Tropical Storm NOUL Advisory 9月16日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (THIRTEEN)
WARNING NR 002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
TROPICAL STORM (TS) 13W (THIRTEEN), LOCATED APPROXIMATELY 186 NM
SOUTHWEST OF MANILA, PHILIPPINES, HAS TRACKED WEST-NORTHWESTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS THE CENTRAL CONVECTION HAS DEEPENED AND
FORMATIVE BANDING HAS BEGUN TO WRAP INTO AN OBSCURED LOW LEVEL
CIRCULATION. THE INITIAL POSITION IS PLACED WITH LOW CONFIDENCE BASED
ON THE EIR LOOP AND EXTRAPOLATION FROM THE LAST POSITION. THE INITIAL
INTENSITY OF 35 KTS IS HIGHER THAN AGENCY DVORAK ESTIMATES TO REFLECT
THE IMPROVED EIR STRUCTURE. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT
WITH VERY WARM (30-32C) SEA SURFACE TEMPERATURES, MODERATE
WESTWARD/EQUATORWARD OUTFLOW, AND (LIGHT 10-15KT) RELATIVE EASTERLY
VERTICAL WIND SHEAR THAT IS MITIGATED BY THE STORM MOTION THAT IS IN-
PHASE WITH THE UPPER LEVEL WIND FLOW. TS 13W IS TRACKING ALONG THE
SOUTHERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR) TO THE NORTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY FROM
THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. UNDER THE STR, TS 13W WILL TRACK GENERALLY WEST-NORTHWESTWARD
THROUGHOUT THE FORECAST PERIOD ACROSS THE SOUTH CHINA SEA, MAKE
LANDFALL OVER CENTRAL VIETNAM NEAR HUE, THAN DRAG DEEP INTO THE
INDOCHINA PENINSULA THROUGH LAOS AND CROSS INTO THAILAND BY TAU 72.
THE FAVORABLE ENVIRONMENT WILL PROMOTE STEADY INTENSIFICATION TO A PEAK
OF 70 KNOTS BY TAU 48. AFTERWARD, LAND INTERACTION AND INCREASING VWS
WILL RAPIDLY ERODE THE SYSTEM DOWN TO 45 KNOTS BY TAU 72.
   C. AFTER TAU 72, TS 13W WILL CONTINUE TO DETERIORATE AS IT DRAGS
ACROSS THE MOUNTAINOUS TERRAIN OF NORTHERN THAILAND, LEADING TO
DISSIPATION AS IT CROSSES INTO MYANMAR. NUMERICAL MODEL SOLUTIONS ARE
IN FAIR AGREEMENT BUT GIVEN THE FORMATIVE NATURE OF THE SYSTEM AND THE
LOW CONFIDENCE IN THE INITIAL POSITION THERE IS OVERALL LOW CONFIDENCE
IN THE JTWC FORECAST TRACK.//
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