WDPS32 PGTW 040900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 16P (KEVIN) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 22.3S 173.3E INITIAL INTENSITY: 135 KTS GEOGRAPHIC REFERENCE: 394 NM SOUTHEAST OF PORT VILA, VANUATU MOVEMENT PAST 6 HOURS: SOUTHEASTWARD AT 24 KTS SIGNIFICANT WAVE HEIGHT: 55 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: TC KEVIN HAS REACHED ITS MAX INTENSITY OF 135 KTS AND IS NOW ON A DECAYING TREND. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) AND A 040604Z SSMIS 91GHZ IMAGE DEPICT A SYMMETRICAL SYSTEM WITH CONVECTIVE BANDING WRAPPING INTO THE LOW LEVEL CIRCULATION CENTER (LLCC). TC KEVIN IS IN A FAVORABLE ENVIRONMENT FOR FURTHER TROPICAL ACTIVITY. THESE CONDITIONS ARE CHARACTERIZED BY CONSTANT POLEWARD OUTFLOW ALOFT, LOW (10-15 KTS) VERTICAL WIND SHEAR (VWS), A HEALTHY 850 MB VORTICITY SIGNATURE, AND BORDERLINE WARM (26-27 C) SEA SURFACE TEMPERATURES (SST). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE AFOREMENTIONED MSI AND MULTI-AGENCY FIX LOCATIONS. THE INITIAL INTENSITY OF 135 KTS IS ASSESSED WITH MEDIUM CONFIDENCE. IT IS SET SLIGHTLY HIGHER THAN MULTI-AGENCY DVORAKS AND MORE ALIGNED WITH THE AUTOMATED DVORAK ESTIMATES. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE EAST-NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T6.5 - 127 KTS KNES: T6.5 - 127 KTS PHFO: T6.5 - 127 KTS NFFN: T6.5 – 127 KTS CIMSS SATCON: 131 KTS AT 040217Z CIMSS ADT: 135 KTS AT 040700Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 10-15 KTS SST: 26-27 CELSIUS OUTFLOW: MODERATE POLEWARD ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: MEDIUM INITIAL WIND RADII: MEDIUM 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TC KEVIN IS TAKING A PATH VERY SIMILAR TO ITS PREDECESSOR, TC 15P (JUDY). THE SYSTEM CONTINUES ITS SOUTHEASTWARD TRACK AS IT HUGS THE OUTER PERIPHERY OF STR TO THE EAST-NORTHEAST. BY TAU 12, TC KEVIN WILL ENTER A MORE HOSTILE ENVIRONMENT CHARACTERIZED BY STRONGER VWS AND WILL DECREASE IN INTENSITY TO 120 KNOTS AS A RESULT. BY TAU 24, THE SYSTEM WILL BEGIN ITS SUBTROPICAL TRANSITION AND FURTHER DECREASE IN INTENSITY TO 100 KNOTS AS THE SYSTEM CROSSES INTO EVEN COOLER (24-25 C) SSTS. BY TAU 36, TC KEVIN WILL CONTINUE ITS SUBTROPICAL TRANSITION AND WILL START TO FEEL THE EFFECTS OF DRY AIR ENTRAINMENT FROM THE NORTHWEST BEING WRAPPED INTO THE CENTER. BY TAU 48, THE SYSTEM WILL BECOME FULLY SUBTROPICAL. MODEL DISCUSSION: THE JTWC TRACK CONSENSUS MEMBERS ARE IN EXTREMELY TIGHT AGREEMENT SHOWING A CONTINUOUS SOUTHEASTWARD TRAJECTORY. THE NAVGEM TRACKER IS THE OUTLIER WITH A MORE SOUTHWARD TRACK THAN THE OTHER CONSENSUS MEMBERS. BECAUSE OF THIS, THE JTWC FORECAST TRACK TO PLACED SLIGHTLY TO THE LEFT OF CONSENSUS THROUGHOUT THE FORECAST PERIOD. THE FORECAST MODEL ENVELOPE HAS A 27 NM SPREAD BY TAU 24 WHICH PROGRESSIVELY INCREASES TO 122 NM BY TAU 48 BY TAKING INTO ACCOUNT THE MORE SOUTHWARD NAVGEM TRACK. AS A RESULT, THE JTWC FORECAST TRACK IS SET WITH HIGH CONFIDENCE. THE JTWC INTENSITY CONSENSUS MEMBERS ARE ALSO IN GOOD AGREEMENT SHOWING A DECREASING TREND AS THE SYSTEM MAKES ITS SUBTROPICAL TRANSITION. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: MEDIUM// NNNN