WDXS33 PGTW 022100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 23S (HONDE) WARNING NR 011// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 27.2S 46.3E INITIAL INTENSITY: 60 KTS GEOGRAPHIC REFERENCE: 448 NM SOUTHEAST OF EUROPA ISLAND MOVEMENT PAST 6 HOURS: SOUTHWARD AT 01 KTS SIGNIFICANT WAVE HEIGHT: 25 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS TROPICAL CYCLONE 23S (HONDE) WITH A DEGRADED CONVECTIVE STRUCTURE, THE BANDING EYE THAT WAS PREVIOUSLY PRESENT HAS WASHED OUT. RIGHT AROUND 1800Z, STRONG CONVECTIVE BURSTS ARE BEGINNING TO FORM OVER THE LOW-LEVEL CIRCULATION CENTER. MODELS ARE PICKING UP ELEVATED UPPER-LEVEL NORTHERLY VERTICAL WIND SHEAR. THIS COULD BE THE CULPRIT, ALONG WITH THE DRY AIR OVER THE WESTERN PERIPHERY, FOR THE DEGRADED CONVECTION. POLEWARD OUTFLOW REMAINS STRONG AND SEA SURFACE TEMPERATURES REMAIN RELATIVELY WARM (26-27 C) THOUGH. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE ANIMATED EIR SATELLITE IMAGERY. THE INITIAL INTENSITY OF 60 KTS IS ALSO ASSESSED WITH MEDIUM CONFIDENCE BASED ON THE AGENCY DVORAK AND OBJECTIVE INTENSITY ESTIMATES LISTED BELOW. INITIAL WIND RADII BASIS: PERSISTENCE FROM EARLIER SCATTEROMETER DATA CURRENT STEERING MECHANISM: COMPETING STEERING PATTERN WITH A SUBTROPICAL RIDGE (STR) TO THE EAST AND WEST OF THE SYSTEM. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS KNES: T3.5 - 55 KTS FMEE: T3.5 - 55 KTS DEMS: T3.5 - 55 KTS CIMSS SATCON: 57 KTS AT 021551Z CIMSS ADT: 59 KTS AT 021800Z CIMSS AIDT: 58 KTS AT 021800Z CIMSS DMINT: 49 KTS AT 021800Z CIMSS DPRINT: 53 KTS AT 021800Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINAL VWS: 10-15 KTS SST: 26-27 CELSIUS OUTFLOW: STRONG POLEWARD OTHER FACTORS: DRY AIR WITHIN THE WESTERN PERIPHERY AND NORTHERLY UPPER-LEVEL VERTICAL WIND SHEAR ANALYSIS CONFIDENCE: INITIAL POSITION: MEDIUM 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 23S IS FORECAST TO LEAVE THE COMPETING STEERING PATTERN AND BEGIN TRACKING SOUTH-SOUTHEASTWARD AS THE STR TO THE EAST BECOMES THE PRIMARY STEERING MECHANISM. THE SYSTEM IS FORECAST TO CONTINUE ON A SOUTH-SOUTHEASTWARD TRACK THROUGH TAU 72. AFTER TAU 72, 23S WILL HAVE ROUNDED THE RIDGE AXIS AND WILL ACCELERATE MORE EASTWARD AS IT BEGIN TO INTERACT WITH THE UPPER-LEVEL JET. EXTRATROPICAL TRANSITION IS EXPECTED TO COMPLETE NO LATER THAN TAU 96, MORE LIKELY AROUND TAU 84. REGARDING INTENSITY, 23S IS FORECAST TO MAINTAIN INTENSITY THROUGH TAU 24 AS POLEWARD OUTFLOW REMAINS STRONG AND SEA SURFACE TEMPERATURES REMAIN OVER 26 C. DRY AIR IS EXPECTED TO PERSIST, WHICH WILL PUT A CAP ON FURTHER INTENSIFICATION. AFTER TAU 24, SEA SURFACE TEMPERATURES WILL BEGIN TO DROP AND EASTERLY VERTICAL WIND SHEAR WILL BEGIN TO PICK UP, CAUSING WEAKENING. EASTERLY SHEAR WILL RISE TO NEAR 30 KTS AT TAU 48 AND THEN 45 KTS AT TAU 72. BY THE END OF THE FORECAST PERIOD, 23S WILL HAVE TRANSITIONED INTO A COLD-CORE LOW WITH AN INTENSITY OF AROUND 35 KTS. MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN VERY GOOD AGREEMENT REGARDING THE TRACK OF 23S WITH A CROSS-TRACK SPREAD OF 66 NM (WHEN DISCOUNTING NAVGEM) AND MINIMAL ALONG-TRACK SPREAD AT TAU 96. THEREFORE, THE JTWC TRACK FORECAST IS PLACED WITH OVERALL HIGH CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD AGREEMENT REGARDING THE INTENSITY AS WELL. THROUGH TAU 72, THERE IS ABOUT A 8 KNOT SPREAD BETWEEN MODELS. AFTER TAU 72, WEAKENING TRENDS BEGIN TO DIFFER WITH COAMPS-TC AND HAFS-A BEING THE MOST AGGRESSIVE IN WEAKENING THE VORTEX. THE JTWC INTENSITY FORECAST IS PLACED WITH HIGH CONFIDENCE THOUGH TAU 72 AND MEDIUM CONFIDENCE THEREAFTER. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH TRACK 72-120 HR: HIGH INTENSITY 0 - 72 HR: HIGH INTENSITY 72-120 HR: MEDIUM// NNNN