WDPN31 PGTW 230900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TYPHOON 17W (SAUDEL) WARNING NR 020// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 21.9N 140.9E INITIAL INTENSITY: 110 KTS GEOGRAPHIC REFERENCE: 768 NM EAST-SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 14 KTS SIGNIFICANT WAVE HEIGHT: 45 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TYPHOON 17W (SAUDEL) WITH A SLIGHTLY RAGGED EYE AS THE SYSTEM CONTINUES TO UNDERGO AN EYEWALL REPLACEMENT CYCLE (ERC) WHICH HAS STALLED FURTHER INTENSIFICATION. THE MSI ALSO SHOWS A STRONG BAND OF CONVECTION WRAPPING INTO THE CENTER ALONG THE WESTERN PERIPHERY OF THE SYSTEM. THE ERC WAS CONFIRMED BY A 230422Z AMSR2 36 GHZ MICROWAVE IMAGE, WHICH SHOWED A CLEAR MOAT FEATURE SURROUNDING THE INNER EYEWALL. THE AMSR2 IMAGE ALSO REVEALED THAT THE OUTER EYEWALL IS BECOMING MORE DOMINANT, HINTING THAT THE ERC IS WELL UNDERWAY. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EYE IN ANIMATED MSI AND EXTRAPOLATION FROM THE AMSR2 IMAGE. THE INITIAL INTENSITY OF 110 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS INTENSITY ESTIMATES LISTED BELOW. ENVIRONMENTAL ANALYSIS INDICATES THAT 17W IS IN A FAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG RADIAL OUTFLOW ALOFT, LOW (5-10 KTS) VERTICAL WIND SHEAR, AND WARM (29-30 C) SEA SURFACE TEMPERATURES. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF AN ELONGATED SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.0 - 115 KTS RJTD: T5.5 - 102 KTS RCTP: T6.0 - 115 KTS KNES: T5.5 - 102 KTS CIMSS SATCON: 114 KTS AT 230600Z CIMSS ADT: 112 KTS AT 230600Z CIMSS AIDT: 105 KTS AT 230600Z CIMSS D-MINT: 115 KTS AT 230417Z CIMSS D-PRINT: 109 KTS AT 230600Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: ONGOING EYEWALL REPLACEMENT CYCLE 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 17W IS FORECAST TO CONTINUE TRACKING WEST- NORTHWESTWARD, ALONG THE SOUTHWESTERN PERIPHERY OF THE STR TO THE NORTHEAST THROUGH TAU 24. NEAR TAU 24, THE STR IS EXPECTED TO MERGE WITH A SEPARATE STR CENTERED OVER SOUTHERN JAPAN, WHICH WILL KEEP 17W ON A WEST-NORTHWESTWARD TRAJECTORY THROUGH TAU 60. LANDFALL OVER NORTHERN OKINAWA IS FORECAST TO OCCUR RIGHT AROUND TAU 60. AFTER TAU 60, TRACK SPEEDS ARE EXPECTED TO SLOW AS THE RIDGING TO THE NORTH PROPAGATES EASTWARD AND THE STEERING INFLUENCE TRANSITIONS TO A STR CENTERED OVER EASTERN CHINA. 17W IS THEN FORECAST TO BEGIN TRACKING WEST-SOUTHWESTWARD, ALONG THE SOUTHEASTERN EXTENT OF THAT STR THROUGH THE REMAINDER OF THE FORECAST PERIOD. IN TERMS OF INTENSITY, 17W IS NOW FORECAST TO MAINTAIN ITS CURRENT INTENSITY OF 110 KTS THROUGH TAU 36 AS THE SYSTEM ATTEMPTS TO RECOVER FROM THE ONGOING ERC. 17W IS NOW ALSO ENTERING WATERS CONTAINING A LOWER OCEAN HEAT CONTENT (OHC), WHICH WILL ALSO SLIGHTLY HINDER THE CHANCES FOR REDEVELOPMENT AFTER THE ERC COMPLETES. AFTER TAU 36, NORTHWESTERLY SHEAR AND DRY AIR ENTRAINMENT FROM THE WEST IS EXPECTED TO INCREASE, CAUSING 17W TO GRADUALLY WEAKEN AS IT APPROACHES OKINAWA. ONCE THE SYSTEM ENTERS THE EAST CHINA SEA, NORTHERLY SHEAR INDUCED BY THE STRONG RIDGE OVER CHINA WILL CAUSE FURTHER WEAKENING THROUGH THE REMAINDER OF THE FORECAST PERIOD. MODEL DISCUSSION: MODEL TRACK GUIDANCE REMAINS IN GOOD AGREEMENT THROUGH TAU 72 W…

