000 AXNT20 KNHC 201203 TWDAT TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 705 AM EST WED NOV 20 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1115 UTC. ...SPECIAL FEATURE... THE CENTER OF SUBTROPICAL STORM MELISSA AT 20/0900 UTC IS NEAR 34.8N 50.2W...ABOUT 1380 KM/745 NM...TO THE EAST-NORTHEAST OF BERMUDA. MELISSA IS MOVING NORTHEASTWARD 20 KNOTS. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 988 MB. THE MAXIMUM SUSTAINED WIND SPEEDS ARE 45 KNOTS WITH GUSTS TO 55 KNOTS. PUBLIC ADVISORIES ON SUBTROPICAL STORM MELISSA ARE ISSUED UNDER WMO HEADER WTNT34 KNHC AND UNDER AWIPS HEADER MIATCPAT4. FORECAST/ADVISORIES ON SUBTROPICAL STORM MELISSA ARE ISSUED UNDER WMO HEADER WTNT24 KNHC AND UNDER AWIPS HEADER MIATCMAT4. LARGE SWELLS WILL CONTINUE TO AFFECT BERMUDA...SECTIONS OF THE NORTHERN LEEWARD ISLANDS...PUERTO RICO...HISPANIOLA...AND THE SOUTHEASTERN BAHAMAS DURING THE NEXT COUPLE OF DAYS...CAUSING LIFE- THREATENING SURF AND RIP CURRENTS. PLEASE REFER TO STATEMENTS FROM YOUR LOCAL WEATHER SERVICE OFFICE FOR MORE DETAILS. CONVECTIVE PRECIPITATION...SCATTERED STRONG FROM 34N TO 36N BETWEEN 49W AND 51W. WIDELY SCATTERED MODERATE TO ISOLATED STRONG FROM 31N TO 34N BETWEEN 47W AND 51W. PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT1/FZNT01 KWBC...FOR MORE DETAILS ABOUT THE WINDS AND SEA HEIGHTS THAT ACCOMPANY SUBTROPICAL STORM MELISSA. A MIDDLE LEVEL TO UPPER LEVEL TROUGH IS IN THE ATLANTIC OCEAN THROUGH 32N50W TO 27N51W 24N51W 18N62W...INTO THE SOUTHEASTERN CORNER OF THE CARIBBEAN SEA NEAR 13N63W...BEYOND 8N67W IN VENEZUELA. CYCLONIC WIND FLOW COVERS THE ATLANTIC OCEAN TO THE WEST OF 32N43W 17N50W 9N60W. UPPER LEVEL SOUTHWESTERLY WIND FLOW IS STREAMING FROM CENTRAL VENEZUELA...BEYOND 17N54W IN THE ATLANTIC OCEAN. AN UPPER LEVEL RIDGE IS ALONG 5N49W 13N47W 24N41W BEYOND 32N39W. ONE SURFACE TROUGH IS ALONG 28N51W 25N53W 23N55W. A SECOND SURFACE TROUGH IS ALONG 19N53W 16N55W 12N57W. CONVECTIVE PRECIPITATION...WIDELY SCATTERED MODERATE TO ISOLATED STRONG FROM 9N TO 20N BETWEEN 45W AND 60W...AND WITHIN 150 NM ON EITHER SIDE OF 20N48W 26N46W BEYOND 32N42W. ...THE ITCZ/THE MONSOON TROUGH... THE MONSOON TROUGH PASSES ACROSS COASTAL GUINEA NEAR 8N13W TO 7N15W. THE ITCZ CONTINUES FROM 7N15W TO 5N20W 6N23W 4N30W 3N38W. CONVECTIVE PRECIPITATION...SCATTERED TO NUMEROUS STRONG WITHIN 90 NM ON EITHER SIDE OF 6N11W 5N20W 4N30W 3N31W 6N37W 10N45W. RAINSHOWERS ARE POSSIBLE ELSEWHERE TO THE SOUTH OF 10N TO THE EAST OF 60W. ...DISCUSSION... THE GULF OF MEXICO... A MIDDLE LEVEL TO UPPER LEVEL RIDGE EXTENDS FROM EL SALVADOR... THROUGH THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...ACROSS WESTERN CUBA...SOUTHEASTERN FLORIDA...BEYOND 32N77W IN THE ATLANTIC OCEAN. MIDDLE LEVEL TO UPPER LEVEL SOUTHWESTERLY TO WESTERLY WIND FLOW COVERS THE GULF OF MEXICO. THE BASE OF A MIDDLE LEVEL TO UPPER LEVEL TROUGH REACHES 34N55W IN THE ATLANTIC OCEAN. THE TROUGH SUPPORTS A COLD FRONT THAT PASSES THROUGH 32N63W TO 29N70W AND 28N77W. A STATIONARY FRONT CONTINUES FROM 28N77W TO 28N81W 26N87W AND 26N94W. CONVECTIVE PRECIPITATION...BROKEN TO OVERCAST MULTILAYERED CLOUDS AND POSSIBLE