Tropical Storm FENGSHEN Advisory Dom, 17-11

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN) WARNING
NR 024//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 26W (FENGSHEN), LOCATED APPROXIMATELY 166 NM
NORTH-NORTHEAST OF MINAMI TORI SHIMA, JAPAN, HAS TRACKED EASTWARD AT
28 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS A RAPIDLY WEAKENING SYSTEM WITH ISOLATED
DEEP CONVECTION SHEARED EAST OF THE DECOUPLED LOW-LEVEL CIRCULATION
CENTER (LLCC). VISIBLE SATELLITE IMAGERY INDICATES A WELL-DEFINED,
FULLY-EXPOSED LLCC, WHICH SUPPORTS THE INITIAL POSITION WITH GOOD
CONFIDENCE. THE INITIAL INTENSITY IS ASSESSED AT 60 KNOTS BASED ON A
PGTW DVORAK ESTIMATE OF T3.5/4.0 (55/65 KNOTS) AND A 17/0704Z CIMSS
SATCON ESTIMATE OF 57 KNOTS, CONSISTENT WITH THE TIGHTLY-CURVED
SHALLOW BANDING STRUCTURE EVIDENT IN A 170423Z SSMI 37GHZ MICROWAVE
IMAGE. TS 26W IS DECAYING RAPIDLY WITHIN A HOSTILE ENVIRONMENT WITH
STRONG (40-50 KNOTS) WEST-SOUTHWESTERLY VERTICAL WIND SHEAR AND DRY
AIR ENTRAINMENT. THE SYSTEM IS TRACKING ON THE POLEWARD SIDE
OF A DEEP-LAYERED SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. OVER THE NEXT 12 HOURS, TS 26W WILL CONTINUE RAPIDLY WEAKENING
WITHIN THE HOSTILE ENVIRONMENT AND IS FORECAST TO SLOW SIGNIFICANTLY
AS A STRONG LOW-LEVEL HIGH BUILDS QUICKLY NORTH OF THE SYSTEM. AFTER
TAU 12, TS 26W WILL TURN SOUTHWARD TO WESTWARD AS IT STEERS UNDER
THE DOMINANT LOW-LEVEL HIGH POSITIONED TO THE NORTH. TS 26W SHOULD
DISSIPATE BETWEEN TAU 36 TO TAU 48. NUMERICAL MODEL GUIDANCE IS IN
FAIR AGREEMENT, THEREFORE, THERE IS MODERATE CONFIDENCE IN THE JTWC
FORECAST TRACK.//
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