WDPN31 PGTW 272100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (KULAP) WARNING NR 009// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 31.0N 144.2E INITIAL INTENSITY: 55 KTS GEOGRAPHIC REFERENCE: 343 NM SOUTHEAST OF YOKOSUKA, JAPAN MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 18 KTS SIGNIFICANT WAVE HEIGHT: 27 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A CONSOLIDATING SYSTEM WITH DEEP CONVECTION WRAPPING INTO A PERSISTENT CONVECTIVE CLOUD STRUCTURE, WHICH IS OBSCURING A LOW LEVEL CIRCULATION CENTER (LLCC). ADDITIONALLY, A 271852Z SSMIS 37GHZ DEPICTS FORMATIVE CONVECTIVE BANDING OVER THE NORTHERN QUADRANT WRAPPING INTO THE LLCC. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON ANIMATED SHORTWAVE INFRARED SATELLITE IMAGERY, AS WELL AS AN EARLIER 271121Z METOP-B ASCAT PASS. THE INITIAL INTENSITY IS ALSO PLACED WITH MEDIUM CONFIDENCE BASED ON THE AFOREMENTIONED METOP-B ASCAT WHICH SHOWS UP TO 50 KNOT WIND BARBS ON THE EASTERN PERIPHERY. ALONG WITH A BLEND OF THE AUTOMATED DVORAK ESTIMATES INTENSITIES FROM CMISS ADT OF 49 KNOTS, WHILE SATCON SHOWS UP TO 56 KNOTS IN COMBINATION WITH SUBJECTIVE AGENCY DVORAK INTENSITIES FROM PGTW T3.0, RJTD T3.5, AND KNES T3.0. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: WESTERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T3.5 - 55 KTS KNES: T3.0 - 45 KTS CIMSS SATCON: 56 KTS AT 271559Z CIMSS ADT: 49 KTS AT 271940Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG 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: TS 19W HAS ROUNDED THE RIDGE AXIS OF THE DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE EAST AND HAS INCREASED ITS TRACK SPEED UP TO 18 KTS TOWARD THE NORTHEAST. ADDITIONALLY, A DEEP SHORTWAVE TROUGH UPSTREAM OVER NORTHERN CHINA IS EXPECTED TO ERODE AND WEAKEN THE STR TO THE EAST, WHICH WILL ULTIMATELY ALLOW 19W TO CONTINUE TO ACCELERATE NORTHEASTWARD. BETWEEN TAU 24 AND TAU 36, THE SYSTEM WILL INTENSIFY TO A MAXIMUM WIND SPEED OF 70 KNOTS, AS STRONG SHEAR IS OFFSET BY VERY STRONG DIVERGENT POLEWARD OUTFLOW ALOFT. BY TAU 36, AS THE SYSTEM BEGINS TO INTERACT WITH THE DEEP SHORTWAVE TROUGH, THE SYSTEM WILL ALSO INDUCE WARM AIR ADVECTION WHICH WILL AMPLIFY AND DEEPEN THE SHORTWAVE UPPER-LEVEL TROUGH. AS THIS OCCURS THE TROUGH WILL BECOME NEGATIVELY TILTED WHICH WILL ALLOW 19W TO BEGIN TO UNDERGO EXTRA-TROPICAL TRANSITION (ETT). BY TAU 48, THE SYSTEM WILL COMPLETE EXTRA-TROPICAL TRANSITION (ETT) AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES A WARM SECLUSION TYPE EXTRA-TROPICAL LOW, WHILE DECREASING ITS INTENSITY SLIGHTLY DUE TO COOLER SEA SURFACE TEMPERATURE VALUES (25-26C) AND STRONG VERTICAL WIND SHEAR. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE ARE IN VERY GOOD AGREEMENT THROUGH TAU 24, WITH ONLY A 70 NM SPREAD IN MODEL TRACK SOLUTIONS. BY TAU 48, THE MODEL GUIDANCE INCREASES IN UNCERNTANTY WITH A GRADUAL ALONG-TRACK SPREAD TO 200 NM. THIS IS LIKELY DUE TO HOW NUMERICAL MODELS ARE HANDLING LARGE SCALE DEEP SHORTWAVE UPPER LEVEL TROUGHS. BECAUSE OF THIS, SOME INTERACTIONS WITH 19W ARE BEHAVING DIFFERENTLY. OVERALL THE JTWC TRACK FORECAST IS ASSESSED WITH HIGH CONFIDENCE, WITH THE JTWC TRACK FORECAST REMAINING CLOSE TO THE MULTI-MODEL CONSENSUS. THE INTENSITY FORECAST IS ASSESSED WITH MEDIUM CONFIDENCE WITH GFS DECAY SHIPS (DSHA), HWRF, AND GFS GUIDANCE SHOWING A PEAK OF 70 KNOTS, WITH CTR1 GUIDANCE ON THE HIGH END UP TO 85 KNOTS. THEREFORE, THE JTWC INTENSITY FORECAST REMAINS CLOSE TO THE MULTI-MODEL CONSENSUS THROUGH OUT THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN