Tropical Storm FENGSHEN Advisory Wed Nov 13

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W (FENGSHEN)
WARNING NR 008//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 26W (FENGSHEN), LOCATED APPROXIMATELY 620NM
EAST-NORTHEAST OF WFO GUAM, HAS TRACKED WEST AT 11 KNOTS OVER THE PAST
SIX HOURS.
ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS PERSISTENT DEEP
CONVECTION SHEARED TO THE SOUTHWEST OF THE LOW LEVEL CIRCULATION CENTER
(LLCC). THE INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON
THE DEFINED FEATURE IN THE 130609Z SSMIS 89GHZ COLORIZED MICROWAVE
IMAGE. THE INITIAL INTENSITY OF 45KTS IS BASED ON MULTI-AGENCY DVORAK
INTENSITY ESTIMATES OF T2.5-3.0 (42-45 KNOTS). THE SYSTEM IS, OVERALL,
IN A FAVORABLE AREA FOR FURTHER DEVELOPMENT WITH WARM (29-30 CELSIUS)
SEA SURFACE TEMPERATURES, LOW (10-15 KNOT) VERTICAL WIND SHEAR (VWS)
AND FAIR EQUATORWARD OUTFLOW DISPLACED TO THE SOUTH OF THE LLCC. THE
CYCLONE IS TRACKING ALONG THE SOUTHWESTERN PERIPHERY 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. TS 26W WILL CONTINUE ON ITS CURRENT TRACK SOUTHWEST OF THE STR
THROUGH TAU 24 BEFORE IT TURNS POLEWARD AROUND TAU 48 AS IT ROUNDS THE
WESTERN EDGE OF THE STR AXIS. THE OVERALL FAVORABLE ENVIRONMENT WILL
PROMOTE GRADUAL INTENSIFICATION TO A PEAK 80 KNOTS BY TAU 72. THERE IS
GOOD CONFIDENCE IN THE JTWC TRACK FORECAST AS MODEL GUIDANCE HAS
IMPROVED WITH A SPREAD OF 100 NM AT TAU 48.
   C. AFTER TAU 72, TS 26W WILL TURN MORE EAST-NORTHEASTWARD AND WILL
RAPIDLY WEAKEN AS IT INTERACTS WITH AN APPROACHING MIDLATITUDE TROUGH
AND UNDERGOES STRONG VWS. THE SYSTEM IS EXPECTED TO BEGIN EXTRA-
TROPICAL TRANSITION BY TAU 72. HOWEVER, THERE IS SOME UNCERTAINTY IN
THE TRACK AT TAU 96 AS RIDING BUILDS IN TO THE WEST OF TC 26W. BY TAU
120, THE SYSTEM WILL BE REDUCED TO 30 KNOTS AND IS EXPECTED TO COMPLETE
EXTRA-TROPICAL TRANSITION. DUE TO THE COMPLEX, EVOLVING STEERING
PATTERN, THERE IS LOW CONFIDENCE IN THE EXTENDED PORTION OF THE JTWC
FORECAST TRACK.//
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