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Subtropical Storm MELISSA Forecast Discussion Number 6

2013-11-19 21:46:43| National Hurricane Center (Atlantic)

Issued at 500 PM AST TUE NOV 19 2013 000 WTNT44 KNHC 192046 TCDAT4 SUBTROPICAL STORM MELISSA DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142013 500 PM AST TUE NOV 19 2013 MELISSA APPEARS TO BE ON THE CUSP OF MAKING THE TRANSITION FROM A SUBTROPICAL TO A TROPICAL CYCLONE. TWO EARLIER ASCAT OVERPASSES CAPTURED THE WIND FIELD IN THE EASTERN SEMICIRCLE...WHICH INDICATED THAT THE OUTER WIND FIELD HAD WEAKENED AND THAT THE INNER-CORE WIND FIELD HAD CONTRACTED INWARD WITH THE RADIUS OF MAXIMUM WINDS NOW AT ABOUT 40-50 NMI. IN ADDITION...AN 1119 UTC AMSU OVERPASS SHOWED THAT A PRONOUNCED UPPER-LEVEL WARM CORE HAD DEVELOPED OVER THE LOW-LEVEL CENTER. THESE SATELLITE INDICATORS WOULD SUGGEST THAT MELISSA WAS NOW A TROPICAL CYCLONE. HOWEVER...THE AMSU DATA ALSO REVEALED THAT THERE WAS STILL A STRATOSPHERIC CONNECTION TO THE WARM CORE. THIS...PLUS THE LACK OF ANY DEEP CONVECTION NEAR THE WELL-DEFINED LOW-LEVEL CENTER...ARGUES FOR KEEPING MELISSA A SUBTROPICAL STORM. SINCE THE ASCAT PASSES MISSED THE WESTERN SEMICIRCLE WHERE THE STRONGEST WINDS WERE LIKELY OCCURRING IN SOME VIGOROUS CONVECTION...THE INTENSITY IS BEING MAINTAINED AT 55 KT BASED ON A SUBTROPICAL SATELLITE CLASSIFICATION FROM TAFB...AND EARLIER 53-56 KT AMSU INTENSITY ESTIMATES FROM CIRA AND CIMSS. THE INITIAL MOTION ESTIMATE IS NOW 040/14 KT. MELISSA HAS FINALLY MADE THE MUCH ANTICIPATED TURN TO THE NORTHEAST AHEAD OF A STRONG COLD FRONT AND ASSOCIATED DEEP-LAYER TROUGH. NHC MODEL GUIDANCE IS IN EXCELLENT AGREEMENT ON THE CYCLONE ACCELERATING NORTHEASTWARD OVER THE NEXT 2-3 DAYS BEFORE TURNING NORTHWARD AND MERGING WITH A FRONTAL SYSTEM IN 4-5 DAYS OVER THE FAR NORTH ATLANTIC. THE OFFICIAL FORECAST TRACK WAS SHIFTED TO THE RIGHT OF THE PREVIOUS ADVISORY TRACK AFTER 36 HOURS...AND LIES CLOSE TO THE MULTI-MODEL CONSENSUS TVCA AND THE FLORIDA STATE SUPERENSEMBLE MODEL. THE VERTICAL SHEAR HAS DROPPED SHARPLY TO ABOUT 7 KT...WHICH HAS ALLOWED THE LOW- AND MID-/UPPER-LEVEL CIRCULATION CENTERS TO FINALLY BECOME VERTICALLY ALIGNED. THE ONLY THING PREVENTING MELISSA FROM MAKING THE TRANSITION TO A TROPICAL CYCLONE IS THE LACK OF SIGNIFICANT DEEP CONVECTION ORGANIZING AROUND THE LOW-LEVEL CENTER. HOWEVER...SHALLOW TO MODERATE CONVECTION HAS BEEN DEVELOPING NEAR THE CENTER AND IN THE DRY SLOT IN THE EASTERN SEMICIRCLE DURING THE PAST COUPLE OF HOURS...AND ONLY A SLIGHT INCREASE IN THE DEPTH AND COVERAGE OF THE CONVECTION WOULD ALLOW MELISSA TO STRENGTHEN SLIGHTLY AND ALSO QUICKLY TRANSITION TO A TROPICAL STORM. THE CYCLONE IS EXPECTED TO MOVE OVER COOLER WATER AND INTO A DRIER AND MORE STABLE AIRMASS IN 24-36 HOURS...WHICH SHOULD INDUCE STEADY WEAKENING. BY 48 HOURS...INCREASING VERTICAL WIND SHEAR SHOULD ENHANCE THE WEAKENING PROCESS AND ALSO CAUSE MELISSA TO TRANSITION TO A POST-TROPICAL EXTRATROPICAL CYCLONE. THE FORECAST CLOSELY FOLLOWS THE INTENSITY CONSENSUS MODEL ICON. TRACK...INTENSITY... AND WIND RADII FORECASTS DURING THE EXTRATROPICAL STAGE WERE COORDINATED WITH THE NOAA OCEAN PREDICTION CENTER. FORECAST POSITIONS AND MAX WINDS INIT 19/2100Z 33.0N 53.7W 55 KT 65 MPH 12H 20/0600Z 34.9N 51.4W 60 KT 70 MPH 24H 20/1800Z 37.4N 46.7W 55 KT 65 MPH 36H 21/0600Z 40.1N 41.1W 50 KT 60 MPH 48H 21/1800Z 42.4N 35.4W 50 KT 60 MPH...POST-TROP/EXTRATROP 72H 22/1800Z 47.0N 26.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 96H 23/1800Z 53.5N 24.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 120H 24/1800Z...DISSIPATED $$ FORECASTER STEWART

