Tropical Storm MANGKHUT Advisory Sat Sep 15

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (MANGKHUT) WARNING NR 33//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 26W (MANGKHUT), LOCATED APPROXIMATELY 211 NM NORTH
OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 16 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS
THE LARGE CYCLONE NO LONGER HAS AN EYE AND THE DEEP CONVECTION HAS
BEEN SERIOUSLY DEGRADED BY ITS PASSAGE OVER LUZON. DESPITE THAT IT
REMAINS AN INTENSE TROPICAL CYCLONE. THE INITIAL POSITION IS PLACED
WITH GOOD CONFIDENCE BASED ON THE MSI IMAGERY AND SYNOPTIC
OBSERVATIONS FROM ACTIVE REPORTING STATIONS ON THE ISLAND. THE
PASSAGE OVER LUZON SIGNIFICANTLY ERODED THE CONVECTIVE STRUCTURE OF
THE CYCLONE, MAKING THE INTENSITY DIFFICULT TO ESTIMATE. THEREFORE,
THERE IS LOW CONFIDENCE IN THE INITIAL INTENSITY, WHICH IS ASSESSED
AT 115 KNOTS, USING THE RJTD DVORAK CURRENT INTENSITY ESTIMATES OF
T6.0 (115 KTS). THE ENVIRONMENT IS MARGINALLY FAVORABLE, WITH
MODERATE VERTICAL WIND SHEAR AND RADIAL OUTFLOW. SEA SURFACE
TEMPERATURE IN THE SOUTH CHINA SEA (SCS) IS 27-29 CELSIUS. TY 26W IS
TRACKING ALONG THE SOUTHERN PERIPHERY OF A DEEP-LAYERED SUBTROPICAL
RIDGE (STR) TO THE NORTH.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
    B. THROUGH TAU 72, THE STR TO THE NORTH WILL CONTINUE TO STEER
TY 26W ON A WEST-NORTHWESTWARD TRACK. EXPECT SLIGHT INTENSIFICATION
IN THE SCS AND RAPID WEAKENING AFTER MAKING LANDFALL SOUTH OF HONG
KONG AROUND TAU 36. FULL DISSIPATION IS EXPECTED BY TAU 72. THE
INTENSITY FORECAST IS HEDGED ABOVE THE INTENSITY GUIDANCE BECAUSE
ENVIRONMENTAL CONDITIONS SHOULD REMAIN MODERATELY FAVORABLE THROUGH
TAU 36. SPREAD IN THE TRACK GUIDANCE IS 175 NM AT TAU 72, THEREFORE
THERE IS GOOD CONFIDENCE IN THE JTWC FORECAST TRACK.//
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