WDPN32 PGTW 110300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (PEILOU) WARNING NR 017// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 24.4N 155.8E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 674 NM WEST-NORTHWEST OF WAKE ISLAND MOVEMENT PAST 6 HOURS: NORTHEASTWARD AT 25 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS DISORGANIZED CONVECTION OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC) OF TROPICAL STORM (TS) 13W. A WEDGE OF DRY AIR TO THE WEST OF THE SYSTEM CAN BE OBSERVED IN ANIMATED WATER VAPOR IMAGERY MAKING ITS WAY INTO THE VORTEX CORE. SOME PRESSURE FROM SOUTHERLY VERTICAL WIND SHEAR IS ALSO EVIDENT, DISPLACING THE REMAINING CONVECTION SLIGHTLY NORTH OF THE ASSESSED CENTER. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON LOW-LEVEL CLOUD MOTION BRIEFLY EXPOSED IN THE SOUTHEASTERN QUADRANT AND TRACKING CONVECTIVE FEATURES IN ANIMATED MSI. THE INITIAL INTENSITY OF 35 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND OVERALL LACK OF STRUCTURAL CHANGE IN THE ANIMATED MSI. THE ENVIRONMENT IS CHARACTERIZED AS MARGINAL WITH WARM SEA SURFACE TEMPERATURES AND LOW VERTICAL WIND SHEAR, OFFSET BY THE DRY AIR ENTRAINMENT AND WEAK OUTFLOW ALOFT. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: EASTERN PERIPHERY OF A LARGE, LOW-LEVEL CYCLONIC GYRE CENTERED TO THE WEST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS RJTD: T2.5 - 35 KTS RCTP: T3.0 - 45 KTS KNES: T2.5 - 35 KTS CIMSS ADT: 53 KTS AT 110000Z CIMSS AIDT: 43 KTS AT 110000Z CIMSS D-PRINT: 45 KTS AT 110000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 5-10 KTS SST: 28-29 CELSIUS OUTFLOW: WEAK POLEWARD OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE WEST 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 13W (PEILOU) HAS ACCELERATED NORTHEASTWARD OVER THE PAST 6 HOURS ON A TRACK THAT IS SEPARATING IT FROM THE EASTERN PERIPHERY OF THE CYCLONIC GYRE CENTERED TO THE WEST. AN EXTENSION OF A SUBTROPICAL RIDGE BUILDING IN SOUTH OF THE SYSTEM IS HELPING TO MAINTAIN THE NORTHEASTWARD TRACK OVER THE NEXT 24 HOURS, EVENTUALLY STEERING THE SYSTEM EAST-NORTHEASTWARD BY TAU 36. THE INTENSITY IS EXPECTED TO STEADILY DECREASE FOR THE DURATION OF THE FORECAST PERIOD AS DRY AIR CONTINUES TO INTRUDE INTO THE CORE, SEA SURFACE TEMPERATURES DECREASE, AND WESTERLY VWS INCREASES. DISSIPATION IS EXPECTED UNDER THESE UNFAVORABLE ENVIRONMENTAL CONDITIONS BY TAU 36. MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN GOOD AGREEMENT ABOUT THE NORTHEASTWARD TRAJECTORY FOLLOWED BY AN EAST-NORTHEASTWARD TURN BY TAU 36, WITH A CROSS-TRACK SPREAD OF 75 NM AT THAT TIME. THE JTWC TRACK FORECAST IS PLACED CLOSE TO THE MULTI-MODEL CONSENSUS WITH HIGH CONFIDENCE. MODEL INTENSITY GUIDANCE IS ALSO IN AGREEMENT ABOUT THE WEAKENING TREND OF 13W, WITH THE NOTABLE EXCEPTION OF THE DECAY SHIPS SOLUTIONS, WHICH SUGGEST STEADY INTENSIFICATION. THIS ABERRATION IS LIKELY DUT TO THE FACT THAT SHIPS LOSES TRACK OF THE VORTEX AND REVERTS TO CLIMATOLOGY BASED SOLUTIONS. THE JTWC INTENSITY FORECAST IS PLACED ON THE LOW END OF THE GUIDANCE ENVELOPE WITH MEDIUM CONFIDENCE, DISCOUNTING THE SHIPS SOLUTIONS AS OUTLIERS. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH INTENSITY 00-72 HR: MEDIUM// NNNN

WDPN33 PGTW 110300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (CHAN-HOM) WARNING NR 017// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 36.8N 143.7E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 173 NM EAST-NORTHEAST OF NARITA AIRPORT MOVEMENT PAST 6 HOURS: WESTWARD AT 18 KTS SIGNIFICANT WAVE HEIGHT: 29 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) MOVING BRISKLY WESTWARD TOWARD CENTRAL HONSHU. THE ARRANGEMENT OF CONVECTION AND DRY AIR AROUND THE CIRCULATION HAS ROTATED COUNTERCLOCKWISE OVER THE PAST SIX HOURS, WITH LIMITED CONVECTION NOW CONFINED SOUTHWEST AND SOUTH OF THE LLCC, WHILE A DEEP-LAYER DRY SLOT HAS ENVELOPED THE EASTERN SEMICIRCLE AND IS NOW ROTATING INTO THE NORTHERN SEMICIRCLE. AFTER PASSING OVER A COLD OCEAN EDDY EARLIER, THE STORM IS NOW OVER A WARMER EDDY OF 26C TO 27C SEA SURFACE TEMPERATURES, YET CONVECTIVE COVERAGE HAS NOT IMPROVED. THE STORM CONTINUES TO DEGRADE OVERALL IN TERMS OF CONVECTIVE STRUCTURE. THE CIRCULATION REMAINS VIGOROUS, HOWEVER, AND A RECENT 102359Z ASCAT-C SCATTEROMETER PASS REVEALED THAT THE WIND FIELD REMAINS PERSISTENT DESPITE THE STORM'S DEGRADING SATELLITE APPEARANCE, WITH 45 TO 50 KT WINDS ARCING THROUGH THE NORTHERN SEMICIRCLE OF THE CIRCULATION. THE INITIAL INTENSITY IS THUS BUMPED TO 50 KT. GALE-FORCE WIND RADII HAVE EXPANDED RELATIVE TO SIX HOURS AGO, AND ARE NOW APPROACHING COASTAL AREAS OF NORTHERN HONSHU. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE NORTH AND A DEEP UPPER LOW TO THE SOUTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.5 - 35 KTS RCTP: T2.5 - 35 KTS CIMSS D-MINT: 40 KTS AT 102031Z CIMSS D-PRINT: 37 KTS AT 102330Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 25-30 KTS SST: 26-27 CELSIUS OUTFLOW: MODERATE WESTWARD OTHER FACTORS: DEEP-LAYER DRY AIR WRAPPING AROUND THE EASTERN AND NORTHERN SEMICIRCLES 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: TROPICAL STORM 14W (CHAN-HOM) CONTINUES TO MARCH TOWARD CENTRAL HONSHU WITH PACE AS IT PINWHEELS AROUND THE NORTHERN PERIPHERY OF A DEEP UPPER-LEVEL LOW TO ITS SOUTH. THIS UPPER LOW IS IMPOSING STRONG EASTERLY WIND SHEAR AND INJECTING DEEP-LAYER DRY AIR INTO THE CIRCULATION, WHICH SHOULD PREVENT INTENSIFICATION IN THE FINAL HOURS PRIOR TO LANDFALL IN JAPAN. THE CURRENTLY BARREN CONVECTIVE STRUCTURE SUPPORTS THIS CONCLUSION, THOUGH A POTENT WIND FIELD WILL NEVERTHELESS MOVE ASHORE. LANDFALL IN IBARAKI PREFECTURE, JAPAN IS EXPECTED IN LESS THAN 12 HOURS, FOLLOWED BY A GENERALLY WESTWARD TRACK ACROSS THE MOUNTAINOUS TERRAIN OF CENTRAL HONSHU, WHICH WILL RESULT IN QUICK WEAKENING BELOW TROPICAL STORM INTENSITY. EMERGENCE OVER THE SOUTHERN SEA OF JAPAN IS EXPECTED IN ABOUT 24 HOURS, WHERE HOSTILE ENVIRONMENTAL CONDITIONS CONSISTING OF STRONG WIND SHEAR AND DRY AIR ARE EXPECTED TO PREVENT REDEVELOPMENT. INDEED, MODELS AGREE THAT 14W WILL ARRIVE IN THE SEA OF JAPAN IN A STATE OF SUCH DISREPAIR THAT ITS STRUCTURE WILL UNRAVEL, RESULTING IN DISSIPATION IN AROUND 48 HOURS WITHIN AN UNFAVORABLE ENVIRONMENT. MODEL DISCUSSION: PHYSICS-BASED AND AI-BASED MODEL TRACK GUIDANCE HAS COME INTO TIGHTER AGREEMENT OVER THE PAST SIX HOURS AND CONNOTES HIGH CONFIDENCE IN THE TRACK FORECAST. THE JTWC FORECAST TRACK LEANS TOWARD THE SOUTHERN HALF OF THE GUIDANCE ENVELOPE THROUGH 12 HOURS, THEN CLOSE TO THE MULTI-MODEL CONSENSUS THEREAFTER. INTENSITY GUIDANCE IS ALSO IN TIGHT AGREEMENT, AND THE JTWC INTENSITY FORECAST IS MADE WITH HIGH CONFIDENCE. FORECAST CONFIDENCE: TRACK 0…