000
AXNT20 KNHC 270516
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SAT DEC 27 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 8N12W 4N24W 3N45W 1N51W. CLUSTERS OF 
SCATTERED MODERATE/STRONG CONVECTION ARE WITHIN 150 NM S OF THE 
ITCZ FROM 13W-26W AND WITHIN 225 NM N OF THE ITCZ FROM 26W-40W. 
CLUSTERS OF SCATTERED MODERATE/ISOLATED STRONG CONVECTION ARE 
WITHIN 90/120 NM N OF THE ITCZ FROM 16W-20W AND WITHIN 120/150 
NM S OF THE ITCZ FROM 27W-39W. 

...DISCUSSION...

GULF OF MEXICO...
THE GULF IS DOMINATED BY AN UPPER RIDGE THAT EXTENDS FROM THE 
CARIBBEAN ACROSS W CUBA AND THE E GULF TO OVER THE E US WITH 
MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR NOTED ACROSS THE 
ENTIRE BASIN. SURFACE RIDGE ANCHORED IN THE W ATLC COVERS THE 
GULF GIVING THE ENTIRE GULF RETURN FLOW WITH ISOLATED PATCHES OF 
LOW CLOUDS AND ISOLATED SHOWERS. PATCHES OF FOG ARE INLAND AND 
WITHIN 60/75 NM ALONG THE N GULF COAST FROM MISSISSIPPI/ALABAMA 
BORDER TO CORPUS CHRISTI TEXAS. NEXT MAJOR FRONT TO ENTER THE 
GULF IS EXPECTED LATE SAT/EARLY SUN.

CARIBBEAN SEA...
BROAD UPPER RIDGE DOMINATES THE CARIBBEAN ANCHORED OVER SOUTH 
AMERICA AND A RIDGE AXIS EXTENDING NW ACROSS W CUBA AND THE E 
GULF OF MEXICO INCLUDING PORTIONS OF THE W ATLC COVERING THE 
CARIBBEAN WITH STRONG SUBSIDENCE AND DRY AIR. SURFACE RIDGE 
REMAINS OVER THE ATLC AND WITH THE LOWER PRESSURE OVER SOUTH 
AMERICA IS PRODUCING MODERATE/STRONG ELY TRADE WINDS. THESE 
TRADE WINDS COUPLED WITH LOW LEVEL CONVERGENCE IS BANKING CLOUDS 
WITH SCATTERED SHOWERS AND OVER CENTRAL AMERICA. ISOLATED FAST 
MOVING SHOWERS DOT MUCH OF THE CARIBBEAN WITH THE EXCEPTION OF 
THE FAR NW WHERE MOSTLY CLEAR SKIES PREVAIL. THE MODERATE/STRONG 
TRADE WINDS WILL CONTINUE THROUGH THE MON THEN DIMINISHING AS 
THE HIGH PRESSURE OVER THE ATLC WEAKENS. 
 
ATLANTIC OCEAN...
THE UPPER RIDGE THAT DOMINATES THE CARIBBEAN EXTENDS OVER THE 
FAR W ATLC TO 70W WITH A DEEP LAYERED TROUGH DIPPING S OVER THE 
REMAINDER OF THE W ATLC AND CENTRAL ATLC TO 20N AND THE 
ACCOMPANYING COLD FRONT ENTERING THE REGION NEAR 32N50W 
EXTENDING W ALONG 30N60W TO 30N72W. BROKEN/OVERCAST LOW CLOUDS 
WITH ISOLATED SHOWERS ARE WITHIN 60 NM NW OF THE FRONT. THE HIGH 
PRESSURE CONTINUES TO DOMINATE MOST OF THE W AND CENTRAL ATLC 
BRIDGING THE ABOVE FRONTAL BOUNDARY. A SECOND COLD FRONT ENTERS 
THE E ATLC NEAR 32N17W JUST TO THE W CANARY ISLANDS TO 23N23W 
WITH ANY SHOWER ACTIVITY N OF AREA. THE ASSOCIATED UPPER TROUGH 
IS IS N OF 29N E OF 35W TO THE NW COAST OF AFRICA. UPPER 
DIFFLUENCE AND SW UPPER FLOW ARE ACROSS THE TROPICAL ATLC FROM E 
OF THE WINDWARD ISLANDS NEAR 11N55W ALONG 23N33W TO OVER AFRICA 
S OF THE CANARY ISLANDS NEAR 27N13W WITH DENSE CLOUD COVER WITH 
ISOLATED SHOWERS WITHIN 500 NM S OF THIS LINE. 

$$
WALLACE