Tropical Storm MITAG Advisory 10月2日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (MITAG) WARNING NR
019//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 19W (MITAG), LOCATED APPROXIMATELY 417 NM
SOUTHWEST OF PUSAN, SOUTH KOREA, HAS TRACKED NORTH-NORTHEASTWARD AT
07 KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED
SATELLITE IMAGERY DEPICTS AN EXPOSED LOW-LEVEL CIRCULATION CENTER
(LLCC) WITH RAPIDLY DECAYING DEEP CONVECTION. HOWEVER, A 011706Z
AMSR2 89GHZ COLOR COMPOSITE IMAGE STILL SHOWS TIGHTLY-CURVED SHALLOW
BANDING WRAPPING INTO A DEFINED LLCC, WHICH SUPPORTS THE CURRENT
POSITION WITH FAIR CONFIDENCE. ADDITIONALLY, A 011221Z BYU HIRES
ASCAT IMAGE DEPICTS 40-45 KNOT WINDS OVER THE EAST QUADRANT WITH
EXTENSIVE GALE-FORCE WINDS TO THE NORTHEAST AND EAST. THE SYSTEM IS
CURRENTLY LOCATED WITHIN A BROAD UPPER-LEVEL SUBTROPICAL TROUGH,
WHICH IS CONTRIBUTING TO THE RAPID DECAY OF THE DEEP CONVECTIVE
STRUCTURE AND PRODUCING STRONG (25-30 KNOTS) SOUTHWESTERLY VERTICAL
WIND SHEAR (VWS). SST VALUES ARE MARGINAL AT 24-25C. TS 19W IS
TRACKING ALONG THE NORTHWESTERN PERIPHERY OF A SUBTROPICAL RIDGE
(STR) POSITIONED TO THE SOUTHEAST.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE. THE 34-KNOT WIND RADII HAVE
BEEN ADJUSTED BASED ON A DETAILED ANALYSIS OF RECENT ASCAT DATA.
   B. TS 19W IS FORECAST TO ACCELERATE NORTH-NORTHEASTWARD TO
NORTHEASTWARD THROUGH TAU 24 AS IT ROUNDS THE STR AXIS. TS 19W WILL
BEGIN EXTRA-TROPICAL TRANSITION (ETT) NEAR TAU 24 AS IT INTERACTS
WITH THE MIDLATITUDE WESTERLIES AND BAROCLINIC ZONE, AND MAKES
LANDFALL OVER SOUTHWEST KOREA. THE SYSTEM SHOULD GRADUALLY WEAKEN
DUE TO INCREASING VWS, COOLER SST AND INTERACTION WITH LAND. 19W
WILL TRACK OVER THE SEA OF JAPAN AFTER TAU 36 AND WILL COMPLETE ETT
NEAR TAU 48 AS IT GAINS FRONTAL CHARACTERISTICS AND BECOMES EMBEDDED
WITHIN STRONG MIDLATITUDE WESTERLY FLOW. SST VALUES WILL DECREASE TO
LESS THAN 24C, WHICH WILL FURTHER AID IN WEAKENING THE SYSTEM.
NUMERICAL MODEL GUIDANCE REMAINS IN TIGHT AGREEMENT WITH A 40NM
SPREAD IN SOLUTIONS AT TAU 36, THEREFORE, THERE IS HIGH CONFIDENCE
(LOW UNCERTAINTY) IN THE JTWC FORECAST TRACK THROUGH TAU 36. AFTER
TAU 48, THIS COLD-CORE EXTRA-TROPICAL LOW WILL ACCELERATE EAST-
NORTHEASTWARD OVER NORTHERN HONSHU. THE SYSTEM IS STILL EXPECTED TO
MAINTAIN GALE-FORCE WINDS. DUE TO THE BROAD NATURE OF THIS LOW AND
THE LARGE SPREAD IN THE NUMERICAL MODELS, THERE IS LOW CONFIDENCE IN
THIS PORTION OF THE JTWC FORECAST TRACK.//
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