Tropical Storm KAI-TAK Advisory Thu Aug 16

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KAI-TAK) WARNING NR 17//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 14W (KAI-TAK), LOCATED APPROXIMATELY 155 NM SOUTH OF
HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS OVER THE PAST
SIX HOURS. ANIMATED INFRARED SATELLITE IMAGERY INDICATES THAT DEEP
CONVECTION HAS DECREASED IN AREAL EXTENT OVER THE PAST SIX HOURS
WITH SLIGHT WEAKENING IN DEEP CONVECTIVE BANDING. DESPITE THIS
DEGRADED IR SIGNATURE, A 161247Z SSMIS IMAGE CONTINUES TO INDICATE A
WELL-DEFINED LOW-LEVEL CIRCULATION CENTER WITH TIGHTLY-CURVED
CONVECTIVE BANDING WRAPPING INTO THE CENTER. SATELLITE IMAGERY,
HOWEVER, SHOWS THAT THE BULK OF THE DEEP CONVECTION REMAINS CONFINED
TO THE SOUTHERN SEMI-CIRCLE. ANIMATED WATER VAPOR IMAGERY SHOWS THAT
A TUTT CELL, WHICH WAS LOCATED OVER THE NORTHERN PERIPHERY OF THE
SYSTEM, HAS RAPIDLY TRACKED WEST INTO CHINA AND NORTHEASTERLY UPPER-
LEVEL FLOW HAS SLACKENED LEADING TO THE IMPROVED ENVIRONMENT. THE
INITIAL POSITION IS BASED ON RADAR FIXES AND THE SSMIS IMAGE WITH
GOOD CONFIDENCE. THE INITIAL INTENSITY IS HELD AT 65 KNOTS BASED ON
DVORAK ESTIMATES OF 65 KNOTS FROM PGTW, KNES AND RJTD.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 14W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP
SUBTROPICAL RIDGE (STR) POSITIONED OVER SOUTHEAST CHINA. THE 16/00Z
500MB UPPER-AIR DATA INDICATES THAT THE STR HAS STRENGTHENED AND
BROADENED OVER THE PAST 24 HOURS WITH EASTERLY FLOW ENTRENCHED
ACROSS SOUTHERN CHINA, THEREFORE, MODEL GUIDANCE IS IN TIGHT
AGREEMENT AND SUPPORTS A CONTINUED WESTWARD TO WEST-NORTHWESTWARD
TRACK THROUGH THE FORECAST PERIOD. TY 14W IS EXPECTED TO INTENSIFY
UNDER FAVORABLE CONDITIONS THROUGH TAU 12 BUT SHOULD THEN WEAKEN
SIGNIFICANTLY DUE TO INCREASING INTERACTION WITH LAND. AFTER TAU 24,
TY 14W WILL RAPIDLY DECAY AS IT TRACKS AWAY FROM THE GULF OF TONKIN
AND OVER THE MOUNTAINOUS REGION OF NORTHERN VIETNAM. THERE IS HIGH
CONFIDENCE IN THE FORECAST TRACK.//
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