000
AXNT20 KNHC 280504
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN DEC 28 2008

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 
0445 UTC.

...THE ITCZ...
ITCZ IS ANALYZED ALONG 8N10W 6N24W 7N39W 4N52W. CLUSTERS OF 
SCATTERED MODERATE TO SCATTERED/ISOLATED STRONG CONVECTION ARE 
FROM 1N-8N BETWEEN 12W-30W AND FROM EQUATOR TO 9N BETWEEN 
30W-45W. 

...DISCUSSION...

GULF OF MEXICO...
DEEP LAYERED TROUGH MOVING FROM THE CENTRAL PLAIN STATES TO OVER 
THE MISSISSIPPI VALLEY WITH THE ASSOCIATED COLD FRONT ENTERING 
THE GULF NEAR THE LOUISIANA/TEXAS BORDER JUST OFF THE TEXAS 
COAST TO INLAND ACROSS S TEXAS AND NE MEXICO NEAR CORPUS 
CHRISTI. HEAVY/SCATTERED SHOWERS WITH EMBEDDED THUNDERSTORMS ARE 
WITHIN 60 NM W OF THE FRONT N OF 28N AND WITHIN 30 NM W OF THE 
REMAINDER OF THE FRONT TO INLAND OVER TEXAS. THE REMAINDER OF 
THE GULF WATERS IS DOMINATED BY AN UPPER RIDGE THAT EXTENDS FROM 
THE CARIBBEAN ACROSS W CUBA AND THE FLORIDA PENINSULA TO OVER 
THE E US COAST WITH MODERATE/STRONG SUBSIDENCE AND DRY STABLE 
AIR NOTED E OF A LINE FROM THE ALABAMA COAST TO MEXICO NEAR  
VERACRUZ. SURFACE RIDGE ANCHORED IN THE NW ATLC IS BEGINNING TO 
RETREAT EASTWARD WITH THE APPROACHING FRONT COVERING THE E GULF 
RETURN FLOW WITH ISOLATED PATCHES OF LOW CLOUDS AND ISOLATED 
SHOWERS E OF 90W. THE FRONT IS EXPECTED MOVE E THROUGH SUN THEN 
BEGIN TO DISSIPATE EXITING THE GULF ON TUE. 

CARIBBEAN SEA...
BROAD UPPER RIDGE DOMINATES THE W CARIBBEAN ANCHORED OVER SOUTH 
AMERICA AND EXTENDING A RIDGE AXIS NW ACROSS W CUBA AND THE 
FLORIDA PENINSULA COVERING THE AREA W OF 75W. AN UPPER TROUGH 
OVER THE W/CENTRAL ATLC COVERS THE E CARIBBEAN WITH STRONG 
SUBSIDENCE AND DRY AIR ACROSS THE ENTIRE BASIN. SURFACE RIDGE 
REMAINING OVER THE ATLC CONTINUES TO PRODUCE MODERATE/STRONG 
ELY TRADE WINDS. THESE TRADE WINDS COUPLED WITH LOW LEVEL 
CONVERGENCE IS BANKING LOW CLOUDS WITH SCATTERED SHOWERS INLAND 
CENTRAL AMERICA WITH ISOLATED FAST MOVING SHOWERS DOTTING THE 
REMAINDER OF THE CARIBBEAN. THE MODERATE/STRONG TRADE WINDS WILL 
CONTINUE THROUGH THE MON THEN WEAKEN TUE THROUGH THU. 
 
ATLANTIC OCEAN...
THE UPPER RIDGE THAT DOMINATES THE CARIBBEAN EXTENDS OVER THE 
FAR W ATLC TO 75W WITH A DEEP LAYERED TROUGH EXTENDING S OVER 
THE REMAINDER OF THE W ATLC AND CENTRAL ATLC TO 16N AND THE 
ACCOMPANYING COLD FRONT ENTERING THE REGION NEAR 32N30W 
EXTENDING SW TO 25N55W BECOMING A SURFACE TROUGH TO 25N68W. 
BROKEN/OVERCAST LOW CLOUDS WITH ISOLATED SHOWERS ARE WITHIN 75 
NM NW OF THE FRONT. THE HIGH PRESSURE CONTINUES TO DOMINATE THE 
W AND CENTRAL ATLC BRIDGING THE ABOVE FRONTAL BOUNDARY/SURFACE 
TROUGH. A DISSIPATING COLD FRONT ENTERS THE FAR NE ATLC OFF THE 
COAST OF NW AFRICA NEAR 32N10W SW TO THE CANARY ISLANDS NEAR 
28N16W WITH ANY SHOWER ACTIVITY WELL N OF AREA. UPPER DIFFLUENCE 
AND SW UPPER FLOW ARE ACROSS THE TROPICAL ATLC FROM E OF THE 
WINDWARD ISLANDS NEAR 31N55W ALONG 24N30W TO OVER AFRICA S OF 
THE CANARY ISLANDS NEAR 27N13W WITH DENSE CLOUD COVER AND 
ISOLATED SHOWERS S OF THIS LINE TO THE ITCZ. 

$$
WALLACE