Tropical Storm CHAN-HOM Advisory Mon Oct 12

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (CHAN-HOM) WARNING
NR 027//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 16W (CHAN-HOM), LOCATED APPROXIMATELY 227
NM SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED EAST-
SOUTHEASTWARD AT 09 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY REVEALS AN EXPOSED, DEFINED LOW
LEVEL CIRCULATION CENTER (LLCC) WITH DEEP CONVECTION DISPLACED TO
THE NORTHEAST. AN 110701Z SSMIS 91GHZ MICROWAVE IMAGE DEPICTS
SHALLOW BANDING WRAPPING TIGHTLY INTO THE DEFINED LLCC WITH
DISORGANIZED DEEP CONVECTION OVER THE EASTERN SEMICIRCLE. THE
INITIAL INTENSITY IS ASSESSED AT 35 KNOTS BASED ON DVORAK CURRENT
INTENSITY ESTIMATES RANGING FROM 2.5-3.0 (35-45 KNOTS). TS 16W IS
LOCATED WITHIN A MARGINAL ENVIRONMENT AND IS TRACKING EQUATORWARD
UNDER THE BACK EDGE OF AN UPPER-LEVEL SHORTWAVE TROUGH WITH STRONG
(30-35 KNOTS) VERTICAL WIND SHEAR (VWS). ADDITIONALLY, THERE IS
SIGNIFICANT DRY AIR ENTRAINING INTO THE SYSTEM. TS 16W APPEARS TO BE
A HYBRID/SUBTROPICAL SYSTEM WITH AN ASYMMETRIC APPEARANCE IN THE
TOTAL PRECIPITABLE WATER IMAGERY AND MODERATE BAROCLINICITY. THE
SYSTEM IS TRACKING ALONG THE NORTHEASTERN PERIPHERY OF A LOW-LEVEL
SUBTROPICAL RIDGE POSITIONED TO THE SOUTHWEST.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 16W IS EXPECTED TO TURN SOUTH-SOUTHEASTWARD AS IT TRACKS
ALONG THE EASTERN PERIPHERY OF THE LOW-LEVEL STR THROUGH THE
FORECAST PERIOD. TS 16W WILL WEAKEN STEADILY DUE TO STRONG (>30 KT)
VWS AND CONTINUED DRY AIR ENTRAINMENT WITH DISSIPATION ANTICIPATED
BY TAU 36. NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH TAU
36 BUT DIVERGES AFTER TAU 36. OVERALL, THERE IS FAIR CONFIDENCE IN
THE JTWC FORECAST TRACK. AFTER TAU 72, AS THE SYSTEM TRACKS OVER
WARM SST (28-29C) AND UNDER DECREASING VWS (<20 KNOTS), THERE IS
SOME POTENTIAL FOR IT TO SLOWLY REGENERATE AS A WARM-CORE TROPICAL
SYSTEM.//
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