WDPN32 PGTW 302100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 13W (THIRTEEN) WARNING NR 001// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 20.1N 133.1E INITIAL INTENSITY: 30 KTS GEOGRAPHIC REFERENCE: 482 NM SOUTHEAST OF KADENA AB MOVEMENT PAST 6 HOURS: NORTH-NORTHEASTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A FULLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC), DISPLACED TO THE NORTHEAST OF DISORGANIZED FLARING CONVECTION. THE SYSTEM HAS MODERATE NORTHERLY SHEAR EMANATING FROM STY 12W TO THE NORTH AND IS STRUGGLING TO CONSOLIDATE. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE EXPOSED CIRCULATION. THE INITIAL INTENSITY IS ASSESSED WITH LOW CONFIDENCE BASED ON TWO SHIP OBSERVATIONS TO THE SOUTHEAST AND NORTHEAST NEAR NEAR 30 KNOTS, AND A PARTIAL 301238Z ASCAT-B PASS WITH 25 KNOT WINDS IN THE SOUTHEAST QUADRANT. INITIAL WIND RADII BASIS: NOT APPLICABLE (THERE ARE NO INITIAL WIND RADII). CURRENT STEERING MECHANISM: NORTHWEST SIDE OF A NEAR EQUATORIAL RIDGE (NER) TO THE EAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T1.5 - 25 KTS RJTD: T1.5 - 25 KTS FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 15-20 KTS SST: 30-31 CELSIUS OUTFLOW: WEAK EQUATORWARD OTHER FACTORS: VWS FROM STY 12W ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: LOW INITIAL WIND RADII: NOT APPLICABLE 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THIS INITIAL PROGNOSTIC REASONING MESSAGE ESTABLISHES THE FORECAST PHILOSOPHY. FORECAST DISCUSSION: TD 13W IS FORECAST TO TRACK NORTH-NORTHWEST ALONG THE WEST SIDE OF THE STEERING RIDGE TO THE EAST. THE SYSTEM IS WITHIN 400NM OF STY 12W AND IS IN THE PROCESS OF BEING CAPTURED IN A BINARY INTERACTION. THUS THE TRACK IS EXPECTED TO STEADY APPROACH STY 12W IN A GRADUAL CYCLONIC ARC, ULTIMATELY MERGING WITH THE BROADENING WIND FIELD ASSOCIATED WITH STY 12W AND DISSIPATING AS A DISTINCT, SEPARATE CIRCULATION. THIS EVENTUALITY IS ANTICIPATED NO LATER THAN TAU 48 AS THE SYSTEM SLIDES SOUTH OF OKINAWA. HOWEVER, WHILE THE SYSTEM WILL DISSIPATE AS A SEPARATE SYSTEM, THE WINDS WILL REMAIN HIGH WITH THE FORECAST INTENSITY CURRENTLY FORECAST TO BE 35 KNOTS AS THE SYSTEM MERGES WITH STY 12W. MODEL DISCUSSION: NUMERICAL GUIDANCE IS IN POOR AGREEMENT, WITH THE GALWEM AND UKMET ENSEMBLE TAKING THE SYSTEM MORE SHARPLY WESTWARD AND MERGING WITH STY 12W FASTER THAN THE REMAINDER OF THE GUIDANCE. THE JTWC FORECAST LIES CLOSE TO THE GFS TRACKER, NORTH OF THE CONSENSUS MEAN, WITH LOW CONFIDENCE DUE TO THE VAGARIES ASSOCIATED WITH THE BINARY INTERACTION WITH STY 12W. INTENSITY GUIDANCE IS EXTREMELY UNCERTAIN, WITH AVAILABLE GUIDANCE INDICATING A SPREAD BETWEEN 25 KNOTS (DECAY SHIPS) AND 125 KNOTS (HWRF). OBVIOUSLY BOTH OF THESE OUTLIERS ARE UNLIKELY, AND THE JTWC FORECAST IS HEDGED ABOVE THE SHIPS GUIDANCE, BUT WELL BELOW THE CONSENSUS MEAN AFTER TAU 36, WHEN IT DISPLAYS A STEEP CLIMB TO THE UNREALISTIC PEAKS OF THE HWRF. NEEDLESS TO SAY, CONFIDENCE IS LOW IN THE FORECAST INTENSITY. FORECAST CONFIDENCE: TRACK 0 - 72 HR: LOW INTENSITY 0 - 72 HR: LOW// NNNN