000
AXNT20 KNHC 271110
TWDAT 

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

...THE ITCZ...
ITCZ IS ANALYZED ALONG 7N10W 4N22W 4N36W 1N51W. SCATTERED 
MODERATE/STRONG CONVECTION IS WITHIN 90/120 NM N OF THE ITCZ AND 
WITHIN 90 NM S OF THE ITCZ FROM 18W-24W. CLUSTERS OF SIMILAR 
CONVECTION ARE WITHIN 120 NM ON BOTH SIDES OF THE ITCZ FROM 
24W-36W AND WITHIN 120 NM OFF THE COAST OF THE IVORY COAST FROM 
5W TO THE BORDER OF LIBERIA. CLUSTERS OF SCATTERED MODERATE/ 
ISOLATED STRONG CONVECTION ARE WITHIN 90 NM S OF THE ITCZ FROM 
15W-18W AND WITHIN 200 NM ON BOTH SIDES OF THE ITCZ FROM 
36W-40W. 

...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 E OF 90W. PATCHES OF FOG ARE 
INLAND AND WITHIN 60/75 NM ALONG THE N GULF COAST FROM PANAMA 
CITY FLORIDA TO CORPUS CHRISTI TEXAS. UPPER LAYERED TROUGH IS 
MOVING ACROSS THE CENTRAL PLAIN STATES TO OVER N MEXICO WITH THE 
NEXT MAJOR FRONT ENTERING THE GULF LATE TODAY/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 LOW 
CLOUDS WITH SCATTERED SHOWERS INLAND CENTRAL AMERICA. ISOLATED 
FAST MOVING SHOWERS DOT MUCH OF THE CARIBBEAN FROM 11N19N WHILE 
THE REMAINDER OF THE AREA 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 EXTENDING S OVER 
THE REMAINDER OF THE W ATLC AND CENTRAL ATLC TO 20N AND THE 
ACCOMPANYING COLD FRONT ENTERING THE REGION NEAR 32N45W 
EXTENDING W TO 29N61W DISSIPATING NEAR 29N68W. BROKEN/OVERCAST 
LOW CLOUDS WITH ISOLATED SHOWERS ARE WITHIN 60/75 NM NW OF THE 
FRONT. THE HIGH PRESSURE CONTINUES TO DOMINATE THE W AND CENTRAL 
ATLC BRIDGING THE ABOVE FRONTAL BOUNDARY. A SECOND COLD FRONT 
ENTERS THE FAR E ATLC NEAR 32N15W THROUGH THE CANARY ISLANDS TO 
24N20W WITH ANY SHOWER ACTIVITY WELL N OF AREA. THE ASSOCIATED 
UPPER TROUGH IS N OF 29N E OF 28W TO INLAND OVER NW AFRICA. 
UPPER DIFFLUENCE AND SW UPPER FLOW ARE ACROSS THE TROPICAL ATLC 
FROM E OF THE WINDWARD ISLANDS NEAR 11N56W ALONG 22N34W TO OVER 
AFRICA S OF THE CANARY ISLANDS NEAR 27N13W WITH DENSE CLOUD 
COVER AND ISOLATED SHOWERS WITHIN 500 NM S OF THIS LINE. 

$$
WALLACE