000 AXNT20 KNHC 161142 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST FRI DEC 16 2011 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...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N11W TO 08N17W TO 05N34W TO 07N50W. ISOLATED MODERATE CONVECTION IS FROM 05N-08N BETWEEN 21W-32W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL RIDGE REMAINS ANCHORED IN THE WESTERN CARIBBEAN SEA AND EXTENDS NORTHWARD CONTINUING TO IMPACT THE GULF AND FLORIDA PENINSULA THIS MORNING. THE RIDGE AXIS EXTENDS FROM THE NW CARIBBEAN SEA NEAR 20N84W NE TO BEYOND 32N78W WITH WATER VAPOR IMAGERY INDICATING A DRY AND STABLE AIRMASS UNDER MOSTLY SOUTHWESTERLY FLOW ALOFT. THIS UPPER LEVEL FEATURE IS SUPPORTIVE OF A SURFACE RIDGE ANCHORED BY A 1023 MB HIGH CENTERED OVER THE SW NORTH ATLC NEAR 33N69W WHICH EXTENDS A RIDGE AXIS WEST- SOUTHWESTWARD ACROSS THE FLORIDA PENINSULA TO THE WESTERN GULF WATERS NEAR 24N96W. MOSTLY E TO SE WINDS IN THE RANGE OF 10 TO 15 KT ARE OBSERVED OVER MUCH OF THE GULF THIS MORNING...WITH WINDS VEERING SOUTHERLY OVER THE NW GULF AHEAD OF AN EMERGING COLD FRONT ALONG THE TEXAS GULF COAST. WATER VAPOR IMAGERY ALSO INDICATES AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING NE ACROSS THE TEXAS PANHANDLE AND WESTERN OKLAHOMA WHICH IS SUPPORTING THE WEAK COLD FRONT INTO THE NW WATERS THIS MORNING. NORTHERLY WINDS BEHIND THE FRONT ARE EXPECTED TO INCREASE TO 20 KT AND PERSIST THROUGHOUT THE DAY FRIDAY AS THE FRONT BECOMES DIFFUSE LATE AS THE UPPER LEVEL SHORTWAVE MOVES TO THE NE. SURFACE HIGH PRESSURE WILL THEN BUILD ACROSS THE GULF THROUGH THE WEEKEND WITH NORTHEASTERLY WINDS PERSISTING THROUGH SUNDAY NIGHT. CARIBBEAN SEA... AN UPPER LEVEL RIDGE INFLUENCES MUCH OF THE WESTERN CARIBBEAN WITH AN AXIS EXTENDING FROM OVER NORTHERN COLOMBIA NEAR 11N72W NORTHWESTWARD TO OVER THE YUCATAN CHANNEL NEAR 22N87W. SOUTHWEST OF THIS RIDGE AXIS...SOUTHERLY DIFFLUENT FLOW ALOFT CONTINUES TO ENHANCE SCATTERED SHOWERS AND ISOLATED TSTMS S OF 14N BETWEEN 76W-84W...INCLUDING PORTIONS OF PANAMA AND COSTA RICA. MOST OF THIS CONVECTIVE ACTIVITY IS FOCUSED IN THE VICINITY OF THE MONSOON TROUGH AXIS WHICH EXTENDS FROM THE E PACIFIC ALONG 09N TO NORTHERN COLOMBIA. OTHERWISE THE REMAINDER OF THE WESTERN CARIBBEAN W OF 70W IS UNDER STRONG NE TRADES DUE TO AN INCREASED PRESSURE GRADIENT FROM BUILDING HIGH PRESSURE OVER THE SW NORTH ATLC. FARTHER EAST...NORTHWESTERLY FLOW ALOFT DOMINATES ON THE SOUTHWESTERN PERIPHERY OF AN UPPER LEVEL TROUGH ACROSS THE CENTRAL ATLC. A REMNANT COLD FRONT...ANALYZED AS A SHEAR LINE EXTENDS INTO THE EASTERN CARIBBEAN THROUGH THE MARTINIQUE PASSAGE NEAR 15N61W THEN WESTWARD ALONG 14N66W TO 12N76W. ISOLATED SHOWERS ARE OCCURRING WITHIN 75 NM EITHER SIDE OF THE SHEAR LINE AS IT CONTINUES TO DRIFT SOUTHWARD. AN EARLIER ASCAT PASS AROUND 16/0132 UTC INDICATED STRONG NE WINDS NORTH OF THE SHEAR LINE AXIS IN THE RANGE OF 20 TO 25 KT. HIGH PRESSURE IS FORECAST TO REMAIN ANCHORED NE OF THE BAHAMAS THROUGH THE REMAINDER OF THE WEEKEND MAINTAINING AN AREA OF INCREASED E-NE TRADES OVER THE CENTRAL AND EASTERN CARIBBEAN. ATLANTIC OCEAN... AN UPPER LEVEL RIDGE CONTINUES TO SLIDE EASTWARD OVER THE SW NORTH ATLC WITH AXIS EXTENDING FROM THE NW CARIBBEAN SEA NEAR 20N84W NE TO BEYOND 32N78W. A MOSTLY DRY AND STABLE AIRMASS IS ASSOCIATED WITH THIS UPPER LEVEL FEATURE AND THIS CONTINUES TO SUPPORT A 1023 MB SURFACE HIGH CENTERED NEAR 33N69W. MOSTLY NE TO E WINDS ARE OBSERVED W OF 60W WITH A FEW FAST-MOVING ISOLATED SHOWERS EXPECTED THROUGHOUT THE DAY FRIDAY ACROSS THE BAHAMAS... TURKS AND CAICOS...AND AREAS OFFSHORE OF THE FLORIDA PENINSULA W OF 78W. FARTHER EAST...A SHARP UPPER LEVEL TROUGH WITH AXIS ALONG 55W CONTINUES TO SUPPORT A FRONTAL BOUNDARY ANALYZED INTO THE DISCUSSION AREA NEAR 32N48W EXTENDING SOUTH INTO A 1006 MB LOW NEAR 29N49W THEN SOUTHWARD TO A 1004 MB LOW NEAR 22N51W THEN SOUTHWESTWARD TO THE MARTINIQUE PASSAGE NEAR 15N61W AND INTO THE EASTERN CARIBBEAN SEA. A PRE-FRONTAL TROUGH IS LOCATED SE OF THE FRONT ALONG 10N53W TO 17N49W TO 22N49W. LOW-LEVEL CONVERGENCE EAST OF THE SURFACE TROUGH AND ALONG WITH STRONG MIDDLE TO UPPER LEVEL DIFFLUENCE IS GENERATING A BROAD AREA OF SCATTERED SHOWERS AND ISOLATED TSTMS FROM 10N-32N BETWEEN 41W-50W. A FEW ISOLATED SHOWERS ARE ALSO OCCURRING WITHIN 75 NM EITHER SIDE OF THE COLD FRONT S OF 20N AND WEST OF THE COLD FRONT FROM 24N-29N BETWEEN 51W-56W IN ASSOCIATION WITH THE MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 26N54W. THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A 1034 MB HIGH CENTERED SW OF THE IBERIAN PENINSULA NEAR 35N19W. THE RIDGE AXIS EXTENDS SW FROM THE HIGH TO 32N24W TO 12N38W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN