Tropical Storm CHOI-WAN Advisory Çar, 07.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 23W (CHOI-WAN) WARNING NR 18//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 23W (CHOI-WAN), LOCATED APPROXIMATELY 222 NM
NORTHWEST OF MINAMI TORI SHIMA, HAS TRACKED NORTHWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED IR IMAGERY INDICATES A
SLIGHT IMPROVEMENT IN CONVECTIVE ORGANIZATION WITH DEEP CONVECTIVE
BANDING WRAPPING INTO A BROAD LOW-LEVEL CIRCULATION CENTER. A
061711Z SSMI IMAGE REFLECTS THE BROAD NATURE OF THE SYSTEM AND SHOWS
FRAGMENTED DEEP CONVECTION WRAPPING INTO AN ELONGATED, APPROXIMATELY
160-NM EYEWALL-LIKE FEATURE. THE 061711Z SSMI 37GHZ IMAGE SHOWS AN
ELONGATED MICROWAVE EYE FEATURE, WHICH SUPPORTS THE CURRENT POSITION
WITH FAIR CONFIDENCE. THE CURRENT INTENSITY REMAINS ASSESSED AT 70
KNOTS BASED ON DVORAK INTENSITY ESTIMATES RANGING FROM 65 TO 77
KNOTS. UPPER-LEVEL ANALYSIS DEPICTS A VIGOROUS POLEWARD OUTFLOW
CHANNEL ASSOCIATED WITH A DEEP TROUGH ENTRENCHED SOUTH OF JAPAN. TY
23W IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF A DEEP,
POLEWARD-ORIENTED STR.
3. FORECAST REASONING.
   A. NO CHANGE TO FORECAST PHILOSOPHY SINCE THE PREVIOUS PROGNOSTIC
REASONING MESSAGE. WIND RADII HAVE BEEN ADJUSTED SLIGHTLY BASED ON
RECENT SCATTEROMETRY DATA, WHICH CONTINUES TO SHOW AN EXPANSIVE
REGION OF GALE-FORCE WINDS ESPECIALLY OVER THE NORTHERN SEMI-CIRCLE.
   B. TY CHOI-WAN WILL CONTINUE TO TRACK POLEWARD THROUGH THE
FORECAST PERIOD. TY 23W MAY INTENSIFY SLIGHTLY THROUGH TAU 12 DUE TO
FAVORABLE POLEWARD OUTFLOW. BY TAU 12, TY 23W IS FORECAST TO BEGIN
EXTRA-TROPICAL TRANSITION (ETT) AS IT BEGINS TO INTERACT WITH THE
BAROCLINIC ZONE, ENCOUNTERS INCREASING VERTICAL WIND SHEAR AND
TRACKS OVER COOLER SST. TY 23W WILL COMPLETE ETT BY TAU 36 AS IT
GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED WITHIN THE
MIDLATITUDE WESTERLIES. THE SYSTEM IS EXPECTED TO MAINTAIN STORM
FORCE WINDS AND EXPANSIVE GALE-FORCE WINDS, WHICH COULD ENCROACH ON
THE COASTAL REGIONS OF NORTHERN JAPAN. DYNAMIC MODEL GUIDANCE
REMAINS IN VERY TIGHT AGREEMENT THROUGHOUT THE FORECAST PERIOD
LEADING TO HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.//
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