000
AXNT20 KNHC 040551
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 AM EST FRI DEC 04 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
0515 UTC.

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 5N9W 4N13W 6N32W 3N51W. SCATTERED 
SHOWERS AND CLUSTERS OF ISOLATED MODERATE CONVECTION ARE FROM THE 
EQUATOR TO 12N BETWEEN 25W-42W.

...DISCUSSION...

GULF OF MEXICO...
AS OF 0300 UTC...A STATIONARY FRONT EXTENDS FROM MIAMI FLORIDA 
ACROSS THE WESTERN FLORIDA STRAITS SW TO THE YUCATAN CHANNEL. MOSAIC 
DOPPLER RADAR IMAGERY AND LIGHTNING DATA SHOW ISOLATED SHOWERS AND 
TSTMS WITHIN 60 NM EITHER SIDE OF THE FRONTAL BOUNDARY. THIS FRONTAL 
SYSTEM IS SUPPORTED ALOFT BY A LONGWAVE UPPER LEVEL TROUGH COVERING 
THE CENTRAL CONUS WITH SWLY UPPER LEVEL FLOW COVERING THE ENTIRE 
GULF. INCREASED MIDDLE TO UPPER LEVEL MOISTURE IS OBSERVED IN WATER 
VAPOR IMAGERY WITH SWLY FLOW AHEAD OF THE NEXT MID-LEVEL SHORTWAVE 
TROUGH CURRENTLY OVER THE SW CONUS AND NW MEXICO THAT IS EXPECTED TO 
INDUCE CYCLOGENESIS OVER THE WESTERN GULF BY FRIDAY AFTERNOON. THE 
ASSOCIATED COLD FRONT IS FORECAST TO PUSH EAST THROUGH THE GULF BY 
LATE SATURDAY PRODUCING STRONG NORTHERLY WINDS BEHIND THE FRONT.

CARIBBEAN SEA...
AN UPPER LEVEL RIDGE COVERS THE WESTERN CARIBBEAN W OF 70W ANCHORED 
IN THE E PACIFIC WITH AXIS EXTENDING ACROSS NICARAGUA/HONDURAS 
THROUGH THE WINDWARD PASSAGE INTO THE W ATLC. STRONG SUBSIDENCE AND 
THE LACK OF MOISTURE IS NOTED ON WATER VAPOR IMAGERY WHICH 
ACCOMPANIES THE UPPER LEVEL ANTICYCLONIC CIRCULATION BRINGING 
TRANQUIL WEATHER AND FAIR SKIES TO MUCH OF THE BASIN. HOWEVER...WITH 
THE STATIONARY FRONT DRAPED ACROSS THE YUCATAN CHANNEL...ISOLATED 
SHOWERS AND TSTMS ARE N OF 20N FROM 81W-88W. EAST OF 70W...AN UPPER 
LEVEL TROUGH AXIS EMBEDDED WITHIN VERY STRONG SUBSIDENCE EXTENDS 
FROM THE CENTRAL ATLC ALONG 17N60W 13N68W TO NORTHERN COLOMBIA. 
ISOLATED LOW-LEVEL SHOWERS ARE BEING USHERED IN ON FRESH TO STRONG 
TRADEWINDS ACROSS THE EASTERN CARIBBEAN AND LESSER ANTILLES MAINLY E 
OF 70W. ALSO...LOW-LEVEL SPEED CONVERGENCE OF THE EASTERLY  
TRADEWINDS ACROSS THE SW CARIBBEAN ARE GENERATING ISOLATED SHOWERS 
WITHIN 60 NM ALONG THE COAST OF WESTERN PANAMA AND COSTA RICA. 

ATLANTIC OCEAN...
A COLD FRONT EXTENDS ACROSS THE W ATLC AND ENTERS THE DISCUSSION 
AREA NEAR 32N73W TO NEAR MIAMI FLORIDA. SATELLITE IMAGERY AND 
LIGHTNING DATA INDICATE ISOLATED SHOWERS AND TSTMS ARE OCCURRING 
WITHIN 90 NM EAST OF THE FRONT. ABUNDANT MOISTURE IS NOTED ALOFT AS 
SWLY UPPER LEVEL FLOW DOMINATES ACROSS THE W ATLC W OF 66W. THE 
REMAINDER OF THE W ATLC IS COVERED BY A SURFACE RIDGE ANCHORED ON A 
1029 MB HIGH CENTERED NEAR 35N47W. THE RIDGE IS SUPPORTED ALOFT BY 
AN AMPLIFIED UPPER LEVEL RIDGE AXIS EXTENDING FROM THE WESTERN 
CARIBBEAN THROUGH THE WINDWARD PASSAGE TO BEYOND 32N62W. ACROSS THE 
CENTRAL ATLC...AN UPPER LEVEL LOW IS CENTERED NEAR 24N42W. THIS 
UPPER LEVEL FEATURE SUPPORTS A COLD FRONT THAT ENTERS THE DISCUSSION 
AREA NEAR 32N38W EXTENDING SW TO 30N40W WHERE IT CONTINUES AS A 
SURFACE TROUGH TO 23N44W. SCATTERED SHOWERS AND ISOLATED MODERATE 
CONVECTION COVER THE AREA FROM 20N-32N BETWEEN 35W-44W. THIS 
ACTIVITY IS LARGELY ENHANCED BY THE UPPER LEVEL LOW CENTER. THE 
REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE 
RIDGE ANCHORED BY A 1030MB HIGH CENTERED E OF THE AZORES NEAR 
37N16W. 

$$
HUFFMAN