Tropical Storm MANGKHUT Advisory Thu Sep 13

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR SUPER TYPHOON 26W (MANGKHUT) WARNING
NR 25//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   SUPER TYPHOON (STY) 26W (MANGKHUT), LOCATED APPROXIMATELY 592 NM
EAST OF MANILA, PHILIPPINES, HAS TRACKED WESTWARD AT 13 KNOTS OVER
THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY
DEPICTS A 185NM DIAMETER CONVECTIVE CORE WITH A 25NM ROUND EYE AND
BANDING FEATURE. DUE TO THE LACK OF HIGH RESOLUTION MICROWAVE
IMAGERY, IT IS DIFFICULT TO DETERMINE IF THE EYEWALL REPLACEMENT
CYCLE (ERC) HAS COMPLETED. HOWEVER, STY 26W HAS WEAKENED SLIGHTLY
WITH WARMING CLOUD TOPS AND IS NOW ASSESSED AT 145 KNOTS BASED ON
DVORAK CURRENT INTENSITY ESTIMATES RANGING FROM 7.0 (140 KNOTS) TO
7.5 (155 KNOTS). UPPER-LEVEL ANALYSIS CONTINUES TO INDICATE A VERY
FAVORABLE ENVIRONMENT WITH RADIAL OUTFLOW, ENHANCED BY A TUTT CELL
TO THE EAST, AND LOW VERTICAL WIND SHEAR. ADDITIONALLY, WARM SST (29-
30C) AND HIGH OCEAN HEAT CONTENT VALUES ARE VERY FAVORABLE. STY 26W
IS TRACKING WESTWARD UNDER THE STEERING INFLUENCE OF A DEEP-LAYERED
SUBTROPICAL RIDGE (STR) ENTRENCHED TO THE NORTH.
 3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. STY 26W WILL TRACK WEST-NORTHWESTWARD THROUGH THE FORECAST
PERIOD WITH LANDFALL ALONG THE NORTHEAST COAST OF LUZON BY TAU 42.
STY 26W WILL MAINTAIN STY INTENSITY THROUGH TAU 36 UNDER VERY
FAVORABLE ENVIRONMENTAL CONDITIONS. AFTER TAU 36, STY 26W WILL
WEAKEN SIGNIFICANTLY AS IT TRACKS OVER THE MOUNTAINOUS REGION OF
LUZON, RE-EMERGING OVER THE SOUTH CHINA SEA (SCS) NEAR TAU 54 NEAR
110 KNOTS.
   C. AFTER TAU 72, STY MANGKHUT WILL CONTINUE ON A WEST-
NORTHWESTWARD TRAJECTORY UNDER THE STEERING INFLUENCE OF THE STR.
THE SYSTEM WILL TRACK ACROSS THE SCS JUST SOUTH OF HONG KONG MAKING
LANDFALL OVER SOUTHERN CHINA NEAR TAU 96. THE SYSTEM WILL WEAKEN BY
TAU 96 DUE TO INTERACTION WITH LAND WITH MORE RAPID WEAKENING AS IT
TRACKS INTO NORTHERN VIETNAM BY TAU 120. THE DYNAMIC MODEL GUIDANCE
AND ENSEMBLE MODEL GUIDANCE REMAINS IN EXCEPTIONALLY TIGHT AGREEMENT
LENDING HIGH CONFIDENCE IN THE JTWC FORECAST TRACK.//
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