000 AXNT20 KNHC 111143 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST TUE DEC 11 2012 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 MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 10N14W TO 08N19W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N19W TO 03N30W TO 04N47W TO 04N51W. ISOLATED MODERATE CONVECTION IS FROM 04N-07N BETWEEN 10W-18W. SCATTERED MODERATE CONVECTION IS FROM 07N-13N BETWEEN 36W-48W. ...DISCUSSION... GULF OF MEXICO... BROAD MIDDLE TO UPPER LEVEL TROUGHING IS OVER MUCH OF THE CONUS WHICH IS PROVIDING THE GULF WITH SOUTHWESTERLY FLOW ALOFT. THE TROUGHING SUPPORTS A COLD FRONT ANALYZED INTO THE GULF REGION ACROSS THE FLORIDA PANHANDLE ALONG 30N85W TO 26N90W TO THE MEXICO COAST NEAR 20N97W. ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE FRONT E OF 90W...AND ACROSS MUCH OF THE WESTERN GULF NORTH OF THE FRONT W OF 90W. ANOTHER IMPACT WITH THE FRONT IS 20 TO 25 KT NORTHERLY WINDS FOLLOW IN WAKE OF THE FRONT S OF 26N. OTHERWISE...THE REMAINDER OF THE GULF IS UNDER THE INFLUENCE OF WEAK PRE-FRONTAL TROUGHING WITH ISOLATED SHOWERS AND TSTMS OCCURRING PRIMARILY EAST OF A SURFACE TROUGH ANALYZED FROM 28N85W TO 23N88W TO 19N92W FROM 24N-28N E OF 86W...INCLUDING PORTIONS OF THE CENTRAL AND SOUTHERN FLORIDA PENINSULA. THE COLD FRONT IS EXPECTED TO CONTINUE MOVING EASTWARD INTO THE SW NORTH ATLC AND NW CARIBBEAN BY THURSDAY AS HIGH PRESSURE BUILDS IN ACROSS THE GULF WITH PERSISTENT N-NE WINDS. CARIBBEAN SEA... MUCH OF THE BASIN THIS MORNING IS UNDER TRANQUIL CONDITIONS AS WATER VAPOR IMAGERY INDICATES AN UPPER LEVEL RIDGE WITH AXIS ALONG 73W IS PROVIDING A RELATIVELY DRY AND STABLE ATMOSPHERE. A FEW ISOLATED SHOWERS AND TSTMS ARE HOWEVER OCCURRING OVER PORTIONS OF THE SW CARIBBEAN S OF 11N DUE TO CLOSE PROXIMITY OF THE MONSOON TROUGH AXIS WHICH EXTENDS FROM THE EASTERN PACIFIC REGION ALONG 08N TO NORTHERN COLOMBIA NEAR 08N77W. OTHERWISE...A FEW PASSING LOW-TOPPED ISOLATED SHOWERS ARE NOTED ON SATELLITE IMAGERY ACROSS SW HISPANIOLA...THE ADJACENT WATERS SURROUNDING THE WINDWARD PASSAGE...PUERTO RICO AND THE US/UK VIRGIN ISLANDS...AND THE SE CARIBBEAN S OF 15N E OF 65W. WHILE CONDITIONS ARE CONVECTIVELY QUIET...THE EXISTING PRESSURE GRADIENT BETWEEN A STRONG CENTRAL ATLC RIDGE AND LOWER PRESSURE ACROSS NORTHERN SOUTH AMERICA IS PROVIDING FOR ENHANCED EASTERLY TRADE WIND FLOW IN THE RANGE OF 20 TO 30 KT. THESE TRADES ARE EXPECTED TO PERSIST THROUGH LATE THURSDAY. ATLANTIC OCEAN... A MIDDLE TO UPPER LEVEL RIDGE IS OVER THE SW NORTH ATLC WITH AXIS EXTENDING NORTHWARD ALONG 73W FROM THE WESTERN CARIBBEAN SEA. WATER VAPOR IMAGERY INDICATES FAIRLY DRY AIR REMAINS S OF 26N...HOWEVER WITH THE APPROACH OF A FRONTAL TROUGH CURRENTLY OVER THE SE CONUS AND EASTERN GULF OF MEXICO...SCATTERED SHOWERS AND TSTMS ARE OCCURRING ACROSS PORTIONS OF THE FLORIDA PENINSULA...AND SW NORTH ATLC WATERS NW OF A LINE FROM 26N79W TO 32N74W. OTHERWISE...THE REMAINDER OF THE SW NORTH ATLC AND CENTRAL ATLC ARE UNDER THE INFLUENCE OF A 1027 MB HIGH CENTERED NEAR 32N55W. A SURFACE RIDGE AXIS EXTENDS SW FROM THE HIGH TO THE BAHAMAS AND CUBA. FARTHER EAST...AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY IN THE VICINITY OF 28N48W THAT CONTINUES TO SUPPORT A STATIONARY FRONT ANALYZED FROM 32N23W TO 29N27W TO 25N28W THAT BECOMES A SHEAR LINE SW TO 10N60W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING WITHIN 90 NM EITHER SIDE OF THE STATIONARY FRONT. AS FOR THE SHEAR LINE...RECENT SCATTEROMETER PASSES INDICATE THE PRESENCE OF THE AXIS WITH STRONGER WINDS TO THE NORTH AND WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS OCCURRING WITHIN 240 NM EITHER SIDE OF THE SHEAR LINE AXIS. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN