WDXS31 PGTW 190300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 24S (IALY) WARNING NR 006// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 7.5S 46.6E INITIAL INTENSITY: 55 KTS GEOGRAPHIC REFERENCE: 686 NM NORTH OF ANTANANARIVO, MADAGASCAR MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 05 KTS SIGNIFICANT WAVE HEIGHT: 18 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS AN IRREGULAR CENTRAL DENSE OVERCAST FEATURE, WITH RAPIDLY-CYCLING BURSTS OF DEEP CONVECTION. AN 182247Z ATMS 88.2 GHZ MICROWAVE IMAGE REVEALS DEEP CONVECTIVE BANDING PRIMARILY OVER THE WESTERN SEMICIRCLE WRAPPING TIGHTLY INTO THE NORTHERN QUADRANT OF THE CORE. A PARTIAL 190007Z SSMIS 91 GHZ MICROWAVE IMAGE REVEALS A LIKELY MICROWAVE EYE FEATURE, WHICH SUPPORTS THE INITIAL POSITION WITH HIGH CONFIDENCE AND REFLECTS THE SHORT-TERM CONSOLIDATION TREND. ENVIRONMENTAL CONDITIONS REMAIN FAVORABLE, WITH LOW TO MODERATE VERTICAL WIND SHEAR AND MODERATE RADIAL OUTFLOW FUELING THE RECENT PHASE OF CONSOLIDATION. THE INITIAL INTENSITY OF 55 KTS IS ASSESSED WITH HIGH CONFIDENCE BASED ON CONCURRENT T3.5 (55 KNOTS) ESTIMATES FROM ALL AGENCIES. OBJECTIVE DVORAK ESTIMATES RANGE FROM 49 TO 57 KNOTS AND BOLSTER THE INITIAL INTENSITY ESTIMATE. A RECENT 181459Z RCM-2 SAR PASS MISSED WELL TO THE EAST. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR) EXTENSION TO THE SOUTH, WITH PRIMARY STR ENTRENCHED TO THE NORTHWEST OVER EAST CENTRAL AFRICA. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS KNES: T3.5 - 55 KTS DEMS: T3.5 - 55 KTS FMEE: T3.5 - 55 KTS CIMSS SATCON: 57 KTS AT 182300Z CIMSS ADT: 53 KTS AT 190000Z CIMSS AIDT: 49 KTS AT 190000Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE VWS: 15-20 KTS SST: 28-29 CELSIUS OUTFLOW: MODERATE RADIAL ANALYSIS CONFIDENCE: INITIAL POSITION: HIGH INITIAL INTENSITY: HIGH INITIAL WIND RADII: LOW 3. FORECAST REASONING. SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO THE FORECAST FROM THE PREVIOUS WARNING. FORECAST DISCUSSION: TROPICAL CYCLONE (TC) 24S IS EXPECTED TO GRADUALLY TURN NORTHWARD OVER THE NEXT 12 HOURS AS IT TRANSITIONS TO THE STEERING INFLUENCE OF THE NORTH-SOUTH ORIENTED STR POSITIONED OVER EAST CENTRAL AFRICA. DUE TO THE FAVORABLE CONDITIONS EXPECTED THROUGH TAU 12, THE SYSTEM MAY INTENSIFY TO 60 KNOTS OVER THE NEXT SIX HOURS BEFORE THE ONSET OF DRY AIR ENTRAINMENT OCCURS NEAR TAU 12. AFTER TAU 12, SIGNIFICANT DRY AIR ADVECTING EASTWARD FROM TANZANIA WILL ENTRAIN INTO THE NORTHERN REGION OF THE SYSTEM LEADING TO A STEADY WEAKENING TREND AND EVENTUAL DISIPATION BY TAU 48 AS THE SYSTEM TRACKS NORTHWARD. MODEL DISCUSSION: WITH THE EXCEPTION OF NAVGEM (THE SOLE OUTLIER WEST OF THE AIDS ENVELOPE), DETERMINISTIC MODEL GUIDANCE REMAINS IN FAIR AGREEMENT WITH A 35 TO 50 NM CROSS-TRACK SPREAD IN SOLUTIONS FROM TAU 36 TO TAU 48. EPS AND GEFS PROBABILISTIC GUIDANCE SHOWS A SIMILAR NORTHWARD SPREAD OF SOLUTIONS, WITH DISSIPATION HIGHLY LIKELY EQUATORWARD OF 5 DEGREES SOUTH LATITUDE. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN