000
AXNT20 KNHC 210541
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 AM EST MON DEC 21 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.

...THE ITCZ...

FROM COASTAL LIBERIA NEAR 6N10W TO 7N25W 4N35W 3N45W...INTO
EXTREME NORTHEASTERN BRAZIL TO 1N52W. STRONG SHOWERS ARE WITHIN
30 NM ON EITHER SIDE OF 3N BETWEEN 44W AND 45W. POSSIBLE SHOWERS
ARE ELSEWHERE TO THE SOUTH OF 7N.

...DISCUSSION...

THE GULF OF MEXICO...
UPPER LEVEL SOUTHWESTERLY WIND FLOW ORIGINATES IN THE EASTERN 
PACIFIC OCEAN...BETWEEN 80W AND 20N98W 12N96W 8N96W. THIS FLOW
IS PUSHING MOISTURE FROM THAT AREA ACROSS GUATEMALA AND MEXICO
INTO THE SOUTHWESTERN CORNER OF THE GULF OF MEXICO NORTHWARD
AND NORTHEASTWARD. THIS FLOW CROSSES FLORIDA BOUND FOR THE 
ATLANTIC OCEAN...AS PART OF LARGER SCALE UPPER LEVEL 
ANTICYCLONIC FLOW. UPPER LEVEL MOISTURE COVERS THE ENTIRE GULF
OF MEXICO...EXCEPT FOR THE EXTREME NORTHWESTERN CORNER. 

THE CARIBBEAN SEA...
UPPER LEVEL ANTICYCLONIC FLOW ORIGINATES IN THE EASTERN PACIFIC 
OCEAN...BETWEEN 80W AND 20N98W 12N96W 8N96W. THIS FLOW CONTINUES 
INTO THE WESTERN CARIBBEAN SEA...CURVING ACROSS CUBA AND BEYOND. 
THE HIGH LEVEL MOISTURE WITH THIS FLOW COVERS THE AREA TO THE 
WEST OF A LINE FROM HAITI TO THE NORTHEASTERN COAST OF COLOMBIA.
DRY AIR IN SUBSIDENCE COVERS THE REST OF THE CARIBBEAN SEA TO 
THE EAST OF THE HIGH LEVEL MOISTURE. THE ANTICYCLONIC FLOW THAT 
IS IN THE WESTERN CARIBBEAN SEA ULTIMATELY IS PART OF BROADER 
LARGE SCALE ANTICYCLONIC FLOW THAT EXTENDS INTO THE ATLANTIC 
OCEAN BEYOND 30N50W. A STATIONARY FRONT CONTINUES FROM THE 
SOUTHERN BAHAMAS...THROUGH THE WINDWARD PASSAGE TO JAMAICA...
TO 15N80W AND CURVING TO THE NORTHERN BORDER OF COSTA RICA AND 
PANAMA. A SURFACE TROUGH IS WITHIN 90 NM TO 180 NM TO THE 
SOUTHEAST OF THE FRONT FROM 10N TO 20N. LOW CLOUDS AND POSSIBLE
PRECIPITATION ARE TO THE WEST OF THE SURFACE TROUGH.
  
THE ATLANTIC OCEAN...
ALL THE MIDDLE LEVEL TO UPPER LEVEL CYCLONIC FLOW THAT SUPPORTS 
THE CURRENT ATLANTIC OCEAN FRONTAL BOUNDARIES IS WELL TO THE 
NORTH OF THE AREA. UPPER LEVEL ANTICYCLONIC FLOW THAT STARTS IN 
THE WESTERN CARIBBEAN SEA MOVES ACROSS CUBA AND THE BAHAMAS INTO 
THE CENTRAL ATLANTIC OCEAN BEYOND 30W50W...TO THE AREA TO THE 
WEST OF THE EAST CENTRAL ATLANTIC OCEAN 32N30W 21N31W TROUGH. 
THE ORIGINAL COLD FRONT THAT PASSED THROUGH THE GULF OF MEXICO 
TWO DAYS AGO NOW PASSES THROUGH 32N51W TO 26N60W TO 21N70W IN THE
SOUTHERN BAHAMAS. A STATIONARY FRONT CONTINUES FROM THE SOUTHERN 
BAHAMAS...THROUGH THE WINDWARD PASSAGE TO JAMAICA...TO 15N80W 
AND CURVING TO THE NORTHERN BORDER OF COSTA RICA AND PANAMA. A 
SURFACE TROUGH IS WITHIN 90 NM TO 180 NM TO THE SOUTHEAST OF THE 
FRONT FROM 10N TO 20N. A SURGE OF COMPARATIVELY COLDER AIR IS AT 
LEAST 600 NM TO THE NORTHWEST OF THE ORIGINAL COLD FRONT TO THE 
NORTH OF 29N. LITTLE TO NO PRECIPITATION IS DETECTED WITH THE 
FRONTS AT THIS TIME. AN EAST CENTRAL ATLANTIC OCEAN DEEP LAYER 
TROUGH PASSES THROUGH 32N30W TO 21N31W. THIS TROUGH SUPPORTS
A COLD FRONT THAT PASSES THROUGH 32N14W...ACROSS THE CANARY 
ISLANDS TO 25N20W 20N30W TO 19N36W. LITTLE TO NO PRECIPITATION 
ACCOMPANIES THIS FRONT AT THIS TIME. SURFACE HIGH PRESSURE IS
IN BETWEEN THE ORIGINAL COLD FRONT AND THE EASTERN ATLANTIC
COLD FRONT...AROUND A 1017 MB HIGH PRESSURE CENTER 
THAT IS NEAR 19N46W.

$$
MT