WDPN31 PGTW 120900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 02W (MALAKAS) WARNING NR 022// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.8N 135.1E INITIAL INTENSITY: 85 KTS GEOGRAPHIC REFERENCE: 643 NM SOUTHWEST OF IWO TO MOVEMENT PAST 6 HOURS: NORTHWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 30 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THAT TY 02W HAS FINALLY BEGUN THE ANTICIPATED RAPID INTENSIFICATION, AND IS STARTED TO DEVELOP A SOLID EYE, WHICH WHILE RAGGED AT ANALYSIS TIME, HAS IN THE SUBSEQUENT HOURS BEGUN TO RAPIDLY CLEAR OUT AND WARM. THE ANIMATED VISIBLE AND INFRARED IMAGERY INDICATES DEVELOPMENT OF HOT TOWERS IN ALL QUADRANTS, OUTLINING THE RAPIDLY DEVELOPING EYEWALL. A TIMELY 120659Z SSMIS 91GHZ IMAGE DEPICTS A SOLID EYEWALL ACROSS THE SOUTHERN HEMISPHERE THOUGH IT IS STILL OPEN AND RAGGED ON THE NORTHERN SIDE. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE CLOUD-FILLED EYE FEATURE AT ANALYSIS TIME AND IN AGREEMENT WITH THE AGENCY FIX POSITIONS. THE INITIAL INTENSITY IS INCREASED TO 85 KNOTS WITH MEDIUM CONFIDENCE, IN LINE WITH THE SUBJECTIVE ESTIMATES BETWEEN T4.5-T5.0 (77 TO 90 KNOTS) AND CLOSE TO THE ADT ESTIMATE OF 82 KNOTS. AS MENTIONED HOWEVER, SUBSEQUENT RAPID DEVELOPMENT MEANS THIS INITIAL INTENSITY MAY BE A BIT LOW. ANALYSIS REVEALS A VERY SUPPORTIVE ENVIRONMENT WITH LOW VWS, EXTREMELY GOOD DUAL CHANNEL OUTFLOW ENHANCED BY IMPROVING POLEWARD OUTFLOW INTO THE DEEP WESTERLIES AND WARM SSTS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: WESTERN SIDE OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.0 - 90 KTS RJTD: T4.5 - 77 KTS RCTP: T5.0 - 90 KTS KNES: T5.0 - 90 KTS CIMSS SATCON: 71 KTS AT 120422Z CIMSS ADT: 82 KTS AT 120540Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE VWS: 5-10 KTS SST: 27-28 CELSIUS OUTFLOW: STRONG DUAL-CHANNEL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. WITH THE ONSET OF RAPID INTENSIFICATION HOWEVER, THE PEAK INTENSITY HAS BEEN INCREASED BY 15 KNOTS. ADDITIONALLY, THE FORECAST HAS BEEN TRUNCATED TO 96 HOURS DUE TO EXTRATROPICAL TRANSITION. FORECAST DISCUSSION: OVER THE PAST SIX HOURS, TY MALAKAS HAS SLOWED SIGNIFICANTLY, DOWN TO 04 KNOTS, AS IT HAS REACHED THE AXIS OF THE STEERING RIDGE TO THE EAST. OVER THE NEXT 12 HOURS, THE SYSTEM SHOULD ROUND THE AXIS AND BEGIN TO ACCELERATE, SLOWLY AT FIRST BUT STEADILY INCREASING, TO THE NORTHEAST THROUGH THE REMAINDER OF THE FORECAST PERIOD. NOW AT THE RIDGE AXIS, TY MALAKAS IS PRIMED FOR RAPID INTENSIFICATION (RI) IN NEARLY OPTIMUM CONDITIONS, THE ONLY POTENTIAL SHOW STOPPER IN THE NEAR-TERM IS THE POSSIBLE PRESENCE OF SOME DRY AIR IN THE MID-LEVELS ON THE EASTERN SIDE OF THE CIRCULATION, WHICH LOOKS TO BE WRAPPING IN ON THE NORTHERN EDGE OF THE CORE AT PRESENT. SHOULD THE SYSTEM OVERCOME THIS INFLUX OF DRY AIR, AND ALL INDICATIONS ARE THAT IT WILL, IT SHOULD RAPIDLY INTENSIFY UP TO A PEAK OF 125 KNOTS IN THE NEXT 12-24 HOURS. THE PARTY WON'T LAST LONG HOWEVER AND BY TAU 36, INCREASING WESTERLY SHEAR WILL BEGIN TO MAKE ITS PRESENCE KNOWN AND THE SYSTEM WILL BEGIN TO WEAKEN. BY TAU 48, MODELS SUGGEST SHEAR VALUES IN THE RANGE OF 35-40 KNOTS AS WELL AS AN INFLUX OF DRY AIR PUNCHING IN FROM THE WEST, WHICH WILL INDUCE ADDITIONAL, MORE RAPID WEAKENING AS THE SYSTEM STARTS TO DECOUPLE. BY TAU 72, TY 02W WILL MOVE UNDER AN UPPER-LEVEL POLAR JET STREAM, MOVE OVER COOLER WATERS AND BECOME ENGULFED IN DRY AIR, MARKING THE ONSET OF EXTRATROPICAL TRANSITION (ETT). NO LATER THAN TAU 96, TY 02W IS EXPECTED TO BECOME A STRONG STORM-FORCE COLD-CORE LOW WITH AN EXPANSIVE WIND FIELD. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE GUIDANCE IS IN VERY GOOD AGREEMENT, WITH MINIMAL CROSS-TRACK SPREAD THROUGH THE FORECAST PERIOD. AS EXPECTED WITH RECURVING SYSTEMS HOWEVER, ALONG-TRACK SPREAD INCREASES AFTER TAU 36, ROUGHLY 200NM AT TAU 72 INCREASING TO OVER 550NM BY TAU 96. THE JTWC FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, ON THE WESTERN SIDE OF THE ENVELOPE AND NEAR THE CONSENSUS MEAN IN TERMS OF ALONG-TRACK POSITIONING, WITH HIGH CONFIDENCE IN THE FIRST 72 HOURS BUT LOW MEDIUM THEREAFTER DUE TO THE ENHANCED ALONG-TRACK UNCERTAINTY. INTENSITY GUIDANCE IS ALSO IN RELATIVELY GOOD AGREEMENT, WITH ALL CONSENSUS MEMBERS SHOWING INTENSIFICATION THROUGH TAU 24 FOLLOWED BY GENERAL WEAKENING THEREAFTER. ADDITIONALLY, ALL RI AIDS HAVE BEEN TRIGGERED ON THIS RUN, AND THE COAMPS-TC ENSEMBLE INDICATES AN 80 PERCENT PROBABILITY OF RI. HENCE THE JTWC INTENSITY FORECAST CLOSELY TRACKS THE RIPA GUIDANCE TO A PEAK OF 125 KNOTS, THEN LIES ABOVE THE CONSENSUS MEAN THROUGH THE REMAINDER OF THE FORECAST. CONFIDENCE IN THE INTENSITY FORECAST IS HIGH IN THE NEAR-TERM BUT THE TIMING OF THE ONSET OF WEAKENING AND THE ULTIMATE PEAK INTENSITY, SUGGESTS MEDIUM CONFIDENCE IN THE LONGER TERM FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: HIGH INTENSITY 72-120 HR: MEDIUM// NNNN