WDPN31 PGTW 011500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHAN-HOM) WARNING 
NR 05//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (CHAN-HOM), LOCATED APPROXIMATELY 652 NM 
EAST-SOUTHEAST OF ANDERSEN AFB, HAS TRACKED WESTWARD AT 05 KNOTS 
OVER THE PAST SIX HOURS. ANIMATED EIR SATELLITE IMAGERY DEPICTS 
DEEPENED CENTRAL CONVECTION WITH TIGHTLY-CURVED BANDING WRAPPING 
INTO AN OBSCURED LLCC. THE CURRENT POSITION IS BASED ON THE EIR 
LOOP, A 011046Z METOP-A MICROWAVE IMAGE AS WELL AS SATELLITE FIXES 
FROM PGTW AND RJTD. THE INITIAL INTENSITY OF 45 KNOTS BASED ON 
MATCHING DVORAK INTENSITY ESTIMATES OF T3.0 FROM PGTW AND RJTD. 
UPPER-LEVEL ANALYSIS INDICATES THAT THE SYSTEM IS LOCATED IN AN AREA 
OF LOW TO MODERATE (10 TO 20 KNOT) VWS AND GOOD DIFFLUENCE ALOFT. TS 
09W IS CURRENTLY TRACKING ALONG THE SOUTHERN PERIPHERY OF A STR TO 
THE NORTH.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 09W WILL MAINTAIN A WESTWARD TRAJECTORY THROUGH TAU 48 
UNDER THE INFLUENCE OF THE DOMINANT STEERING STR. MARGINALLY 
FAVORABLE CONDITIONS WILL PERSIST, LEADING TO GRADUAL 
INTENSIFICATION. BEYOND TAU 48, THE STEERING ENVIRONMENT BECOMES 
MORE COMPLICATED AS TS CHAN-HOM BEGINS TO INTERACT WITH A TROPICAL 
AREA OF DISTURBANCE (94W) MENTIONED IN THE ABPW10 PGTW 010600. 
CONCURRENTLY, THE STR WILL BEGIN TO RETREAT TO THE EAST, ALLOWING TS 
09W TO TURN NORTHWESTWARD.
   C. TS 09W IS EXPECTED TO TRACK NORTHWESTWARD THROUGH THE 
REMAINDER OF THE FORECAST PERIOD. AVAILABLE MODEL GUIDANCE IS 
OVERALL IN GOOD AGREEMENT; HOWEVER, DUE TO THE UNCERTAINTY IN THE 
CURRENT TRACK SPEED AND INTENSITY FORECAST IN THE EXTENDED TAUS, 
THERE IS LOW CONFIDENCE IN THE JTWC FORECAST.//
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