000
AXNT20 KNHC 131157
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST TUE JAN 13 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY
THROUGH 1015 UTC.

...THE ITCZ...

FROM SIERRA LEONE NEAR 8N12W TO 5N20W TO 4N30W TO 3N40W...
CROSSING THE EQUATOR ALONG 46W...INTO NORTHEASTERN BRAZIL
NEAR 2S49W. SCATTERED MODERATE SHOWERS TO ISOLATED STRONG 
THUNDERSTORMS ARE FROM 4N TO 5N BETWEEN 9W AND 14W...
AND SOUTH OF 7N BETWEEN 16W AND 34W.

...DISCUSSION...

THE GULF OF MEXICO...AND THE ATLANTIC OCEAN WEST OF 60W...
A DEEP LAYER TROUGH IS DIGGING SOUTHWARD...FROM THE NORTH 
CENTRAL U.S.A. INTO SOUTH TEXAS AND NORTHERN MEXICO. THIS
FEATURE SUPPORTS A COLD FRONT THAT CURRENTLY IS MOVING THROUGH 
SOUTH CENTRAL TEXAS. A SHALLOW STATIONARY FRONT STRETCHES FROM 
LAKE OKEECHOBEE FLORIDA INTO THE CENTRAL GULF OF MEXICO...TOWARD 
THE SOUTHWESTERN CORNER OF THE AREA. THIS FRONT IS UNDERNEATH 
UPPER LEVEL SOUTHWESTERLY WIND FLOW THAT IS PREVALENT EVERYWHERE 
EXCEPT FOR THE COAST FROM SOUTHEASTERN LOUISIANA TO MEXICO
NEAR 24N. WIDELY SCATTERED MODERATE SHOWERS AND POSSIBLE 
THUNDERSTORMS ARE IN THE NORTHEASTERN GULF WATERS. THE 
STATIONARY FRONT CONTINUES NORTHEAST OF LAKE OKEECHOBEE 
FLORIDA...TO THE ATLANTIC OCEAN NEAR 31N81W...BECOMING WARM
FROM 31N81W TO 30N71W...AND THEN AS A COLD FRONT FROM 30N71W
NORTHEASTWARD BEYOND 32N60W. GALE-FORCE WINDS OR FASTER ARE 
FORECAST TO DEVELOP TO THE NORTH OF THE COLD FRONT DURING THE 
NEXT 24 HOURS. AT LEAST TWO MORE FRONTAL BOUNDARIES ARE FORECAST 
TO MOVE THROUGH THE GULF WATERS DURING THE NEXT FEW DAYS. 

THE CARIBBEAN SEA...
MIDDLE TO UPPER LEVEL DRY AIR IN SUBSIDENCE SURROUNDS A MIDDLE
TO UPPER LEVEL TROUGH THAT PASSES THROUGH THE ATLANTIC OCEAN 
FROM 13N52W TO 12N68W. UPPER LEVEL ANTICYCLONIC FLOW COVERS THE 
AREA WEST OF 70W. THIS ANTICYCLONIC FLOW IS PART OF A BROADER
UPPER LEVEL RIDGE THAT EXTENDS FROM THE WESTERN CARIBBEAN SEA 
INTO THE CENTRAL ATLANTIC OCEAN NORTHEASTWARD BEYOND 32N52W.
A TIGHT SURFACE PRESSURE GRADIENT BETWEEN HIGH PRESSURE NORTH
OF THE AREA AND THE SEMI-PERMANENT SURFACE LOW PRESSURE IN
COLOMBIA AND PANAMA IS PRODUCING MODERATE TO STRONG TRADEWINDS 
WITH OCCASIONAL GUSTS TO GALE FORCE ACROSS THE BASIN. THE 
COMPARATIVELY FASTEST WINDS USUALLY ARE NEAR THE COAST OF
COLOMBIA. THE NEXT COLD FRONT IS FORECAST TO REACH WESTERN
CUBA AND THE NORTHWESTERN CARIBBEAN SEA LATE TUESDAY.
THE SAME FRONT WILL EXTEND FROM CENTRAL CUBA TO HONDURAS
ON WEDNESDAY.

THE ATLANTIC OCEAN...
A MIDDLE TO UPPER LEVEL TROUGH EXTENDS FROM 29N31W TO 21N41W TO
13N52W INTO THE SOUTHEASTERN CARIBBEAN SEA NEAR 12N68W. MIDDLE 
TO UPPER LEVEL DRY AIR IN SUBSIDENCE SURROUNDS THIS TROUGH...
FROM 5N IN GUYANA AND VENEZUELA TO 30N BETWEEN 40W AND 70W. 
SHOWERS ARE POSSIBLE FROM 10N TO 16N BETWEEN 40W AND 50W. 
A SURFACE RIDGE PASSES THROUGH 32N32W TO 29N44W TO 28N60W TO 
27N74W. UPPER LEVEL SOUTHWESTERLY WIND FLOW IS TO THE EAST OF 
THE TROUGH. BROKEN TO OVERCAST MULTILAYERED CLOUDS ARE SOUTH OF 
21N BETWEEN 24W AND 50W.

$$
MT