000
AXNT20 KNHC 282358
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
705 PM EST SUN DEC 27 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.

...THE ITCZ...

FROM THE SOUTHERN COAST OF LIBERIA TO 6N17W TO 3N30W 2N45W...
NORTHEASTERN BRAZIL NEAR 1N50W. SHOWERS ARE POSSIBLE TO THE
SOUTH OF 5N BETWEEN 20W AND EXTREME NORTHEASTERN COASTAL BRAZIL.

...DISCUSSION...

THE GULF OF MEXICO...
AN UPPER LEVEL TROUGH ON WATER VAPOR IMAGERY HAS PUSHED 
SOUTHWARD AND NOW REACHES 26N IN FLORIDA. DRY AIR IN SUBSIDENCE 
ACCOMPANIES THE TROUGH. CYCLONIC FLOW THAT IS AROUND THE TROUGH 
COVERS THE AREA FROM THE ATLANTIC OCEAN TO THE GULF OF MEXICO
TO THE NORTH OF 26N BETWEEN 72W AND 90W. A SURFACE TROUGH 
REMAINS IN THE WESTERN GULF OF MEXICO...NOW ALONG A LINE FROM 
CIUDAD DEL CARMEN MEXICO TO 23N95W TO 28N96W. DRY AIR IN 
SUBSIDENCE ALSO COVERS THE REST OF THE GULF OF MEXICO EVERYWHERE
ELSE...EXCEPT FOR THE UPPER TEXAS COAST/COASTAL WATERS OF 
SOUTHWESTERN LOUISIANA. SHOWERS ARE POSSIBLE IN MULTILAYERED 
CLOUDS THAT ARE TO THE WEST OF 26N96W 23N93W 19N91W.

THE CARIBBEAN SEA...
A SURFACE TO LOW LEVEL TROUGH EXTENDS FROM NORTHWESTERN COASTAL 
COLOMBIA TO 13N78W. ISOLATED SHOWERS HAVE BEEN DISSIPATING IN 
THE AREA TO THE SOUTH OF 11N BETWEEN 79W AND 81W...ALONG THE 
COAST OF PANAMA. THIS TROUGH IS PART OF THE COMPARATIVELY LARGER 
SCALE BROAD SURFACE CYCLONIC FLOW THAT THE COVERS THE AREA TO 
THE SOUTH OF 16N. NORTHEASTERLY SURFACE TO LOW-LEVEL WIND FLOW 
COVERS THE NORTHWESTERN CORNER OF THE AREA TO THE WEST OF THE 
LINE FROM SOUTHEASTERN CUBA TO NORTHEASTERN COASTAL NICARAGUA.
LOW CLOUDS COVER THE AREA FROM THE NORTHEASTERN CARIBBEAN SEA 
ISLANDS TO 21N BETWEEN 60W AND 69W...ASSOCIATED WITH A REMNANT 
CLOUD LINE/SHEAR AXIS. BROAD MIDDLE LEVEL TO UPPER LEVEL 
ANTICYCLONIC FLOW COVERS THE AREA. 

THE ATLANTIC OCEAN...
A WESTERN ATLANTIC COLD FRONT PASSES THROUGH 31N68W TO 28N71W TO 
24N74W. A LINE OF LOW LEVEL CLOUDS IS WITHIN 30 NM ON EITHER 
SIDE OF 30N72W 26N76W 23N81W IS MOVING EASTWARD WITH TIME...
BEHIND THE COLD FRONT. ISOLATED MODERATE SHOWERS ARE WITHIN
30 NM TO 60 NM ON EITHER SIDE OF 23N70W 26N69W 27N67W 28N66W
30N62W. AN EASTERN ATLANTIC OCEAN TROUGH ON WATER VAPOR IMAGERY 
PASSES THROUGH 31N30W TO 25N33W TO 18N40W TO 13N49W. THIS TROUGH 
SUPPORTS THE COLD FRONT THAT PASSES THROUGH 31N18W TO 25N26W 
17N40W AND 16N44W. A STATIONARY FRONT CONTINUES FROM 16N44W TO 
18N58W. A REMNANT CLOUD LINE/SHEAR AXIS CONTINUES FROM 18N58W
TO 19N64W AND 19N69W. SHOWERS ARE POSSIBLE WITHIN 60 NM TO
90 NM ON EITHER SIDE OF THE FRONTAL BOUNDARY/SHEAR AXIS.

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

$$
MT