000
AXNT20 KNHC 071754
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 PM EST WED JAN 07 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1715 UTC.

...THE ITCZ...

ITCZ IS CENTERED ALONG 7N8W 2N18W 3N34W ALONG THE EQUATOR W OF 
48W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 90 
NM ALONG THE COAST OF LIBERIA OF W AFRICA BETWEEN 9W-11W. 
CLUSTERS OF SCATTERED MODERATE ARE FROM THE ITCZ TO S OF THE 
EQUATOR BETWEEN 18W-25W. 

...DISCUSSION...

GULF OF MEXICO...
AT OF 1500 UTC...THE COLD FRONT HAS MOVED OFF THE E COAST OF THE 
US CROSSING FLORIDA BETWEEN JACKSONVILLE AND ST. AUGUSTINE INTO 
THE GULF NEAR S TAMPA BAY EXTENDING SW TO 21N94W THEN S INTO 
MEXICO NEAR VERACRUZ. THE N PORTION OF THE FRONT IS MOVING SE 
NEAR 25 KT. MOSAIC DOPPLER RADAR SHOWS A BAND OF SHOWERS AND 
ISOLATED THUNDERSTORMS ALONG THE FRONT WITH SCATTERED SHOWERS 
WITHIN 90/120 NM W OF THE FRONT E OF 85W AND WITHIN 75 NM W OF 
THE FRONT ELSEWHERE. ISOLATED LOW LEVEL FAST MOVING SHOWERS ARE 
SE OF THE FRONT. THE ASSOCIATED UPPER LEVEL TROUGH IS OVER THE E 
US WITH THE UPPER LOW OVER THE UPPER MISSISSIPPI VALLEY. A JET 
STREAM WITH WINDS OF 90-150 KT COVERS MUCH OF THE GULF NW OF THE 
FRONT. A SURFACE RIDGE IS BUILDING BEHIND THE FRONT OVER TEXAS 
AND MEXICO FORCING DRY AIR OVER THE NW GULF AND THUS CLEAR SKIES 
PREVAIL FROM PANAMA CITY FLORIDA TO TAMPICO MEXICO. AN UPPER 
LEVEL RIDGE COVERING THE W CARIBBEAN EXTENDS OVER THE SE GULF 
AND INTO THE SW ATLC. THIS FRONT IS EXPECTED TO EXIT THE GULF 
LATE TONIGHT/THU MORNING. 

CARIBBEAN SEA...
A MID/UPPER LEVEL RIDGE DOMINATES THE W CARIBBEAN EXTENDING N 
FROM AN UPPER LEVEL HIGH NEAR 11N76W ACROSS CUBA COVERING 
PORTIONS OF THE GULF OF MEXICO AND THE SW ATLC. AN UPPER LEVEL 
TROUGH FROM THE CENTRAL ATLANTIC COVERS THE REMAINDER OF THE E 
CARIBBEAN NEAR E OF 67W ACROSS THE LESSER ANTILLES INTO THE 
TROPICAL ATLC. A LARGE MASS OF DRY AIR COVERS THE ENTIRE 
CARIBBEAN BUT DUE TO LOW LEVEL INSTABILITY PATCHES OF LOW CLOUDS 
WITH EMBEDDED ISOLATED FAST MOVING SHOWERS DOT THE ENTIRE 
CARIBBEAN. MODERATE TO STRONG TRADE WINDS ARE ACROSS THE BASIN 
WITH LOW/MID CLOUDS BANKING ALONG THE MOUNTAINS OF W PARANA AND 
COSTA RICA AND OVER THE CARIBBEAN WATERS S OF 12N W OF 81W. THE 
COLD FRONT IN THE GULF OF MEXICO IS EXPECTED TO ENTER THE 
CARIBBEAN LATE TONIGHT/THUS MORNING THEN DISSIPATING THROUGH 
FRI. 

ATLANTIC OCEAN...
AT OF 1500 UTC...THE COLD FRONT HAS MOVED OFF THE E COAST OF THE 
US ENTERING THE REGION NEAR 32N80W CROSSING FLORIDA BETWEEN 
JACKSONVILLE AND ST. AUGUSTINE INTO THE GULF OF MEXICO WITH GALE 
FORCE SW WINDS WITHIN 180 NM E OF FRONT AND N OF 29N. AN 
UPPER RIDGE ANCHORED IN THE CARIBBEAN EXTENDS ACROSS CUBA INTO 
THE W ATLC BEYOND 32N76W. THE REMAINDER OF THE ATLC IS DOMINATED 
BY AN UPPER LEVELS TROUGH/RIDGE/TROUGH PATTERN. HOWEVER...THE 
SURFACE IS DOMINATED BY A RIDGE THAT COVERS THE AREA W OF 75W 
ANCHORED BY 1026 MB HIGH NEAR 32N36W. THE UPPER RIDGE IS 
PRODUCING A TROPICAL JET STREAM WITH WINDS OF 90-120 KT WITHIN 
200/250 NM OF LINE FROM 15N46W 20N30W TO INLAND OVER AFRICA NEAR 
20N16W. THE COLD FRONT IS EXPECTED TO MOVE ACROSS THE W ATLC AND 
WEAKEN IN THE CENTRAL ATLC BY SAT. 

$$
WALLACE