WDPN31 PGTW 112100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (NINE) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 28.8N 135.9E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 435 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN MOVEMENT PAST 6 HOURS: NORTHWARD AT 02 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A LOW LEVEL CIRCULATION WHICH HAS TUCKED UNDER A FLARE-UP IN CONVECTIVE ACTIVITY, AFTER HAVING BEEN FULLY EXPOSED PREVIOUSLY. THE LOW LEVEL CIRCULATION CENTER (LLCC) IS EMBEDDED WITHIN A LARGER REGION OF CYCLONIC ROTATION, OUTLINED BY AN AREA OF FLARING CONVECTION. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON A 111234Z ASCAT-B PASS, ALONG WITH THE ANIMATED ENHANCED INFRARED SATELLITE IMAGERY. THE INITIAL INTENSITY IS SET AT 35 KNOTS WITH HIGH CONFIDENCE BASED ON THE IMPROVING CONVECTIVE STRUCTURE AND THE PREVIOUSLY MENTIONED ASCAT-B PASS. ADDITIONALLY, THE ASSESSED INTENSITY IS INLINE WITH PGTW DVORAK FIX INTENSITY OF T2.5. ENVIRONMENTAL CONDITIONS ARE CURRENTLY MODERATELY CONDUCIVE FOR DEVELOPMENT WITH WARM SEA SURFACE TEMPERATURES (29-30C), AN MODERATE TO STRONG EQUATORWARD OUTFLOW. ALTHOUGH THESE FAVORABLE ENVIRONMENTAL PARAMETERS ARE OFFSET BY CIMSS AUTOMATED ANALYSIS SHEAR VALUES OF 25-30 KNOTS. THE FAIR AMOUNT OF WIND SHEAR IS THE INHIBITING FACTOR WHICH IS HAVING AN IMPACT ON THE NORTHERN CONVECTIVE ENVELOPE AND CONTINUING TO STRUGGLE IN ALLOWING THE LLCC TO MAINTAIN UNDER THE CONVECTION. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T2.0 - 30 KTS KNES: T1.5 - 25 KTS CIMSS SATCON: 32 KTS AT 111235Z CIMSS ADT: 33 KTS AT 111740Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 25-30 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM INITIAL INTENSITY: HIGH INITIAL WIND RADII: HIGH 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TS 09W HAD SINCE BEEN MOVING IN A SOMEWHAT ERRATIC MOTION BUT IS NOW BECOMING MORE CONSOLIDATED, AND THE SYSTEM HAS BEGUN TO SLOWLY START TO TRACK NORTH ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST. BY TAU 24, TS 09W WILL BEGIN TO ACCELERATE TO THE NORTHEAST AS IT ROUNDS THE EDGE OF THE SUBTROPICAL RIDGE AXIS ALONG WITH ANOTHER STEERING RIDGE TO THE WEST OF THE SYSTEM. THE SYSTEM IS FORECAST TO CONTINUE TRACKING TO THE NORTHEAST BEFORE MAKING LANDFALL ALONG THE IZU ENINSULA BETWEEN TAU 36 AND TAU 48. TS 09W REMAINS IN HIGH NORTHERLY WIND SHEAR OF 25-30 KNOTS, HOWEVER IT HAS BEEN ABLE TO CONSOLIDATE INTO A MORE DEFIND LLCC OVER THE PAST 12 HOURS. MODEL GUIDANCE DOES SUGGEST THE WIND SHEAR WILL HOLD STRONG THROUGH TAUS 12 TO 24 ALONG WITH A DECREASE IN UPPER LEVEL DIVERGENCE, WHICH WILL BE AN INHIBITING FACTOR IN SIGNIFICANT INTENSIFICATION AT THE BEGINNING OF THE FORECAST. HOWEVER, BETWEEN TUA 24 AND TAU 36 THE MODEL GUIDANCE SUGGEST A DECREASE IN VERTICAL WIND SHEAR AHEAD OF AN APPROACHING 200MB TROUGH. THE COMBINED EFFECT OF A DECREASE IN VERTICAL WIND SHEAR, INCREASE IN POLEWARD UPPER LEVEL OUTFLOW ALOFT, ALONG WITH HIGH SEA SURFACE TEMPERATURES (29-30C) WILL ALLOW FOR A BRIEF WINDOW OF INTENSIFICATION UP TO 55 KTS JUST PRIOR TO LANDFALL. AFTER TAU 48 AS THE SYSTEM EMERGES BACK OVER WATER IT WILL BEGIN TO ACCELERATE QUICKLY TO THE NORTHEAST AS IT INTERACTS WITH AN APPROACHING UPPER LEVEL TROUGH UPSTREAM. THEN BETWEEN TAU 72 AND TAU 96 THE UPPER LEVEL TROUGH BECOMES NEGATIVELY TILTED ALLOWING FOR EXTRATROPICAL TRANSITION, ADDITIONALLY, THE NEGATIVE EFFECTS OF MUCH COOLER SEA SURFACE TEMPERATURES WILL ALLOW FOR THE SYSTEM TO STEADILY DECREASE IN INTENSITY AS IT ULTIMATELY BECOMES A COLD CORE VERTICALLY STACKED SYSTEM AS IT APPROACHES THE KAMCHATKE PENINSULA. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN OVERALL GOOD AGREEMENT ON THE TRACK FORECAST WITH ALL CONSENSUS MODELS IN TIGHT AGREEMENT THROUGH TAU 72. BY TAU 96 AS THE SYSTEM INTERACTS WITH THE APPROACHING UPPER LEVEL TROUGH, THERE BECOMES MORE OF A SPREAD IN GUIDANCE UP TO 300NM. THE JTWC FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST THROUGH TAU 36. BETWEEN TAU 36 AND TAU 48 THE TRACK HAS SHIFTED SLIGHTLY TO THE EAST AND THE MAJORITY OF THE NUMERICAL MODELS HAVE ALL COME INTO BETTER AGREEMENT. BY TAU 72 THE TRACK REMAINS INLINE WITH THE PREVIOUS FORECAST BEFORE ACCELERATING TO THE NORTHEAST THROUGH TAU 96 FOR THESE REASONS THE JTWC TRACK FORECAST IS PLACED WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE REMAINS INLINE WITH THE PREVIOUS FORECAST AND CONSISTENT WITH PREVIOUS MODEL RUNS. RELIABLE MODEL INTENSITY GUIDANCE INDICATES AN INTENSIFICATION TREND THROUGH TAU 36 AND TAU 48 AFTER WHICH ALL MODELS WEAKEN THE SYSTEM, WHICH IS IN LINE WITH THE JTWC INTENSITY FORECAST. DUE TO THE RANGE OF MODEL INTENSITY TRENDS THE JTWC INTENSITY FORECAST IN PLACED WITH LOW CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN