000
AXNT20 KNHC 230633
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST SUN DEC 23 2007

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL 
AMERICA...THE GULF OF MEXICO...THE CARIBBEAN SEA...NORTHERN 
SECTIONS OF SOUTH AMERICA...AND THE 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 0615 UTC

...ITCZ...
ITCZ AXIS ALONG 7N13W 4N40W 3N55W. SCATTERED MODERATE CONVECTION 
WITHIN 120 NM OF N AXIS FROM 39W-48W.  ISOLATED MODERATE 
CONVECTION WITHIN 90 NM OF AXIS FROM 23W-32W.

...DISCUSSION...
GULF OF MEXICO...
STRONG COLD FRONT ENTERED NW GULF EARLIER TODAY AND HAS REACHED 
FROM SE LOUISIANA TO  MEXICAN COAST NEAR 22N98W THEN NWD ALONG E 
SLOPES OF SIERRA MADRE TO 26N100W.  FRONT SUPPORTED BY LARGE 
AMPLITUDE LONGWAVE TROUGH ACROSS CENTRAL PLAINS PRODUCING VERY 
WINTRY WEATHER ACROSS ITS PATH.  WELL DEFINED LINE OF CONVECTION 
MARKS FRONTAL BOUNDARY.  N GALE FORCE WINDS EXPECTED IN SW GULF 
LATER TONIGHT THROUGH LATE SUN.  BROKEN LOW LEVEL STRATIFIED 
CLOUDINESS AND ISOLATED SHOWERS ASSOCIATED WITH DISSIPATED WARM 
FRONT LINGERS AHEAD OF COLD FRONT.  E GULF APPEARS QUIET FOR 
TIME BEING...BUT TRANQUILITY WILL NOT LAST TOO LONG AS COLD 
FRONT SHOULD BRING STRONG NLY WINDS SUN NIGHT THROUGH MON.  HIGH 
PRES BUILDS BEHIND FRONT AND MAINTAINS COLL DRY NE FLOW THROUGH 
REMAINDER OF FORECAST PERIOD. 

CARIBBEAN SEA...
MID TO UPPER RIDGE WELL ANCHORED OVER W CARIB WITH FLOW ALOFT 
BECOMING ZONAL E OF 60W.  ABUNDANT MODERATE TO STRONG SUBSIDENCE 
ACROSS ENTIRE BASIN MAINTAINS IT DRY AND STABLE CURTAILING 
VERTICAL DEVELOPMENT EVEN WHEN SURFACE UPLIFT IS AVAILABLE LIKE 
WITH SURFACE TROUGH ALONG 69W/70W OFF COAST OF VENEZUELA.  
SLIGHTLY DEEPER PRECIP...ALSO ISOLATED...IN SW CARIBBEAN S OF 
11N W OF 80W AS TRADES COLLIDE WITH MOUNTAIN RANGE IN PANAMA AND 
COSTA RICA.   

ATLANTIC OCEAN...
MAIN FEATURE IN W ATLC IS LOW PRES AT 28N69W...1010 MB...WITH 
COLD FRONT EXTENDING FROM 29N66W TO E CUBA AND TROUGH TO 25N72W 
TO 25N80W.  LOW PRES WELL SUPPORTED BY LONGWAVE TROUGH RUNNING 
ALONG CENTRAL ATLC AND SHORTWAVE TROUGH NEAR 30N67W.  MOST DEEP 
CONVECTION...SCATTERED TSTMS...REMAIN E OF CENTER UNDER 
DIFFLUENT ZONE ALOFT ASSOCIATED WITH SHORTWAVE AND COLD FRONT.
LITTLE SIGNIFICANT CONVECTION ASSOCIATED WITH SURFACE TROUGH.  

TAIL END OF OLD FRONTAL BOUNDARY 32N38W 28N48W 27N55W MOVING NWD 
IS FORECAST TO BE OUT OF AREA WITHIN 12 HRS BY MODEL ENSEMBLE. 
LITTLE SIGNIFICANT CLOUDINESS ALONG THIS WEAK BOUNDARY.  WEAK 
SURFACE TROUGH IN TROPICAL ATLC E OF NRN LEEWARDS ALONG 59W FROM 
16N-21N.  NIGHT CHANNEL VIS IMAGERY SHOWS DISTINCT TURNING IN 
LOW-LEVEL CLOUDS BUT LITTLE IN WAY OF DEEP CONVECTION.  
SCATTERED SHOWERS WITHIN 180 NM E OF AXIS.  E ATLC UNDER 
UMBRELLA OF LARGE HIGH PRES RIDGE KEEPING LOW PROFILE WITH 
STRONG ZONAL FLOW ALOFT DOMINATING WEATHER PATTERN.  

$$
WALLY BARNES