TC 16P(KEVIN) Super Typhoon Intensity//Remnants 11S(FREDDY) Tropical Cyclone Formation Alert//15P(JUDY) subtropical//0403utc

JTWC IS ISSUING 6HOURLY WARNINGS AND 3HOURLY SATELLITE BULLETINS ON TC 16P(KEVIN). 3HOURLY SATELLITE BULLETINS ARE ISSUED ON SS 15P(JUDY) AND THE REMNANTS OF TC 11S(FREDDY).

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL CYCLONE 16P (KEVIN) HAS UNDERGONE A PERIOD OF EXTREMELY RAPID INTENSIFICATION (ERI) OVER THE PAST 12 HOURS WITH INTENSITY INCREASING FROM 95 KNOTS TO AT LEAST 130 KNOTS, OVER 25 KNOTS OF THAT INTENSIFICATION OCCURRING IN JUST THE LAST SIX HOURS. ONCE CLEAR OF THE SOUTHERN VANUATU ISLANDS, THE GLOVES CAME OFF AND KEVIN COMMENCED A METEORIC DEVELOPMENT PHASE, THE EYE RAPIDLY CLEARED OUT AND IS NOW 21NM WIDE. EYE TEMPERATURES WERE NEAR +9C AT 0000Z AND HAVE SUBSEQUENTLY CONTINUED TO WARM AND ARE NEAR +16C AT 0100Z. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EYE IN THE EIR IMAGERY, THOUGH COULD BE SLIGHTLY OFFSET DOWN-TRACK DUE TO SOME POSSIBLE TILT IN THE VORTEX AND THE LACK OF RECENT MICROWAVE IMAGERY TO CLARIFY THE CORE STRUCTURE. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM CONFIDENCE AT 130 KNOTS BASED ON A BLEND OF AGENCY DVORAK CURRENT INTENSITY ESTIMATES, THE SATCON (132 KTS), ADT (131 KTS), AND OPEN-AIIR (132 KTS) ESTIMATES. SUBSEQUENT ADT ESTIMATES HAVE CONTINUED TO RISE, APPROACHING T7.0 BY 0100Z. OBVIOUSLY THE ENVIRONMENT REMAINS VERY CONDUCIVE THOUGH CIMSS SHEAR ANALYSIS REVEALS 15 KNOTS OF NORTHWESTERLY SHEAR, BUT CLEARLY THE SYSTEM IS ABLE TO FIGHT OFF THIS SHEAR FOR THE TIME BEING. SSTS REMAIN WARM AND OUTFLOW ALOFT IS STRONG, WITH A POLEWARD OUTFLOW CHANNEL ENHANCING THE MESOSCALE ANTICYCLONE DIRECTLY OVER TOP OF THE SYSTEM.

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: NO SIGNIFICANT CHANGE IN THE FORECAST TRACK IS EXPECTED THROUGH THE FORECAST PERIOD, WITH TC 15P ACCELERATING SOUTHEASTWARD ALONG THE WESTERN SIDE OF THE STEERING RIDGE CENTERED SOUTH OF SAMOA. TRACK SPEEDS ARE LIKELY TO SLOW TOWARDS THE END OF THE FORECAST AS THE STEERING GRADIENT IS ANTICIPATED TO WEAKEN SLIGHTLY. OTHERWISE, THE FORECAST TRACK REMAINS VERY CONSISTENT WITH THE PREVIOUS JTWC FORECASTS. IN TERMS OF INTENSITY, TC 16P HAS CLEARLY EXCEEDED ALL EXPECTATIONS IN REACHING ITS CURRENT INTENSITY. PASSING OVER WATERS ALREADY CHURNED UP BY THE PASSAGE OF TC JUDY, IT APPEARED UNLIKELY THERE WOULD BE ENOUGH ENERGY TO SUPPORT THE SYSTEM REACHING ITS CURRENT INTENSITY. THE STRONG RADIAL OUTFLOW COMBINED WITH A TAP INTO THE DIVERGENT POLEWARD OUTFLOW ON THE UPSTREAM SIDE OF A MID-LATITUDE TROUGH FUELED RAPID AXISYMMETRIZATION AS THE SYSTEM MOVED INTO OPEN WATERS. THESE FACTORS WERE LIKELY JUST ENOUGH TO OFFSET THE RELATIVELY LOW OHC AVAILABLE AND ENABLED THE ERI SEEN THIS MORNING. BUT AS THE CIMSS SHEAR ANALYSIS REVEALS, CONDITIONS ARE ALREADY STARTING TO CHANGE, WITH SHEAR NOW UP TO ABOUT 15 KNOTS. SHEAR IS EXPECTED TO CONTINUE TO RISE SHARPLY OVER THE NEXT 12 HOURS OR SO, AND IS EXPECTED TO REACH 30 KNOTS BY ABOUT TAU 12 AND INCREASING RAPIDLY THEREAFTER. IN THE NEXT SIX HOURS OR SO, TC 16P WILL LIKELY PEAK AT 135-140 KNOTS, AS EVIDENCED BY THE CONTINUING UPTICK IN ADT ESTIMATES. BUT BY TAU 12 IT WILL START TO FEEL THE EFFECTS OF THE INCREASING SHEAR AND A DECREASE IN AVAILABLE ENERGY AS IT MOVES INTO STEADILY COOLER WATERS AND BEGIN TO WEAKEN. BY TAU 36, SHEAR WILL INCREASE AGAIN TO OVER 45 KNOTS, AND EFFECTIVELY DECAPITATE THE SYSTEM, LEADING TO RAPID WEAKENING. SIMULTANEOUSLY THE SYSTEM WILL BE SMOTHERED BY MID-LEVEL DRY AIR ENCROACHING FROM THE WEST, MARKING THE START OF SUBTROPICAL TRANSITION (STT). BY TAU 48, THE REMNANT LOW-LEVEL CIRCULATION THAT WAS ONCE TC 16P, WILL COMPLETE STT AS A STRONG GALE-FORCE SUBTROPICAL LOW.

MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN VERY TIGHT AGREEMENT, WITH ONLY 75NM OF SPREAD AT THE END OF THE FORECAST PERIOD. THE JTWC FORECAST REMAINS CONSISTENT WITH PREVIOUS FORECASTS AND LIES NEAR MULTI-MODEL CONSENSUS MEAN WITH HIGH CONFIDENCE. INTENSITY FORECAST IS IN GENERALLY GOOD AGREEMENT, THOUGH THE GFS AND HWRF ARE A BIT UNREALISTIC INDICATING EXTREMELY RAPID WEAKENING BEGINNING AT THE START OF THE FORECAST. THE COAMPS-TC IS A BIT MORE REALISTIC, SHOWING A SLIGHT INTENSIFICATION THROUGH TAU 06 FOLLOWED BY RAPID WEAKENING TO THE END OF THE FORECAST PERIOD. THE JTWC TRACKS THE COAMPS-TC TO TAU 12, THEN LIES ABOUT 5-10 KNOTS ABOVE THE CONSENSUS MEAN THROUGH THE REMAINDER OF THE FORECAST PERIOD, WITH MEDIUM CONFIDENCE.

THE AREA OF CONVECTION (REMNANTS 11S) PREVIOUSLY LOCATED NEAR 21.8S 38.1E IS NOW LOCATED NEAR 22.0S 38.7E. APPROXIMATELY 130 NM WEST- NORTHWEST OF EUROPA ISLAND. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY REVEALS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) THAT IS SLOWLY BECOMING MORE TUCKED BENEATH THE PERSISTENT DEEP CONVECTION WITHIN THE EASTERN PERIPHERIES. ENVIRONMENTALS ARE RIPE FOR FURTHER DEVELOPMENT OF 11S WITH WARM SEA SURFACE TEMPERATURES (28-29C), LOW VWS (10-15KT), AND NOTEWORTHY EQUATORWARD AND POLEWARD OUTFLOW. GLOBAL MODELS ARE IN GOOD AGREEMENT WITH 11S TRACKING GENERALLY EASTWARD WITH DEVELOPMENT AND INTENSIFICATION IN THE NEXT 12-36 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 27 TO 33 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1001 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS UPGRADED TO HIGH.

GLOBAL MODELS ARE IN GOOD AGREEMENT WITH 11S TRACKING GENERALLY EASTWARD WITH DEVELOPMENT AND INTENSIFICATION IN THE NEXT 12-36 HOURS.

THE AREA OF CONVECTION (INVEST 15P) PREVIOUSLY LOCATED NEAR 27.1N 174.8W IS NOW LOCATED NEAR 27.7S 172.6W, APPROXIMATELY 418 NM SOUTH-SOUTHEAST OF TONGA. THE SYSTEM IS CURRENTLY CLASSIFIED AS A SUBTROPICAL CYCLONE, GENERALLY CHARACTERIZED AS HAVING BOTH TROPICAL AND MIDLATITUDE CYCLONE FEATURES. THE REMNANTS OF TC 15P (JUDY) HAS BEEN COMPLETELY DECOUPLED AND WILL REMAIN OVER COOLER (24-25 C) SEA SURFACE TEMPERATURES (SSTS) OVER THE NEXT 24-48 HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 040400Z SSMIS 91 GHZ PASS SHOW A WELL- DEFINED, FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH THE PARENT CONVECTION SHEARED TO THE EAST DUE TO INTENSE (60-70 KT) VERTICAL WIND SHEAR (VWS). GLOBAL NUMERICAL MODELS SHOW TC 15P TRACKING EASTWARD WITH LITTLE TO NO FURTHER TROPICAL DEVELOPMENT. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 48 TO 52 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 985 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS IS LOW.