000
AXNT20 KNHC 301735
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 PM EST TUE DEC 30 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1715 UTC.

...THE ITCZ...
THE ITCZ AXIS IS CENTERED ALONG 7N9W 3N29W 1N35W 2N42W 1N51W. 
SMALL CLUSTERS OF ISOLATED MODERATE CONVECTION ARE WITHIN 120 NM 
OF THE ITCZ FROM 17W-35W. 

...DISCUSSION...

GULF OF MEXICO...
A 1017 MB LOW IS ALONG THE TEXAS COAST NEAR GALVESTON WITH A 
WEAK SURFACE TROUGH EXTENDING THROUGH THE LOW FROM JUST N OF 
BEAUMONT TEXAS TO 27N96W IN THE NW GULF WITH HEAVY SHOWERS AND 
POSSIBLE ISOLATED THUNDERSTORMS WITHIN 90 NM SE OF THE SURFACE 
TROUGH AND SCATTERED SHOWERS DOTTING THE AREA N OF 27N W OF 88W 
AND N OF 22N W OF 95W. A SURFACE RIDGE DOMINATES THE E GULF 
ANCHORED BY A 1034 MB HIGH NEAR WASHINGTON DC GIVING THE GULF 
MOSTLY E TO SE WINDS WITH THE EXCEPTION OF NW TO N WINDS WEST OF 
THE SURFACE TROUGH. AN UPPER LEVEL TROUGH COVERS MUCH OF THE 
CENTRAL/E US AND IS MOVING ACROSS N GULF PRODUCING A MODERATE 
UPPER LEVEL JET ACROSS THE N GULF N OF A LINE FROM TAMPICO 
MEXICO TO FORT MYERS FLORIDA WITH WINDS ESTIMATED TO BE 90 TO 
120 KT. A COLD FRONT IS EXPECTED TO DEVELOP IN THE VICINITY OF 
THE SURFACE TROUGH OVER THE NEXT FEW HOURS AND WILL MOVE E 
ACROSS THE W GULF WITH THE FRONT REACHING FLORIDA BIG BEND TO NE 
MEXICO LATE THU...THEN MOVE SE OF AREA BY LATE FRI. STRONG HIGH 
PRESSURE WILL BUILD IN BEHIND THE FRONT ON FRI THEN WEAKENS SAT 
THROUGH SUN...WITH ANOTHER COLD FRONT PUSHING OFF THE TEXAS 
COAST BY LATE SUN NIGHT INTO EARLY NEXT WEEK.

CARIBBEAN SEA...
THE REMNANTS OF A FRONTAL BOUNDARY IN THE FORM OF A SURFACE 
TROUGH ENTERS THE CARIBBEAN OVER THE VIRGIN ISLANDS SW TO 15N72W 
WITH SCATTERED SHOWERS WITHIN 90 NM NW OF THE TROUGH INCLUDING 
PUERTO RICO. A BROAD UPPER RIDGE COVERS THE CARIBBEAN ANCHORED 
ALONG N OF THE GULF OF VENEZUELA NEAR 14N71W WITH STRONG 
SUBSIDENCE AND MOSTLY DRY STABLE OVER THE AREA SUPPRESSING ANY 
DEEP CONVECTION. A SURFACE RIDGE OVER THE W ATLC AND E GULF OF 
MEXICO IS PRODUCING A STRONG PRESSURE GRADIENT OVER THE 
CARIBBEAN GENERATING FRESH TO STRONG EASTERLY TRADE WINDS OVER 
MAINLY THE E AND CENTRAL CARIBBEAN THROUGH FRI THEN DIMINISH 
STARTING FRI AS A COLD FRONT PUSHES INTO THE NW CARIBBEAN. THE 
FRONT WILL REACH FROM E CUBA TO HONDURAS SAT...BEFORE 
DISSIPATING SUN FROM THE MONA PASSAGE TO NICARAGUA SUN. 
MEANWHILE A SURFACE TROUGH CURRENTLY OVER THE NE CARIBBEAN WILL 
PUSH TOWARD THE LEEWARD ISLANDS THEN STALL AND DISSIPATE ALONG 
18N THROUGH FRI.  

ATLANTIC OCEAN...
A SURFACE RIDGE DOMINATES THE W ATLC INTO THE E GULF OF MEXICO 
ANCHORED BY A 1034 MB HIGH NEAR WASHINGTON DC WITH A COLD FRONT 
ENTERING THE CENTRAL ATLC NEAR 32N49W EXTENDING SW ALONG 24N56W 
TO THE VIRGIN ISLANDS NEAR 18N65W WHERE IT CONTINUES AS A 
SURFACE TROUGH INTO THE CARIBBEAN. THE UPPER TROUGH SUPPORTING 
THE FRONT COVERS THE AREA N OF 23N BETWEEN 41W-62W WITH THE 
UPPER LOW CENTERED OVER THE CANADIAN MARITIMES. SCATTERED 
SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 180 NM E 
OF THE FRONT N OF 23N WITH SCATTERED SHOWERS WITHIN 120 NM W OF 
THE FRONT S OF 23N. GALE FORCE WINDS ARE E OF THE FRONT N OF 
28N. A SECOND SURFACE RIDGE COVERS THE E ATLC ANCHORED BY A 1027 
MB HIGH NEAR 31N33W. SRN FLOW WILL INCREASE N OF THE BAHAMAS 
TONIGHT IN ADVANCE OF THE NEXT COLD FRONT MOVING OFF THE GEORGIA 
COAST BY EARLY THU. THE FRONT WILL REACH FROM 32N75W TO CENTRAL 
FLORIDA BY LATE THU AND FROM BERMUDA TO THE SE BAHAMAS FRI NIGHT 
THEN WILL EXTEND THROUGH THE CENTRAL ATLC TO THE MONA PASSAGE BY 
SAT NIGHT INTO SUN.

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

$$
WALLACE