Tropical Storm TALIM Advisory Çar, 20.06.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 06W (TALIM) WARNING NR
09//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 06W (TALIM), LOCATED APPROXIMATELY 320 NM
SOUTHWEST OF TAIPEI, TAIWAN, HAS TRACKED NORTH-NORTHEASTWARD AT 08
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED (EIR)
SATELLITE IMAGERY SHOWS THE LOW LEVEL CIRCULATION CENTER (LLCC) HAS
BEEN COMPLETELY SHEARED FROM THE DEEP CONVECTION AS AN UPPER LEVEL
SUBTROPICAL RIDGE (STR) LOCATED OVER SOUTHEASTERN CHINA HAS CAUSED
VERTICAL WIND SHEAR (VWS) TO INCREASE OVER THE PAST 12 HOURS. THE
LLCC HAS SEEN A RECENT SHIFT NORTHWARD TOWARDS COASTAL CHINA FROM
THE PREVIOUS FORECAST, HOWEVER THE OVERALL STEERING ENVIRONMENT WILL
CONTINUE TO TRACK THE LLCC TO THE NORTHEAST, TOWARDS THE TAIWAN
STRAIT, AROUND THE NORTHWESTERN QUADRANT OF A DEEP LAYERED STR. THE
INITIAL POSITION IS BASED ON THE EIR IMAGERY SHOWING THE FULLY
EXPOSED LLCC. THE INITIAL INTENSITY HAS BEEN REDUCED TO 45 KNOTS
BASED ON THE NOTED SHEARING OF DEEP CONVECTION ASSOCIATED WITH HIGH
VWS OVER TS 06W. A 2.0/3.0 DVORAK FIX FROM PGTW SUPPORTS THE
WEAKENING OBSERVED IN EIR.
3. FORECAST REASONING.
   A. THE FORECAST PHILOSOPHY HAS SHIFTED SLIGHTLY BEYOND TAU 36,
SHOWING THE TRACK MORE SOUTHWARD THAN THE PREVIOUS FORECAST, AND
WITH A SLIGHTLY QUICKER EXTRA-TROPICAL TRANSITION (ETT) TIME.
   B. TS 06W WILL STRUGGLE OVER THE NEXT 12 HOURS TO MAINTAIN
INTENSITY AS VWS REMAINS HIGH (20 TO 30 KNOTS), ASSOCIATED WITH AN
UPPER LEVEL STR LOCATED OVER SOUTHEASTERN CHINA. AS TS 06W MOVES
TOWARDS THE TAIWAN STRAIT, IT IS EXPECTED TO MOVE OUT FROM UNDER THE
STRONG NORTHEASTERLY FLOW AROUND THE STR AND INTO A REGION OF WEAKER
UPPER LEVEL WINDS. DURING THIS TRANSITION PERIOD, SOUTHWESTERLY FLOW
AROUND A STATIONARY UPPER LEVEL TROUGH IS EXPECTED TO INCREASE THE
POLEWARD OUTFLOW CHANNEL BETWEEN TAU 24 AND 36. THE SEA SURFACE
TEMPERATURES WILL REMAIN FAVORABLE THROUGH TAU 24 (26 TO 28
CELSIUS), WHEN COMBINED WITH THE BRIEF IMPROVEMENT IN THE POLEWARD
OUTFLOW, WILL HELP TS 06W TO INTENSIFY. BEYOND TAU 36, THE MID-
LATITUDE FLOW WILL CAUSE AN INCREASE IN COLD AIR ADVECTION WITHIN
THE LOW- TO MID-LEVELS OF TS 06W, LEADING TO THE START OF THE ETT
PROCESS. THE STEERING STR WILL BUILD CAUSING AN INCREASE IN TRACK
SPEEDS OVER THE NEXT 24 HOURS, WITH INCREASING SPEEDS AS THE LLCC IS
ABSORBED INTO THE BAROCLINIC ZONE ALONG THE EASTERN COAST OF JAPAN.
FULL ETT TRANSITION IS EXPECTED BY TAU 48. MODEL GUIDANCE IS IN POOR
AGREEMENT WITH THE CURRENT FORECAST AS THEY ATTEMPT TO TRACK THE
SYSTEM OVER KYUSHU, SHIKOKU, AND HONSHU, CROSSING RUGGED TERRAIN.
THE CURRENT FORECAST KEEPS THE TRACK ALONG THE NORTHERN PERIPHERY OF
THE STEERING STR IN LATER TAUS, WHICH WILL KEEP THE SYSTEM FURTHER
SOUTH OF THE CONSENSUS AND IS MORE IN LINE WITH ECMWF.//
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