WDPN32 PGTW 230900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (NARRA) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.6N 108.1E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 126 NM EAST OF HANOI, VIETNAM MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 01 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL STORM 18W (NARRA) WITH A PARTIALLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) AND DEEP CONVECTION CONFINED TO THE WESTERN PERIPHERY, CLOSE TO THE COAST. A 230610Z AMSR2 89 GHZ MICROWAVE IMAGE REVEALED DEFINED LOW-LEVEL CLOUDS TIGHTLY WRAPPING INTO THE CENTER, SUPPORTING THE INITIAL POSITION WITH HIGH CONFIDENCE. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE AGREEMENT OF T2.5 FROM ALL FIXING AGENCIES. ENVIRONMENTAL ANALYSIS INDICATES THAT 18W IS IN A MARGINALLY FAVORABLE ENVIROMENT CHARACTERIZED BY MODERATE EQUATORWARD OUTFLOW ALOFT, LOW TO MODERATE (15-20 KTS) NORTHEASTERLY VERTICAL WIND SHEAR, AND VERY WARM (30-31 C) SEA SURFACE TEMPERATURES. INITIAL WIND RADII BASIS: 230213Z METOP-B ASCAT SCATTEROMETER DATA CURRENT STEERING MECHANISM: A COMPETING STEERING PATTERN WITH A NEAR EQUATORIAL RIDGE (NER) TO THE SOUTH AND A SUBTROPICAL RIDGE (STR) TO THE NORTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T2.5 - 35 KTS RCTP: T2.5 - 35 KTS KNES: T2.5 - 35 KTS DEMS: T2.5 - 35 KTS CIMSS ADT: 39 KTS AT 230610Z CIMSS AIDT: 42 KTS AT 230610Z CIMSS D-MINT: 36 KTS AT 230601Z CIMSS D-PRINT: 39 KTS AT 230610Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 15-20 KTS SST: 30-31 CELSIUS OUTFLOW: MODERATE EQUATORWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH 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 18W IS FORECAST TO DRIFT SLOWLY SOUTHWARD OVER THE NEXT 24 HOURS AS IT REMAINS PLACED WITHIN A COMPETING STEERING ENVIRONEMENT. THE ACTUAL TRACK OF 18W IS LIKELY TO BE ERRATIC DURING THIS TIME, WHICH IS NOT CAPTURED BY THE JTWC FORECAST. AROUND TAU 36, THE NER TO THE SOUTH IS EXPTECTED TO BUILD TO THE SOUTHEAST OF 18W, CAUSING IT TO MAKE AN EASTWARD AND THEN NORTHWARD TURN TOWARD THE SOUTHERN COAST OF CHINA. IN TERMS OF INTENSITY, 18W IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY OF 35 KTS THROUGH TAU 24 AS THE SHEAR REMAINS RELATIVELY LOW. AFTER TAU 24, NORTHEASTERLY SHEAR WILL INCREASE, CAUSING THE SYSTEM TO BEGIN ON A WEAKENING TREND AS IT APPROACHES THE COAST OF CHINA. 18W IS THEN FORECAST TO QUICKLY DISSIPATE AFTER MAKING LANDFALL AROUND TAU 72. MODEL DISCUSSION: MODEL TRACK GUIDANCE CONTINUES TO BE IN POOR AGREEMENT UNDER THE EFFECTS OF THE COMPETING STEERING ENVIRONMENT. MODELS GENERALLY SHOW A SOUTHWARD TRACK THROUGH TAU 24 FOLLOWED BY A POLEWARD TURN, HOWEVER THERE IS SIGNIFICANT SPREAD THROUGHOUT THE ENTIRE FORECAST DURATION. THE JTWC TRACK FORECAST IS PLACED CLOSER TO THE ECMWF AND EXPERIMENTAL GOOGLE DEEPMIND ENSEMBLE MEANS WITH LOW CONFIDENCE. INTENSITY GUIDANCE AGREES ON A STEADY INTENSITY THROUGH TAU 24 FOLLOWED BY GRADUAL WEAKENING THROUGH TAU 72 WITH NO SIGNIFICANT OUTLIERS. THE JTWC INTENSITY FORECAST CLOSELY FOLLOWS THE CONSENSUS WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: LOW INTENSITY 00-72 HR: MEDIUM// NNNN

