WDXS32 PGTW 010300 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 22S (HALIMA) WARNING NR 018// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 19.4S 84.0E INITIAL INTENSITY: 40 KTS GEOGRAPHIC REFERENCE: 997 NM SOUTHEAST OF DIEGO GARCIA MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 04 KTS SIGNIFICANT WAVE HEIGHT: 14 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED ENHANCED INFRARED SATELLITE IMAGERY (EIR) DEPICTS A MEDIUM-SIZED SYSTEM WITH ITS ASSOCIATED CONVECTION BEING SHEARED SOUTHEASTWARD AWAY FROM THE PARTIALLY EXPOSED LOW-LEVEL CIRCULATION (LLC). THE CENTRAL CONVECTION REMAINS OFFSET TO THE SOUTHEAST OF THE LLC, WHICH HAS WANED SIGNIFICANTLY OVER THE LAST TWELVE HOURS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE 312328Z SSMIS 37GHZ MICROWAVE EYE. THE INITIAL INTENSITY OF 40KTS IS BASED ON THE HIGHER END OF PGTW AND THE AUTOMATED DVORAK ESTIMATES. ANALYSIS INDICATES A MARGINALLY UNFAVORABLE ENVIRONMENT WITH THE WARM SST AND STRONG POLEWARD OUTFLOW OFFSET BY MODERATE VWS AND COLD DRY AIR INTRUSION AT THE LOW LEVELS. INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK CURRENT STEERING MECHANISM: EASTERN EXTENSION OF THE NEAR EQUATORIAL RIDGE (NER) TO THE NORTHWEST, AND A SUBTROPICAL RIDGE (STR) TO THE SOUTHWEST. AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T2.5 - 35 KTS CIMSS SATCON: 41 KTS AT 312245Z CIMSS ADT: 39 KTS AT 010015Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY UNFAVORABLE 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: TC HALIMA HAS FINALLY MADE THE TURN BACK TO THE WEST AS PREVIOUSLY FORECASTED DUE TO THE RETROGRADING NER. A BUILDING STR TO THE SOUTHWEST IS BEGINNING TO ASSUME STEERING AND WILL DRIVE THE SYSTEM GENERALLY WESTWARD THROUGH THE REMAINDER OF THE FORECAST, WHICH IS NOW ONLY OUT TO TAU 48 DUE TO INCREASING SHEAR AS THE STORM MOTION IS BOMBARDED BY DRY AIR INTRUSION AND THE OUT-OF-PHASE WITH THE UPPER LEVEL WIND FLOW. THIS WILL SLOWLY ERODE THE SYSTEM TOWARD DISSIPATION BY TAU 48, OR POSSIBLY SOONER. MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT WITH THE WESTWARD TRAJECTORY AND THEY REMAIN ONLY 60NM APART FROM THE FAR RIGHT (NAVGEM) AND LEFT (AFUM) OUTLIERS. THIS LENDS OVERALL HIGH CONFIDENCE IN THE JTWC TRACK FORECAST, WHICH IS LAID CLOSE TO AND SLIGHTLY LEFT OF THE MODEL CONSENSUS. THE INTENSITY IS SPLIT WITH HWRF INDICATING A SLIGHT INCREASE TO A PEAK INTENSITY OF 45KTS WITHIN THE NEXT 24 HOURS, WHEREAS GFS INDICATES THE SYSTEM DROPPING BELOW WARNING CRITERIA BY TAU 48. THIS UNCERTAINTY IN THE FORECAST LENDS LOW CONFIDENCE FOR THE JTWC INTENSITY FORECAST. FORECAST CONFIDENCE: TRACK 0 - 72 HR: HIGH INTENSITY 0 - 72 HR: LOW// NNNN