Tropical Storm MITAG Advisory Thu Oct 03

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (MITAG) WARNING NR
021//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 19W (MITAG), 182 NM SOUTH-SOUTHWEST OF KUNSAN
AB, SOUTH KOREA, HAS TRACKED NORTH-NORTHEASTWARD AT 15 KNOTS OVER THE
PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS
A SEMI-EXPOSED, RAGGED, BUT WELL-DEFINED LOW-LEVEL CIRCULATION
DE-COUPLED FROM THE DEEP CONVECTION TO THE NORTH. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE MSI LOOP. THE
INITIAL INTENSITY OF 45 KNOTS IS BASED ON AN OVERALL ASSESSMENT OF
AGENCY DVORAK ESTIMATES AND CONSISTENT WITH A RECENT ASCAT DIRECT
PASS. UPPER LEVEL ANALYSIS INDICATES THE SYSTEM IS IN AN AREA OF
STRONG (GREATER THAN 30KTS) SOUTHERLY VERTICAL WIND SHEAR (VWS). SST
VALUES AT 25-26C ARE ALSO NON-CONDUCIVE. TS 19W IS TRACKING ALONG
THE NORTHWESTERN PERIPHERY OF A NORTH-SOUTH ORIENTED SUBTROPICAL
RIDGE (STR) POSITIONED TO THE EAST.       .
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 19W IS FORECAST TO ACCELERATE NORTHEASTWARD TO
EAST-NORTHEASTWARD ON THE POLEWARD SIDE OF THE STR AXIS, MAKING
LANDFALL JUST AFTER TAU 06 SOUTH OF KUNSAN. AFTER TAU 18, IT WILL
EXIT INTO THE SEA OF JAPAN (SOJ) AND BEGIN EXTRA-TROPICAL TRANSITION
(ETT) AS IT INTERACTS WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC
ZONE, CROSSING THE SOJ AND NORTHERN HONSHU, INTO THE PACIFIC OCEAN
JUST SOUTH OF THE KURIL ISLANDS BY TAU 72. THE SYSTEM SHOULD
CONTINUE TO WEAKEN DUE TO THE STRONG VWS, LAND INTERACTION AND
COOLER SST, DROPPING TO 40KTS BY TAU 12 OVER THE RUGGED TERRAIN OF
SOUTH KOREA. HOWEVER, BY TAU 24, DURING ETT IN THE SOJ, IT WILL
SLIGHTLY INTENSIFY AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES
EMBEDDED IN THE BAROCLINIC ZONE WITH AN EXPANDED WIND FIELD. BY TAU
48, THE SYSTEM WILL TRANSFORM INTO A GALE-FORCE COLD CORE LOW.
INTERACTION WITH NORTHERN HONSHU WILL DEGRADE THE CYCLONE DOWN TO
35KTS, POSSIBLY WEAKER, BY TAU 72, AS IT BECOMES MORE DIFFICULT TO
DIFFERENTIATE ITS BROAD WIND FIELD FROM THE MIDLATITUDE BAROCLINIC
FLOW. NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT WITH
MINIMAL SPREAD IN SOLUTIONS UP TO TAU 48, LENDING HIGH CONFIDENCE IN
THE JTWC FORECAST TRACK THROUGH TAU 48, THEN LOW CONFIDENCE
AFTERWARD.//
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