000 AXNT20 KNHC 192350 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 PM EST TUE NOV 19 2013 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. ...SPECIAL FEATURES... SUBTROPICAL STORM MELISSA IS CENTERED NEAR 33.0N 53.7W AT 19/2100 UTC OR ABOUT 560 NM E OF BERMUDA MOVING NE AT 14 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. ISOLATED MODERATE CONVECTION IS FROM 32N-36N BETWEEN 54W-58W. SCATTERED MODERATE CONVECTION IS WELL EAST OF THE CENTER IN THE AREA OF MAXIMUM WARM AIR ADVECTION FROM 27N-40N BETWEEN 41W-50W. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMAT4/WTNT24 KNHC FOR MORE DETAILS. ...ITCZ/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM THE AFRICAN COAST NEAR 09N13W TO 06N20W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N20W TO 05N30W TO 07N47W. ISOLATED MODERATE CONVECTION IS FROM 03N-07N BETWEEN 19W-32W. ...DISCUSSION... GULF OF MEXICO... SOUTHWEST TO WESTERLY FLOW IS NOTED ON WATER VAPOR IMAGERY OVER THE GULF BASIN THIS EVENING EAST OF AN APPROACHING UPPER LEVEL TROUGH WITH AXIS FROM OVER THE BIG BEND REGION OF TEXAS SW TO SOUTHERN BAJA CALIFORNIA NEAR 24N112W. THE MID-LEVEL SHORTWAVE TROUGHING IS NOTED SLIGHTLY NORTH AND EAST OVER THE LOWER MISSISSIPPI RIVER VALLEY AND SUPPORTS A DEVELOPING AREA OF LOW PRESSURE OVER THE WESTERN GULF. AS OF 19/2100 UTC...A 1011 MB LOW IS CENTERED NEAR 25N95W WITH A SURFACE TROUGH AXIS EXTENDING SOUTHWARD TO 22N96W. THE LOW IS FORMING ALONG A FRONTAL WAVE ANALYZED AS A STATIONARY FRONT FROM 26N90W INTO THE LOW CENTER AND THEN INLAND ACROSS NE MEXICO NEAR 25N98W. WITH LOW-LEVEL MOISTURE CONVERGENCE AND AN OVERALL DIFFLUENT ENVIRONMENT ALOFT OVER THE WESTERN GULF...SCATTERED SHOWERS AND ISOLATED TSTMS ARE OCCURRING FROM 23N-29N WEST OF 87W. A PORTION OF THIS CONVECTION E OF 90W REMAINS ASSOCIATED WITH A GRADUALLY WEAKENING COLD FRONT ANALYZED INTO THE GULF VIA THE SW NORTH ATLC AND ACROSS THE CENTRAL FLORIDA PENINSULA THIS EVENING FROM 27N83W TO 26N90W. ISOLATED SHOWERS AND TSTMS ARE OCCURRING GENERALLY WITHIN 120 NM S OF THE FRONT E OF 87W...INCLUDING ACROSS THE SOUTHERN FLORIDA PENINSULA. THE SURFACE LOW IS FORECAST TO REMAIN WEAK AND DRIFT WESTWARD THROUGH LATE WEDNESDAY AS NORTHEASTERLY WINDS VEER E-SE BY EARLY THURSDAY. SOUTHERLY RETURN FLOW WILL THEN ONCE AGAIN DOMINATE OVER THE GULF THROUGH LATE FRIDAY WHEN THE NEXT COLD FRONT IS EXPECTED TO EMERGE OFF THE TEXAS AND LOUISIANA COASTS. CARIBBEAN SEA... AN UPPER LEVEL ANTICYCLONE IS CENTERED OVER THE WESTERN CARIBBEAN NEAR 16N84W AND IS PROVIDING MUCH OF THE BASIN E OF 84W WITH DRY NORTHWESTERLY FLOW ALOFT. IN ADDITION...AN UPPER LEVEL TROUGH IS NOTED ON WATER VAPOR IMAGERY E OF 66W BUT IS HOWEVER REMAINING VERY DRY AND STABLE ALOFT. WITH OVERALL STABILITY ALOFT DOMINATING...CONDITIONS AT THE SURFACE REMAIN FAIRLY TRANQUIL WITH ONLY A FEW AREA OF ISOLATED LOW-TOPPED SHOWERS OCCURRING THIS EVENING. ONE AREA IS FROM 13N-16N BETWEEN 66W-69W AND THE OTHER AREA IS FROM 14N-19N BETWEEN 70W- 76W...INCLUDING PORTIONS OF HISPANIOLA. FARTHER WEST...THE UPPER LEVEL ANTICYCLONE IS PROVIDING AMPLE LIFT TO GENERATE ISOLATED SHOWERS AND TSTMS ACROSS THE NW CARIBBEAN FROM 17N-20N BETWEEN 83W-89W. FINALLY...A FEW ISOLATED SHOWERS AND TSTMS ARE NOTED S OF 11N...INCLUDING INLAND PORTIONS OF PANAMA AND COSTA RICA DUE TO THE CLOSE PROXIMITY OF THE MONSOON TROUGH ANALYZED ALONG 07N/ 08N BETWEEN NORTHERN COLOMBIA AND EXTREME SOUTHERN COSTA RICA. TRADES ARE FORECAST TO REMAIN 20 KT OR LESS THROUGH THE REMAINDER OF THE WEEK INTO THE UPCOMING WEEKEND. ...HISPANIOLA... CURRENTLY A FEW ISOLATED LOW-TOPPED SHOWERS ARE OCCURRING OVER PORTIONS OF HISPANIOLA AND THE SOUTHERN COASTAL WATERS STRETCHING INTO THE CENTRAL CARIBBEAN SEA. WHILE THIS LOW-LEVEL MOISTURE CONTINUES TO LINGER...ALOFT MIDDLE TO UPPER LEVEL NORTHWESTERLY FLOW IS PROVIDING A VERY DRY AND STABLE ENVIRONMENT LIMITING OVERALL DEEPER CONVECTION. A WEAK PRESSURE GRADIENT REMAINS OVER THE ISLAND AND GIVEN THE STABILITY...FAIR CONDITIONS AND TRANQUIL WEATHER IS EXPECTED OVER THE NEXT FEW DAYS. ATLANTIC OCEAN... A DEEP LAYERED MIDDLE TO UPPER LEVEL TROUGH CONTINUES TO MOVE NORTHEASTWARD OVER THE EXTREME NORTHEASTERN CONUS AND WESTERN NORTH ATLC THAT SUPPORTS A COLD FRONT ANALYZED INTO THE DISCUSSION AREA NEAR 32N70W. THE FRONT CONTINUES W-SW TO THE CENTRAL FLORIDA PENINSULA NEAR 28N81W AND INTO THE GULF OF MEXICO. WITH MOST OF THE UPPER LEVEL DYNAMICS WELL NORTH OF THE AREA...ISOLATED SHOWERS AND TSTMS ARE OCCURRING N OF 26N TO THE FRONTAL BOUNDARY BETWEEN 64W AND 80W. A WEAK SURFACE RIDGE REMAINS TO THE SOUTH OF THE FRONT FOCUSED ON A 1014 MB HIGH CENTERED NEAR 26N71W. FARTHER EAST...THE MIDDLE TO UPPER LEVEL LOW ASSOCIATED WITH SUBTROPICAL STORM MELISSA IS CENTERED NEAR 33N53W AND EXTENDS A TROUGH AXIS SOUTHWARD ALONG 25N56W TO A BROAD BASE OVER THE EASTERN CARIBBEAN SEA NEAR 13N67W. WHILE MELISSA CONTINUES TO TRACK TO THE NORTHEAST...SURFACE TROUGHING RESULTS OVER THE CENTRAL ATLC FROM 13N57W TO 22N52W AND PROVIDES FOCUS FOR LOW-LEVEL MOISTURE CONVERGENCE. THIS CONVERGENCE ALONG WITH A LARGE AREA OF UPPER LEVEL DIFFLUENCE EAST OF THE UPPER LEVEL TROUGH IS GENERATING SCATTERED SHOWERS AND TSTMS FROM 11N- 32N BETWEEN 42W-52W. FINALLY...THE REMAINDER OF THE EASTERN ATLC IS UNDER THE INFLUENCE OF A SURFACE RIDGE ANCHORED BY A SOUTHWARD MOVING 1027 MB HIGH CENTERED SOUTH OF THE AZORES NEAR 35N26W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ HUFFMAN