WDXS31 PGTW 100900 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 25S (KARIM) WARNING NR 007// RMKS/ 1. FOR METEOROLOGISTS. 2. 6 HOUR SUMMARY AND ANALYSIS. SUMMARY: INITIAL POSITION: 16.6S 92.0E INITIAL INTENSITY: 60 KTS GEOGRAPHIC REFERENCE: 1295 NM WEST OF LEARMONTH, AUSTRALIA MOVEMENT PAST 6 HOURS: SOUTH-SOUTHEASTWARD AT 13 KTS SIGNIFICANT WAVE HEIGHT: 22 FEET SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION: ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A UNIFORM CENTRAL DENSE OVERCAST (CDO) OBSCURING THE LOW-LEVEL CIRCULATION CENTER (LLCC). THERE IS PERSISTENT DEEP CONVECTION AROUND THE LLCC WITH ROBUST RADIAL OUTFLOW AS SEEN ON THE MSI LOOP WITH STRONG STRIATIONS FROM THE CIRRUS CANOPY. THERE IS ALSO NOTICEABLE DRY-AIR ENTRAINING FROM THE NORTH TO THE EASTERN SEMICIRCLE. THE INITIAL POSITION AND INTENSITY ARE PLACED WITH HIGH CONFIDENCE THROUGH EXTRAPOLATION FROM A BULLSEYE PASS AS SEEN ON AN OLDER 100337Z METOP-B ASCAT IMAGE AND BOTH 100717Z SSMIS 89GHZ AND 37GHZ IMAGES. INITIAL WIND RADII BASIS: PERSISTENCE CURRENT STEERING MECHANISM: SOUTHWEST PERIPHERY OF A SUBTROPICAL RIDGE (STR) POSITIONED TO THE NORTHEAST AGENCY DVORAK AND AUTOMATED FIXES: PGTW: T3.5 - 55 KTS APRF: T3.5 - 55 KTS CIMSS SATCON: 62 KTS AT 100711Z CIMSS ADT: 59 KTS AT 100540Z FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE VWS: 20-25 KTS SST: 26-27 CELSIUS OUTFLOW: STRONG RADIAL OTHER FACTORS: DRY AIR ENTRAINMENT IN THE UPPER-LEVELS 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: TC 25S WILL REMAIN ON A SOUTH-SOUTHEASTWARD TRACK ALONG THE WESTERN PERIPHERY OF THE NEAR EQUATORIAL RIDGE (NER) THROUGH TAUS 12 AND 24. THE STEERING FLOW BETWEEN A BROAD UPPER-LEVEL TROUGH AND A SUBTROPICAL RIDGE POSITIONED TO THE EAST WILL CONTINUE TO HINDER THE SOUTHERLY TRACK BY TAU 36. AT THAT TIME, A STRONG LOW-LEVEL HIGH WILL BUILD IN FROM THE SOUTH FORCING THE TRACK MOTION EQUATORWARD DUE TO THE LOW-LEVEL SOUTHEASTERLY FLOW. CONCURRENTLY, TC 25S WILL BEGIN ENCOUNTERING A HARSHER ENVIRONMENT WITH INCREASING VERTICAL WIND SHEAR AND CONVERGENCE ALOFT DUE TO AN APPROACHING UPPER-LEVEL TROUGH, AND COOLER SSTS (25-26C). THE HARSH ENVIRONMENT WILL CAUSE THE SYSTEM TO BEGIN THE DISSIPATION PROCESS STARTING BY TAU 48 AND REACH COMPLETION WHILE DRIER AIR WRAPS INTO THE SYSTEM FROM THE NORTH, AND BY TAU 72 WILL DISSIPATE OVER THE INDIAN OCEAN AS IT MOVES EQUATORWARD. MODEL DISCUSSION: MODEL GUIDANCE REMAINS IN FAIR AGREEMENT AS THE SYSTEM TRACKS SOUTHEAST AND THEN HOOKS BACK EQUATORWARD BY TAU 36. THERE IS MEDIUM CONFIDENCE IN THE OVERALL JTWC TRACK AS MODEL CONSENSUS REMAINS AT 150NM SPREAD THROUGH THE FORECAST PERIOD, WHICH THE TRACK IS LAID CLOSE TO, BUT LEFT OF THE MODEL CONSENSUS. THE JTWC INTENSITY FORECAST IS PLACED WITH MEDIUM CONFIDENCE, AND IS SET SLIGHTLY ABOVE ICNW AND REMAINS SLIGHTLY HIGHER THROUGH THE FORECAST UP TO DISSIPATION AT OR JUST BEFORE TAU 72. FORECAST CONFIDENCE: TRACK 0 - 72 HR: MEDIUM INTENSITY 0 - 72 HR: MEDIUM// NNNN