WDPN32 PGTW 220300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W (MINDULLE) WARNING
NR 18//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 10W (MINDULLE), LOCATED APPROXIMATELY 63 NM SOUTH-
SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED NORTH-NORTHEASTWARD AT
11 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS CONVECTION WRAPPING AROUND THE LOW-LEVEL CIRCULATION
CENTER (LLCC) WITH A DRY SLOT INTRUDING INTO THE EASTERN SEMICIRCLE.
THE
INITIAL POSITION IS PLACED WITH GOOD CONFIDENCE WITH BOTH SATELLITE
FIXES AND RADAR REFLECTIVITY IMAGERY FROM JAPAN. THE INITIAL
INTENSITY IS MAINTAINED AT 50 KNOTS BASED ON DVORAK ESTIMATES OF
T3.5 FROM PGTW AND KNES. INITIAL 34-KNOT WIND RADII WERE SLIGHTLY
REDUCED BASED ON SURFACE OBSERVATIONS FROM THE SHIZUOKA AND CHIBA
PREFECTURES INDICATING SUSTAINED WIND SPEEDS STILL WELL BELOW
TROPICAL STORM FORCE. TS 10W HAS BEGUN ITS TURN TOWARD THE NORTHEAST
AS IT BEGINS TO BE STEERED BY THE SOUTHWESTERLY FLOW AHEAD OF AN
APPROACHING MID-LATITUDE TROUGH. UPPER-LEVEL ENVIRONMENTAL
CONDITIONS REMAIN FAVORABLE WITH GOOD RADIAL OUTFLOW EXCEPT IN THE
WESTERN SEMICIRCLE AND LOW VERTICAL WIND SHEAR (5-10 KNOTS) OVER THE
SYSTEM.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TS 10W IS EXPECTED TO TRACK TO THE NORTHEAST FOLLOWING THE
SOUTHWESTERLY STEERING FLOW AHEAD OF THE MID-LATITUDE TROUGH. A DRY
SLOT HAS WRAPPED INTO THE SYSTEM FROM THE SOUTHEAST, AND A MOAT
SURROUNDING THE LLCC DEVOID OF CONVECTION IS EVIDENT IN BOTH
ENHANCED INFRARED IMAGERY AND RADAR REFLECTIVITY FROM JAPAN. THIS
IMPLIES THAT ALTHOUGH SUSTAINED TROPICAL STORM FORCE WINDS ARE STILL
EXPECTED EAST OF THE LLCC, THE THREAT OF STRONGER WIND GUSTS
ASSOCIATED WITH HIGHER MOMENTUM AIR BEING MIXED DOWN TOWARD THE
SURFACE BY MESOSCALE CONVECTIVE DOWNDRAFTS WILL BE LOWER AS LONG AS
THE DRY SLOT PERSISTS. TS 10W IS EXPECTED TO MAKE LANDFALL WITHIN
THE NEXT SEVERAL HOURS AND WILL ACCELERATE TO THE NORTHEAST
THEREAFTER. AS VERTICAL WIND SHEAR INCREASES AND THE CIRCULATION OF
TS 10W BEGINS TO INTERACT WITH THE MID-LATITUDE BAROCLINIC ZONE, IT
WILL BEGIN EXTRATROPICAL TRANSITION BETWEEN TAUS 12 AND 24 AND
BECOME FULLY EXTRATROPICAL BY TAU 36. OVERALL, THERE IS HIGH
CONFIDENCE IN THE JTWC TRACK FORECAST./=