000 AXNT20 KNHC 170555 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 105 AM EST FRI DEC 17 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0515 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 10N14W 09N20W 04N33W 05N47W 04N52W. SCATTERED MODERATE CONVECTION IS FROM 01N-10N BETWEEN 24W-32W. ISOLATED MODERATE CONVECTION IS WITHIN 90 NM EITHER SIDE OF A LINE FROM 06N33W TO 12N47W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL RIDGING AND STRONG SUBSIDENCE IS NOTED ALOFT ON WATER VAPOR IMAGERY ACROSS THE GULF THIS EVENING. HOWEVER...AN UPPER LEVEL TROUGH IS PROGRESSING ACROSS THE SW CONUS AND NW PORTION OF MEXICO ALONG 107W THAT IS SUPPORTING A COLD FRONT ANALYZED FROM THE TEXAS AND LOUISIANA GULF COAST BORDER TO NEAR CORPUS CHRISTI NEAR 27N97W. OVERALL THE FRONT LACKS ANY SIGNIFICANT CONVECTION...WITH ISOLATED SHOWERS POSSIBLE WITHIN 60 NM OF THE FRONT. MORE IMPORTANTLY...S-SW RETURN FLOW OVER THE ENTIRE GULF IS ADVECTING LOW-LEVEL MOISTURE AND ISOLATED SHOWERS OVER THE NORTH-CENTRAL AND NE GULF COAST N OF 27N BETWEEN THE FLORIDA BIG BEND REGION AND 92W. LOOKING AHEAD FOR THE UPCOMING WEEKEND...THE WEAK FRONTAL BOUNDARY IS FORECAST TO SWEEP ACROSS THE GULF BY LATE SATURDAY AND INTRODUCE NORTHERLY WINDS TO 20 KT OVER THE REGION THROUGH EARLY SUNDAY. CARIBBEAN SEA... VERY STRONG SUBSIDENCE AND DRY AIR ALOFT IS NOTED ACROSS THE NW CARIBBEAN THAT CONTINUES TO SUPPORT A SURFACE RIDGE EXTENDING FROM THE W ATLC AND FLORIDA PENINSULA TO THE GULF OF HONDURAS N OF 15N AND W OF 80W. OVERALL STABLE CONDITIONS PERSIST AS A RESULT...WITH MOSTLY SCATTERED TO BROKEN STRATOCUMULUS CLOUDS NOTED ON SATELLITE IMAGERY. ON THE SOUTHERN PERIPHERY OF THE SURFACE RIDGE OVER THE EASTERN AND CENTRAL CARIBBEAN...A SHEAR LINE IS ANALYZED FROM DOMINICA TO 15N70W TO 16N75W. AN RECENT 17/0202 UTC ASCAT PASS CAPTURED STRONGER E-NE WINDS OVER THE NE CARIBBEAN NORTH OF THE SHEAR LINE...THEN GENERALLY LIGHTER EASTERLY TRADES SOUTH OF THE SHEAR LINE AXIS. LOW-LEVEL SPEED CONVERGENCE IN VICINITY OF THIS BOUNDARY IS PROVIDING FOCUS FOR WIDELY SCATTERED SHOWERS N OF 15N E OF 78W. ELSEWHERE...A SURFACE TROUGH IS ANALYZED FROM THE NORTHERN COAST OF COLOMBIA NEAR 11N74W TO 16N77W. NEAR THE NORTHERN PORTION OF THE TROUGH AXIS...AND WESTERN EXTENT OF THE SHEAR LINE...STRONGER LOW-LEVEL CONVERGENCE IS GENERATING SCATTERED SHOWERS FROM 15N-19N BETWEEN 74W-78W. ATLANTIC OCEAN... MOSTLY DRY AIR AND STRONG SUBSIDENCE RESIDES WITHIN WESTERLY ZONAL UPPER LEVEL FLOW ACROSS THE W ATLC W OF 50W THAT CONTINUES TO SUPPORT A BROAD SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 28N68W. MOSTLY FAIR CONDITIONS ARE FOUND WITHIN THE INFLUENCE OF THIS FEATURE. OVER THE CENTRAL ATLC...AN UPPER LEVEL TROUGH IS NOTED NORTH OF THE DISCUSSION AREA IN THE VICINITY OF 50W AND SUPPORTS A COLD FRONT THAT ENTERS THE REGION NEAR 32N46W THEN EXTENDS SW ALONG 24N50W TO GUADELOUPE NEAR 16N61W. THE FRONT BECOMES MORE DIFFUSE S OF 25N...HOWEVER ISOLATED SHOWERS STILL REMAIN WITHIN 90 NM EITHER SIDE OF THE FRONT. FARTHER EAST...AN UPPER LEVEL LOW CENTERED NEAR 33N21W CONTINUES TO IMPACT MUCH OF THE EASTERN ATLC E OF 40W DRIVING A STRONG 994 MB LOW CENTERED WEST OF THE MADEIRA ISLANDS NEAR 33N21W. THIS PARTIALLY OCCLUDED LOW EXTENDS A COLD FRONT INTO THE AREA ALONG 32N15W ACROSS THE CANARY ISLANDS NEAR 28N17W THEN ALONG 23N23W 22N32W. ISOLATED SHOWERS ARE MAINLY OCCURRING WITHIN 120 NM EAST OF THE FRONT...HOWEVER LOW-LEVEL MOISTURE AND POSSIBLE ISOLATED SHOWERS LINGER WEST OF THE FRONT FROM 21N-28N BETWEEN THE FRONT AND 40W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN