WDIO31 PGTW 240300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 05B (SITRANG) WARNING NR 003// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 17.7N 89.2E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 312 NM SOUTH-SOUTHWEST OF CHITTAGONG, BANGLADESH MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 11 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A VERY LARGE CYCLONE (600NM+ DIAMETER) SPANNING MOST OF THE BAY OF BENGAL WITH BROAD AND DEEP RAIN BANDS AHEAD AND TO THE RIGHT OF A WIDE CENTRAL DENSE OVERCAST THAT IS OFFSET NORTHWARD BUT STILL OBSCURING THE LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS BASED ON A RAGGED BUT DEFINED MICROWAVE LLC FEATURE IN THE 232348Z GPM 89GHZ IMAGE. THE INITIAL INTENSITY IS BASED ON AGENCY AND AUTOMATED DVORAK ESTIMATES. INITIAL WIND RADII BASIS: SCATTEROMETER DATA CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS DEMS: T2.5 - 35 KTS CIMSS ADT: 39 KTS AT 231815Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 29-30 CELSIUS OUTFLOW: STRONG POLEWARD AND EQUATORWARD 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: TC SITRANG WILL CONTINUE ON ITS NORTH-NORTHEASTWARD TRACK ALONG THE NORTH-WESTERN EDGE OF THE STR AND MAKE LANDFALL OVER BANGLADESH, APPROXIMATELY 54NM TO THE WEST OF CHITTAGONG, A FEW HOURS BEFORE TAU 24. THE FAVORABLE ENVIRONMENT WILL FUEL AN INTENSIFICATION TO A PEAK OF 50KTS BY TAU 12. AFTERWARD, INCREASING VWS AND EVENTUAL LANDFALL WILL RAPIDLY ERODE THE SYSTEM DOWN TO 35KTS AT LANDFALL, THEN DISSIPATION BY TAU 36. MODEL DISCUSSION: NUMERICAL MODELS ARE IN VERY TIGHT AGREEMENT WITH VERY MINIMAL AND GRADUAL SPREAD TO 90NM BY TAU 36, LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN