Super Typhoon 28W(RAI): explosive intensification from CAT 1 to CAT 5 over 24hours//Landfall imminent , 16/03utc

FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: SUPER TYPHOON (STY) 28W IS FORECAST TO CONTINUE TRACKING WEST-NORTHWESTWARD THROUGH 72H, BEFORE TURNING SHARPLY POLEWARD INTO A BREAK IN THE SUBTROPICAL RIDGE (STR) TO THE NORTH THROUGH 120H. THE SYSTEM IS EXPECTED TO MAKE LANDFALL NEAR THE NORTHEAST COAST OF MINDANAO AND THE SIARGAO AND DINAGAT ISLANDS WITHIN THE NEXT 6-8 HOURS, THEN CROSS OVER THE VISAYAS AND EMERGE INTO THE SULU SEA BY 24H. THE SYSTEM WILL THEN CROSS THE NORTHERN TIP OF PALAWAN BEFORE ENTERING THE SOUTH CHINA SEA BY 48H. STY 28W HAS LIKELY REACHED PEAK INTENSITY. CLOUD TOPS HAVE BEEN STEADILY WARMING OVER THE PAST THREE HOURS. ADDITIONALLY, THE MICROWAVE-BASED PROBABILITY OF EYEWALL REPLACEMENT CYCLE (M-PERC) FULL-MODEL PREDICTION INDICATED A 100 PERCENT PROBABILITY OF EWRC, LENDING HIGH CONFIDENCE TO THE ANALYSIS OF RECENT MICROWAVE IMAGERY AND THE FORECAST OF NEAR-TERM EWRC. THE FORECAST CALLS FOR WEAKENING TO 125 KNOTS/CAT 4 BY 12H, DUE TO THE IMPACT OF THE EWRC AND LAND INTERACTION AS THE SYSTEM CROSSES THE SURIGAO STRAIT. WHILE THE EWRC APPEARS IMMINENT, THE LACK OF RECENT MICROWAVE IMAGERY MAKES IT DIFFICULT TO CONFIRM AND THUS THERE IS HIGH UNCERTAINTY IN THE AMOUNT OF WEAKENING EXPECTED. IT REMAINS POSSIBLE THAT THE SYSTEM COULD EXPERIENCE SOME SLIGHT INTENSIFICATION BETWEEN TAU 00 AND TAU 12 THOUGH THIS SEEMS UNLIKELY. AS THE STORM CROSSES THE PHILIPPINE ISLANDS, DISRUPTION OF THE LOW LEVEL INFLOW COMBINED WITH INCREASED VWS WILL WEAKEN THE SYSTEM, AND IT WILL CROSS INTO THE SOUTH CHINA SEA AS A 95 KNOT/CAT 2 TYPHOON. DURING THE 24 PERIOD BETWEEN 48/72H, THE SYSTEM WILL INTENSIFY ONCE MORE AS IT TAPS INTO STRONGLY DIVERGENT POLEWARD OUTFLOW, WHICH WILL OFFSET MODESTLY INCREASED SOUTHERLY WIND SHEAR, TO A PEAK OF 110 KNOTS/CAT 3 AT 72H. AFTER THIS POINT HOWEVER, AN INFLUX OF COOLER, DRIER AIR FROM A NORTHEAST SURGE, AND DRAMATICALLY INCREASING VWS WILL SMOTHER AND DECAPITATE THE SYSTEM, LEADING TO RAPID WEAKENING THROUGH THE END OF THE FORECAST.

