000
AXNT20 KNHC 121803
TWDAT 

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL  
105 PM EST SUN DEC 12 2010

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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 
1745 UTC.

...ITCZ...
 
THE ITCZ AXIS IS ANALYZED FROM THE COAST OF LIBERIA NEAR 5N9W 
CONTINUING WEST ALONG 3N20W 6N29W 6N32W 5N40W 3N51W. A SURFACE 
TROUGH IS EMBEDDED WITHIN THE ITCZ AXIS ALONG 31W S OF 12N. 
SCATTERED MODERATE CONVECTION IS FROM 2N TO 8N BETWEEN 28W AND 
48W.

...DISCUSSION...

GULF OF MEXICO...
A COLD FRONT EXTENDS ACROSS THE GULF FROM NORTHERN FLORIDA NEAR 
30N83W TO TAMPICO MEXICO NEAR 21N97W ALONG 24N90W. A PRE-FRONTAL 
TROUGH ASSOCIATED WITH STRONG SHOWERS AND THUNDERSTORMS IS 40 NM 
AHEAD OF THE FRONT N OF 27N. SCATTERED SHOWERS ARE ALSO WITHIN 
20 NM EITHER SIDE OF THE FRONT S OF 27N. THE SYSTEM IS SUPPORTED 
BY AN UPPER LEVEL LONGWAVE/DEEP LAYER TROUGH OVER THE EASTERN 
CONUS. GALE FORCE WINDS ARE NOTED BEHIND THE FRONT...AS WELL AS 
STRONG SUBSIDENCE AND CLEARING NOTED ON WATER VAPOR AND 
SATELLITE IMAGERY. THIS IS PROVIDING THE REMAINDER OF THE BASIN 
MOSTLY FAIR WEATHER CONDITIONS. EXPECT THE FRONT TO CONTINUE TO 
RACE ACROSS THE GULF AND REACH SOUTHERN FLORIDA LATE TONIGHT.

CARIBBEAN SEA...
DRY AIR AND SUBSIDENCE COVER THE BASIN...KEEPING MUCH OF THE 
CARIBBEAN UNDER FAIR CONDITIONS THIS AFTERNOON. HOWEVER...A 
SHEARLINE EXTENDS FROM THE SW TIP OF HAITI NEAR 18N74W TO THE SW 
BASIN ALONG 16N79W 11N80W. THE AXIS DEPICTS A LINE OF SURFACE 
CONVERGENCE BETWEEN N-NE WINDS ACROSS THE NW CARIBBEAN AND TRADE 
WINDS ACROSS THE REMAINDER OF THE BASIN. THE SURFACE CONVERGENCE 
IS SUPPORTING ISOLATED SHOWERS WITHIN 40 NM EITHER SIDE OF THE 
AXIS N OF 15N. THE ACTIVITY IS EXPECTED TO CONTINUE OVER THE 
NEXT 24 HOURS...WITH NORTHERLY WINDS INCREASING IN THE NW BASIN 
AHEAD OF THE COLD FRONT THAT IS MOVING ACROSS THE GULF OF 
MEXICO. THE FRONT SHOULD REACH THE NW CARIBBEAN LATE TONIGHT. 

ATLANTIC OCEAN...
DRY AIR AND STRONG SUBSIDENCE COVER THE WESTERN ATLC W OF 56W. 
HOWEVER...CONDITIONS IN THE FAR WESTERN ATLC ARE EXPECTED TO 
DETERIORATE AS A COLD FRONT ENTERS THE BASIN WITH STRONG SHOWERS 
AND THUNDERSTORMS...AS WELL AS GALE FORCE WINDS IN THE WAKE OF 
ITS PATH. DESPITE THE LACK OF UPPER LEVEL SUPPORT...A SURFACE 
TROUGH EXTENDS ALONG 30N55W 26N61W 21N64W...CONTINUING AS A 
SHEAR LINE TO 17N67W. NO DEEP CONVECTION IS PRESENT IN THE 
VICINITY OF THE TROUGH AND SHEAR AXIS. A SECOND SURFACE TROUGH 
IS TO THE SE ALONG 26N57W 22N56W 18N58W WITH ISOLATED SHOWERS 
WITHIN 30 NM OF THE AXIS. TO THE E OF THIS BOUNDARY...SCATTERED 
SHOWERS ARE FROM 21N TO 27N BETWEEN 42W AND 54W ASSOCIATED WITH 
AN UPPER LEVEL JET IN THE ZONAL WLY FLOW ALOFT. THE REMAINDER OF 
THE E ATLC IS DOMINATED BY A SURFACE RIDGE ANCHORED BY A WEAK 
1019 MB HIGH NEAR 25N40W. A COLD FRONT CLIPS THE DISCUSSION AREA 
N OF THE RIDGE ALONG 32N28W 29N36W 28N45W. SCATTERED SHOWERS ARE 
WITHIN 70 NM EAST OF THE AXIS N OF 29N.  

FOR ADDITIONAL INFORMATION PLEASE VISIT
HTTP://WWW.HURRICANES.GOV/MARINE

$$

GARCIA