000
AXNT20 KNHC 281115
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1045 UTC.

...THE ITCZ...
ITCZ IS ANALYZED ALONG 7N10W 4N30W 6N45W 4N52W. SCATTERED 
MODERATE/STRONG CONVECTION IS FROM 2N-5N BETWEEN 36W-41W AND 
FROM 8N-10N BETWEEN 36W-40W. CLUSTERS OF SIMILAR CONVECTION ARE 
FROM 1N-5N BETWEEN 10W-20W. CLUSTERS OF SCATTERED MODERATE/ 
ISOLATED STRONG CONVECTION ARE FROM 1N-5N BETWEEN 20W-35W AND 
FROM 7N-11N BETWEEN 35W-37W. 

...DISCUSSION...

GULF OF MEXICO...
DEEP LAYERED TROUGH MOVING ACROSS THE MISSISSIPPI VALLEY WITH 
THE ASSOCIATED COLD FRONT ENTERING THE GULF OVER SE LOUISIANA 
NEAR VERMILION BAY TO ALONG THE COAST OF MEXICO FROM BROWNSVILLE 
TEXAS TO TAMPICO THEN INLAND OVER MEXICO ALONG THE E SLOPES OF 
THE SIERRA MADRE MOUNTAINS. SCATTERED SHOWERS WITH EMBEDDED 
ISOLATED THUNDERSTORMS ARE W OF A LINE FROM FORT WALTON BEACH 
FLORIDA ALONG 26N90W TO MEXICO BETWEEN TUXPAN AND VERACRUZ. 
DENSE CLOUD COVER WITH SCATTERED SHOWERS ARE W OF THE FRONTAL 
BOUNDARY TO INLAND OVER LOUISIANA...TEXAS AND NE MEXICO. THE 
REMAINDER OF THE GULF WATERS IS DOMINATED BY AN UPPER RIDGE THAT 
EXTENDS FROM THE CARIBBEAN ACROSS W CUBA AND THE E COAST OF 
FLORIDA INTO THE W ATLC WITH MODERATE/STRONG SUBSIDENCE AND DRY 
STABLE AIR NOTED E OF A LINE FROM PANAMA CITY FLORIDA TO MEXICO 
NEAR VERACRUZ. SURFACE RIDGE ANCHORED IN THE NW ATLC CONTINUES 
TO SHIFT EASTWARD WITH THE APPROACHING FRONT COVERING THE E 
GULF RETURN FLOW WITH ISOLATED PATCHES OF LOW CLOUDS AND 
ISOLATED SHOWERS E OF 87W. THE FRONT IS EXPECTED MOVE E THROUGH 
TODAY 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 E 
COAST OF FLORIDA 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 
REMAINS OVER THE ATLC AND CONTINUES TO PRODUCE MODERATE/STRONG 
ELY TRADE WINDS. THESE TRADE WINDS COUPLED WITH LOW LEVEL 
CONVERGENCE IS BANKING LOW CLOUDS WITH SCATTERED SHOWERS INLAND 
W PANAMA...COSTA RICA...AND S NICARAGUA 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 70W 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 32N28W 
EXTENDING SW TO 25N45W DISSIPATING TO 24N58W BECOMING A REMNANT 
SURFACE TROUGH TO 25N69W. BROKEN/OVERCAST LOW CLOUDS WITH 
ISOLATED SHOWERS ARE WITHIN 75 NM NW OF THE COLD FRONT. THE HIGH 
PRESSURE CONTINUES TO DOMINATE THE W AND CENTRAL ATLC BRIDGING 
THE ABOVE FRONTAL BOUNDARY/SURFACE TROUGH. UPPER DIFFLUENCE AND 
SW UPPER FLOW ARE ACROSS THE TROPICAL ATLC FROM NEAR 16N50W 
ALONG 24N29W 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