000
AXNT20 KNHC 200540
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST TUE JAN 20 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 THE COAST OF LIBERIA ALONG 10W TO THE EQUATOR ALONG 27W...
ALONG THE EQUATOR TO 35W...INTO NORTHEASTERN BRAZIL NEAR 3S45W.
SCATTERED STRONG SHOWERS AND THUNDERSTORMS ARE FROM 1N TO 3N 
BETWEEN 7W AND 14W. ISOLATED MODERATE SHOWERS TO LOCALLY STRONG
THUNDERSTORMS ARE ELSEWHERE SOUTH OF 5N EAST OF 52W...AND SOUTH
OF 10N BETWEEN 50W AND 60W.
 
...DISCUSSION...

THE GULF OF MEXICO AND THE ATLANTIC OCEAN WEST OF 70W...
A DEEP-LAYER TROUGH HAS DUG INTO THE GULF OF MEXICO. CYCLONIC 
FLOW FROM THIS TROUGH COVERS THE ENTIRE AREA. THIS TROUGH
SUPPORTS ONE COLD FRONT THAT PASSES FROM THE ATLANTIC OCEAN 
BETWEEN THE NORTHERN BAHAMAS AND FLORIDA THROUGH THE STRAITS
OF FLORIDA TO THE YUCATAN PENINSULA AND THE SOUTHWESTERN CORNER
OF THE AREA. A SECOND COLD FRONT PASSES THROUGH THE FLORIDA
PANHANDLE INTO THE NORTHWESTERN CORNER OF THE AREA. THE GFS
MODEL FOR 200 MB FORECASTS WINDS RANGING FROM 130 KT TO 150 KT
IN THE EASTERN GULF OF MEXICO ACROSS FLORIDA INTO THE ATLANTIC
OCEAN WEST OF 70W. THE FEW UPPER AIR SOUNDING REPORTS SHOWED
CORE WINDS OF A JET STREAM CLOSER TO 90 KT. I AM NOT SURE ABOUT
THE LEVEL OF THE ATMOSPHERE FOR THOSE 90 KT WINDS. EXPECT
COMPARATIVELY MUCH COLDER TEMPERATURES IN THE U.S.A. NORTHERN
GULF COAST AREAS AND IN FLORIDA FOR AT LEAST THE NEXT 48 HOURS
OR SO. GALE WIND CONDITIONS ARE FORECAST IN THE ATLANTIC OCEAN
NORTH OF 27N BETWEEN 65W AND 78W FOR THE NEXT 24 HOURS OR SO.

THE CARIBBEAN SEA...
UPPER LEVEL SOUTHWESTERLY WIND FLOW FROM THE SOUTHWESTERN CORNER 
OF THE GULF OF MEXICO AND THE YUCATAN PENINSULA OF MEXICO MERGES
WITH THE CYCLONIC FLOW AROUND THE BASE OF THE DEEP LAYER TROUGH
IN THE SOUTHEASTERN CORNER OF THE GULF OF MEXICO. COMPLETELY 
SEPARATE UPPER LEVEL ANTICYCLONIC FLOW MOVES FROM COLOMBIA AND 
PANAMA TOWARD CUBA. A SURFACE TROUGH PASSES FROM THE JAMAICA 
CHANNEL TOWARD EASTERN PANAMA. THIS TROUGH IS DENOTED BY A 
DEFINITE CLOUD LINE. SHOWERS ARE POSSIBLE IN THE CLOUD LINE
WITH THE TROUGH. THIS TROUGH IS FORECAST TO CONTINUE TO DRIFT
WESTWARD AND DISSIPATE ALONG 80W DURING THE LATE NIGHT AND EARLY 
MORNING HOURS OF TODAY. THE NEXT COLD FRONT WILL MOVE THROUGH 
THE YUCATAN CHANNEL LATE ON TUESDAY AND REACH FROM HISPANIOLA
TO NICARAGUA LATE ON WEDNESDAY. NORTHWESTERLY WINDS OF 20 KT
WILL FOLLOW THE FRONT.

THE REST OF THE ATLANTIC OCEAN EAST OF 70W...
A NOW-SHALLOW COLD FRONT...WITHOUT AS MUCH UPPER LEVEL SUPPORT 
AS IT HAD EARLIER...PASSES THROUGH 32N57W TO 27N64W. IT 
CONTINUES AS A SURFACE TROUGH FROM 27N64W TO 22N71W. ISOLATED
MODERATE SHOWERS ARE WITHIN 30 NM ON EITHER SIDE OF THE TROUGH.
AN UPPER LEVEL RIDGE IS ALONG 42W/43W FROM 10N TO BEYOND 32N.
MIDDLE LEVEL EASTERLY FLOW THAT IS SLIGHTLY CYCLONIC IS MOVING 
THROUGH THE AREA FROM 10N TO 27N BETWEEN 29W AND 60W. A SECOND 
SMALLER UPPER LEVEL RIDGE IS ALONG 34W SOUTH OF 19N. BROAD 
SURFACE ANTICYCLONIC WIND FLOW COVERS THE AREA BETWEEN AFRICA
AND 60W.

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