Tropical Storm KAI-TAK Advisory Fri Aug 17

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KAI-TAK) WARNING NR 16//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 14W (KAI-TAK), LOCATED APPROXIMATELY 195 NM SOUTH-
SOUTHEAST OF HONG KONG, HAS TRACKED WESTWARD AT 13 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI)
INDICATES AN IMPROVED LOW-LEVEL CIRCULATION CENTER (LLCC) WITH
TIGHTLY-CURVED CONVECTIVE BANDING WRAPPING INTO A DEFINED CENTER. A
160621Z AMSU IMAGE INDICATES THAT THE BULK OF THE DEEP CONVECTION
REMAINS CONFINED TO THE SOUTHERN SEMI-CIRCLE; HOWEVER, DEEP
CONVECTIVE BANDING HAS IMPROVED OVER THE NORTH QUADRANT DUE TO A
DECREASE IN VERTICAL WIND SHEAR TO 10-15 KNOTS AND IMPROVED POLEWARD
OUTFLOW. 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 THE AFOREMENTIONED MSI AND PARTIAL AMSU IMAGE WITH GOOD
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 65 KNOTS BASED ON
DVORAK ESTIMATES OF 65 KNOTS FROM BOTH PGTW AND RJTD AND IS ALSO
SUPPORTED BY RECENT CIMSS AMSU OBJECTIVE INTENSITY ESTIMATES.
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 12-18 BUT SHOULD THEN WEAKEN
SIGNIFICANTLY DUE TO INCREASING INTERACTION WITH LAND. AFTER TAU 30,
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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