WDPN31 PGTW 110300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (CHAN-HOM) WARNING 
NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 16W (CHAN-HOM), LOCATED APPROXIMATELY 190 NM 
SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED EASTWARD AT 09 KNOTS 
(KTS) OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE 
IMAGERY (MSI) REVEALS A PARTIALLY-EXPOSED, DEFINED LOW LEVEL 
CIRCULATION CENTER (LLCC) WITH DEEP FLARING CONVECTION DISPLACED TO 
THE NORTHEAST. A 102225Z GMI 89 GHZ MICROWAVE IMAGE DEPICTS A BROAD 
LLCC WITH FRAGMENTED REGIONS OF FLARING CONVECTION TO THE NORTHEAST. 
BASED ON THE MSI AND MICROWAVE IMAGERY, THERE IS GOOD CONFIDENCE IN 
THE INITIAL POSITION. DVORAK CURRENT INTENSITY ESTIMATES OF T2.5-3.5 
(35-45 KTS) BY PGTW AND RJTD SUPPORT THE INITIAL INTENSITY OF 40 
KTS. FURTHERMORE, A 102304Z ASCAT-A IMAGE SHOWS A LARGE SWATH OF 35-
40 KT WINDS IN THE NORTHWEST QUADRANT, LENDING GOOD CONFIDENCE TO 
THE INITIAL INTENSITY. STRONG VERTICAL WIND SHEAR (VWS) AND 
CONTINUED DRY AIR ENTRAINMENT CONTRIBUTE TO AN OVERALL MARGINAL 
ENVIRONMENT. TS 16W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE 
BAROCLINIC ZONE AND THUS EXPERIENCING BAROCLINIC INFLUENCES WITHIN 
THE ZONAL SUBTROPICAL WESTERLY FLOW. BROAD LOW-LEVEL SUBTROPICAL 
RIDGES (STR) ENTRENCHED TO THE EAST AND SOUTHWEST OF THE SYSTEM ARE 
ALSO INFLUENCING THE STEERING ENVIRONMENT.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS 
PROGNOSTIC REASONING MESSAGE.
   B. TS 16W IS EXPECTED TO TURN SOUTHEASTWARD AS IT TRANSITS ALONG 
THE EASTERN PERIPHERY OF THE LOW-LEVEL STR LOCATED TO THE SOUTHWEST. 
AFTERWARDS, THE SYSTEM WILL CONTINUE SOUTHWARD FOR THE DURATION OF 
THE FORECAST PERIOD. TS 16W WILL WEAKEN THROUGHOUT THE PERIOD DUE TO 
HIGH (>30 KT) VWS AND CONTINUED DRY AIR ENTRAINMENT WITH DISSIPATION 
ANTICIPATED BY TAU 48. THE STR TO THE EAST, ALTHOUGH FORECAST TO 
WEAKEN, SHOULD LIMIT EASTWARD PROGRESSION. NUMERICAL MODEL GUIDANCE, 
WITH THE EXCEPTION OF THE JGSM SOLUTION, HAS COME INTO BETTER 
AGREEMENT AND THEN DIVERGES AFTER TAU 36 WITH A 50 NM SPREAD BY TAU 
48. DUE TO THIS SPREAD, THERE IS FAIR CONFIDENCE IN THE JTWC 
FORECAST TRACK.//
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