WDPN33 PGTW 230900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 19W (NINETEEN) WARNING NR 004// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 13.4N 135.9E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 267 NM NORTHWEST OF YAP MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) ASSOCIATED WITH TROPICAL DEPRESSION (TD) 19W (NINETEEN) ACCELERATING NORTHEASTWARD. DEEP CONVECTION HAS BEEN DISPLACED TO THE SOUTHWEST AS A RESULT OF STRONG GRADIENT FLOW IN WHICH THE LLCC IS CURRENTLY EMBEDDED, MULTIPLIED BY 10-15 KT VERTICAL WIND SHEAR (VWS) FROM THE NORTHEAST. ADDITIONAL ENVIRONMENTAL ANALYSIS REVEALS MARGINAL CONDITIONS FOR FURTHER DEVELOPMENT. SEA SURFACE TEMPERATURES (SST) REMAIN WARM (29-30 C) AND OUTFLOW IS ENHANCED BY A MODERATE EQUATORWARD CHANNEL. WHILE PERSISTENT TROPOSPHERIC MOISTURE IS HIGHLY CONCENTRATED WITHIN THE WESTERN QUADRANT, SIGNIFICANT DRY-AIR INTRUSION EMBEDDED TO THE EAST AND NORTHEAST CONTINUES TO ENVELOPE THE SYSTEM. STRUCTURALLY, TD 19W IS BECOMING MORE ELONGATED AS WITNESSED BY 230420Z GW1 AMSR2 MICROWAVE IMAGERY AND SUPPORTED BY AN EARLIER (230057Z) METOP-C ASCAT PASS. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON VISIBLE IMAGERY OF THE FULLY EXPOSED LLCC. THE INITIAL INTENSITY OF 30 KTS IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON A 230230Z OSCAT PASS, AND THE AUTOMATED AND AGENCY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: NEAR-EQUATORIAL RIDGE (NER) TO THE SOUTHEAST AND LOW-LEVEL SOUTHWESTERLIES AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T1.5 - 25 KTS KNES: T2.5 - 35 KTS CIMSS SATCON: 39 KTS AT 230610Z CIMSS ADT: 34 KTS AT 230610Z CIMSS AIDT: 31 KTS AT 230610Z CIMSS D-MINT: 27 KTS AT 230500Z CIMSS D-PRINT: 31 KTS AT 230640Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: MODERATE EQUATORWARD OTHER FACTORS: DRY AIR ENTRAINMENT THROUGHOUT THE EASTERN SEMICIRCLE ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TD 19W IS CURRENTLY ACCELERATING NORTHEASTWARD, DRIVEN BY THE STEERING INFLUENCE OF A NER ANCHORED TO THE EAST- SOUTHEAST AND ENHANCED BY LOW-LEVEL SOUTHWESTERLIES. AROUND TAU 24, THE DOMINANT STEERING INFLUENCE WILL SHIFT TO A SUBTROPICAL RIDGE POSITIONED TO THE NORTHEAST, VEERING TD 19W NORTHWARD AND NORTHWESTWARD ALONG THE SUBSIDED WAKE OF TYPHOON 17W (SAUDEL). WHILE THE VWS IS EXPECTED TO REMAIN INITIALLY LOW, MODEL GUIDANCE INDICATES SIGNIFICANT UPTICK JUST PRIOR TO TAU 24, WHICH COMBINED WITH INCREASING ENTRAINMENT OF DRY AIR INTO THE CORE WILL INITIATE A WEAKENING TREND, DEPRESSING INTENSITY TO 20-25 KTS BY TAU 36. TOWARDS TAU 48, TD 19W WILL STRUGGLE TO PRESERVE ITS VERTICAL STRUCTURE AS IT ENTERS THE REGION OF SHEARED TAIL END WINDS OF TYPHOON 17W. ACCORDINGLY, COMPLETE DISSIPATION OVER OPEN WATER IS PROJECTED BY TAU 48, ALTHOUGH AN ACCELERATED DECAY TIMELINE REMAINS VIABLE SHOULD INCREASED VERTICAL WIND SHEAR AND DRY AIR ADVECTION BE MORE PRONOUNCED AS CURRENTLY MODELED. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE EXHIBITS FAIR INITIAL CONSISTENCY, EVIDENCED BY A CONSTRAINED 115 NM CROSS-TRACK SPREAD AT TAU 48, WITH ALL MAJOR GLOBAL AND MESOSCALE SYSTEMS RESOLVING COHERENT MOTION UNDER CURRENT STEERING FORCING. WHILE THE OFFICIAL JTWC…