Tropical Storm VONGFONG Advisory 10.10.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 19W (VONGFONG) WARNING NR 30//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 19W (VONGFONG), LOCATED APPROXIMATELY 313 NM SOUTH-
SOUTHEAST OF KADENA AB, OKINAWA, JAPAN, HAS TRACKED NORTH-
NORTHWESTWARD AT 07 KNOTS OVER THE PAST SIX HOURS. ANIMATED
MULTISPECTRAL SATELLITE IMAGERY DEPICTS A 25 NM CLOUD-FILLED EYE
WITH THINNING CONVECTION OVER THE NORTHERN PERIPHERY AND WESTERN
SEMI-CIRCLE. THE CURRENT POSITION IS BASED ON THE EYE FEATURE ON THE
MSI WITH HIGH CONFIDENCE. THE INITIAL INTENSITY HAS DECREASED TO 125
KNOTS BASED ON AN OVERALL ASSESSMENT OF DVORAK CURRENT INTENSITY
ESTIMATES FROM ALL REPORTING AGENCIES AND THE CURRENT STRUCTURE.
UPPER-LEVEL ANALYSIS CONTINUES TO INDICATE FAVORABLE VERTICAL WIND
SHEAR (VWS) AND EXCELLENT OUTFLOW THAT IS SUSTAINING THE CONVECTION.
TY 19W IS CURRENTLY TRACKING ALONG THE WESTERN PERIPHERY OF AN
EXTENSION OF THE SUBTROPICAL RIDGE (STR) TO THE EAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY 19W WILL CONTINUE TRACKING NORTHWARD OVER NEXT 24 HOURS AS
IT ROUNDS THE WESTERN EDGE OF THE STEERING STR. BETWEEN TAU 24 AND
36, A MIGRATORY SHORTWAVE RIDGE PASSING FROM THE NORTHWEST WILL
MOMENTARILY DEFLECT TY 19W NORTH-NORTHWESTWARD. BY TAU 48, A MID-
LATITUDE TROUGH PASSING OVER THE KOREA PENINSULA WILL WEAKEN THE
PRIMARY STEERING STR AND CAUSE THE CYCLONE TO RECURVE NORTH-
NORTHEASTWARD. CONCURRENTLY, THE SYSTEM WILL BEGIN EXTRA-TROPICAL
TRANSITION (ETT) AS IT ACCELERATES NORTHEASTWARD ALONG SOUTHERN
JAPAN. INCREASING VWS ASSOCIATED WITH THE MID-LATITUDE WESTERLIES
WILL WEAKEN THE SYSTEM TO 70 KNOTS BY TAU 72.
   C. IN THE EXTENDED TAUS, CONTINUED INTERACTION WITH THE
MIDLATITUDE WESTERLIES WILL RAPID WEAKEN TY 19W FOR THE REMAINDER OF
THE FORECAST PERIOD. BY TAU 96, TY VONGFONG IS EXPECTED TO COMPLETE
ETT AS IT BECOMES A GALE FORCE COLD-CORE LOW OVER NORTHERN JAPAN.
AVAILABLE MODEL GUIDANCE IS OVERALL IN GOOD AGREEMENT, LENDING HIGH
CONFIDENCE TO JTWC TRACK FORECAST THAT IS POSITIONED CLOSE TO AND
SLIGHTLY FASTER THAN THE MULTI-MODEL CONSENSUS.//
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