RAINSHOWERS ARE ELSEWHERE TO THE NORTH OF 24N. A NORTHWEST-TO-SOUTHEAST ORIENTED TROUGH IS ALONG 27N98W 19N93W FROM THE DEEP SOUTH OF TEXAS TO THE SOUTHWESTERN CORNER OF THE GULF OF MEXICO. CONVECTIVE PRECIPITATION...ISOLATED MODERATE TO THE SOUTH OF 27N TO THE WEST OF 90W. A SECOND SURFACE TROUGH IS ALONG 25N85W...TO THE NORTHEASTERN CORNER OF THE YUCATAN PENINSULA...TO 17N87W IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA. CONVECTIVE PRECIPITATION...ISOLATED MODERATE TO THE SOUTH OF 26N TO THE EAST OF 88W. A THIRD SURFACE TROUGH RUNS FROM THE NORTHERN BAHAMAS TO THE FLORIDA KEYS. CONVECTIVE PRECIPITATION...TO THE NORTH OF THE LINE FROM 30N60W 27N70W 25N75W TO 25N81W IN THE FLORIDA KEYS. A SURFACE RIDGE PASSES THROUGH NORTHERN LOUISIANA INTO CENTRAL TEXAS. FOR THE OFFSHORE OIL PLATFORM SITES THAT ARE TO THE NORTH OF 27N TO THE WEST OF 88W... LOW CLOUD CEILINGS ARE OBSERVED AT THE FOLLOWING ICAO STATIONS...KMZG...KBBF...KBQX...KVAF...KEMK...KGUL...KMDJ...AND CLEARING SKIES AT KDLP. MIDDLE LEVEL CEILINGS ARE BEING OBSERVED AT THE FOLLOWING ICAO STATIONS KGUL...KEHC...AND KGBK. FAIR SKIES/CLEAR SKIES AT OR LOWER THAN 12000 FEET ARE BEING REPORTED AT THE REST OF THE ICAO STATIONS. LOW CLOUD CEILINGS COVER THE TEXAS COASTAL PLAINS FROM THE HOUSTON METROPOLITAN AREA SOUTHWARD TO THE DEEP SOUTH OF TEXAS. MULTILAYERED CLOUD CEILINGS COVER THE AREA FROM MARY ESTHER TO VALPARAISO AND TO DESTIN IN THE FLORIDA PANHANDLE. LOW CLOUD CEILINGS COVER THE AREA FROM APALACHICOLA TOWARD MARIANNA BETWEEN TALLAHASSEE AND PANAMA CITY. A HIGH CEILING COVERS PERRY. MULTILAYERED CLOUD CEILINGS COVER THE AREA FROM BROOKSVILLE TO THE TAMPA METROPOLITAN AREA TO SARASOTA TO PUNTA GORDA. THE VISIBILITIES ARE ONE MILE OR LESS WITH FOG IN THE FORT MYERS METROPOLITAN AREA. ...HISPANIOLA... LARGE SWELLS FROM SUBTROPICAL STORM MELISSA WILL CONTINUE TO AFFECT HISPANIOLA...PUERTO RICO...SECTIONS OF THE NORTHERN LEEWARD ISLANDS...AND THE SOUTHEASTERN BAHAMAS DURING THE NEXT COUPLE OF DAYS...CAUSING LIFE-THREATENING SURF AND RIP CURRENTS. PLEASE REFER TO STATEMENTS FROM YOUR LOCAL WEATHER SERVICE OFFICE FOR MORE DETAILS. A SURFACE TROUGH IS ALONG 19N73W IN THE WESTERN SECTIONS OF HAITI...ACROSS SOUTHWESTERN HAITI...TO 17N75W AND TO 15N77W. CONVECTIVE PRECIPITATION...ISOLATED MODERATE FROM 13N TO 20N BETWEEN 70W AND 80W. MIDDLE LEVEL TO UPPER LEVEL NORTHWESTERLY WIND FLOW IS MOVING ACROSS HISPANIOLA. THIS WIND FLOW IS RELATED TO THE CYCLONIC WIND FLOW THAT IS MOVING AROUND THE TROUGH THAT IS PART OF SUBTROPICAL STORM MELISSA. COMPARATIVELY DRIER AIR...APPARENT IN WATER VAPOR SATELLITE IMAGERY...ALSO COVERS HISPANIOLA. SCATTERED TO BROKEN LOW LEVEL AND MIDDLE LEVEL CLOUDS AND POSSIBLE RAINSHOWERS COVER HISPANIOLA. THE GFS FORECAST FOR 250 MB SHOWS THAT NORTHWESTERLY WIND FLOW WILL PASS ON TOP OF HISPANIOLA DURING THE NEXT 48 HOURS. A TROUGH WILL CUT ACROSS THE NORTHEASTERN CORNER OF THE CARIBBEAN SEA TOWARD THE NETHERLANDS ANTILLES FOR THE ENTIRE TIME. THE GFS FORECAST FOR 500 MB SHOWS THAT NORTHERLY WIND FLOW WILL PASS ON TOP OF HISPANIOLA FOR THE NEXT 48 HOURS. AN ANTICYCLONIC CIRCULATION CENTER WILL BE IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA FOR THE ENTIRE TIME. THE GFS FORECAST FOR 700 MB SHOWS THAT HISPANIOLA WILL START WITH WEAK TO SLIGHTLY ANTICYCLONIC WIND FLOW FOR THE FIRST 12 TO 18 HOURS. CYCLONIC WIND FLOW WITH AN INVERTED TROUGH WILL COVER THE AREA FOR MOST OF THE REST OF THE FORECAST PERIOD...UNTIL THE LAST 6 HOURS OR SO WHEN ANTICYCLONIC WIND FLOW RETURNS. THE REST OF THE CARIBBEAN SEA... A MIDDLE LEVEL TO UPPER LEVEL RIDGE EXTENDS FROM WESTERN NICARAGUA...THROUGH THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA...ACROSS WESTERN CUBA...SOUTHEASTERN FLORIDA AND THE BAHAMAS...BEYOND 32N76W IN THE ATLANTIC OCEAN. ONE SURFACE TROUGH IS IN THE WESTERN CARIBBEAN SEA ALONG 14N80W 15N82W 17N84W. A SECOND SURFACE TROUGH IS ALONG 25N85W IN THE GULF OF MEXICO...TO THE NORTHEASTERN CORNER OF THE YUCATAN PENINSULA...TO 17N87W IN THE NORTHWESTERN CORNER OF THE CARIBBEAN SEA. CONVECTIVE PRECIPITATION...ISOLATED MODERATE TO THE NORTH OF 16N TO THE WEST OF 80W. A THIRD SURFACE TROUGH IS IN THE EASTERN CARIBBEAN SEA ALONG 17N64W 15N67W 13N68W. SCATTERED TO BROKEN LOW CLOUDS AND POSSIBLE RAINSHOWERS ARE FROM 13N TO 20N BETWEEN 56W AND 70W IN THE ATLANTIC OCEAN AND IN THE CARIBBEAN SEA. MIDDLE LEVEL TO UPPER LEVEL CYCLONIC WIND FLOW COVERS THE AREA THAT IS TO THE EAST OF 75W. THE CYCLONIC WIND FLOW IS ASSOCIATED WITH THE WIND FLOW THAT IS MOVING AROUND SUBTROPICAL STORM MELISSA IN THE ATLANTIC OCEAN. MIDDLE LEVEL TO UPPER LEVEL ANTICYCLONIC WIND FLOW COVERS THE CARIBBEAN SEA THAT IS TO THE WEST OF 75W. THE REST OF THE ATLANTIC OCEAN... A MIDDLE LEVEL TO UPPER LEVEL CYCLONIC CIRCULATION CENTER IS NEAR 17N23W JUST TO THE EAST OF THE CAPE VERDE ISLANDS. CYCLONIC WIND FLOW COVERS THE AREA FROM 4N TO 23N BETWEEN 10W AND 40W. A SURFACE RIDGE PASSES THROUGH A 1026 MB HIGH PRESSURE CENTER THAT IS NEAR 32N27W...TO 28N32W 25N37W 19N46W AND 12N50W. THIS RIDGE IS TO THE EAST OF SUBTROPICAL STORM MELISSA. SURFACE ANTICYCLONIC WIND FLOW MOVES AROUND A 1015 MB HIGH PRESSURE CENTER THAT IS NEAR 27N67W...BETWEEN THE 32N63W 29N70W 28N77W COLD FRONT THAT IS TO THE NORTHWEST...AND TWO TROUGHS... ONE ALONG 28N51W 25N53W 23N55W AND THE SECOND ONE ALONG 19N53W 16N55W 12N57W...THAT ARE TO THE EAST AND SOUTHEAST. PLEASE READ THE HIGH SEAS FORECAST...MIAHSFAT1/FZNT01 KWBC...FOR MORE DETAILS ABOUT THE WINDS AND SEA HEIGHTS THAT ACCOMPANY SUBTROPICAL STORM MELISSA. A SECOND AREA OF INTEREST CONSISTS OF WEST TO SOUTHWEST WINDS 20 TO 30 KNOTS AND SEA HEIGHTS 10 TO 15 FEET TO THE NORTH OF 27N BETWEEN 41W AND 56W...EXCEPT 14 TO 21 FEET TO THE NORTH OF 29N BETWEEN 47W AND 54W. A THIRD AREA OF INTEREST CONSISTS OF WINDS 20 KNOTS OR LESS AND SEA HEIGHTS 8 TO 11 FEET ELSEWHERE TO THE EAST OF 70W TO LINE FROM 31N36W TO 17N55W TO 17N62W. A FOURTH AREA OF INTEREST CONSISTS OF A COLD FRONT FROM 31N65W TO 28N77W THEN STATIONARY TO 28N81W. EXPECT WINDS 20 KNOTS OR LESS AND SEA HEIGHTS 8 TO 10 FEET TO THE NORTH OF 27N TO THE WEST OF 70W. A FIFTH AREA OF INTEREST CONSISTS OF WINDS 20 KNOTS OR LESS AND SEA HEIGHTS 8 FEET FROM 13N TO 22N TO THE EAST OF 38W. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ MT