000 AXNT20 KNHC 171159 TWDAT TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 705 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 09N13W 07N30W TO THE EQUATOR NEAR 50W. ISOLATED MODERATE CONVECTION IS FROM 03N-07N BETWEEN 12W-17W. WIDELY SCATTERED MODERATE CONVECTION IS WITHIN 120 NM EITHER SIDE OF A LINE FROM 01N29W TO 09N40W. ISOLATED MODERATE CONVECTION IS FROM 01N-04N BETWEEN 38W-43W. ...DISCUSSION... GULF OF MEXICO... UPPER LEVEL RIDGING AND STRONG SUBSIDENCE IS NOTED ALOFT ON WATER VAPOR IMAGERY ACROSS THE EASTERN GULF THIS MORNING. HOWEVER...THE UPPER LEVEL RIDGE IS GIVING WAY TO AN UPPER LEVEL TROUGH PROGRESSING ACROSS NEW MEXICO AND WEST TEXAS ALONG 104W THAT IS SUPPORTING A COLD FRONT ANALYZED FROM VERMILION BAY NEAR 30N92W SE TO NEAR BROWNSVILLE TEXAS AND INLAND OVER NORTHERN MEXICO. OVERALL THE FRONT LACKS ANY SIGNIFICANT CONVECTION... HOWEVER...LOW-LEVEL ADVECTION AND CONVERGENCE OF MOISTURE ON S-SW RETURN FLOW LOCATED ON THE WESTERN PERIPHERY OF A WESTERN ATLC SURFACE RIDGE IS GENERATING ISOLATED SHOWERS WITHIN 180 NM SE OF THE COLD FRONT. 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 THIS MORNING. ON THE SOUTHERN PERIPHERY OF THE SURFACE RIDGE OVER THE EASTERN AND CENTRAL CARIBBEAN...A SHEAR LINE IS ANALYZED FROM THE MARTINIQUE PASSAGE TO 14N67W TO 15N73W. AN RECENT 17/0202 UTC ASCAT PASS CAPTURED STRONGER NE WINDS OVER THE NE CARIBBEAN NORTH OF THE SHEAR LINE...THEN GENERALLY LIGHTER E-NE TRADES SOUTH OF THE SHEAR LINE AXIS. LOW-LEVEL SPEED CONVERGENCE IN VICINITY OF THIS BOUNDARY IS PROVIDING FOCUS FOR ISOLATED SHOWERS N OF THE SHEAR LINE BETWEEN 63W-74W. ELSEWHERE...A SURFACE TROUGH IS ANALYZED FROM THE NORTHERN COAST OF COLOMBIA NEAR 09N76W TO 17N76W. NEAR THE NORTHERN PORTION OF THE TROUGH AXIS...STRONGER LOW-LEVEL CONVERGENCE...DUE PARTIALLY TO STRONGER NE WINDS FUNNELING THROUGH THE WINDWARD PASSAGE...IS GENERATING SCATTERED SHOWERS AND ISOLATED TSTMS FROM 15N-20N BETWEEN 74W-78W. ATLANTIC OCEAN... MOSTLY DRY AIR AND STRONG SUBSIDENCE RESIDES WITHIN WESTERLY ZONAL UPPER LEVEL FLOW ACROSS THE W ATLC W OF 45W THAT CONTINUES TO SUPPORT A BROAD SURFACE RIDGE ANCHORED BY A 1021 MB HIGH CENTERED NEAR 27N67W. MOSTLY FAIR CONDITIONS ARE FOUND WITHIN THE INFLUENCE OF THIS FEATURE THIS MORNING. OVER THE CENTRAL ATLC...AN UPPER LEVEL TROUGH AND MID-LEVEL LOW IS NOTED ON WATER VAPOR IMAGERY NORTH OF THE DISCUSSION AREA IN THE VICINITY OF 37N47W THAT SUPPORTS A COLD FRONT ENTERING THE REGION NEAR 32N44W THEN EXTENDING SW TO 25N48W. MOST OF THE FRONT S OF 25N HAS BECOME DIFFUSE WITH A SURFACE TROUGH TRAILING S-SW ALONG 26N47W TO 17N51W. ISOLATED SHOWERS REMAIN WITHIN 120 NM EAST OF THE COLD FRONT S OF 31N...WITH MORE ENHANCED DEEPER CONVECTION EXTENDING WITHIN 120 NM EAST OF THE FRONT N OF 31N. FARTHER EAST...AN UPPER LEVEL LOW CENTERED NEAR 34N19W CONTINUES TO IMPACT MUCH OF THE EASTERN ATLC E OF 30W DRIVING A STRONG 988 MB LOW CENTERED WEST OF THE MADEIRA ISLANDS NEAR 33N20W. THIS PARTIALLY OCCLUDED LOW EXTENDS A COLD FRONT INTO THE AREA ALONG 32N13W ACROSS THE EASTERNMOST CANARY ISLANDS NEAR 28N15W THEN BECOMING MORE DIFFUSE ALONG 23N20W 21N27W. ISOLATED SHOWERS ARE MAINLY OCCURRING WITHIN 120 NM EAST OF THE FRONT. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN