Tropical Storm FENGSHEN Advisory 09 Σεπ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 13W (FENGSHEN) WARNING
NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 13W (FENGSHEN), LOCATED APPROXIMATELY 233 NM
SOUTH-SOUTHEAST OF YOKOSUKA, JAPAN, HAS TRACKED EAST-NORTHEASTWARD
AT 16 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
(EIR) SATELLITE IMAGERY DEPICTS TIGHTLY-CURVED BANDING OVER THE
NORTHERN PERIPHERY WRAPPING INTO A WELL-DEFINED LLCC AND A CLOUD
FILLED EYE FEATURE. A 081810Z TRMM MICROWAVE IMAGE ALSO REVEALS A
MICROWAVE EYE WITH THE MAJORITY OF THE DEEP CONVECTION OVER THE
NORTHERN SEMI-CIRCLE. THE CURRENT POSITION IS BASED ON THE EIR
ANIMATION AND MICROWAVE IMAGE WITH HIGH CONFIDENCE. THE INITIAL
INTENSITY OF 60 KNOTS IS BASED ON DVORAK INTENSITY ESTIMATES AND A
081210Z ASCAT PASS. UPPER-LEVEL ANALYSIS INDICATES TS FENGSHEN
CONTINUES TO HAVE EXCELLENT POLEWARD OUTFLOW DUE TO A MID-LEVEL JET
TO THE NORTHEAST OF THE SYSTEM, WHICH OFFSETS THE HIGH LEVELS (40 TO
50 KNOTS) OF VERTICAL WIND SHEAR. TS 13W CONTINUES TO TRACK ALONG
THE NORTHERN PERIPHERY OF A DEEP SUBTROPICAL RIDGE (STR) WITHIN A
MID-LATITUDE TROUGH NORTH OF THE SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 13W WILL CONTINUE TO TRACK NORTHEASTWARD ALONG THE STR
THROUGHOUT THE FORECAST PERIOD AS IT CONTINUES TO BECOME
EXTRATROPICAL (XT). INDICATION OF A SLIGHT WARMING OF THE LOWER
LEVELS BASED ON AN AMSU CROSS SECTION SHOWS THE SYSTEM STARTING TO
BECOME BAROCLINIC AND DEVELOPING A WEAK WARM FRONTAL PATTERN.
FENGSHEN WILL CONTINUE TO BECOME XT AS THE WESTERLIES CONTINUE TO
ENVELOP THE SYSTEM THROUGH TAU 24, COMPLETING XT BY TAU 36. THIS
WILL BE ACCOMPANIED BY GREATER TRACK SPEEDS AND GRADUAL WEAKENING IN
INTENSITY. MODELS ARE IN VERY GOOD AGREEMENT, LEADING TO HIGH
CONFIDENCE IN THE JTWC FORECAST.//
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