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: STY 28W HAS UNDERGONE AN IMPRESSIVE RAPID INTENSIFICATION, INCREASING FROM 65 TO 140 KNOTS( CAT 1 TO 5) IN THE LAST 24 HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A COMPACT, 11KM EYE, SURROUNDED BY DEEP CYCLING CONVECTION. CLOUD TOPS HAVE WARMED SLIGHTLY OVER THE LAST COUPLE OF HOURS, BUT THE HIGH RESOLUTION EIR AND MSI SHOW IMPRESSIVE GRAVITY WAVES EMANATING OUT FROM THE EYEWALL CONVECTION. A 152204Z SSMIS 91GHZ IMAGE SHOWED AN INNER EYEWALL WITH A NASCENT SECONDARY EYEWALL BEGINNING TO EMERGE, PARTICULARLY ON THE SOUTH AND EASTERN FLANKS, INDICATING AN IMMINENT EYEWALL REPLACEMENT CYCLE (EWRC). THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE 11KM EYE IN THE VISIBLE AND INFRARED IMAGERY AS WELL AS EXTRAPOLATION OF THE MICROWAVE EYE IN THE AFOREMENTIONED MICROWAVE IMAGE. THE INITIAL INTENSITY IS ASSESSED AT A SOMEWHAT GENEROUS 140 KNOTS/CAT 5, ON THE HIGHER END OF THE AGENCY DVORAK CURRENT INTENSITY ESTIMATES, HEDGED HIGHER THAN THE ADT BASED ON THE RAW ADT WHICH AT THE 0000Z WAS T7.5. THE SYSTEM HAS LIKELY REACHED PEAK INTENSITY. THE SYSTEM IS MOVING GENERALLY JUST NORTH OF WEST, BUT THE TROCHOIDAL MOTION ABOUT THE MEAN TRACK MEANS THAT SOME NEAR-TERM VARIATIONS IN THE TRACK ARE TO BE EXPECTED. THE ENVIRONMENT REMAINS HIGHLY FAVORABLE OVERALL, WITH VERY WARM SSTS, HIGH OHC, GOOD WESTWARD AND POLEWARD OUTFLOW AND MODERATE EASTERLY VWS.

MODEL DISCUSSION: TRACK GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH 72H, WITH A SPREAD OF LESS THAN 185KM AT 72H. SPREAD INCREASED TO 315KM BY 120H BETWEEN THE NAVGEM ON THE RIGHT AND ECMWF ON THE LEFT OF THE GUIDANCE ENVELOPE. THE JTWC FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST AND CLOSELY TRACKS THE CONSENSUS MEAN THROUGH 48H, THEN SLIGHTLY TO THE LEFT OF THE MEAN THROUGH 120H. INTENSITY GUIDANCE IS IN GOOD AGREEMENT AS WELL, WITH ALL MEMBERS INDICATING IMMEDIATE WEAKENING FROM 00H WITH THE HWRF BEING THE MOST BEARISH, TAKING THE SYSTEM DOWN TO 60 KNOTS WITHIN 24 HOURS, WHILE THE COAMPS-TC IS THE MOST BULLISH, WITH THE MINIMUM OF 110 KNOTS AS THE SYSTEM CROSSES THE PHILIPPINES FOLLOWED BY A SECOND PEAK OF 125 KNOTS IN THE SOUTH CHINA SEA. THE JTWC FORECAST IS ABOUT 15 KNOTS ABOVE THE CONSENSUS MEAN, BUT LOWER THAN THE COAMPS-TC THROUGH 36H, THEN SLIGHTLY BELOW THE COAMPS-TC BUT ABOVE THE REMAINDER OF THE GUIDANCE THROUGH 120H. CONFIDENCE IN THE TRACK IS HIGH TRENDING MEDIUM IN THE LONG-RANGE, WHILE CONFIDENCE IN THE INTENSITY IS MEDIUM TRENDING LOW IN THE LONG-RANGE DUE TO UNCERTAINTIES SURROUNDING THE IMPACT OF THE EWRC AND TERRAIN INDUCED WEAKENING.

THE AREA OF CONVECTION (INVEST 97W) PREVIOUSLY LOCATED NEAR 4.8N 107.1E IS NOW LOCATED NEAR 4.4N 105.0E, APPROXIMATELY 375 KM NORTH-NORTHEAST OF SINGAPORE. ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A PARTIAL 152347Z SSMIS 91GHZ MICROWAVE IMAGE DEPICT FLARING CONVECTION DISPLACED TO THE NORTHWEST OF A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLC). A 160243Z PARTIAL ASCAT-C IMAGE SHOWS 20KT WIND BARBS IN THE EASTERN SEMICIRCLE. ENVIRONMENTAL ANALYSIS INDICATES A MARGINALLY FAVORABLE ENVIRONMENT WITH GOOD POLEWARD OUTFLOW, WARM (27-28C) SEA SURFACE TEMPERATURES OFFSET BY MODERATE (15-20KT) VERTICAL WIND SHEAR. GLOBAL MODELS ARE IN AGREEMENT THAT INVEST 97W WILL PERSIST AND SLOWLY TRACK WESTWARD OVER THE NEXT 72 HOURS. MAXIMUM SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1005 MB. THE POTENTIAL FOR THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24 HOURS REMAINS MEDIUM.