THIS TROUGH SUPPORTS A 
COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N67W TO 
28N70W TO THE CENTRAL BAHAMAS NEAR 24N76W THEN TO CENTRAL CUBA 
NEAR 22N80W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 75 
NM EITHER SIDE OF THE FRONT. HIGH PRESSURE WILL CONTINUE TO 
BUILD IN BEHIND THE FRONT FROM THE EASTERN GULF OF MEXICO ACROSS 
THE REMAINDER OF THE SW NORTH ATLC THROUGH EARLY FRIDAY. FARTHER 
EAST...AN UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM 32N40W TO 
25N40W TO 16N48W SUPPORTS A COLD FRONT ANALYZED ALONG 32N42W TO 
25N45W THEN AS A DISSIPATING COLD FRONT WESTWARD TO 24N55W. 
LOW-LEVEL MOISTURE REMAINS LIMITED WITH THIS FRONT...HOWEVER 
ISOLATED SHOWERS ARE WITHIN 150 NM EAST OF THE FRONT FOCUSED 
ALONG A PRE-FRONTAL SURFACE TROUGH FROM 30N40W TO 24N45W. THE 
REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A 
SURFACE RIDGE WITH AXIS FROM EAST OF THE AZORES NEAR 37N21W TO 
23N35W.

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

$$
HUFFMAN