000
AXNT20 KNHC 152356
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
705 PM EST TUE DEC 15 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 
2315 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 6N11 4N17W 6N36W 2N50W. ISOLATED 
MODERATE CONVECTION FROM 4N-9N BETWEEN 21W-42W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 2100 UTC...AN UPPER LEVEL TROUGH AXIS EXTENDS FROM THE 
GREAT LAKES REGION THROUGH THE CENTRAL PLAINS ACROSS TEXAS AND 
INTO NW MEXICO SUPPORTING A COLD FRONT THAT EXTENDS FROM THE 
FLORIDA PANHANDLE ALONG 29N90W 27N96W TO THE SOUTHERN TIP OF 
TEXAS AND INLAND ACROSS NE MEXICO NEAR 26N97W. A PRE-FRONTAL 
TROUGH IS ALSO ANALYZED FROM THE COLD FRONT NEAR 27N95W TO 
22N96W. LOW-LEVEL CONVERGENCE NEAR THE SURFACE BOUNDARIES AND 
UPPER LEVEL DIFFLUENCE LOCATED EAST OF THE UPPER LEVEL TROUGH 
ARE GENERATING NUMEROUS SHOWERS AND SCATTERED TSTMS ACROSS A 
LARGE PORTION OF THE NW GULF WATERS NW OF A LINE FROM PANAMA 
CITY FLORIDA TO NEAR TUXPAN MEXICO. N-NE WINDS UP TO 30 KT ARE 
FORECAST NW OF THE FRONT WHILE THE REMAINDER OF THE GULF IS 
UNDER E-SE WINDS TO 15 KT AS DEPICTED BY A RECENT 15/1600 UTC 
ASCAT PASS AS WELL AS SHIP AND BUOY OBSERVATIONS OVER THE PAST 
FEW HOURS. AS THE FRONT SAGS SOUTHWARD OVER THE NE GULF...AN 
AREA OF LOW PRESSURE IS FORECAST TO DEVELOP OVER THE NW GULF AND 
MOVE E-NE OVER THE NORTHERN GULF WATERS LATE THURSDAY INTO 
FRIDAY USHERING IN AN AREA OF BRISK NORTHERLY WINDS BEHIND THE 
ASSOCIATED COLD FRONT.

CARIBBEAN SEA...
STRONG EASTERLY TRADEWINDS CONTINUE ACROSS THE CARIBBEAN AS A 
RESULT OF A STRONG PRESSURE GRADIENT BETWEEN HIGH PRESSURE OVER 
THE W ATLC AND LOW PRESSURE OVER NORTHERN COLOMBIA. GALE FORCE 
WINDS TO 35 KT REMAIN NEAR THE COAST OF COLOMBIA AND ARE 
FORECAST TO PERSIST THROUGH LATE WEDNESDAY. STRONG SUBSIDENCE IS 
NOTED ON WATER VAPOR IMAGERY ACROSS THE BASIN AND FOCUSED ON AN 
UPPER LEVEL RIDGE WITH AXIS ALONG 72W. THE RIDGE AND ASSOCIATED 
DRY AIR IS PROVIDING GENERALLY FAIR WEATHER OVER THE CARIBBEAN 
SEA. HOWEVER...ISOLATED LOW-LEVEL SHOWERS EMBEDDED IN THE 
EASTERLY TRADES ARE MOVING QUICKLY ACROSS PORTIONS OF THE 
EASTERN CARIBBEAN E OF 72W AND ALONG THE CENTRAL AMERICA COAST S 
OF 20N W OF 82W.

ATLANTIC OCEAN...
AN UPPER LEVEL SHORTWAVE TROUGH IS OVER THE CENTRAL ATLC ALONG 
43W N OF 27N AND SUPPORTS A COMPLEX 1010 MB LOW CENTERED NEAR 
31N47W. A COLD FRONT EXTENDS FROM THE LOW ALONG 28N50W TO 28N57W 
WHERE IT TRANSITIONS TO A DISSIPATING STATIONARY FRONT ALONG 
32N70W TO NEAR THE CENTRAL SOUTH CAROLINA COAST. PRIMARILY 
ACROSS THE W ATLC...AN UPPER LEVEL RIDGE IS IN PLACE EXTENDING 
FROM THE CENTRAL CARIBBEAN ALONG 72W AND SUPPORTS A 1021 MB HIGH 
CENTERED NEAR 27N68W. AREAS OF ISOLATED SHOWERS ARE WITHIN 120 
NM EITHER SIDE OF THE FRONT. FARTHER EAST...A DEEP LAYER TROUGH 
LOCATED OVER THE EASTERN NORTH ATLC IS SUPPORTING A COLD FRONT 
THAT ENTERS THE DISCUSSION AREA NEAR 32N14W EXTENDING THROUGH 
THE CANARY ISLANDS NEAR 28N17W TO 21N32W. LOW-LEVEL CONVERGENCE 
NEAR THE FRONT AND AN AREA OF UPPER LEVEL DIFFLUENCE EAST OF THE 
UPPER LEVEL TROUGH AXIS IS GENERATING POSSIBLE ISOLATED SHOWERS 
WITHIN 60 NM OF THE FRONT AND NORTH OF THE FRONT TO 33N E OF 33W.

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

$$
HUFFMAN