Tropical Storm TALIM Advisory 17.09.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (TALIM) WARNING NR
34//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 20W (TALIM), LOCATED APPROXIMATELY 120 NM SOUTH OF
SASEBO, JAPAN, HAS TRACKED NORTHEASTWARD AT 14 KNOTS OVER THE PAST
SIX HOURS. ANIMATED ENHANCED MULTISPECTRAL SATELLITE IMAGERY DEPICTS
DEEPENING CONVECTION IN THE NORTHWESTERN QUADRANT THAT IS PARTIALLY
OBSCURING A LOW LEVEL CIRCULATION CENTER (LLCC). THE NORTHERN
PORTION OF THE SYSTEM IS NOW OVER SOUTHERN JAPAN. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTIALLY
EXPOSED LLCC IN THE MULTI-SPECTRAL LOOP AND A LOW REFLECTIVITY AREA
VISIBLE IN ANIMATED RADAR IMAGERY FROM JMA. THE INITIAL INTENSITY OF
55 KNOTS IS HEDGED ON THE LOWER END OF MULTI AGENCY DVORAK CURRENT
INTENSITY ESTIMATES RANGING FROM T3.5 TO T4.0 (55-65 KNOTS) FROM
PGTW AND RJTD RESPECTIVELY, AND IS SUPPORTED BY A SATCON ESTIMATE OF
52 KNOTS. ENVIRONMENTAL ANALYSIS SHOWS THAT THE STRONG POLEWARD
OUTFLOW CHANNEL, ENHANCED BY THE MID-LATITUDE JET, AND HIGH SEA
SURFACE TEMPERATURES, ARE BEING OFFSET BY POOR EQUATORWARD OUTFLOW
AND HIGH(25-30 KNOTS) VERTICAL WIND SHEAR. TS TALIM IS CONTINUING TO
ACCELERATE NORTHEAST ALONG THE NORTHWESTERN PERIPHERY OF A 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. TS 20W WILL TRACK TO THE NORTHEAST AND GRADUALLY ACCELERATE
FOR THE DURATION OF THE FORECAST. THE SUBTROPICAL RIDGE WILL REMAIN
THE PRIMARY STEERING FEATURE. THE SYSTEM WILL MAKE LANDFALL WITHIN
THE NEXT THREE HOURS TO THE SOUTH OF SASEBO, AS THE NORTHERN
PORTIONS OF THE SYSTEM ARE ALREADY OVER SOUTHERN JAPAN. OVER THE
NEXT 12 HOURS, THE SYSTEM WILL TRACK ACROSS KYUSHU, THEN SOUTHERN
HONSHU, AND EXIT INTO THE SEA OF JAPAN SHORTLY AFTER TAU 12. SLIGHT
WEAKENING WILL OCCUR AS TS 20W INTERACTS WITH THE TERRAIN OF
SOUTHERN JAPAN. COOL SEA SURFACE TEMPERATURES AND HIGH VERTICAL WIND
SHEAR WILL PREVENT RE-INTENSIFICATION AS THE SYSTEM TRACKS THROUGH
THE SEA OF JAPAN. INCREASED INTERACTION WITH A MID-LATITUDE TROUGH
WILL CAUSE THE SYSTEM TO BEGIN EXTRATROPICAL TRANSITION BY TAU 24.
TS 20W IS FORECAST TO COMPLETE EXTRATROPICAL TRANSITION BY TAU 48 AS
IT BECOMES IMBEDDED IN THE MID-LATITUDE TROUGH. TS TALIM WILL MAKE A
SECONDARY LANDFALL OVER SOUTHERN HOKKAIDO BEFORE EXITING OUT INTO
THE SEA OF OKHOSTK AS A COLD CORE LOW WITH A LARGE GALE FORCE WIND
FIELD TRACKS TO THE NORTHEAST. DYNAMIC MODEL GUIDANCE REMAINS IN
TIGHT AGREEMENT WITH ONLY A MINOR SHIFT TO THE EAST IN THE TRACK
LENDING HIGH CONFIDENCE IN THE JTWC TRACK FORECAST.//
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