Tropical Storm FENGSHEN Advisory 11月17日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 26W (FENGSHEN) WARNING NR 022//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON (TY) 26W (FENGSHEN), LOCATED APPROXIMATELY 447 NM EAST-
NORTHEAST OF IWO TO, JAPAN, HAS TRACKED EAST-NORTHEASTWARD AT 24
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY THE SYSTEM HAS BECOME MORE RAGGED AND ELONGATED WITH WARMING
CONVECTIVE TOPS. THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE
BASED ON A 5-NM PINHOLE EYE IN THE EIR LOOP, ADJUSTED FOR TILT AND
LINED UP WITH A MICROWAVE EYE IN THE 161542Z GCOM 36GHZ COLORIZED
IMAGE. THE INITIAL INTENSITY OF 100KTS IS BASED ON AN OVERALL
ASSESSMENT OF AGENCY DVORAK ESTIMATES THAT INDICATE A WEAKENING
TREND. TY 26W DRIFTED INTO AN AREA OF STRONG (>30KTS) VERTICAL WIND
SHEAR(VWS) AND COOLING SSTS (<27C) THAT ARE PARTLY OFFSET BY
EXCELLENT POLEWARD OUTFLOW. THE CYCLONE IS ACCELERATING ON THE
POLEWARD SIDE OF THE DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST.
3. FORECAST REASONING.
   A.  THERE IS NO SIGNIFICANT CHANGE TO THE FORECAST PHILOSOPHY
FROM THE PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TY FENGSHEN WILL TRACK MORE EASTWARD UNDER THE STR. AFTER TAU
24, AS THE SYSTEM RAPIDLY ERODES DUE TO INCREASING VWS AND COOLING
SSTS, A SECONDARY, MID- TO LOW-LAYERED STR TO THE NORTH WILL ASSUME
STEERING AND LOOP THE CYCLONE SOUTHWESTWARD. THE NEGATIVE COMBINED
EFFECTS OF HIGH VWS AND COOL SSTS WILL RESULT IN DISSIPATION BY TAU
48. THE MAJORITY OF THE NUMERICAL MODELS ARE IN BROAD AGREEMENT WITH
THIS LOOPING TRACK BUT WITH SIGNIFICANT DIFFERENCES IN THE TRACK
SPEED AND THE TIMING OF THE LOOP. IN VIEW OF THIS COMPLEX STEERING
AND THE LARGE VARIANCE IN THE NUMERICAL MODEL SOLUTIONS, THERE IS
LOW CONFIDENCE IN THE JTWC TRACK FORECAST.//
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