000 AXNT20 KNHC 202352 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE NOV 20 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2315 UTC. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N13W TO 07N17W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 07N17W TO 06N20W TO 08N28W TO 07N33W TO 08N41W TO 06N48W TO 08N57W. WIDELY SCATTERED MODERATE CONVECTION IS FROM 03N-11N BETWEEN 26W-40W. MUCH OF THIS CONVECTION IS ENHANCED BY A MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 17N41W PROVIDING MAXIMUM DIFFLUENCE EAST OF THE UPPER LEVEL TROUGH AXIS. ...DISCUSSION... GULF OF MEXICO... WATER VAPOR IMAGERY INDICATES FAIRLY ZONAL WESTERLY FLOW OVER MUCH OF THE GULF THIS EVENING...HOWEVER A MID-LEVEL SHORTWAVE TROUGH IS PROGRESSING OVER THE LOWER MISSISSIPPI RIVER VALLEY CURRENTLY AND PROVIDING FOR SOME ISOLATED SHOWERS OVER INLAND PORTIONS OF THE FLORIDA PANHANDLE...SOUTHERN ALABAMA...AND GEORGIA. ELSEWHERE OVER THE GULF...SURFACE RIDGING ANCHORED OVER THE NW GULF WATERS IS PROVIDING NORTH-NORTHEASTERLY WINDS IN THE RANGE OF 10 TO 20 KT WITH THE SURFACE RIDGE AXIS EXTENDING SOUTHWARD ALONG THE EASTERN MEXICO COAST. DUE TO LOW-LEVEL CONVERGENCE...A SURFACE TROUGH IS ANALYZED FROM 18N92W TO 23N93W AND IS PROVIDING FOCUS FOR MOISTURE CONVERGENCE AND ISOLATED SHOWERS S OF 24N BETWEEN 88W-97W. THE RIDGING IS FORECAST TO REMAIN ANCHORED OVER THE SE CONUS WITH N-NE WINDS PERSISTING THROUGH EARLY THURSDAY. CARIBBEAN SEA... SOUTHWESTERLY TO WESTERLY UPPER LEVEL FLOW DOMINATES OVER THE CARIBBEAN THIS EVENING AND IS PROVIDING FOR MAXIMUM UPPER LEVEL DIFFLUENCE EAST OF AN UPPER LEVEL TROUGH AXIS FROM 20N87W TO 10N92W. LOW-LEVEL CONVERGENCE IS ALSO MAXIMIZED OVER THE SW CARIBBEAN EAST OF THE UPPER LEVEL TROUGH AND IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 08N-16N BETWEEN 76W-83W. LOW-LEVEL MOISTURE AND THE CONVECTIVE DEBRIS CLOUDINESS STREAMS NORTHEASTWARD ACROSS PORTIONS OF HISPANIOLA AND PUERTO RICO THIS EVENING INTO AN UPPER LEVEL TROUGH OVER THE SW NORTH ATLC WITH AXIS ALONG 67W. A FEW ALTHOUGH THE REGION LACKS A SURFACE BOUNDARY...ENOUGH MIDDLE TO UPPER LEVEL DYNAMICS ARE IN PLACE TO GENERATE ISOLATED SHOWERS AND TSTMS WITHIN 120 NM EITHER SIDE OF A LINE FROM 20N65W TO 15N76W. OTHERWISE...THE OVERALL SYNOPTIC PATTERN IS LIKELY TO CHANGE LITTLE OVER THE NEXT FEW DAYS AS A LOW PRESSURE AREA REMAINS OVER THE SW NORTH ATLC WITH TROUGHING DIPPING SOUTHWARD ACROSS THE EASTERN CARIBBEAN AND RIDGING HOLDING IN PLACE OVER THE NW CARIBBEAN. ATLANTIC OCEAN... A COMPLEX AREA OF SURFACE LOW PRESSURE IS LOCATED OVER THE SW NORTH ATLC IS CONTINUES TO BE SUPPORTED WITH A MIDDLE TO UPPER LEVEL LOW CENTERED NEAR 35N64W. THE MAIN 997 MB OCCLUDED LOW IS CENTERED NEAR 35N65W AND EXTENDS A COLD FRONT INTO THE DISCUSSION AREA NEAR 32N60W THEN SW TO 24N67W. LOCATED IN AN AREA OF MAXIMUM UPPER LEVEL DIFFLUENCE...SCATTERED SHOWERS AND TSTMS ARE OCCURRING WITHIN 420 NM EAST OF THE COLD FRONT. ISOLATED SHOWERS ARE ELSEWHERE SE OF THE COLD FRONT FROM 18N-24N BETWEEN 52W-67W. SECONDARY AND TERTIARY WAVES OF ENERGY FOLLOW IN WAKE OF THE PRIMARY COLD FRONT AS TWO WEAK LOWS ARE EASTWARD MOVING ALONG 29N BETWEEN 68W AND 76W. FARTHER EAST...THE REMAINDER OF THE CENTRAL AND EASTERN ATLC IS UNDER THE INFLUENCE OF SURFACE RIDGING ANCHORED BY A 1025 MB HIGH CENTERED NEAR 36N35W. HOWEVER...WATER VAPOR IMAGERY INDICATES A MIDDLE TO UPPER LEVEL SHORTWAVE TROUGH EXTENDS FROM 32N23W TO 24N29W AND SUPPORTS A COLD FRONT ANALYZED FROM 32N17W TO 29N31W THAT BECOMES STATIONARY TO 30N44W TO 32N50W...BRIDGING THE PREVIOUSLY MENTIONED SURFACE RIDGE. ISOLATED SHOWERS ARE OCCURRING WITHIN 60 NM EITHER SIDE OF THE FRONTAL BOUNDARY. FINALLY...A MIDDLE TO UPPER LEVEL LOW IS CENTERED NEAR 17N41W AND CONTINUES TO PROVIDING MAXIMUM UPPER LEVEL DIFFLUENCE E OF 40W. WIDELY SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 11N-22N BETWEEN 27W-42W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN