WDIO31 PGTW 271500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 02B (ARNAB) WARNING NR 007// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 16.3N 82.7E INITIAL INTENSITY: 120 KTS GEOGRAPHIC REFERENCE: 497 NM SOUTHWEST OF KOLKATA, INDIA MOVEMENT PAST 6 HOURS: WESTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 39 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A COMPACT SYSTEM APPROACHING LANDFALL WITH A DETERIORATING CONVECTIVE PRESENTATION, CHARACTERIZED BY RAPID CLOUD-TOP WARMING AND CONTRACTION OF THE EYE FEATURE. ANIMATED RADAR DATA FROM THE INDIA METEOROLOGICAL DEPARTMENT (IMD) DEPICTS A QUICKLY FILLING EYE, WITH OUTERMOST SPIRAL BANDS BEGINNING TO BRUSH THE SHORELINE OF THE GODAVARI RIVER DELTA. A 271046Z SSMIS 89 GHZ MICROWAVE IMAGE REVEALED A SMALL INNER CORE OF DEEP CONVECTION FORMING AN INNER EYEWALL, AS WELL AS SIGNIFICANT DRY AIR TO THE EAST WRAPPING INTO THE CORE ALONG THE NORTHERN FLANK. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON RADAR DATA AND EXTRAPOLATION OF THE 271046Z MICROWAVE IMAGERY. ANALYSIS OF CIMSS RAW ADT DATA SUGGESTS THE SYSTEM REACHED PEAK INTENSITY BETWEEN 271000Z AND 271030Z BEFORE BEGINNING TO DETERIORATE, THOUGH MAXIMUM SUSTAINED WINDS REMAIN ELEVATED. INITIAL INTENSITY IS INCREASED TO 120 KTS, ASSESSED WITH HIGH CONFIDENCE BASED ON THE OVERALL CONGRUENCE OF SUBJECTIVE AND OBJECTIVE INTENSITY ESTIMATES NOTED BELOW. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE OVERALL, WITH LOW TO MODERATE EASTERLY VERTICAL WIND SHEAR (VWS), WARM SEA SURFACE TEMPERATURES (SSTS), HIGH OCEANIC HEAT CONTENT (OHC), AND VIGOROUS POLEWARD OUTFLOW, TEMPERED BY PROXIMITY TO LAND, INCREASING MID-LEVEL SHEAR, AND DRY AIR ENTRAINMENT. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHWESTERN FLANK OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED OVER EXTREME SOUTHERN CHINA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.0 - 115 KTS DEMS: T4.5 - 77 KTS CIMSS SATCON: 114 KTS AT 271030Z CIMSS ADT: 122 KTS AT 271130Z CIMSS AIDT: 122 KTS AT 271130Z CIMSS D-MINT: 119 KTS AT 271046Z CIMSS D-PRINT: 121 KTS AT 271130Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: STRONG POLEWARD OTHER FACTORS: PROXIMITY TO LAND. ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THE FORECAST HAS BEEN TRUNCATED TO 48 HOURS DUE TO ANTICIPATED DISSIPATION OVER LAND. FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 02B HAS MAINTAINED A FASTER-THAN-EXPECTED WESTWARD TRAJECTORY OVER THE PAST SIX HOURS AND IS NOW APPROACHING THE COAST SLIGHTLY AHEAD OF SCHEDULE. HOWEVER, RECENT FRAMES OF BOTH EIR AND RADAR IMAGERY SUGGEST THE SYSTEM IS DECELERATING AS IT NEARS THE COASTLINE, AS ANTICIPATED BY GLOBAL GUIDANCE, DUE TO BINARY INTERACTION WITH INVEST 90B, WHICH IS RAPIDLY DEVELOPING APPROXIMATELY 280 NM TO THE SOUTHEAST. AS 90B PROPAGATES RAPIDLY NORTHWARD, IT WILL IMPART A DEFLECTIVE PULL, RETARDING TC 02BS WESTWARD TRANSLATION, DELAYING LANDFALL, AND CAUSING A BRIEF STALL ALONG THE GODAVARI DELTA COASTLINE. NUMERICAL MODEL TRACKERS SMOOTH THIS MOTION OUT OVER 12-HOUR TIME STEPS; HOWEVER, PROGNOSTIC FIELDS IN GFS, ECMWF, HAFS-A, AND HWRF CLEARLY RESOLVE THIS NEAR-TERM BINARY OSCILLATION, DIFFERING ONLY IN WHERE LANDFALL OCCURS AND HOW FAR INLAND THE SYSTEM TRACKS BEFORE STALLING. THE FORECAST TRACK CALLS FOR LANDFALL ALONG THE SOUTHWESTERN COAST OF THE GODAVARI RIVER DELTA BY TAU 12, BUT PRIOR TO LANDFALL, THE SYSTEM IS LIKELY TO SKIRT THE COASTLINE OR STALL BRIEFLY. INVEST 90B IS MOVING RAPIDLY NORTHWARD, IS EXPECTED TO CONTINUE ACCELERATING, AND WILL BE POSITIONED NORTHEAST OF TC 02B WITHIN THE NEXT 12-18 HOURS. AS 90B EJECTS TO THE NORTHEAST, TC 02B WILL RESUME A NORTHWARD TRACK FROM TAU 12 ONWARD THROUGH THE REMAINDER OF THE FORECAST PERIOD ALONG THE WESTERN PERIPHERY OF THE LOW- TO MID-LEVEL STR TO THE EAST. REGARDING INTENSITY, THE SYSTEM PEAKED NEAR 271000Z; LAND PROXIMITY, STRENGTHENING EASTERLY SHEAR, AND DRY AIR INTRUSION ARE NOW IMPINGING ON THE INNER CORE, LEADING TO RAPID CONVECTIVE DETERIORATION. WEAKENING WILL CONTINUE, THOUGH LANDFALL OVER THE SATURATED DELTA REGION AND THE ASSOCIATED BROWN OCEAN EFFECT WILL MODERATE THE PACE OF WEAKENING THROUGH TAU 12. MORE RAPID WEAKENING WILL OCCUR AFTER TAU 12, WITH TC 02B FORECAST TO DISSIPATE OVER LAND BELOW THE 35-KT WARNING THRESHOLD WITHIN 48 HOURS DUE TO TERRAIN FRICTION. MODEL DISCUSSION: TRACK GUIDANCE IS IN STRONG AGREEMENT, THOUGH NEAR-TERM TRACK DEVIATIONS ARE SMOOTHED OUT BY THE 12-HOUR TIME STEPS OF THE MODEL TRACKERS. NAVGEM IS THE ONLY OUTLIER, SHOWING LANDFALL ALONG THE NORTHEASTERN COAST OF THE GODAVARI DELTA REGION BEFORE TURNING NORTH. THE REMAINDER OF THE GUIDANCE PACKAGE IS CLOSELY PACKED AROUND THE JTWC FORECAST, WHICH IS POSITIONED NEAR THE MULTI- MODEL CONSENSUS MEAN WITH HIGH CONFIDENCE. CONFIDENCE IS TEMPERED SOMEWHAT IN THE NEAR TERM DUE TO UNCERTAINTIES REGARDING THE BINARY INTERACTION WITH 90B AND THE EXACT TIMING AND LOCATION OF LANDFALL. INTENSITY GUIDANCE IS IN STRONG AGREEMENT. THE JTWC FORECAST IS PLACED ON THE UPPER EDGE OF THE ENVELOPE THROUGH TAU 12 TO ACCOUNT FOR THE BROWN OCEAN EFFECT, THEN TRACKS NEAR THE GOOGLE DEEPMIND (GDM) SOLUTION THROUGH THE REMAINDER OF THE FORECAST. FORECAST CONFIDENCE: TRACK 00-72 HR: HIGH INTENSITY 00-72 HR: MEDIUM// NNNN