000
AXNT20 KNHC 230513
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST TUE DEC 23 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 CENTERED ALONG 9N10W 4N22W 4N35W EQ48W. A SURFACE TROUGH 
IS N OF THE ITCZ ALONG 40W FROM 7N-16N. CLUSTERS OF SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION ARE FROM 2N-7N BETWEEN 
7W-23W AND FROM 4N-10N BETWEEN 42W-57W INCLUDING THE SOUTH 
AMERICAN COAST. 
  
...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT EXTENDS FROM THE W ATLC THROUGH THE FLORIDA STRAITS 
TO 24N82W THEN CONTINUING AS A STATIONARY FRONT ALONG 22N92W TO 
A 1018 MB SURFACE LOW LOCATED NEAR 24N96W WITH A SECOND 
STATIONARY FRONT S FROM THE LOW TO 19N95W. A SURFACE RIDGE 
EXTENDS OVER THE E US AND THE N GULF BRIDGING THE FRONT DRAPED 
ACROSS THE GULF. BROKEN/OVERCAST STRATOCUMULUS LOW CLOUDS WITH 
ISOLATED SHOWERS COVERS MUCH OF THE GULF EXCEPT N OF 25N E OF 
87W WHERE CLEAR SKIES PREVAIL. A SURFACE TROUGH EXTENDS N FROM 
THE SURFACE LOW ALONG THE TEXAS GULF COAST FROM BROWNSVILLE TO 
GALVESTON. MODERATE/STRONG SUBSIDENCE AND DRY STABLE AIR ARE 
NOTED ACROSS S FLORIDA AND THE S GULF WATERS...MAINLY S OF 25N. 

CARIBBEAN SEA...
THE CARIBBEAN REMAINS UNDER THE INFLUENCE OF A BROAD UPPER HIGH 
CENTERED NEAR 14N69W AND ENCOMPASSES THE ENTIRE CARIBBEAN BASIN 
WITH STRONG SUBSIDENCE IN DRY AIR. THIS UPPER LEVEL FEATURE ALSO 
ENVELOPS CENTRAL AMERICA AND THE NW PORTION OF SOUTH AMERICA. 
HOWEVER...AREAS OF SHALLOW LOW LEVEL MOISTURE STREAM ACROSS THE 
BASIN USHERED IN ON NE-E TRADE WINDS. ISOLATED TO SCATTERED 
SHOWERS ARE NOTED MOVING ACROSS THE LEEWARD/VIRGIN ISLANDS N OF 
14N E OF 65W...FROM 16N-19N BETWEEN 70W-80W IN THE N/CENTRAL 
CARIBBEAN...AND W OF 80W ACROSS THE W CARIBBEAN TO OVER CENTRAL 
AMERICA. LOOKING AHEAD...STRONG HIGH PRESSURE IS FORECAST TO 
BUILD N OF AREA WITH INCREASING TRADE WINDS EXPECTED OVER THE 
TROPICAL ATLC AND MUCH OF THE CARIBBEAN WED THROUGH FRI.
 
ATLANTIC OCEAN...
A COLD FRONT ENTERS THE W ATLC NEAR 32N64W AND EXTENDS ACROSS 
THE NW BAHAMAS NEAR 25N77W THROUGH THE FLORIDA STRAITS INTO THE 
GULF OF MEXICO. BROKEN/OVERCAST STRATOCUMULUS LOW CLOUDS WITH 
ISOLATED SHOWERS ARE WITHIN 150 NM NW OF THE FRONT WITH COLD AIR 
STRATOCUMULUS CLOUDS COVERING THE REMAINDER OF THE AREA N OF 
THE FRONT. A BROAD UPPER LEVEL RIDGE EXTENDS FROM THE CARIBBEAN 
WITH AXIS THEN CONTINUES ACROSS THE VIRGIN/LEEWARD ISLANDS NE TO 
BEYOND 32N48W. MOSTLY FAIR WEATHER CONDITIONS ARE OBSERVED E OF 
THE COLD FRONT TO 30W. A SURFACE TROUGH IS IN THE CENTRAL ATLC 
EXTENDING FROM 26N45W TO 20N46W SUPPORTED BY UPPER LEVEL 
TROUGHING OVER THE E/CENTRAL ATLC WITH THE AXIS ENTERING THE 
AREA NEAR 32N21W SW ALONG 22N31W INTO THE TROPICS ALONG 16N40W 
AND THEN W TO NEAR 14N58W. UPPER DIFFLUENCE E OF THIS UPPER 
TROUGH ALONG WITH AN UPPER RIDGE AMPLIFIED ALONG THE W AFRICAN 
COAST IS ENHANCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS 
WITHIN 200 NM EITHER SIDE OF A LINE FROM 12N34W TO OVER W AFRICA 
NEAR MAURITANIA AND WESTERN SAHARA. NE TO E WINDS ARE EXPECTED 
TO INCREASE ACROSS THE TROPICS TO AT LEAST MIDWEEK AS STRONG 
HIGH PRESSURE BUILDS N OF AREA. 

$$
WALLACE