WDXS31 PGTW 061500 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 03S (THREE) WARNING NR 002// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 9.4S 86.5E INITIAL INTENSITY: 35 KTS GEOGRAPHIC REFERENCE: 843 NM EAST OF DIEGO GARCIA MOVEMENT PAST 6 HOURS: NORTHWARD AT 01 KTS SIGNIFICANT WAVE HEIGHT: 12 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS A PARTIALLY EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) DISPLACED TO THE EAST OF THE PRIMARY CONVECTIVE MASS. THE LATEST IMAGERY SUGGESTS CONVECTION IS REDEVELOPING IN THE VICINITY OF, AND MAY NOW BE COVERING UP, THE LLCC ONCE MORE. A 061141Z SSMIS 91GHZ IMAGE DEPICTED LOW-LEVEL RAIN BANDS WRAPPING INTO THE EXPOSED LLCC WITH DEEP CONVECTION FLARING JUST WEST OF THE CENTER AND WEAKER CONVECTION EXTENDING TO THE SOUTHWEST. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE BASED ON THE MICROWAVE IMAGE NOTED ABOVE. THE LATEST WINDSPEED MEASUREMENT CAME FROM A 060738Z AMSR2 WINDSPEED IMAGE WHICH SHOWED A SMALL PATCH OF GALE-FORCE WINDS IN THE SOUTHWEST QUADRANT AND 30-33 KNOT WINDS IN THE NORTHWEST QUADRANT. THE INITIAL INTENSITY OF 35 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE USING THE AMSR2 ESTIMATE IN CONJUNCTION WITH THE BULK OF AGENCY AND OBJECTIVE FIX DATA. ENVIRONMENTAL CONDITIONS ARE MARGINALLY FAVORABLE WITH WARM SSTS AND STRONG POLEWARD OUTFLOW OFFSET BY MODERATE TO HIGH VWS. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: WEAK STEERING PATTERN BETWEEN WEAK EQUATORIAL WESTERLIES TO THE NORTH AND A SUBTROPICAL RIDGE (STR) TO THE SOUTHEAST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS KNES: T3.0 - 45 KTS FMEE: T2.5 - 35 KTS CIMSS SATCON: 43 KTS AT 060719Z CIMSS ADT: 35 KTS AT 060915Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 27-28 CELSIUS OUTFLOW: STRONG POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH 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: OVER THE PAST SIX TO TWELVE HOURS, TC 03S HAS SLOWED DOWN SIGNIFICANTLY AS THE STEERING PATTERN HAS WEAKENED AND THE LOW-LEVEL AND VORTEX BECAME DECOUPLED FROM THE DEEP CONVECTIVE CORE. OVER THE NEXT 24 HOURS THE SYSTEM IS EXPECTED TO DRIFT SLOWLY TOWARDS THE SOUTHWEST AS THE GRADIENT TIGHTENS UP ON THE WESTERN SIDE OF THE STR TO THE EAST. BY TAU 36 THE STR TO THE EAST REORIENTS TO A MORE NORTH-SOUTH AXIS, ALLOWING FOR TC 03S TO ASSUME A MORE SOUTHWARD TRACK, WHICH IS EXPECTED TO CONTINUE THROUGH ABOUT TAU 72. SHEAR IS FORECASTED TO WEAKEN SLIGHTLY OVER THE NEXT 24 HOURS, AND IF THE SYSTEM CAN SUSTAIN DEEP CONVECTION AROUND THE LLCC IN THE DIVERGENT UPPER-LEVEL OUTFLOW, AND PUSH BACK ON THE SHEAR, MARGINAL INTENSIFICATION IS POSSIBLE THROUGH TAU 72. BY TAU 72, A SHARP 500MB TROUGH AXIS IS EXPECTED TO BE CLOSING IN ON TC 03S AND AS THIS AXIS PASSES, THE COMBINATION OF STRONG MID-LEVEL NORTHWESTERLY SHEAR AND DRY AIR BEHIND THE TROUGH WILL DECAPITATE THE SYSTEM, LEADING TO RAPID WEAKENING. BY TAU 96, A TRANSITORY HIGH PRESSURE SYSTEM WILL SLIDE INTO POSITION DUE SOUTH OF TC 03S AND THE NOW SIGNIFICANTLY WEAKENED REMNANTS OF TC 03S WILL MOVE WEST ALONG NORTHERN SIDE OF THE STRONG RIDGE TO THE SOUTH. MODEL DISCUSSION: DETERMINISTIC AND ENSEMBLE TRACK GUIDANCE IS IN AGREEMENT ON THE OVERALL SCENARIO AND THE BULK OF THE DETERMINISTIC TRACKERS LIE WITHIN A GRADUALLY EXPANDING ENVELOPE, 150NM WIDE AT TAU 72. THE NOTABLE EXCEPTIONS ARE THE NAVGEM AND GALWEM MODELS WHICH DEPICT AN UNREALISTIC TRACK SOUTHWARD INTO THE STRONG TRANSITORY RIDGE AFTER TAU 72, AND THESE MODELS HAVE BEEN DISCOUNTED. THE ENVELOPE EXPANDS A BIT BY TAU 96 BUT WITH THE EXCEPTION OF THE TRACKERS NOTED ABOVE, ALL CONSENSUS MEMBERS CONCUR ON A SHARP TURN TO THE WEST BY TAU 96. THE JTWC TRACK IS POSITIONED NEAR THE CONSENSUS MEAN WITH MEDIUM CONFIDENCE. THERE ARE NO SURPRISES IN THE INTENSITY GUIDANCE, WITH THE MESOSCALE MODELS SUGGESTING A HIGHER PEAK INTENSITY (45 KNOTS) THAN THE DECAY SHIPS AND GLOBAL MODELS (35 KNOTS). THE JTWC FORECAST LIES SLIGHTLY HIGHER THAN THE CONSENSUS MEAN, AND CLOSE TO THE HWRF THROUGH THE FORECAST PERIOD WITH MEDIUM CONFIDENCE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM TRACK 72-120 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM INTENSITY 72-120 HR: MEDIUM// NNNN