WDPN31 PGTW 162100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (DUJUAN) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.6N 149.7E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 363 NM NORTHEAST OF ANDERSEN AFB MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TROPICAL STORM (TS) 24W IS STEADILY INTENSIFYING. ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A CONSOLIDATING CONVECTIVE STRUCTURE CHARACTERIZED BY A SMALL CENTRAL DENSE OVERCAST, INCREASED OUTER BANDING, AND EXPANDING OUTFLOW ALOFT. OVERSHOOTING CLOUD TOPS AS COLD AS -90 DEGREES CELSIUS HAVE BEEN ESTIMATED NEAR THE CENTER. A 161442Z GMI 89 GHZ MICROWAVE IMAGE DEPICTS A COMPACT, NASCENT INNER CORE, WITH A PARTIAL RING OF DEEP CONVECTION THAT IS MOST DEVELOPED IN THE SOUTHWEST QUADRANT. WHILE CONVECTION AND OUTFLOW ALONG THE NORTHWESTERN PERIPHERY HAVE BEEN SUPPRESSED DUE TO AN UPPER-LEVEL TROUGH NEAR THE FAR NORTHERN MARIANA ISLANDS, THE OVERALL ENVIRONMENT IS FAVORABLE, WITH VERY WARM SEA SURFACE TEMPERATURES (SST) OF 29-30 DEGREES CELSIUS AND LOW VERTICAL WIND SHEAR (VWS). THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE NEAR THE FORMATIVE MID-LEVEL CIRCULATION CENTER. THE FIVE MOST RECENT D-MINT ESTIMATES BETWEEN 1253Z AND 1557Z SPANNED 40-47 KTS, AND ADT, AIDT, AND D-PRINT ARE APPROACHING 40 KTS. BASED ON THE INCREASING OBJECTIVE ESTIMATES FROM CIMSS AND THE IMPROVED CONVECTIVE SIGNATURE, THE INITIAL INTENSITY HAS BEEN RAISED TO 40 KTS WITH MEDIUM CONFIDENCE. THIS ASSESSMENT MAY BE CONSERVATIVE, GIVEN THAT SUBJECTIVE AND OBJECTIVE ESTIMATES ARE PRONE TO BIAS LOW FOR COMPACT SYSTEMS. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SOUTHERN EXTENSION OF THE LOW- TO MID-LEVEL SUBTROPICAL RIDGE CENTERED NEAR 37N 165E AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T2.5 - 35 KTS RCTP: T2.5 - 35 KTS CIMSS SATCON: 38 KTS AT 161556Z CIMSS ADT: 39 KTS AT 161730Z CIMSS AIDT: 36 KTS AT 161730Z CIMSS D-MINT: 40 KTS AT 161557Z CIMSS D-PRINT: 40 KTS AT 161730Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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. FORECAST DISCUSSION: TS 24W IS TRAVELING POLEWARD ALONG THE SOUTHWESTERN PERIPHERY OF THE STR CENTERED EAST OF HONSHU. THE POLEWARD MOTION FOLLOWS A TURN DURING THE PAST 18 HOURS UNDER THE STEERING INFLUENCE OF A NEAR-EQUATORIAL RIDGE POSITIONED SOUTHEAST OF THE SYSTEM. THE VORTEX WILL GRADUALLY TURN NORTHWESTWARD AT TAU 12 AS THE STR MIGRATES WESTWARD. FROM TAU 60 TO TAU 96, TS 24W WILL TURN POLEWARD, CROSS THE AXIS OF THE DEEP-LAYER STR, AND ACCELERATE NORTHEASTWARD AS THE MID-LATITUDE WESTERLY FLOW BECOMES THE DOMINANT STEERING MECHANISM. FAVORABLE ENVIRONMENTAL CONDITIONS, INCLUDING VERY WARM SST AND LOW VWS, WILL SUPPORT STEADY TO RAPID INTENSIFICATION (RI) OVER THE NEXT 12 HOURS. FROM TAU 12 TO TAU 36, VWS WILL INCREASE TO AROUND 20 KTS, CAUSING THE INTENSITY TREND TO LEVEL OFF. AFTER TAU 36, TS 24W WILL TAP INTO A POLEWARD OUTFLOW CHANNEL, ALLOWING FOR RENEWED INTENSIFICATION DESPITE THE MODERATE VWS. AFTER TAU 72, A WEAKENING TREND WILL COMMENCE AS THE UNFAVORABLE EFFECTS OF INCREASING VWS MORE THAN OFFSET THE DEVELOPMENTAL BENEFITS OF STRONG POLEWARD OUTFLOW. INCREASING BAROCLINIC FORCING WILL SUPPORT EXTRATROPICAL TRANSITION, WHICH WILL BE WELL UNDERWAY BY TAU 120. MODEL DISCUSSION: THE OVERALL GUIDANCE ENVELOPE HAS TIGHTENED MODESTLY SINCE THE LAST CYCLE, WITH THE CROSS-TRACK SPREAD AT TAU 96 DECREASING FROM 180 NM TO 165 NM. A NOTABLE CHANGE HAS BEEN A GENERAL WESTWARD SHIFT IN THE AI MODEL SOLUTIONS TOWARD THE JTWC MULTI-MODEL CONSENSUS (CONW). THE JTWC FORECAST TRACK IS PLACED NEAR THE CONSENSUS THROUGH TAU 48. THEREAFTER, THE FORECAST HAS BEEN SHIFTED WESTWARD RELATIVE TO THE PREVIOUS FORECAST, TOWARD BUT NOT QUITE AS FAR WEST AS THE CONSENSUS. AS A RESULT, THE JTWC TRACK LIES ALONG THE EASTERN SIDE OF THE CORE MODEL GROUPING AFTER TAU 48. MULTIPLE RI AIDS HAVE ONCE AGAIN TRIGGERED. GIVEN THE RECENT IMPROVEMENT IN THE SATELLITE PRESENTATION OF THE SYSTEM AND THE FAVORABLE ENVIRONMENTAL CONDITIONS, THE JTWC FORECAST INTENSITY CALLS FOR A 15-KT INCREASE IN THE NEXT 12 HOURS, FOLLOWED BY A SLOWING OF THE INTENSIFICATION TREND AT TAU 24. COAMPS-TC AND GFS AGGRESSIVELY INTENSIFY THE SYSTEM TO TYPHOON INTENSITY WITHIN 24 HOURS. THE JTWC FORECAST REMAINS JUST BELOW THESE MORE AGGRESSIVE SOLUTIONS AND IS PLACED CLOSER TO THE EXPERIMENTAL GOOGLE DEEPMIND SOLUTION. MOST AIDS DEPICT A NEAR-STEADY INTENSITY FROM TAU 24 TO TAU 36, FOLLOWED BY VARYING DEGREES OF INTENSIFICATION. HAFS-A, WHICH MAINTAINS A COMPACT INNER CORE, IS THE STRONGEST SOLUTION, REACHING AROUND 100 KTS AT TAU 60. THE JTWC INTENSITY FORECAST IS NEAR THE CENTER OF THE GUIDANCE ENVELOPE AT TAU 60 AND TAU 72, CLOSEST TO THE STATISTICAL-DYNAMICAL SHIPS GUIDANCE BUT SLIGHTLY HIGHER THAN DEEPMIND. AFTER TAU 72, THE FORECAST IS CLOSELY ALIGNED WITH DEEPMIND AND GFS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH TRACK 72-120 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN