Tropical Storm TEMBIN Advisory sab, 25.08.

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 15W (TEMBIN) WARNING NR 25//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TYPHOON 15W (TEMBIN), LOCATED APPROXIMATELY 245 NM SOUTHWEST OF
TAIPEI, TAIWAN, HAS TRACKED WEST-SOUTHWESTWARD AT 07 KNOTS OVER THE
PAST SIX HOURS.  ANIMATED MULTISPECTRAL SATELLITE IMAGERY SHOWS THE
SYSTEM HAS MAINTAINED DEEP CENTRAL CONVECTION WITH RAIN BANDS
BEGINNING TO WRAP ANEW INTO THE LOW LEVEL CIRCULATION CENTER (LLCC).
THE INITIAL POSITION IS BASED ON A MICROWAVE EYE FEATURE IN THE
242226Z SSMI-S 37 GHZ COLOR COMPOSITE IMAGE. CURRENT INTENSITY OF 75
KNOTS IS BASED ON CONGRUENT DVORAK ESTIMATES FROM PGTW, KNES AND
RJTD. UPPER LEVEL ANALYSIS INDICATES A MESOSCALE ANTICYCLONE ALOFT
THAT CONTINUES TO PROVIDE A RADIAL VENTING MECHANISM AND LOW VERTICAL
WIND SHEAR (05 TO 10 KNOTS) OVER THE SYSTEM HAVE HELPED SUSTAIN ITS
INTENSITY. THE CYCLONE IS TRACKING ALONG THE SOUTHERN EXTENSION OF A
DEEP-LAYERED SUBTROPICAL RIDGE (STR) TO THE NORTHWEST AND APPEARS TO
BE DRIFTING INTO A WEAK STEERING ENVIRONMENT.
3. FORECAST REASONING.
   A. NO CHANGE TO THE FORECAST PHILOSOPHY SINCE THE PREVIOUS
PROGNOSTIC REASONING MESSAGE.
   B. TY 15W WILL CONTINUE TO MOVE IN A GENERALLY SOUTHWESTWARD
DIRECTION OVER THE NEXT 12 TO 24 HOURS. AS THE STEERING STR WEAKENS
WITH THE APPROACH OF A MID-LATITUDE TROUGH FROM THE NORTHWEST, THE
NEAR EQUATORIAL RIDGE TO THE SOUTHEAST WILL STEER TY 15W TO DRIFT
EASTWARD AFTER TAU 36. THE SYSTEM WILL SLIGHTLY INTENSIFY DUE TO
CONTINUED FAVORABLE UPPER- LEVEL ENVIRONMENT, PRIOR TO MAKING A
SECONDARY LANDFALL INTO TAIWAN BEFORE TAU 72.
   C. AFTER TAU 72, A BUILDING STR TO THE NORTHEAST WILL ASSUME
STEERING AND ACCELERATE THE SYSTEM POLEWARD. NUMERIC MODELS INDICATE
TY 15W WILL HAVE BINARY INTERACTION WITH TY 16W, WHICH IS CURRENTLY
SOUTHEAST OF OKINAWA. THIS INTERACTION WILL BE AT THE EXPENSE OF TY
15W, CAUSING IT TO STEADILY WEAKEN AS THE OUTFLOW OF TY 16W IS
EXPECTED TO HAMPER THE OUTFLOW FROM TY 15W. DYNAMIC MODEL GUIDANCE
REMAINS IN AGREEMENT AS FAR AS LOOPING THE CYCLONE BACK INTO TAIWAN
WITH THE EXCEPTION OF GFDN THAT ABRUPTLY DEFLECTS THE VORTEX POLEWARD
INTO CHINA AFTER TAU 36. HOWEVER, THERE IS A LARGE SPREAD IN THE
FORECAST ENVELOPE BEYOND TAU 72. THE CONFIDENCE IN THIS TRACK
FORECAST REMAINS LOW.    //
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