Tropical Storm TALIM Advisory Sat Sep 16

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (TALIM) WARNING NR
32//
RMKS//
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM 20W (TALIM), LOCATED APPROXIMATELY 245 NM SOUTH-
SOUTHWEST OF SASEBO, JAPAN, HAS TRACKED EAST-NORTHEASTWARD AT 10
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE
IMAGERY DEPICTS DEEPENING CONVECTION WITH COOLING CLOUD TOPS ON THE
WESTERN EDGE BEGINNING TO WRAP INTO THE SYSTEM CENTER. THERE IS HIGH
CONFIDENCE IN THE INITIAL POSITION BASED ON ANIMATED RADAR IMAGERY
FROM JMA AND A LOW REFLECTIVITY FEATURE OBSERVED IN A 161045Z 89GHZ
AMSU-B IMAGE. THE INITIAL INTENSITY IS ASSESSED AT 55 KNOTS WHICH IS
BASED ON MULTI-AGENCY DVORAK ESTIMATES RANGING FROM T2.5 TO T4.0 (35
TO 65 KNOTS) AND A 161043Z SATCON ESTIMATE OF 51 KNOTS. UPPER-LEVEL
ANALYSIS SHOWS MODERATE VERTICAL WIND SHEAR ASSOCIATED WITH A WELL
ESTABLISHED UPPER-LEVEL RIDGE TO THE SOUTHEAST HINDERING EQUATORWARD
OUTFLOW. POLEWARD OUTFLOW REMAINS ROBUST FEEDING INTO THE MID-
LATITUDE JET WITH A DEVELOPING TROUGH JUST UPSTREAM. DUE TO THE SLOW
TRACK MOTION OF TS 20W OVER THE LAST SEVERAL DAYS, OCEAN UPWELLING
HAS BROUGHT COOLER WATERS TO THE SURFACE HELPING TO WEAKEN THE
SYSTEM. HOWEVER, SSTS BENEATH TS 20W ARE BEGINNING TO WARM AS THE
SYSTEM IS ACCELERATING EAST-NORTHEAST ALONG THE 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 CONTINUE TO ACCELERATE NORTHEASTWARD ALONG THE
NORTHWEST EXTENT OF THE STR FOR THE DURATION OF THE FORECAST. AS THE
SYSTEM TRACKS NORTHEASTWARD CONDITIONS WILL IMPROVE DUE TO WARMER
SSTS AND ENHANCED POLEWARD OUTFLOW AS THE TROUGH DEEPENS AND
APPROACHES TS 20W. SOUTHERLY WIND SHEAR IS EXPECTED TO REMAIN FAIRLY
STRONG OVER THE NEXT 12 HOURS WHICH WILL HELP MITIGATE A BRIEF
INTENSIFICATION PERIOD BEFORE TS 20W MAKES LANDFALL SOUTHEAST OF
SASEBO, JAPAN REACHING A PEAK INTENSITY OF 65 KNOTS. SHORTLY AFTER
TAU 24 TS 20W WILL BEGIN INTERACTING WITH THE APPROACHING TROUGH
WITH SUBSTANTIAL BAROCLINIC SUPPORT. TS 20W WILL TRANSITION INTO A
SIGNIFICANT EXTRATROPICAL LOW BY TAU 48 MAINTAINING GALE FORCE WINDS
WITH EXTENDED REACH, ESPECIALLY IN THE SOUTHEASTERN QUADRANT.
NUMERICAL MODEL GUIDANCE STILL SHOWS RELATIVELY TIGHT GROUPING WITH
A SLIGHT EASTWARD SHIFT TOWARD THE 00Z ECMWF SOLUTION. THE JTWC
FORECAST TRACK IS PLACED NEAR THE MULTI-MODEL CONSENSUS WITH HIGH
CONFIDENCE.//
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