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Summary for Subtropical Storm MELISSA (AT4/AL142013)

2013-11-19 21:46:20| National Hurricane Center (Atlantic)

...MELISSA TURNS NORTHEASTWARD OVER THE CENTRAL ATLANTIC... ...COULD STILL TRANSITION TO A TROPICAL STORM TONIGHT... As of 5:00 PM AST Tue Nov 19 the center of MELISSA was located near 33.0, -53.7 with movement NE at 16 mph. The minimum central pressure was 982 mb with maximum sustained winds of about 65 mph.

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Subtropical Storm MELISSA Public Advisory Number 6

2013-11-19 21:46:20| National Hurricane Center (Atlantic)

Issued at 500 PM AST TUE NOV 19 2013 000 WTNT34 KNHC 192045 TCPAT4 BULLETIN SUBTROPICAL STORM MELISSA ADVISORY NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142013 500 PM AST TUE NOV 19 2013 ...MELISSA TURNS NORTHEASTWARD OVER THE CENTRAL ATLANTIC... ...COULD STILL TRANSITION TO A TROPICAL STORM TONIGHT... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...33.0N 53.7W ABOUT 645 MI...1040 KM E OF BERMUDA MAXIMUM SUSTAINED WINDS...65 MPH...100 KM/H PRESENT MOVEMENT...NE OR 40 DEGREES AT 16 MPH...26 KM/H MINIMUM CENTRAL PRESSURE...982 MB...29.00 INCHES WATCHES AND WARNINGS -------------------- THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. DISCUSSION AND 48-HOUR OUTLOOK ------------------------------ AT 500 PM AST...2100 UTC...THE CENTER OF SUBTROPICAL STORM MELISSA WAS LOCATED NEAR LATITUDE 33.0 NORTH...LONGITUDE 53.7 WEST. THE STORM IS MOVING TOWARD THE NORTHEAST NEAR 16 MPH...26 KM/H. THIS GENERAL MOTION ACCOMPANIED BY A STEADY INCREASE IN FORWARD SPEED IS EXPECTED DURING THE NEXT COUPLE OF DAYS. MAXIMUM SUSTAINED WINDS ARE NEAR 65 MPH...100 KM/H...WITH HIGHER GUSTS. A SLIGHT INCREASE IN STRENGTH IS POSSIBLE TONIGHT AND WEDNESDAY MORNING...FOLLOWED BY GRADUAL WEAKENING. MELISSA COULD STILL TRANSITION TO A TROPICAL STORM TONIGHT OR ON WEDNESDAY. WINDS OF 40 MPH EXTEND OUTWARD UP TO 275 MILES...445 KM FROM THE CENTER. THE ESTIMATED MINIMUM CENTRAL PRESSURE IS 982 MB...29.00 INCHES. HAZARDS AFFECTING LAND ---------------------- SURF...LARGE SWELLS WILL CONTINUE TO AFFECT BERMUDA...PORTIONS 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 SEE STATEMENTS FROM YOUR LOCAL WEATHER SERVICE OFFICE FOR MORE DETAILS. NEXT ADVISORY ------------- NEXT COMPLETE ADVISORY...1100 PM AST. $$ FORECASTER STEWART

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Subtropical Storm MELISSA Wind Speed Probabilities Number 6

2013-11-19 21:46:11| National Hurricane Center (Atlantic)

