AXNT20 KNHC 022358
TWDAT 

TROPICAL WEATHER DISCUSSION  
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
705 PM EST TUE DEC 02 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
2315 UTC.

...THE ITCZ...
THE ITCZ AXIS IS ANALYZED ALONG 8N12W 6N25W 8N40W INTO THE GUYANAS 
NEAR 3N54W. SCATTERED MODERATE CONVECTION IS FROM 7N-10N BETWEEN 
29W-37W. SIMILAR CONVECTION IS NEAR 8N21W AND NEAR 6N45W. SCATTERED 
MODERATE/ISOLATED STRONG CONVECTION IS OVER THE GUYANAS PARTICULARLY 
OVER THE NORTHERN PART. 

...DISCUSSION...

GULF OF MEXICO...
A DEEP LAYERED TROUGH EXTENDS ACROSS THE SE CONUS AND THE FLORIDA 
PANHANDLE TOWARD THE SW GULF OF MEXICO. THIS TROUGH SUPPORTS A 
SECONDARY/REINFORCING COLD FRONT THAT IS CURRENTLY SE OF THE AREA 
OVER WESTERN CUBA AND THE YUCATAN PENINSULA. MIDDLE TO UPPER LEVEL 
DRY AIR AND STRONG SUBSIDENCE IS OVER THE ENTIRE GULF REGION. BEHIND 
THE FRONT...A 1026 MB HIGH LOCATED NEAR 28N87W DOMINATES THE SE 
CONUS AND MOST OF THE AREA. SCATTERED COLD AIR STRATOCUMULUS CLOUDS 
ARE EVIDENT ON SATELLITE IMAGERY MAINLY OVER THE EASTERN HALF OF THE 
GULF AND THE SW PORTION. SOUTHERLY RETURN FLOW HAS BEEN ESTABLISHED 
OVER THE NW QUADRANT OF THE GULF IN ADVANCE OF THE NEXT COLD FRONT 
FORECAST TO MOVE OFFSHORE THE TEXAS COAST ON WED NIGHT. THE 
COMBINATION OF COLD AIR ADVECTION AND RESULTANT CLEAR SKIES WILL 
ALLOW TEMPERATURES TO DROP INTO THE LOWER/MID 50S IN SOUTH FLORIDA 
TONIGHT...WITH WIND CHILL VALUES LIKELY FALLING INTO THE 45-50F 
RANGE.

CARIBBEAN SEA...
A STATIONARY FRONT EXTENDS ACROSS EASTERN CUBA AND THE CARIBBEAN SEA 
CROSSING BETWEEN THE CAYMAN ISLANDS AND JAMAICA TO NEAR 12N83W. A 
BAND OF MAINLY LOW/MID CLOUDS WITHIN 90 NM EITHER SIDE OF THE FRONT 
CONTAINS EMBEDDED SHOWERS AND POSSIBLE WEAK ISOLATED TSTMS. BEHIND 
THE COLD FRONT...NLY WINDS IN THE 20-25 KT RANGE ARE TRANSPORTING 
ABUNDANT LOW LEVEL MOISTURE WITH MAINLY LIGHT SHOWERS ACROSS 
BELIZE...GUATEMALA AND HONDURAS. A SECONDARY FRONT IS MOVING ACROSS 
WESTERN CUBA AND THE YUCATAN PENINSULA REINFORCING THE PRESENT 
RATHER DRY AND COLD WEATHER CONDITIONS FOR THIS TIME OF THE YEAR 
ACROSS THE AREA PARTICULARLY THE MAJORITY OF THE ISLAND OF CUBA. A 
SURFACE TROUGH IS LOCATED IN THE ERN CARIBBEAN ALONG 68W/69W SOUTH 
OF 17N. THIS TROUGH SHOWS SOME TROPICAL-WAVE LIKE CHARACTERISTICS 
AND WILL CONTINUE TO MOVE WWD ACROSS THE CENTRAL CARIBBEAN ON WED 
REACHING THE ATLANTIC COAST OF NICARAGUA PROBABLY LATE THU. THE 
TROUGH IS CURRENTLY GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS 
OVER THE ABC ISLANDS. THIS ACTIVITY IS BEING ENHANCED BY UPPER LEVEL 
DIFFLUENCE ASSOCIATED WITH AN UPPER-LEVEL RIDGE ANCHORED ON A HIGH N 
OF PUERTO RICO. THE RIDGE AXIS EXTENDS INTO THE E-CENTRAL CARIBBEAN 
THROUGH THE MONA PASSAGE. TYPICAL PATCHES OF LOW LEVEL MOISTURE ARE 
NOTED ACROSS THE LEEWARD ISLANDS AND PUERTO RICO USHERED IN ON E-NE 
15-20 KT TRADES. IN THE UPPER LEVELS...STRONG SWLY WINDS AHEAD OF 
THE DEEP LAYERED TROUGH OVER THE GULF OF MEXICO ARE SEEN OVER NORTH 
CENTRAL AMERICA...THE NW CARIBBEAN AND CUBA. 

ATLANTIC OCEAN...
TWO FRONTAL BOUNDARIES ARE ACROSS THE W ATLC WEST OF 70W. THE FIRST 
ONE IS A STATIONARY FRONT THAT ENTERS THE AREA NEAR 31N70W THEN 
CONTINUES SW ACROSS THE CENTRAL BAHAMAS AND EASTERN CUBA INTO THE 
CARIBBEAN SEA. THE SECOND ONE IS A REINFORCING COLD FRONT WHICH 
EXTENDS FROM A WEAK 1016 MB SFC LOW LOCATED NEAR 33N74W TO WESTERN 
CUBA AND THE YUCATAN PENINSULA. THE AFOREMENTIONED DEEP LAYERED 
TROUGH SUPPORTS THESE FRONTS. UPPER LEVEL SWLY WIND FLOW BETWEEN 
THIS UPPER-LEVEL TROUGH AND AN UPPER-LEVEL RIDGE CENTERED NEAR 
25N62W IS HELPING TO INDUCE SCATTERED SHOWERS AND ISOLATED TSTMS 
ALONG THE FRONTS. TO THE E...A 1028 MB SURFACE HIGH LOCATED N OF 
THE AREA EXTENDS A RIDGE OVER THE CENTRAL AND W ATLC ROUGHLY BETWEEN 
50W-70W. ACROSS THE E-CENTRAL ATLC...A 1011 MB SURFACE LOW IS 
CENTERED NEAR 28N41W. A SURFACE TROUGH ENTERS THE AREA NEAR 31N31W 
THEN CONTINUES SW ALONG 20N34W TO 11N46W. THIS SURFACE FEATURE IS 
SUPPORTED BY SHARP UPPER LEVEL TROUGHING THAT RUNS FROM AN UPPER LOW 
SITUATED NEAR 28N38W ACROSS THE DEEP TROPICS TO NEAR TRINIDAD AND 
TOBAGO ISLANDS. THE REMAINDER OF THE ATLANTIC OCEAN IS UNDER THE 
INFLUENCE OF A BROAD RIDGE CENTERED OVER SIERRA LEONE. UPPER 
DIFFLUENCE BETWEEN THESE TWO UPPER-LEVEL FEATURES IS SUPPORTING 
SCATTERED SHOWERS ALONG AND AHEAD OF THE ABOVE MENTIONED SFC TROUGH. 

$$
GR