WDPN31 PGTW 111500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (NINE) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 28.6N 135.9E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 446 NM SOUTH-SOUTHWEST OF YOKOSUKA, JAPAN MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 02 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY CONTINUES TO SHOW A SOMEWHAT DISORGANIZED SYSTEM, THOUGH IT IS STEADILY IMPROVING. THE PREVIOUSLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) HAS SLID SOUTHEASTWARD AND APPEARS TO HAVE MERGED WITH, OR WILL DO SO IMMINENTLY, WITH WHAT WAS A DEVELOPING AREA OF VORTICITY TO THE SOUTHEAST SEEN IN MICROWAVE IMAGERY FROM SEVEN HOURS AGO. AT THIS POINT, THE POSITION HAS TUCKED UNDER PERSISTENT CONVECTIVE ACTIVITY, OBSCURING IT ONCE MORE. HOWEVER, TIMELY RECEIPT OF AN 111234Z ASCAT-B PASS REVEALED THAT THE LLCC REMAINS SLIGHTLY ELONGATED, BUT HAS CONGEALED IN THE SOUTHEASTERN PORTION OF THE BROADER ROTATION AND LENT HIGH CONFIDENCE TO THE INITIAL POSITION. LIKEWISE, THE SCATTEROMETER DATA PROVIDED HIGH CONFIDENCE IN NUDGING THE INTENSITY UP TO 35 KNOTS, A BIT HIGHER THAN THE OBJECTIVE AND SUBJECTIVE FIXES WHICH RANGED BETWEEN 25-30 KNOTS, AS IT SHOWED AN AREA OF 35-40 KNOT WINDS TO THE SOUTHEAST OF THE CENTER. THE LLCC HAS TRACKED GENERALLY IN A COUNTER-CLOCKWISE LOOP OVER THE PAST SIX HOURS WITH MOTION OF THE LAST THREE HOURS BEING TO THE NORTH, BUT TRACK MADE GOOD SINCE THE PREVIOUS POSITION IS ROUGHLY SOUTHEAST AT 2-3 KNOTS, AS IT MOVES ALONG THE WESTERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR) TO THE EAST. THE ENVIRONMENT IS CHARACTERIZED BY WARM (29-30C) SSTS, AND MODERATE TO STRONG EQUATORWARD OUTFLOW. SHEAR ANALYSIS IS A BIT OF A DICHOTOMY, WITH CIMSS AUTOMATED ANALYSIS SHOWING 5-10 KNOTS OF SHEAR, WHILE HWRF FIELDS SUGGEST 25-30 KNOTS. CLEARLY THE SYSTEM IS EXPERIENCING A FAIR AMOUNT OF SHEAR BASED ON THE SHARP NORTHERN EDGE OF THE CONVECTIVE ENVELOPE AND CONTINUED STRUGGLE TO KEEP THE LLCC UNDER THE CONVECTION, WITH AN ESTIMATED SHEAR VALUE OF 15-20 KNOTS. 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: T2.0 - 30 KTS RJTD: T2.0 - 30 KTS KNES: T1.5 - 25 KTS CIMSS ADT: 28 KTS AT 1140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: AFTER A PERIOD OF SOMEWHAT ERRATIC MOTION WITH MULTIPLE VORTICES, NOW THAT THE LOW LEVEL CORE HAS STARTED TO CONSOLIDATE, IT WILL SLOWLY START TO MOVE NORTH ALONG THE WESTERN PERIPHERY OF THE STR TO THE EAST. AFTER TAU 24, THE SYSTEM WILL ACCELERATE NORTHEASTWARD AS IT ROUNDS THE RIDGE AXIS AS THE STEERING RIDGE SIMULTANEOUSLY SLIDES TO THE SOUTH-SOUTHWEST. TS 09W IS FORECAST TO MAKE LANDFALL ALONG THE IZU PENINSULA BETWEEN TAUS 36 AND 48, MOVE THROUGH THE TOKYO METRO AREA THEN REEMERGE OVER WATER SHORTLY AFTER TAU 48. WHILE TS 