WDPN31 PGTW 031500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 09W (CHAN-HOM) WARNING 
NR 13//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 09W (CHAN-HOM), LOCATED APPROXIMATELY 277 NM 
SOUTHEAST OF ANDERSEN AFB, GUAM HAS TRACKED NORTHEASTWARD AT 04 
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS A BROAD AREA OF POORLY ORGANIZED CONVECTION SHEARED 
WELL TO THE SOUTHWEST OF THE LOW LEVEL CIRCULATION CENTER (LLCC). 
THE INITIAL POSIT IS EXTRAPOLATED FROM AN 031101Z ASCAT BULLSEYE 
WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 45 KNOTS 
BASED ON DVORAK CURRENT INTENSITY ESTIMATES FROM PGTW AND RJTD, 
WHICH ARE SUPPORTED BY THE AFOREMENTIONED ASCAT PASS. TS 09W HAS 
DISPLAYED DIRECT CYCLONE INTERACTION (DCI) WITH A REMANT CIRCULATION 
TO THE NORTHEAST RESULTING IN A NORTHEASTERLY TRACK OVER THE PAST 12 
HOURS. THE REMNANT LLCC, HOWEVER, HAS NO SURFACE REFLECTION IN TWO 
RECENT SCATTEROMETRY PASSES, THEREFORE 09W REMAINS THE 
DOMINANT CIRCULATION. AN AREA OF TROUGHING TO THE NORTH OF TS 09W IS 
STILL IN PLACE PRODUCING INCREASED VERTICAL WIND SHEAR(VWS), 
SUBSIDENCE AND INCREASED CONVERGENCE ALOFT. THESE IMPACTS ARE 
SUPPRESSING CONVECTION.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 09W WILL CONTINUE TO DRIFT NORTH TO NORTHEASTWARD OVER THE 
NEXT 12 HOURS WHILE TS 09W INTERACTS WITH THE REMNANT VORTEX IN A 
WEAK STEERING ENVIRONMENT. AFTER THIS TIME, TS CHAN-HOM WILL TURN 
BACK TO A NORTHWESTWARD TRACK AS THE TUTT CELL RETROGRADES TO THE 
EAST AND THE REMNANT VORTEX DISSIPATES. THE SYSTEM SHOULD GRADUALLY 
BEGIN TO REORGANIZE AS THE EFFECTS OF THE UPPER LEVEL TROUGHING 
SUBSIDES, RESULTING IN LOWER VWS AND IMPROVING OUTFLOW. THIS 
INTENSIFICATION WILL CONTINUE THROUGHOUT THE REMAINDER OF THIS 
FORECAST PERIOD. DYNAMICAL MODELS ARE NOT HANDLING THIS COMPLEX 
CYCLONE INTERACTION AND TUTT CELL IMPACTS. THE OFFICIAL FORECAST IS 
SLOWER THAN CONSENSUS, WITH POOR CONFIDENCE.
   C. IN THE EXTENDED TAUS, TS CHAN-HOM WILL CONTINUE TO TRACK 
NORTHWESTWARD AND FURTHER INTENSIFY AS VWS AND OUTFLOW REMAIN 
FAVORABLE. DYNAMIC MODEL GUIDANCE DIVERGES GREATLY AROUND TAU 96 
ASSOCIATED WITH THE TIMING OF EVENTUAL RECURVATURE. THEREFORE, THERE 
IS LOW CONFIDENCE IN THIS PORTION OF THE FORECAST.//
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