000
AXNT20 KNHC 302349
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST SUN DEC 30 2012

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 08N14W TO 
07N17W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 
07N17W TO 03N26W TO 02N38W TO THE EQUATOR NEAR 45W. SCATTERED 
MODERATE CONVECTION IS FROM 01N-07N BETWEEN 28W-46W.

...DISCUSSION...

GULF OF MEXICO...
A MIDDLE TO UPPER LEVEL RIDGE INFLUENCES THE GULF THIS EVENING 
WITH AXIS EXTENDING ALONG 92W. MOSTLY SOUTHWESTERLY FLOW ALOFT 
DOMINATES ON THE WESTERN PERIPHERY OF AN UPPER LEVEL 
ANTICYCLONIC CIRCULATION CENTERED OVER THE NORTH-CENTRAL 
CARIBBEAN SEA NEAR 19N74W. THIS OVERALL STABLE ENVIRONMENT 
CONTINUES TO SUPPORT SURFACE RIDGING ACROSS THE BASIN ANCHORED 
BY A 1033 MB HIGH CENTERED NORTHERN MISSISSIPPI NEAR 35N89W. 
NORTHEAST TO EASTERLY WINDS PREVAIL AND ARE FORECAST THROUGH THE 
OVERNIGHT HOURS INTO MONDAY AS THE RIDGE DRIFTS SLOWLY EASTWARD 
INTO THE SW NORTH ATLC BY LATE MONDAY. THEREAFTER...SURFACE 
WINDS ARE EXPECTED TO VEER S-SE WITH RETURN FLOW ESTABLISHING 
ITSELF AHEAD OF THE NEXT COLD FRONT FORECAST TO EMERGE OFF THE 
TEXAS AND LOUISIANA COAST BY LATE TUESDAY.

CARIBBEAN SEA...
MUCH OF THE CARIBBEAN SEA IS UNDER THE INFLUENCE OF AN 
ANTICYCLONIC CIRCULATION CENTERED NEAR 19N74W. WATER VAPOR 
IMAGERY INDICATES THAT MOSTLY DRY AIR AND SUBSIDENCE DOMINATES 
THIS BASIN AND SKIES REMAIN RELATIVELY CLEAR THIS EVENING. 
HOWEVER...A STRONG MIDDLE TO UPPER LEVEL LOW AND TROUGH IS NOTED 
IN THE VICINITY OF THE CANADIAN MARITIMES AND EXTENDS A COLD 
FRONT ACROSS THE SW NORTH ATLC INTO THE NW CARIBBEAN FROM 
CENTRAL CUBA NEAR 22N79W TO BELIZE NEAR 17N89W. WHILE THE 
DYNAMICS ALOFT ARE A NON-FACTOR IN PRODUCING CONVECTION...A 
NOTICEABLE DIFFERENCE IN AIRMASS AND STRONGER NE WINDS ARE 
OCCURRING NORTH OF THE FRONTAL BOUNDARY THIS EVENING. THE FRONT 
IS EXPECTED TO BECOME MORE DIFFUSE OVER THE NEXT 24 TO 36 HOURS 
WITH THE STRONGER NE WINDS MERGING WITH AN AREA OF STRONG E-NE 
TRADE WINDS BETWEEN 70W-84W.

ATLANTIC OCEAN...
A STRONG MIDDLE TO UPPER LEVEL LOW AND ASSOCIATED TROUGHING IS 
NOTED ON WATER VAPOR IMAGERY OVER THE CANADIAN MARITIMES THIS 
EVENING THAT SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION 
AREA NEAR 32N62W EXTENDING SW TO THE CENTRAL BAHAMAS NEAR 24N75W 
AND INTO THE NW CARIBBEAN SEA VIA CENTRAL CUBA NEAR 22N79W. 
WHILE MOST OF THE STRONGER UPPER LEVEL DYNAMICS REMAIN N OF 
32N...LOW-LEVEL MOISTURE CONVERGENCE IN THE VICINITY OF THE 
FRONT IS GENERATING ISOLATED SHOWERS WITHIN 90 NM EITHER SIDE OF 
THE BOUNDARY. OTHERWISE THE REMAINDER OF THE SW NORTH ATLC IS 
UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1033 MB 
HIGH CENTERED OVER THE SE CONUS NEAR 35N89W. FARTHER EAST...A 
SURFACE TROUGH ANALYZED IN THE CENTRAL ATLC FROM 19N45W TO 
25N44W TO 31N41W CONTINUES TO DRIFT WESTWARD AND OUT OF THE 
RANGE OF AN UPPER LEVEL LOW CENTERED NEAR 27N32W. THIS SURFACE 
TROUGH CONTINUES TO BECOME MORE DIFFUSE AND LACK ANY SIGNIFICANT 
IMPACT AS IT BECOMES ABSORBED INTO MID-OCEAN RIDGING. 
OTHERWISE...THE REMAINDER OF THE EASTERN ATLC IS INFLUENCED BY 
SURFACE RIDGING ANCHORED BY A 1032 MB HIGH CENTERED NORTH THE 
MADEIRA ISLANDS NEAR 34N16W.

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

$$
HUFFMAN