09W REMAINS UNDER A MODERATE AMOUNT OF NORTHERLY SHEAR, IT HAS BEEN ABLE TO CONSOLIDATE A SINGLE, MORE DEFINED LLCC OVER THE PAST SIX HOURS. HOWEVER, MODEL GUIDANCE SUGGESTS THE SHEAR WILL HOLD FIRM FOR ANOTHER 12 TO 24 HOURS, AND UPPER-LEVEL DIVERGENCE IS EXPECTED TO DECREASE, THE COMBINED EFFECT OF WHICH WILL BE TO INHIBIT SIGNIFICANT INTENSIFICATION THROUGH THIS PERIOD, WITH THE SYSTEM ONLY FORECAST TO REACH 40 KNOTS BY TAU 24. THE BRAKES START TO LET UP BY TAU 36 AS THE SYSTEM MOVES INTO A REGION OF LOWER SHEAR AND DIFFLUENT UPPER-LEVEL OUTFLOW AHEAD OF A 200MB TROUGH. THE COMBINED EFFECTS OF DECREASED SHEAR AND DRAMATICALLY IMPROVED OUTFLOW ALOFT SHOULD ALLOW FOR A BRIEF PERIOD OF INTENSIFICATION, TO A PEAK OF 60 KNOTS BY TAU 48 AS THE OUTFLOW OFFSETS THE SHEAR. THIS BURST OF INTENSIFICATION WILL BE SHORT LIVED AND THE SYSTEM WILL BEGIN TO RAPIDLY WEAKEN AFTER IT PEAKS AT TAU 48. AS IS THE CASE CURRENTLY, THE SYSTEM IS EXPECTED TO REMAIN SOMEWHAT ASYMMETRIC THROUGHOUT THE FORECAST, WITH THE HIGHEST WINDS EXPECTED TO BE IN THE EASTERN HEMISPHERE OF THE CIRCULATION. TS 09W WILL BEGIN EXTRA-TROPICAL TRANSITION SHORTLY AFTER IT EMERGES BACK OVER WATER, AS IT MOVES RAPIDLY NORTH-NORTHEAST AHEAD OF NEGATIVELY TILTED MAJOR SHORTWAVE TROUGH AND ULTIMATELY BECOMES A VERTICALLY STACKED COLD CORE LOW BETWEEN TAUS 72 AND 96 AS IT APPROACHES THE SOUTHERN KURIL ISLANDS. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE GUIDANCE REMAINS IN GOOD OVERALL AGREEMENT ON THE TRACK, WITH ALL CONSENSUS MEMBERS CONSTRAINED IN A TIGHT 65NM ENVELOPE AT TAU 48. AS THE SYSTEM MOVES NORTHWARD AND BECOMES EXTRATROPICAL, MODEL SPREAD INCREASES TO A MODEST 200NM. THE JTWC FORECAST REMAINS CONSISTENT WITH THE PREVIOUS FORECAST, AND REMAINS ON THE EASTERN SIDE OF THE ENVELOPE THROUGH THE FORECAST PERIOD, CLOSELY TRACKING THE HWRF THROUGH TAU 48. CONFIDENCE HAS IMPROVED DUE TO THE INCREASED CONFIDENCE IN THE INITIAL POSITION BUT REMAINS MEDIUM THROUGH TAU 72 AND LOW THEREAFTER. INTENSITY GUIDANCE REMAINS CONSISTENT WITH THE PREVIOUS MODEL RUN, WITH THE DECAY-SHIPS STUBBORNLY STICKING TO THEIR FORECAST OF LITTLE TO NO INTENSIFICATION, WHILE THE HWRF AND CTR1 RAPID INTENSIFICATION (RI) AID STILL PREDICTING A PEAK OF 65 KNOTS AND 90 KNOTS RESPECTIVELY. THE CONSENSUS MEAN SITS AT A PEAK OF 50 KNOTS. THE DETERMINISTIC COAMPS-TC (CTCX) HAS COME ON BOARD WITH A PEAK OF 70 KNOTS AT TAU 48 AND THE CTCX ENSEMBLE PROBABILISTIC INTENSITY NOW SHOWS A RESPECTABLE 50 PERCENT CHANCE OF RI PRIOR TO LANDFALL. WITH SUCH A LARGE SPREAD IN THE GUIDANCE, THERE IS LOW CONFIDENCE IN THE INTENSITY FORECAST, WITH A POSSIBILITY OF A SLIGHTLY HIGHER PEAK BETWEEN THE TAU 36 AND 48 FORECAST POINTS. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: LOW INTENSITY 72-120 HR: LOW// NNNN