Issued at 2100 UTC TUE NOV 19 2013 000 FONT14 KNHC 192045 PWSAT4 SUBTROPICAL STORM MELISSA WIND SPEED PROBABILITIES NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142013 2100 UTC TUE NOV 19 2013 AT 2100Z THE CENTER OF SUBTROPICAL STORM MELISSA WAS LOCATED NEAR LATITUDE 33.0 NORTH...LONGITUDE 53.7 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 55 KTS...65 MPH...100 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN STANDARD TIME (EST)...SUBTRACT 5 HOURS FROM Z TIME CENTRAL STANDARD TIME (CST)...SUBTRACT 6 HOURS FROM Z TIME I. MAXIMUM WIND SPEED (INTENSITY) PROBABILITY TABLE CHANCES THAT THE MAXIMUM SUSTAINED (1-MINUTE AVERAGE) WIND SPEED OF THE TROPICAL CYCLONE WILL BE WITHIN ANY OF THE FOLLOWING CATEGORIES AT EACH OFFICIAL FORECAST TIME DURING THE NEXT 5 DAYS. PROBABILITIES ARE GIVEN IN PERCENT. X INDICATES PROBABILITIES LESS THAN 1 PERCENT. - - - MAXIMUM WIND SPEED (INTENSITY) PROBABILITIES - - - VALID TIME 06Z WED 18Z WED 06Z THU 18Z THU 18Z FRI 18Z SAT 18Z SUN FORECAST HOUR 12 24 36 48 72 96 120 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - DISSIPATED X 1 2 3 8 12 NA TROP DEPRESSION X 5 13 16 23 29 NA TROPICAL STORM 73 75 72 65 59 53 NA HURRICANE 27 19 13 15 11 6 NA - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - HUR CAT 1 26 18 12 14 10 6 NA HUR CAT 2 1 1 1 2 1 1 NA HUR CAT 3 X X X X X X NA HUR CAT 4 X X X X X X NA HUR CAT 5 X X X X X X NA - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - FCST MAX WIND 60KT 55KT 50KT 50KT 45KT 40KT NA II. WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS IP(CP) WHERE IP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (INDIVIDUAL PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 18Z TUE AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 64 KT ARE SHOWN WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 18Z TUE 06Z WED 18Z WED 06Z THU 18Z THU 18Z FRI 18Z SAT PERIODS TO TO TO TO TO TO TO 06Z WED 18Z WED 06Z THU 18Z THU 18Z FRI 18Z SAT 18Z SUN FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT SANTA CRUZ AZO 34 X X( X) X( X) 5( 5) 5(10) X(10) X(10) $$ FORECASTER STEWART

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Subtropical Storm MELISSA Forecast Advisory Number 6

2013-11-19 21:45:36| National Hurricane Center (Atlantic)

Issued at 2100 UTC TUE NOV 19 2013 000 WTNT24 KNHC 192045 TCMAT4 SUBTROPICAL STORM MELISSA FORECAST/ADVISORY NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142013 2100 UTC TUE NOV 19 2013 THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. SUBTROPICAL STORM CENTER LOCATED NEAR 33.0N 53.7W AT 19/2100Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE NORTHEAST OR 40 DEGREES AT 14 KT ESTIMATED MINIMUM CENTRAL PRESSURE 982 MB MAX SUSTAINED WINDS 55 KT WITH GUSTS TO 65 KT. 50 KT....... 90NE 90SE 50SW 60NW. 34 KT.......240NE 150SE 150SW 200NW. 12 FT SEAS..540NE 600SE 600SW 420NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 33.0N 53.7W AT 19/2100Z AT 19/1800Z CENTER WAS LOCATED NEAR 32.5N 54.3W FORECAST VALID 20/0600Z 34.9N 51.4W MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 80NE 80SE 50SW 60NW. 34 KT...240NE 170SE 160SW 200NW. FORECAST VALID 20/1800Z 37.4N 46.7W MAX WIND 55 KT...GUSTS 65 KT. 50 KT... 60NE 60SE 60SW 0NW. 34 KT...240NE 200SE 180SW 210NW. FORECAST VALID 21/0600Z 40.1N 41.1W MAX WIND 50 KT...GUSTS 60 KT. 50 KT... 60NE 70SE 70SW 0NW. 34 KT...240NE 220SE 200SW 220NW. FORECAST VALID 21/1800Z 42.4N 35.4W...POST-TROP/EXTRATROP MAX WIND 50 KT...GUSTS 60 KT. 50 KT... 60NE 90SE 90SW 0NW. 34 KT...240NE 240SE 300SW 240NW. FORECAST VALID 22/1800Z 47.0N 26.0W...POST-TROP/EXTRATROP MAX WIND 45 KT...GUSTS 55 KT. 34 KT...300NE 240SE 210SW 180NW. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 150 NM ON DAY 4 AND 200 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 23/1800Z 53.5N 24.5W...POST-TROP/EXTRATROP MAX WIND 40 KT...GUSTS 50 KT. OUTLOOK VALID 24/1800Z...DISSIPATED REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 33.0N 53.7W NEXT ADVISORY AT 20/0300Z $$ FORECASTER STEWART

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