Tropical Storm VONGFONG Advisory 13 Οκτ.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 19W (VONGFONG) WARNING
NR 41//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 19W (VONGFONG), LOCATED APPROXIMATELY 162 NM
SOUTH-SOUTHWEST OF SASEBO, JAPAN, HAS TRACKED NORTHEASTWARD AT 12
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY DEPICTS AN ELONGATING, PARTIALLY-EXPOSED, LOW-
LEVEL CIRCULATION CENTER (LLCC) WITH LIMITED DEEP CONVECTION SHEARED
OVER THE NORTHWESTERN QUADRANT OF THE LLCC. A 121641Z 36 GHZ GCOMW1
MICROWAVE IMAGE ADDITIONALLY SHOWS THE LLCC IS BEGINNING TO UNRAVEL
AND DEFORM AS THE CONVECTIVE SIGNATURE OF THE SYSTEM CONTINUES TO
DETERIORATE. BASED ON EIR LOOP, THE MICROWAVE IMAGE, AND RADAR
ANIMATION FROM JMA, THERE IS GOOD CONFIDENCE IN THE INITIAL POSITION
AND MOTION. THE INITIAL INTENSITY ASSESSMENT OF 55 KNOTS
REMAINS UNCHANGED AS A 121208Z ASCAT PASS SHOWED A WELL DEVELOPED 50
TO 55 KNOT WIND FIELD. DVORAK INTENSITY ESTIMATES CONTINUE TO FALL
AS THE CONVECTIVE ORGANIZATION WEAKENS AND MAY BE UNREPRESENTATIVE
OF THE CURRENT INTENSITY. UPPER-LEVEL ANALYSIS, ALONG WITH ANIMATED
WATER VAPOR IMAGERY, REVEALS A HOSTILE ENVIRONMENT AS STRONG (30 TO
40 KNOTS) SOUTHWESTERLY VERTICAL WIND SHEAR IS OFFSETTING ENHANCED
POLEWARD OUTFLOW INTO THE MIDLATITUDE WESTERLIES. TS 19W IS
BEGINNING TO ACCELERATE TO THE NORTHEAST AS IT TRACKS ALONG THE
NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE (STR).
3. FORECAST REASONING.
   A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B. TS 19W IS FORECAST TO CONTINUE TO ACCELERATE TO THE NORTHEAST
THROUGH THE REMAINDER OF THE FORECAST PERIOD AS AN APPROACHING
MIDLATITUDE TROUGH DIGS IN FROM THE KOREAN PENINSULA AND PRESSES ON
THE STR. AS THE SYSTEM GAINS LATITUDE AND DRAGS ACROSS JAPAN,
EXTRA-TROPICAL TRANISITION (ETT) WILL BEGIN DUE TO THE SYSTEM
BECOMING EMBEDDED IN THE MID-LATITUDE WESTERLIES. ETT, ALONG WITH
INCREASED LAND INTERACTION, WILL INDUCE A SLIGHT WEAKENING TREND AS
THE SYSTEM BROADENS AND GAINS BAROCLINIC ENERGY WITH THE STRONGEST
WINDS MIGRATING INTO THE DEVELOPING FRONTAL FEATURES. TS 19W IS
EXPECTED TO COMPLETE ETT BY TAU 24 AS IT APPROACHES THE KANTO PLAIN
AS A GALE FORCE, COLD-CORE, LOW. DYNAMIC MODEL GUIDANCE IS IN GOOD
AGREEMENT WITH THE FORECAST SCENARIO AND TRACK; THEREFORE, THERE IS
HIGH CONFIDENCE IN THE FORECAST.//
NNNN
NNNN