WDPN31 PGTW 050300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHAN-HOM) WARNING 
NR 19//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (CHAN-HOM), LOCATED APPROXIMATELY 6 NM 
WEST OF ROTA, HAS TRACKED WEST-NORTHWESTWARD AT 07 KNOTS OVER THE 
PAST SIX HOURS. RECENT ANIMATED MSI DEPICTS PERSISTENT DEEP CENTRAL 
CONVECTION WITH FORMATIVE BANDING OBSCURING THE LLCC. THE CURRENT 
POSITION IS BASED ON THE MSI, PGUA RADAR, AS WELL AS TIGHT GROUPING 
SATELLITE FIXES FROM PGTW AND RJTD WITH HIGH CONFIDENCE. THE CURRENT 
INTENSITY REMAINS AT 40 KNOTS BASED ON THE CURRENT STRUCTURE AND AN 
OVERALL ASSESSMENT OF DVORAK INTENSITY ESTIMATES FROM ALL REPORTING 
AGENCIES. UPPER-LEVEL ANALYSIS INDICATES TS 09W IS LOCATED IN AN 
AREA OF LOW VWS AND GOOD EQUATORWARD AND POLEWARD OUTFLOW THAT IS 
ENHANCED BY THE TUTT CELL TO THE NORTHEAST. TS 09W IS TRACKING ALONG 
THE SOUTHERN PERIPHERY OF THE DEEP-LAYERED STR.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 09W WILL MAINTAIN A WEST-NORTHWESTWARD TO NORTHWESTWARD 
TRAJECTORY UNDER THE STEERING INFLUENCE OF THE STR ENTRENCHED TO THE 
NORTH. SLOW INTENSIFICATION IS EXPECTED AS CHAN-HOM TRACKS ACROSS 
THE MARIANAS ISLANDS. AFTERWARD, UPPER-LEVEL CONDITIONS ARE FORECAST 
TO IMPROVE, ALLOWING TS 09W TO FURTHER INTENSIFY LEADING TO A PEAK 
INTENSITY OF 110 KNOTS.
   C. AFTER TAU 72, TS 09W WILL CONTINUE TO TRACK NORTHWESTWARD 
UNDER THE INFLUENCE OF THE DOMINANT STEERING STR. VWS AND UPPER 
LEVEL DIVERGENCE WILL REMAIN FAVORABLE THROUGH THE END OF THE 
FORECAST PERIOD; HOWEVER, COOLER SST AND LOWER OHC VALUES WILL BEGIN 
TO WEAKEN THE SYSTEM. DYNAMIC MODEL GUIDANCE INDICATES A SLIGHT 
SHIFT TO THE SOUTH OF KADENA. THEREFORE, JTWC TRACK FORECAST HAS 
SHIFTED THE TRACK SLIGHTLY IN THE EXTENDED TAUS TO REFLECT THIS 
CHANGE. DUE TO THE TIGHT GROUPING AMONG AVAILABLE TRACKERS, THE JTWC 
TRACK FORECAST CONFIDENCE LEVEL REMAINS HIGH, WHICH IS POSITIONED 
CLOSE TO MULTI-MODEL CONSENSUS.//
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