Tropical Storm DOKSURI Advisory Fri Sep 15

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 21W (DOKSURI)
WARNING NR 14//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 21W (DOKSURI), LOCATED APPROXIMATELY 122 NM NORTH-
NORTHWEST OF DA NANG, VIETNAM, HAS TRACKED WEST-NORTHWESTWARD AT 14
KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS THE SYSTEM HAS CONTINUED TO INTENSIFY OVER THE PAST
SIX HOURS, WITH AN EYE FEATURE NOW VISIBLE. A 142123Z SSMIS 89GHZ
MICROWAVE IMAGE SHOWED DEEP CONVECTIVE BANDING WRAPPING INTO A WELL
DEFINED MICROWAVE EYE FEATURE, LENDING HIGH CONFIDENCE TO THE
INITIAL POSITION. THE INITIAL INTENSITY IS ASSESSED AT 100 KNOTS
BASED ON THE SUBJECTIVE DVORAK CURRENT INTENSITY ESTIMATES OF T6.0
(115 KNOTS) FROM PGTW AND AUTOMATED DVORAK TECHNIQUE (ADT) ESTIMATES
OF T5.0 (90 KNOTS). TY 21W IS TRACKING STEADILY WESTWARD ALONG THE
SOUTHERN PERIPHERY OF A DEEP-LAYER SUBTROPICAL RIDGE (STR) TO THE
NORTH. TY 21W IS MOVING THROUGH AN ENVIRONMENT WHICH HAS BEEN VERY
CONDUCIVE FOR DEVELOPMENT, LEADING TO THE RECENT RAPID
INTENSIFICATION. VERTICAL WIND SHEAR (VWS) IS LOW, THERE IS AN UPPER-
LEVEL POINT SOURCE PROVIDING ROBUST OUTFLOW AND SEA SURFACE
TEMPERATURES ARE EXCEEDING 31 DEG CELSIUS. TY 21W HAS LIKELY REACHED
ITS PEAK INTENSITY HOWEVER, AS INTERACTIONS WITH THE HIGHER TERRAIN
IN VIETNAM ARE BEGINNING TO TAKE A TOLL ON THE LOW LEVEL INFLOW.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY DOKSURI WILL CONTINUE TRACKING WESTWARD ALONG THE SOUTHERN
PERIPHERY OF THE STR TO THE NORTH AND WILL MAKE LANDFALL WITHIN THE
NEXT 6 HOURS NEAR QUONG DONG, VIETNAM, THEN CONTINUE TO TRACK
INLAND. THE SYSTEM WILL WEAKEN STEADILY AFTER MAKING LANDFALL BUT
WON’T FULLY DISSIPATE FOR SOME TIME, UNTIL AROUND TAU 36. NUMERICAL
MODELS ARE IN GOOD AGREEMENT, AND THERE IS HIGH CONFIDENCE IN THE
JTWC OFFICIAL FORECAST.//
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