WDPN31 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (CHAN-HOM) WARNING NR 029//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 16W (CHAN-HOM), LOCATED APPROXIMATELY 301 NM 
SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED SOUTHWARD AT 07 KNOTS 
(KTS) OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY REVEALS AN EXPOSED, DEFINED LOW LEVEL CIRCULATION CENTER (LLCC) 
WITH LIMITED, WEAKENING DEEP CONVECTION DISPLACED TO THE NORTHEAST. AN 
111928Z SSMIS 91 GHZ MICROWAVE IMAGE REVEALS CONVECTIVE BANDING 
WRAPPING INTO A BROAD RAGGED LLCC. THERE IS GOOD CONFIDENCE IN THE 
INITIAL POSITION WHICH IS PLACED NEAR THE PGTW AND RJTD FIXES DUE TO 
THE FULLY-EXPOSED NATURE OF THE LLCC. THE INITIAL INTENSITY REMAINS 
ASSESSED AT 35 KNOTS BASED ON RECENT ASCAT DATA AND MULTIAGENCY DVORAK 
CURRENT INTENSITY ESTIMATES OF T2.0-2.5 (30-35 KTS) BY PGTW AND RJTD. 
TS 16W IS LOCATED IN A MARGINAL ENVIRONMENT WITH SIGNIFICANT DRY AIR 
ENTRAINING INTO THE SYSTEM AND STRONG (25-30 KTS) VERTICAL WIND SHEAR. 
AS IT IS EXPERIENCING MODERATE BAROCLINICITY, TS 16W APPEARS TO BE A 
HYBRID/SUBTROPICAL SYSTEM AND HAS AN ASYMMETRIC APPEARANCE IN BOTH THE 
WIND FIELD AND TOTAL PRECIPITABLE WATER IMAGERY. TS 16W IS TRACKING 
SOUTHWARD ALONG THE BACK EDGE OF AN UPPER-LEVEL SHORTWAVE TROUGH AND 
THE EASTERN PERIPHERY OF A LOW-LEVEL SUBTROPICAL RIDGE (STR) POSITIONED 
TO THE WEST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 16W IS EXPECTED TO CONTINUE GENERALLY SOUTH-SOUTHEASTWARD AS 
IT TRACKS ALONG THE EASTERN PERIPHERY OF THE LOW-LEVEL STR THROUGH THE 
FORECAST PERIOD. THE SYSTEM WILL STEADILY WEAKEN DUE TO CONTINUED DRY 
AIR ENTRAINMENT AND MODERATE TO HIGH (20-30 KT) VWS WITH DISSIPATION 
ANTICIPATED BY TAU 36. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT 
THROUGH TAU 24 BUT BEGINS TO DIVERGE AFTERWARDS. OVERALL, THERE IS FAIR 
CONFIDENCE IN THE JTWC FORECAST TRACK. THERE IS SOME POTENTIAL FOR TS 
16W TO SLOWLY REGENERATE AS A WARM-CORE TROPICAL SYSTEM AFTER TAU 60 AS 
THE SYSTEM TRACKS OVER WARM SEA SURFACE TEMPERATURES (28-29C) AND UNDER 
DECREASING VWS (<20 KNOTS).//
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