000 AXNT20 KNHC 071757 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 105 PM EST WED DEC 07 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1715 UTC. ...ITCZ/MONSOON TROUGH... THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N10W TO 04N35W TO 04N51W. SCATTERED MODERATE CONVECTION IS FROM 02N-08N BETWEEN 33W-49W...AND FROM 08N-13N BETWEEN 45W-50W. ...DISCUSSION... GULF OF MEXICO... AN UPPER LEVEL SHORTWAVE TROUGH IS PROGRESSING EASTWARD OVER THE MISSISSIPPI RIVER VALLEY AND SUPPORTS A COLD FRONT EXTENDING INTO THE GULF NEAR 30N84W TO 25N89W WHERE IT BECOMES STATIONARY INTO THE SW GULF TO 18N93W. ISOLATED SHOWERS ARE OCCURRING WITHIN 30 NM EITHER SIDE OF THE FRONT WITH MOSTLY OVERCAST SKIES OBSERVED WITHIN 180 NM WEST OF THE FRONT N OF 25N AND OVER THE REMAINDER OF THE SW GULF WEST OF THE FRONT S OF 25N. AS HIGH PRESSURE BUILDS IN ACROSS THE NW GULF...STRONG NORTHERLY WINDS ARE NOTED WEST OF THE FRONT WITH CLOUD COVER CONSISTING OF SCATTERED TO BROKEN STRATOCUMULUS CLOUDS N OF 25N W OF 90W. EAST OF THE FRONT...A PRE-FRONTAL SURFACE TROUGH IS ANALYZED FROM 27N85W TO 22N86W WITH ISOLATED SHOWERS WITHIN 45 NM EAST OF THE BOUNDARY. THE FRONT IS FORECAST TO SWEEP EAST OF THE GULF WATERS BY THURSDAY MORNING AS THE HIGH PRESSURE AREA BUILDS IN ACROSS THE GULF COASTAL PLAINS AND SE CONUS OVER THE WEEKEND. CARIBBEAN SEA... AN UPPER LEVEL LOW IS CENTERED IN THE SW NORTH ATLC NEAR 23N62W AND EXTENDS A TROUGH AXIS SOUTHWESTWARD INTO THE CENTRAL CARIBBEAN TO NEAR 14N79W. NORTH AND WEST OF THIS UPPER LEVEL TROUGH AN ANTICYCLONIC CIRCULATION IS CENTERED NEAR 22N82W WHICH IS ACCOMPANIED BY VERY DRY AND STABLE AIR ALOFT AS NOTED ON WATER VAPOR IMAGERY. WHILE CONDITIONS REMAIN STABLE ALOFT...NE WINDS PREVAIL AT THE SURFACE W OF 70W AND ONLY A FEW ISOLATED LOW-TOPPED SHOWERS ARE NOTED ON VISIBLE SATELLITE IMAGERY OCCURRING MOSTLY IN THE VICINITY OF THE CENTRAL AMERICAN COASTLINE AND GULF OF HONDURAS DUE TO WEAK LOW-LEVEL MOISTURE CONVERGENCE. FARTHER EAST...THE UPPER LEVEL TROUGHING IS PROVIDING AMPLE MIDDLE TO UPPER LEVEL DIFFLUENCE GENERATING AN AREA OF WIDELY SCATTERED SHOWERS SE OF A LINE FROM ANTIGUA TO BONAIRE. OVER THE NEXT FEW DAYS...THE UPPER LEVEL LOW IS FORECAST TO SLOWLY LIFT NORTHWARD INTO THE SW NORTH ATLC WATERS AS A WEAK UPPER LEVEL RIDGE ESTABLISHES ITSELF OVER THE CENTRAL CARIBBEAN ALONG 70W. ATLANTIC OCEAN... AN UPPER LEVEL LOW IS CENTERED NEAR 23N62W WITH A TROUGH AXIS EXTENDING NE TO BEYOND 32N50W...AND SW INTO THE NE CARIBBEAN SEA TO 18N70W. THIS TROUGHING SUPPORTS A 1010 MB LOW CENTERED NEAR 21N54W WITH A LENGTHY SURFACE TROUGH EXTENDING NE TO 32N43W AND SW TO THE WINDWARD ISLANDS NEAR 14N61W. SCATTERED MODERATE CONVECTION APPEARS TO BE SHEARED TO THE NE OF THE LOW CENTER OCCURRING FROM 20N-25N BETWEEN 47W-53W. ELSEWHERE...ISOLATED SHOWERS ARE OCCURRING WITHIN 150 NM EITHER SIDE OF THE ENTIRE SURFACE TROUGH...AND ELSEWHERE FROM 20N-30N BETWEEN 40W AND THE SURFACE TROUGH BOUNDARY. MOST OF THE STRONGER CONVECTIVE ACTIVITY IS ENHANCED DUE TO MIDDLE TO UPPER LEVEL DIFFLUENCE FOCUSED EAST OF THE UPPER LEVEL TROUGH AXIS. OVER THE REMAINDER OF THE SW NORTH ATLC...SURFACE HIGH PRESSURE INFLUENCE CONTINUES W OF 60W ON THE SOUTHERN PERIPHERY OF A 1024 MB HIGH CENTERED NE OF BERMUDA NEAR 35N61W. AN APPROACHING COLD FRONT...CURRENTLY ANALYZED ACROSS CENTRAL GEORGIA AND THE FLORIDA PANHANDLE INTO THE NE GULF OF MEXICO...WILL ENTER THE FAR SW NORTH ATLC WATERS BY LATE THIS EVENING INTO THURSDAY MORNING USHERING IN STRONG NORTHWESTERLY WINDS. FARTHER EAST...AN UPPER LEVEL LOW IS CENTERED NEAR 31N27W BUT HAS MINIMAL IMPACT AT THE SURFACE AS A RIDGE...ANCHORED BY A 1034 MB HIGH CENTERED E-NE OF THE AZORES NEAR 41N17W...CONTINUES TO INFLUENCE MUCH OF THE EASTERN ATLC E OF 40W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN