Tropical Storm KAI-TAK Advisory Cu, 17.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KAI-TAK) WARNING NR 18//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 14W (KAI-TAK), LOCATED APPROXIMATELY 145 NM SOUTH-
SOUTHWEST OF HONG KONG, HAS TRACKED WEST-NORTHWESTWARD AT 14 KNOTS
OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY INDICATES THAT THE DEEP CONVECTION HAS RE-STRENGTHENED OVER
THE LOW LEVEL CIRCULATION CENTER (LLCC) INDICATED BY COOLING CLOUD
TOP TEMPERATURES. A 161415Z AMSU-B IMAGE CONTINUES TO INDICATE A
WELL-DEFINED LOW-LEVEL CIRCULATION CENTER WITH TIGHTLY-CURVED
CONVECTIVE BANDING WRAPPING INTO THE CENTER CONFINED TO THE
SOUTHERN SEMI-CIRCLE. UPPER LEVEL ANALYSIS REVEALS THAT THE TUTT
CELL THAT WAS POSITIONED TO THE NORTHWEST HAS FILLED OVER THE PAST
SIX HOURS AND RAPIDLY TRACKED WEST. THE IMPROVED POLAR OUTFLOW THAT
THE TUTT CELL WAS PROVIDING HAS WEAKENED DUE TO THE INCREASING
DISTANCE FROM TY 14W. THERE IS ALSO WEAK (05-10 KNOT) VERTICAL WIND
SHEAR ACTING UPON THE SYSTEM. THE INITIAL POSITION IS BASED ON
RADAR FIXES FROM THE HONG KONG OBSERVATORY AND THE AMSU-B IMAGE
WITH GOOD CONFIDENCE. THE INITIAL INTENSITY IS HELD AT 65 KNOTS
BASED ON DVORAK ESTIMATES OF 65 KNOTS FROM PGTW, KNES AND RJTD. TY
14W IS TRACKING ALONG THE SOUTHERN PERIPHERY OF THE DEEP
SUBTROPICAL RIDGE (STR) POSITIONED OVER SOUTHEAST CHINA.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 14W WILL CONTINUE TO TRACK UNDER THE DOMINANT STR OVER
CHINA. MODEL GUIDANCE IS IN TIGHT AGREEMENT THROUGH TAU 12 AND
THERE IS SLIGHT SPREAD AFTER THAT WITH WBAR BEING THE RIGHTMOST
OUTLIER TAKING AN UNLIKELY MORE NORTHERN TRACK AND EGRR BEING THE
LEFTMOST OUTLIER TAKING A MORE SOUTHERN COURSE AFTER TAU 24 WHICH
IS ALSO UNLIKELY DUE THE DOMINANT STR. TY 14W WILL HOLD INTENSITY
FOR THE NEXT 12 HOURS DUE TO A FAVORABLE UPPER LEVEL ENVIRONMENT
AND SEA SURFACE TEMPERATURES (28-30 DEGREES CELSIUS) BUT SHOULD
THEN WEAKEN SIGNIFICANTLY DUE TO INCREASING INTERACTION WITH LAND
AS IT NEARS THE LEIZHOU PENINSULA. 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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