000 AXNT20 KNHC 201743 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST MON DEC 20 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 1715 UTC. ...ITCZ... THE ITCZ AXIS IS CENTERED ALONG 7N13W 5N20W 5N30W 3N40W 1N50W. SCATTERED MODERATE CONVECTION IS FROM 1N-4N BETWEEN 12W AND 17W. CLUSTERS OF SCATTERED MODERATE TO STRONG CONVECTION ARE FROM 3N-10N BETWEEN 20W AND 33W. SCATTERED MODERATE CONVECTION IS ALSO FROM THE EQUATOR TO THE ITCZ AXIS BETWEEN 37W AND 39W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE IS MOVING INTO THE WESTERN GULF FROM MEXICO. STRONG SUBSIDENCE AND DRY AIR DOMINATES THE AREA LIMITING ALL BUT A FEW PASSING WIDELY SCATTERED LOW-LEVEL CLOUDS. POSSIBLE ISOLATED SHOWERS DOT THE NW GULF N OF 24N W OF 91W. A WEAK SURFACE TROUGH IS IN THE W GULF ALONG THE COAST OF MEXICO FROM 19N96W TO 24N98W PRODUCING POSSIBLE LOW LEVEL SHOWERS WITHIN 45 NM OF THE AXIS. OTHERWISE...A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED OVER THE SE CONUS WILL CONTINUE TO PROVIDE FAIR WEATHER THIS AFTERNOON AND PERSIST INTO THE MIDDLE PORTION OF THE WEEK. CARIBBEAN SEA... THE CARIBBEAN IS DOMINATED BY AN UPPER RIDGE ANCHORED NEAR 11N56W EAST OF TRINIDAD AND TOBAGO. A DISSIPATING COLD FRONT ENTERS THE AREA THROUGH THE WINDWARD PASSAGE NEAR 20N73W TO NW JAMAICA NEAR 18N78W THEN WESTWARD TO 18N87W. POSSIBLE ISOLATED SHOWERS ARE WITHIN 60 NM S OF THE FRONT. A WEAK SURFACE TROUGH ENTERS THE AREA THROUGH THE MONA PASSAGE NEAR 18N68W ALONG 16N69W TO CABO SAN ROMAN VENEZUELA NEAR 12N70W. SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS ARE WITHIN 150 NM EITHER SIDE OF THE TROUGH AXIS. POCKETS OF SCATTERED SHOWERS ARE OVER THE CENTRAL LESSER ANTILLES. SHOWERS AND POSSIBLE THUNDERSTORMS ARE OVER PANAMA AND COSTA RICA CAUSED BY THE UPPER RIDGE DRAWING MOISTURE N FROM A SURFACE LOW IN THE E PACIFIC. THE REMAINDER OF THE CARIBBEAN IS ENJOYING GENERALLY FAIR WEATHER THIS AFTERNOON. OVER THE NEXT 24 HOURS...EXPECT THE COLD FRONT TO BE BECOME MORE DIFFUSE OVER THE WESTERN CARIBBEAN. ATLANTIC OCEAN... AN UPPER TROUGH COVERS THE W ATLC TO 60W SUPPORTING A COLD FRONT THAT EXTENDS FROM 32N61W ALONG 25N64W TO THE WINDWARD PASSAGE NEAR 20N73W WHERE IT BECOMES DISSIPATING INTO THE NW CARIBBEAN. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE OCCURRING FROM 25N TO BEYOND 32N BETWEEN 52W AND THE FRONT. S OF 25N...A PRE-FRONTAL SURFACE TROUGH EXTENDS S FROM THE COLD FRONT NEAR 25N64W ALONG 21N66W TO THE MONA PASSAGE NEAR 18N68W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHIN 240 NM EITHER SIDE OF THE SURFACE TROUGH FROM 21N-25N...AND SCATTERED SHOWERS AND POSSIBLE ISOLATED THUNDERSTORMS ARE WITHIN 100 NM EITHER SIDE OF THE TROUGH S OF 21N. A 1020 MB HIGH IS FURTHER E CENTERED NEAR 28N45W. AN UPPER TROUGH IS IN THE E ATLC N OF 10N E OF 13W SUPPORTING A WEAK SURFACE TROUGH REMNANT OF A COLD FRONT THAT EXTENDS FROM 31N15W ALONG 24N20W TO 20N27W. ISOLATED SHOWERS ARE OCCURRING WITHIN 75 NM E THE TROUGH. A SHEAR LINE IS ALONG 19N BETWEEN 37W AND 50W WITH NO SIGNIFICANT CONVECTION. A SURFACE TROUGH WITH AN EMBEDDED SURFACE LOW EXTENDS FROM 13N53W THROUGH THE LOW CENTER NEAR 11N54W TO INLAND OVER SURINAME NEAR 6N56W. CLUSTERS OF SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE FROM 9N-13N BETWEEN 48W AND 55W WITH MOSTLY SCATTERED SHOWERS AND ALONG THE COAST OF SURINAME S OF 7N BETWEEN 54W AND 56W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MONTALVO/HUFFMAN