Tropical Storm CHAN-HOM Advisory Sun Oct 11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 16W (CHAN-HOM) WARNING
NR 023//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 16W (CHAN-HOM), LOCATED APPROXIMATELY 240
NM SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED EASTWARD AT 09 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A BROAD, DEFINED LOW-LEVEL CIRCULATION CENTER WITH A WEAK
FRONTAL STRUCTURE AND DEEP CONVECTION SHEARED TO THE EAST. OVERALL,
THERE IS FAIR CONFIDENCE IN THE INITIAL POSITION AND RECENT TRACK
MOTION. A 100714Z ALSO INDICATES AN ASYMMETRIC STRUCTURE WITH
SHALLOW BANDING WRAPPING INTO THE CENTER AND DISORGANIZED DEEP
CONVECTION DISPLACED TO THE NORTHEAST. THE INITIAL INTENSITY REMAINS
ASSESSED AT 50 KNOTS BASED ON RECENT ASCAT DATA; PGTW/RJTD DVORAK
CURRENT INTENSITY ESTIMATES RANGE FROM 2.5 TO 3.5 (35 TO 55 KNOTS).
ENVIRONMENTAL ANALYSIS REVEALS MARGINAL CONDITIONS WITH STRONG
VERTICAL WIND SHEAR (VWS) AND DRY AIR ENTRAINMENT AS WELL AS
BAROCLINIC INFLUENCES. THE SYSTEM IS EMBEDDED WITHIN THE ZONAL
SUBTROPICAL WESTERLY FLOW AND IS TRACKING EASTWARD ALONG THE
SOUTHERN PERIPHERY OF THE BAROCLINIC ZONE. ADDITIONALLY, THERE ARE
BROAD LOW-LEVEL SUBTROPICAL RIDGES ENTRENCHED TO THE EAST AND
SOUTHWEST OF THE SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. DUE TO THE PRESENCE OF THE AFOREMENTIONED LOW-LEVEL
SUBTROPICAL RIDGES, TS 16W IS FORECAST TO DECELERATE AND TURN EAST-
SOUTHEASTWARD TO SOUTHEASTWARD THROUGH THE FORECAST PERIOD AS IT
STEERS ALONG THE EASTERN PERIPHERY OF THE LOW-LEVEL STR POSITIONED
TO THE SOUTHWEST. THE EASTERN STR IS FORECAST TO WEAKEN BUT WILL
CONTINUE TO BLOCK EASTWARD PROGRESSION. TS 16W IS FORECAST TO WEAKEN
THROUGH THE FORECAST PERIOD UNDER STRONG (30-35 KNOTS) VWS AND DRY
AIR ENTRAINMENT WITH DISSIPATION BY TAU 48. NUMERICAL MODEL GUIDANCE
DIVERGES BUT SUPPORTS THE SOUTHEASTWARD TRACK WITH FAIR CONFIDENCE.//
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