WDPN31 PGTW 082100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 18W (CONSON) WARNING NR 012// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 15.6N 119.1E INITIAL INTENSITY: 50 KTS GEOGRAPHIC REFERENCE: 125 NM WEST-NORTHWEST OF MANILA, PHILIPPINES MOVEMENT PAST 6 HOURS: NORTHWESTWARD AT 13 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A DISORGANIZED SYSTEM WITH FLARING CONVECTION OBSCURING THE LOW LEVEL CIRCULATION (LLC). A 081746Z ATMS IMAGE SHOWS FRAGMENTED BANDING WRAPPING INTO A POORLY DEFINED LLC. TS 18W APPEARS TO BE OVER OPEN WATERS OF THE EASTERN SOUTH CHINA SEA BUT STILL LOOKS RAGGED AND DIFFUSE, THUS THERE IS ONLY MEDIUM CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY REMAINS AT 50 KNOTS WHICH IS A CONSENSUS OF KNES AND PGTW DVORAK ESTIMATES. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE WITH LOW VWS, RADIAL OUTFLOW WITH A WEAK POLEWARD OUTFLOW CHANNEL DEVELOPING AND WARM SSTS. THE CYCLONE IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE STR TO THE NORTH. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHWESTERN PERIPHERY OF DEEP-LAYER SUBTROPICAL RIDGE (STR) CENTERED TO THE NORTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.0 - 45 KTS RJTD: T2.5 - 35 KTS KNES: T3.5 - 55 KTS CIMSS SATCON: 59 KTS AT 081656Z CIMSS ADT: 51 KTS AT 081740Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 5-10 KTS SST: 29-30 CELSIUS OUTFLOW: WEAK RADIAL 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 18W IS FORECAST TO CONTINUE TRACKING WEST- NORTHWESTWARD ALONG THE SOUTHWEST SIDE OF THE DEEP STR THROUGH THE NEXT 12-24 HOURS. THE STR IS EXPECTED TO BUILD WHICH WILL TURN TS 18W ONTO A MORE WESTWARD TRACK AFTER TAU 24. A SECONDARY CYCLONE, STY 19W IS CURRENTLY LOCATED APPROXIMATELY 575NM TO THE EAST; HOWEVER, DUE TO THE SMALL SIZE OF BOTH SYSTEMS, BINARY INTERACTION IS NOT EXPECTED. WHILE THE SYSTEM IS BACK OVER WATER, THE LINGERING EFFECTS OF TERRAIN INTERACTION WILL LIMIT INTENSIFICATION FOR THE NEXT 12 HOURS. AFTER TAU 12, THE SYSTEM IS FORECAST TO STEADILY INTENSIFY UNDER FAVORABLE ENVIRONMENTAL CONDITIONS TO A PEAK OF 65 KNOTS AT TAU 72. INCREASING VWS AND DECREASING SSTS AND OHC VALUES WILL SERVE TO OFFSET STRONG WESTWARD OUTFLOW, LEADING TO A SLOW WEAKENING TREND THROUGH THE REMAINDER OF THE FORECAST PERIOD. MODEL DISCUSSION: NAVGEM CONTINUES TO DISPLAY ANOMALOUS BEHAVIOR, SHOWING A DRASTIC TURN NORTHEAST BY TAU 36, THEN BECOMING ABSORBED BY STY 19W. THUS THIS MODEL IS DISCOUNTED AND NOT INCLUDED IN THE CONSENSUS TRACK CALCULATIONS. THE REMAINDER OF THE GUIDANCE IS IN FAIR AGREEMENT OVERALL. THERE IS OVERALL HIGH CONFIDENCE THROUGH TAU 72, AND LOW CONFIDENCE THEREAFTER. INTENSITY GUIDANCE IS IN OVERALL GOOD AGREEMENT THAT SUPPORTS STEADY STATE IN THE NEAR-TERM FOLLOWED BY SLOW AND STEADY INTENSIFICATION TO TAU 72, THEN STEADY WEAKENING. THE JTWC FORECAST IS IN AGREEMENT WITH INTENSITY CONSENSUS (ICNW) WITH MEDIUM CONFIDENCE FOR THE DURATION OF THE FORECAST PERIOD. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: LOW INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN