WDPN31 PGTW 180300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 28W (RAI) WARNING NR 021// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 11.0N 115.9E INITIAL INTENSITY: 110 KTS GEOGRAPHIC REFERENCE: 368 NM SOUTHWEST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: WESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 28 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS CONTINUING DEEP CONVECTION ROTATING OVER AN ASSESSED LOW LEVEL CIRCULATION CENTER. A 172318Z SSMIS 91GHZ IMAGE SHOWS A WELL-DEFINED MICROWAVE EYE WITH THE STRONGEST CONVECTION SEEN IN THE WESTERN SEMI-CIRCLE. TY RAI IS IN A FAVORABLE ENVIRONMENT FOR ONGOING DEVELOPMENT WITH STRONG WESTWARD AND POLEWARD OUTFLOW ALOFT, LOW (5-10 KT) VERTICAL WIND SHEAR (VWS), AND WARM (28-29 C) SEA SURFACE TEMPERATURES. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED MICROWAVE IMAGERY. THE INITIAL INTENSITY OF 110 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON ANALYSIS OF MICROWAVE STRUCTURE AND HEDGED HIGHER THAN MUTLI-AGENCY AND AUTOMATED DVORAK ESTIMATES. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T5.5 - 102 KTS RJTD: T5.5 - 102 KTS KNES: T6.0 - 115 KTS CIMSS SATCON: 93 KTS AT 172319Z CIMSS ADT: 87 KTS AT 172340Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG WESTWARD AND POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TY RAI IS EXPECTED TO INCREASE IN SURFACE SPEED AS IT APPROACHES THE STR AXIS OVER THE NEXT 24 HOURS. AS IT DOES, THE SYSTEM WILL CONTINUE TO BE IN A FAVORABLE ENVIRONMENT AND WILL MAINTAIN ITS MAX INTENSITY OF 110 KTS. AFTER TAU 24, TY RAI WILL CROSS THE 25C ISOTHERM AND WILL REMAIN OVER RELATIVELY COOLER WATERS FOR THE REMAINDER OF THE FORECAST PERIOD. BY TAU 36, TY 28W WILL MAKE ITS TURN NORTHWARD AS IT ROUNDS THE RIDGE AXIS AND WILL ALSO BEGIN TO APPROACH A BROAD AREA OF INCREASED VWS THAT WILL ONLY INCREASE IN SHEAR OVER THE DURATION OF THE FORECAST PERIOD. BY TAU 48, TY RAI WILL MAKES ITS TURN NORTHEASTWARD TO THE OPEN WATERS OF THE NORTHERN SOUTH CHINA SEA AND WILL BEGIN TO LOSE ITS MOISTURE AS DRIER AIR FROM THE WEST BEGINS TO GET WRAPPED INTO THE CENTER THROUGH THE SOUTHERN PERIPHERY. AT THIS TIME, THE SYSTEM WILL FALL UNDER THE INFLUENCE OF STRONG WESTERLIES AND BEGIN DISSIPATION. TY RAI IS FORECAST TO BE COMPLETELY DISSIPATED BY TAU 96, WITH THE POSSIBILITY OF DISSIPATION OCCURRING SOONER. MODEL DISCUSSION: MODEL CONSENSUS (CONW) FOR TRACK GUIDANCE CONTINUES TO BE IN VERY TIGHT AGREEMENT WITH A 41 NM SPREAD AT TAU 24, GRADUALLY INCREASING TO AN 89 NM SPREAD AT TAU 72, LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK THROUGH TAU 72. CONFIDENCE DROPS TO MEDIUM AFTERWARDS DUE TO SPORADIC TRACK POSITION, POSSIBLY DUE TO THE MODELS HAVING A HARD TIME WITH DISSIPATION. THE JGSM TRACK CONTINUES TO BE THE OUTLIER SHOWING A MORE WESTERLY TRACK. INTENSITY GUIDANCE IS IN FAIRLY GOOD AGREEMENT THROUGH TAU 72, LENDING MEDIUM CONFIDENCE IN THE JTWC INTENSITY FORECAST UP UNTIL THAT TIME. AFTER 72, CONFIDENCE DROPS TO LOW DUE TO A HIGHER SPREAD IN INTENSITY PLACEMENT. THE JTWC INTENSITY FORECAST IS SET HIGHER THAN CONSENSUS THROUGH TAU 24 DUE TO THE POSSIBILITY OF RE-INTENSIFICATION IN THE SHORT TERM. AFTERWARDS, THE JTWC INTENSITY IS IN AGREEMENT WITH CONSENSUS THROUGHOUT THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: LOW// NNNN