WDPN31 PGTW 080900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 22W (KROVANH) WARNING NR 029// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 31.1N 132.8E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 195 NM SOUTH OF IWAKUNI, JAPAN MOVEMENT PAST 6 HOURS: NORTHWARD AT 08 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL DEPRESSION 22W (KROVANH) WITH A MOSTLY EXPOSED LOW-LEVEL CIRCULATION CENTER (LLCC) AND PERSISTENT CONVECTION DISPLACED TO THE NORTHWEST OF THE CENTER. THE SHEAR DIRECTION APPEARS TO BE SHIFTING TO SOUTHERLY BASED ON THE DIRECTION OF THE FAINT UPPER-LEVEL CLOUDS RUNNING ACROSS THE VORTEX. THE STRUCTURE OF THE LLCC HAS ALSO BECOME MORE IRREGULAR OVER THE PAST 6 HOURS AS THE SYSTEM APPROACHES THE FRONTAL BOUNDARY OVER HONSHU. NONETHELESS, THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLCC IN ANIMATED MSI. 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 IS IN AN UNFAVORABLE ENVIRONMENT CHARACTERIZED BY STRONG POLEWARD OUTFLOW ALOFT AND WARM (28-29 C) SEA SURFACE TEMPERATURES GREATLY OFFSET BY MODERATE TO HIGH (20-25 KTS) SOUTHERLY VERTICAL WIND SHEAR AND EXTENSIVE DRY AIR ENTRAINMENT. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: THE NORTHWESTERN FLANK OF THE SUBTROPICAL RIDGE (STR) CENTERED SOUTHEAST OF JAPAN AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.0 - 30 KTS RJTD: T1.5 - 25 KTS CIMSS ADT: 32 KTS AT 080610Z CIMSS AIDT: 38 KTS AT 080610Z CIMSS D-MINT: 32 KTS AT 080431Z CIMSS D-PRINT: 30 KTS AT 080610Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE VWS: 20-25 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG POLEWARD OTHER FACTORS: SIGNIFICANT DRY AIR ENTRAINMENT 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 MORE NORTHEASTWARD OVER THE NEXT 12 HOURS AS IT ROUNDS THE NORTHWESTERN PERIPHERY OF THE STR. AFTER TAU 12, THE SYSTEM WILL SKIRT THE SOUTHERN COAST OF JAPAN, NEAR THE SHIKOKU AND KANSAI REGIONS WITH INCREASING TRACK SPEEDS. 22W WILL BE HEAVILY IMPACTED BY THE STATIONARY FRONTAL BOUNDARY THAT IS CURRENTLY DRAPED ACROSS HONSHU, CAUSING THE CIRCULATION TO BECOME STRETCHED AND LIKELY MOVE UNPREDICTABLY. IN TERMS OF INTENSITY, 22W IS FORECAST TO MAINTAIN ITS CURRENT INTENSITY OF 30 KTS THROUGH TAU 12, MOSTLY DUE TO THE WARM WATERS AND STRONG POLEWARD OUTFLOW CHANNEL. FOLLOWING TAU 12, SOUTHWESTERLY SHEAR WILL SIGNIFICANTLY INCREASE, CAUSING THE VORTEX TO ERODE AND SHALLOW OUT. ONCE THE SYSTEM BEGINS TO INTERACT WITH THE MOUNTAINOUS TERRAIN OF JAPAN, 22W WILL QUICKLY WEAKEN WITH DISSIPATION EXPECTED TO OCCUR NEAR TAU 24. EVEN THOUGH THE VORTEX ASSOCIATED WITH 22W BECOMES ABSORBED WITHIN THE FRONTAL BOUNDARY, LOCALIZED AREAS OF ENHANCED WINDS DUE TO TERRAIN FUNNELING MAY PERSIST IN AREAS SUCH AS WAKAYAMA BAY AND ISE BAY. MODEL DISCUSSION: MODEL TRACK GUIDANCE NOW AGREES ON THE NORTHEASTWARD TURN THROUGH TAU 24 WITH MINIMAL CROSS-TRACK SPREAD. HOWEVER, ALONG-TRACK SPREAD CONTINUES TO BE HIGH DUE TO MODELS VARYING IN THE SPEED OF ADVANCE AROUND THE RIDGE. THE JTWC TRACK FORECAST IS PLACED NEAR THE MULTI-MODEL CONSENSUS THROUGHOUT THE SHORT FORECAST PERIOD WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE AGREES ON RAPID DISSIPATION AFTER LANDFALL, THOUGH THE GFS DOES SHOW A BRIEF PERIOD OF INTENSIFICATION TO 35 KTS AT TAU 12, JUST BEFORE LANDFALL OCCURS. THE JTWC INTENSITY FORECAST IS ALSO PLACED NEAR THE CONSENSUS WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 00-72 HR: MEDIUM INTENSITY 00-72 HR: MEDIUM// NNNN