000
AXNT20 KNHC 221123
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 AM EST MON DEC 22 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 CENTERED ALONG 6N9W 3N20W 5N30W 3N40W 1N51W. A SURFACE 
TROUGH IS EMBEDDED WITHIN THE ITCZ ALONG 32W FROM 3N-13N AND 
WITHIN 90/120 NM OF LINE FORM 11N45W TO THE COAST OF SOUTH 
AMERICA NEAR 9N58W. CLUSTERS OF SCATTERED MODERATE CONVECTION 
ARE FROM 6N TO ACROSS THE EQUATOR BETWEEN 8W-24W. SCATTERED 
MODERATE/STRONG CONVECTION IS WITHIN 60 NM OF LINE FROM 15N34W 
TO 13N36W. 
  
...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT EXTENDS FROM THE W ATLC ACROSS CENTRAL FLORIDA INTO 
THE GULF OF MEXICO NEAR FORT MYERS CONTINUING W ALONG 25N90W TO 
INLAND OVER MEXICO BETWEEN TAMPICO AND TUXPAN. BROKEN/OVERCAST 
STRATOCUMULUS LOW CLOUDS WITH ISOLATED SHOWERS ARE N OF THE 
FRONT TO THE N GULF COAST AND INLAND OVER TEXAS. IN THE WAKE OF 
THE FRONT...MODERATE/STRONG N TO NE WINDS WITH DRIER CONDITIONS. 
THE UPPER TROUGH ASSOCIATED WITH THE FRONT DIPS S OVER THE NW 
GULF N OF A LINE FROM BROWNSVILLE TEXAS TO JACKSONVILLE FLORIDA. 
BROAD UPPER RIDGE DOMINATES THE REMAINDER OF THE GULF...THE 
CARIBBEAN...AND THE W ATLC SUPPORTING STRONG SUBSIDENCE AND DRY 
STABLE AIR S OF THE FRONTAL BOUNDARY. THE FRONT IS EXPECTED TO 
CLEAR THE GULF LATER TODAY INTO TUE AS THE STRONG SURFACE RIDGE 
CONTINUES TO BUILD S OVER THE GULF ANCHORED CURRENTLY BY A 1039 
MB HIGH OVER THE CENTRAL PLAIN STATES. 

CARIBBEAN SEA...
THE N CARIBBEAN IS DOMINATED BY A BROAD UPPER RIDGE ANCHORED IN 
THE W ATLC PRODUCING STRONG SUBSIDENCE IN DRY AIR ACROSS THE 
ENTIRE BASIN. A WEAK UPPER LEVEL SHEAR AXIS EXTENDS ACROSS THE 
CARIBBEAN FROM THE W TROPICAL ATLC ACROSS THE LESSER ANTILLES 
NEAR 13N61W ALONG 14N78W TO THE COSTA RICA/NICARAGUA BORDER. 
THUS PATCHES OF LOW LEVEL CLOUDS WITH EMBEDDED SHOWERS ARE 
WITHIN 120 NM OF A LINE FROM OVER THE LESSER ANTILLES NEAR 
14N61W ALONG 17N74W TO CENTRAL AMERICA NEAR 13N84W. THE FRONT IN 
THE GULF OF MEXICO IS EXPECTED TO ENTER THE CARIBBEAN LATER 
TODAY THEN BEGIN TO WEAKEN INTO TUE. 
 
ATLANTIC OCEAN...
A COLD FRONT ENTERS THE W ATLC NEAR 32N72W EXTENDING ACROSS 
CENTRAL FLORIDA AND LAKE OKEECHOBEE INTO THE GULF OF MEXICO NEAR 
FORT MYERS. BROKEN/OVERCAST STRATOCUMULUS LOW CLOUDS WITH 
ISOLATED SHOWERS ARE WITHIN 120 NM N OF THE FRONT. A BROAD UPPER 
LEVEL RIDGE COVERS THE W ATLC AND INTO THE CARIBBEAN AND GULF OF 
MEXICO ANCHORED NEAR THE TURKS AND CAICOS EXTENDING NE TO BEYOND 
32N58W AND ENCOMPASSES THE AREA W OF 50W. A SURFACE TROUGH IS IN 
THE E/CENTRAL ATLC ANALYZED FROM 27N41W TO 18N44W. THIS TROUGH 
IS SUPPORTED BY AN UPPER LEVEL TROUGH OVER THE E/CENTRAL ATLC 
WITH AXIS ENTERING THE AREA NEAR 32N29W TO 20N37W BECOMING A 
SHEAR AXIS INTO THE TROPICS ALONG 13N50W INTO THE CARIBBEAN NEAR 
13N61W. UPPER DIFFLUENCE E OF THIS UPPER TROUGH ALONG WITH AN 
UPPER RIDGE AMPLIFIED OVER THE E ATLC SE OF THE UPPER TROUGH TO 
THE CANARY ISLANDS IS ENHANCING CLOUD COVER WITH ISOLATED 
SHOWERS COVERING THE AREA WITHIN 250 NM OF LINE FROM 9N39W 
24N20W TO JUST INLAND OVER AFRICA NEAR 14N16W. SURFACE RIDGE IS 
OVER THE E ATLC WITH THE AXIS EXTENDING THROUGH 32N23W TO 
20N32W. HIGH PRESSURE ANCHORED N OF THE REGION IS EXPECTED TO 
BUILD SOUTHWARD OVER THE W ATLC ON MON NIGHT INTO TUE TIGHTENING 
THE PRESSURE GRADIENT AND INCREASING NE TO E WINDS ACROSS THE 
CARIBBEAN THEN SPREADING E OVER THE TROPICAL ATLC THROUGH FRI. 

$$
WALLACE