000 AXNT20 KNHC 181739 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST SAT DEC 18 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 1700 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 05N09W 06N20W 06N30W 08N45W...AND ALONG 08N49W TO 06N56W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 2N-8N BETWEEN 18W-30W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 6N-10N BETWEEN 32W-38W. A SURFACE TROUGH IS EMBEDDED WITHIN THE ITCZ EXTENDING FROM 05N46W TO 12N47W. SCATTERED MODERATE TO STRONG CONVECTION IS FROM 6N-13N BETWEEN 42W-50W. AN ASCAT PASS INDICATES THAT A SURFACE LOW MAY BE DEVELOPING ALONG THE TROUGH. ...DISCUSSION... GULF OF MEXICO... AS OF 1500 UTC...A STATIONARY FRONT EXTENDS FROM A SURFACE LOW IN THE WEST ATLANTIC THROUGH N FLORIDA NEAR 30N84W TO A SURFACE LOW NEAR 27N87W WHERE IT BECOMES A COLD FRONT ALONG 26N91W 23N95W TO 19N96W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE WITHING 75 NM EITHER SIDE OF THE FRONTAL BOUNDARIES. 10-15 KT N-NE WINDS ARE BEHIND THE FRONT. A PREFRONTAL TROUGH IS ALONG 26N88W 24N81W 24N94W WITH NO SIGNIFICANT CONVECTION. THIS SYSTEM IS SUPPORTED BY AN UPPER LEVEL LONGWAVE TROUGH EXTENDING FROM ONTARIO CANADA DOWN THE EASTERN CONUS INTO THE WESTERN GULF. WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS...SOME STRONG... ARE MOVING FROM THE EASTERN GULF OVER THE FLORIDA PENINSULA. EXPECT THE FRONT AND LOW TO MOVE E OVER THE NEXT 24 HOURS BRINGING WIDESPREAD SHOWER ACTIVITY TO THE FLORIDA PENINSULA. CARIBBEAN SEA... A SURFACE TROUGH IS OVER THE CENTRAL CARIBBEAN EXTENDING FROM CENTRAL CUBA NEAR 23N80W ALONG 19N79W TO 16N77W. AS OF 1500 UTC...A SURFACE LOW EMBEDDED ALONG THE TROUGH IS ANALYZED NEAR 20N79W. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE N OF THE LOW CENTER ACROSS CUBA WITHIN 100 NM OF THE SURFACE TROUGH. SCATTERED MODERATE CONVECTION E OF THE TROUGH IS FROM 15N-20N BETWEEN 74W-76W. A SHEAR LINE IS ENHANCING THE AREA OF CONVECTION...AND IS ANALYZED ALONG 13N67W TO 16N75W BETWEEN 20-25 KT WINDS TO THE NORTH AND 10-15 KT WINDS TO THE SOUTH. SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS ARE WITHIN 100 NM OF THE LINE. IN THE UPPER LEVELS... A RIDGE EXTENDING FROM THE WESTERN ATLANTIC INTO THE CENTRAL CARIBBEAN PRODUCING STRONG SUBSIDENCE OVER CENTRAL AMERICA AND THE W CARIBBEAN W OF 77W. EXPECT THE SURFACE TROUGH TO BE DRAWN EASTWARD WITH THE FRONTAL SYSTEM MOVING ACROSS THE GULF OF MEXICO SUPPORTING SHOWER ACTIVITY OVER THE E CENTRAL CARIBBEAN OVER THE NEXT 24 HOURS. ATLANTIC OCEAN... THE FRONTAL SYSTEM MOVING ACROSS THE GULF OF MEXICO IS SUPPORTING WIDESPREAD SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE FLORIDA PENINSULA EMERGING OFF THE ERN COAST W OF 77W. THIS AREA IS UNDER DIFFLUENCE ALOFT BETWEEN A LONGWAVE UPPER TROUGH ACROSS THE ERN CONUS AND GULF OF MEXICO AND AN UPPER LEVEL RIDGE ACROSS THE W ATLC. THIS UPPER LEVEL RIDGE IS SUPPORTING SURFACE RIDGING ACROSS THE REMAINDER OF THE W ATLC ANCHORED BY A 1020 MB HIGH NEAR 27N67W PROVIDING MOSTLY FAIR WEATHER E OF 77W. A COLD FRONT ENTERS THE CENTRAL ATLC NEAR 32N34W CONTINUING SW ALONG 28N34W 19N47W BECOMING A SHEAR AXIS TO 15N58W. ISOLATED SHOWERS ARE WITHIN 150 NM AHEAD OF THE FRONT AND WITHIN 60 NM EITHER SIDE OF THE SHEAR LINE. THE SYSTEM IS SUPPORTED BY AN UPPER LEVEL TROUGH EXTENDING FROM NEAR 39N40W TO 23N30W. THE FAR ERN ATLC IS EXPERIENCING MOSTLY FAIR CONDITIONS WEAK RIDGING ALOFT AND AT THE SURFACE. A DISSIPATING COLD FRONT HAS NOW MOVED INLAND OVER NW AFRICA WITH NO ASSOCIATED SHOWER ACTIVITY. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MONTALVO/WALTON