Tropical Storm NEOGURI Advisory Tue Oct 22

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 21W (NEOGURI) WARNING
NR 020//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 21W (NEOGURI), LOCATED APPROXIMATELY 402 NM
SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 20 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A FULLY-EXPOSED, BROAD LOW-LEVEL CIRCULATION WITH DEEP
CONVECTION SHEARED TO THE NORTHEAST. A 210659Z SSMIS 91GHZ COLOR
COMPOSITE MICROWAVE IMAGE DEPICTS A WEAK FRONTAL STRUCTURE WITH
PERSISTENT DEEP CONVECTION OVER THE NORTHERN SEMICIRCLE. OVERALL,
THERE IS GOOD CONFIDENCE IN THE CURRENT POSITION. THE SYSTEM IS
EMBEDDED WITHIN A DEEP MIDLATITUDE SHORTWAVE TROUGH AND HAS
CONTINUED TO RAPIDLY DECAY UNDER A HOSTILE ENVIRONMENT CHARACTERIZED
BY STRONG (55 KNOTS) VERTICAL WIND SHEAR. THE CURRENT INTENSITY IS
ASSESSED CONSERVATIVELY AT 45 KNOTS BASED ON A KNES CURRENT
INTENSITY ESTIMATE OF 3.0 (45 KNOTS) AND RECENT ASCAT DATA SHOWING
40-45 KNOT WIND NORTHERLY WINDS. TS 21W IS TRACKING QUICKLY
NORTHEASTWARD ALONG THE NORTHERN FLANK OF THE SUBTROPICAL RIDGE
WITHIN THE STRONG MIDLATITUDE WESTERLY FLOW.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 21W IS FORECAST TO CONTINUE TRACKING NORTHEASTWARD THROUGH
THE FORECAST PERIOD AND IS EXPECTED TO COMPLETE EXTRA-TROPICAL
TRANSITION WITHIN THE NEXT 12 HOURS. AFTER TRANSFORMING INTO A COLD-
CORE LOW, THE SYSTEM WILL TRACK SOUTH OF TOKYO AND THEN EAST OF
HONSHU MAINTAINING GALE-FORCE WINDS. DUE TO THE BROAD NATURE OF THE
LOW, THERE IS UNCERTAINTY IN THE EXACT CENTER LOCATION AND TRACK.
NUMERICAL MODEL GUIDANCE CONTINUES TO STRUGGLE WITH THIS COMPLEX
TRANSITION, THEREFORE, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST
TRACK AFTER TAU 12.//
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