WDPN31 PGTW 061500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (KROVANH) WARNING NR 022// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 25.7N 131.0E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 179 NM EAST-SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: EAST-NORTHEASTWARD AT 07 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL DEPRESSION 22W (KROVANH) WITH A FULLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) AND FLARING CONVECTION CONFINED TO THE SOUTHWESTERN QUADRANT. 22W HAS STALLED IN PLACE SINCE 061000Z, JUST SOUTHWEST OF MINAMI DAITO JIMA. PRESSURE READINGS FROM SURFACE OBSERVATIONS ON THE ISLAND HAVE DROPPED TO 990 MB AS THE CIRCULATION INCHES CLOSER. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC IN ANIMATED EIR IMAGERY. THE INITIAL INTENSITY OF 30 KTS IS ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK FIXES AND CIMSS INTENSITY ESTIMATES LISTED BELOW. ENVIRONMENTAL ANALYSIS INDICATES THAT 22W REMAINS IN A MARGINAL ENVIRONMENT CHARACTERIZED BY MODERATE POLEWARD OUTFLOW ALOFT, 15-20 KTS SOUTHEASTERLY VERTICAL WIND SHEAR, DRY AIR ENTRAINMENT, AND WARM (28-29 C) SEA SURFACE TEMPERATURES. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: THE NORTHERN PERIPHERY OF AN ELONGATED NEAR EQUATORIAL RIDGE (NER) POSITIONED TO THE SOUTH AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.5 - 25 KTS RJTD: T2.0 - 30 KTS RCTP: T2.0 - 30 KTS KNES: T2.0 - 30 KTS CIMSS ADT: 34 KTS AT 061140Z CIMSS AIDT: 36 KTS AT 061140Z CIMSS D-MINT: 28 KTS AT 060824Z CIMSS D-PRINT: 28 KTS AT 061140Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE POLEWARD OTHER FACTORS: DRY AIR ENTRAINMENT FROM THE WEST ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM 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 22W IS FORECAST TO BEGIN TURNING NORTHEASTWARD WITHIN THE NEXT 6 HOURS AS THE PRIMARY STEERING MECHANISM TRANSITIONS TO THE SUBTROPICAL RIDGE CENTERED TO THE SOUTHEAST OF JAPAN. 22W WILL THEN TRACK GENERALLY NORTHWARD, ALONG THE WESTERN PERIPHERY OF THE RIDGE THROUGH TAU 48. FOLLOWING TAU 48, THE TRAJECTORY IS EXPECTED TO BECOME MORE NORTHEASTWARD WITH AN INCREASING SPEED OF ADVANCE AS THE SYSTEM TRACKS ALONG THE NORTHWESTERN EXTENT OF THE RIDGE. 22W IS FORECAST TO SKIRT THE SOUTHERN COAST OF JAPAN AFTER TAU 60 WITH THE REMNANT VORTEX PASSING SOUTH OF KYOTO, AROUND TAU 72. IN TERMS OF INTENSITY, 22W IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY OF 30 KTS THROUGH TAU 48 UNDER THE EFFECTS OF THE MARGINAL ENVIRONMENT. WHILE DRY AIR ENTRAINMENT IS EXPECTED TO WORSEN, POLEWARD OUTFLOW WILL IMPROVE DUE TO THE SYSTEM TAPPING INTO A JET STREAK EXTENDING OVER NORTHERN HONSHU. AFTER TAU 48, SOUTHEASTERLY SHEAR WILL GREATLY INCREASE, CAUSING 22W TO WEAKEN AS IT APPROACHES SOUTHERN JAPAN. DISSIPATION IS FORECAST TO OCCUR AT AROUND TAU 72, AS THE SHALLOW VORTEX ACCELERATES NORTHEASTWARD AND INTERACTS WITH THE MOUNTAINOUS TERRAIN OF THE SHIKOKU AND KANSAI REGIONS. MODEL DISCUSSION: MODEL TRACK GUIDANCE IS IN MODERATE AGREEMENT THROUGH TAU 48 WITH A CROSS-TRACK SPREAD OF ABOUT 100 NM. THE ECMWF AND EC-AIFS MAKE UP THE WESTERNMOST TRACKERS WHILE THE GFS AND GEFS MEAN MAKE UP THE EASTERNMOST TRACKERS. AFTER TAU 48 THE ALONG-TRACK SPREAD INCREASES SIGNIFICANTLY DUE TO VARYING TRACK SPEEDS AROUND THE RIDGE AXIS. THE GFS AND THE EXPERIMENTAL GOOGLE DEEPMIND ENSEMBLE MEAN ARE QUICKER TO ROUND THE RIDGE WHILE THE JGSM, NAVGEM, AND ECMWF ARE SLOWER. AT TAU 72 THE ALONG-TRACK SPREAD IS MEASURED TO BE OVER 350 NM, CAUSING THERE TO BE LESS CONFIDENCE IN THE FORECAST TRACK PAST THE TAU 48 MARK. THE JTWC TRACK FORECAST IS SITUATED NEAR THE CONSENSUS THROUGH TAU 48 AND THEN CLOSER TO THE GOOGLE DEEPMIND THROUGH TAU 72. INTENSITY GUIDANCE CONTINUES TO HAVE A SLIGHT SPLIT BETWEEN THE MODELS WITH THE PRIMARY OUTLIER BEING HAFS-A. THE REMAINDER OF GUIDANCE SHOWS A STEADY INTENSITY THROUGH TAU 48 FOLLOWED BY WEAKENING WHILE HAFS-A SHOWS A BRIEF PERIOD OF INTENSIFICATION FROM TAU 36 TO TAU 60 WITH A PEAK INTENSITY OF AROUND 40 KTS. THE JTWC INTENSITY FORECAST REFLECTS THE SAME PHILOSOPHY AS THE PREVIOUS WARNING, AND IS PLACED WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM// NNNN