Tropical Storm SEVENTEEN Advisory 9月11日

MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 17W (SEVENTEEN)
WARNING NR 01//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL DEPRESSION (TD) 17W (SEVENTEEN), LOCATED APPROXIMATELY
607 NM EAST-SOUTHEAST OF MISAWA, JAPAN, HAS TRACKED NORTHEASTWARD AT
15 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY DEPICTS A COMPACT, CONSOLIDATING LOW-LEVEL CIRCULATION
CENTER WITH PERSISTENT CENTRAL CONVECTION. A 102037Z SSMIS 91GHZ
IMAGE SHOWS CURVED CONVECTIVE BANDING OVER THE SOUTH QUADRANT
WRAPPING INTO THE EAST QUADRANT. A 102327Z ASCAT IMAGE SHOWS 25
TO 30 KNOT WINDS OVER THE SOUTH AND EAST QUADRANTS OF THE LLCC.
THE CURRENT INTENSITY IS ASSESSED AT 30 KNOTS AND IS BASED ON
DVORAK ESTIMATES RANGING FROM T1.5 (25 KNOTS) TO T2.0 (30 KNOTS)
AND THE ASCAT DATA. THIS SYSTEM IS LOCATED UNDER AN UPPER-LEVEL
RIDGE, AND IS LOCATED SOUTH OF A FRONTAL SYSTEM WITH NO EVIDENCE
OF BAROCLINIC INTERACTION. SST VALUES ARE WARM (27 TO 28C) AND
POLEWARD OUTFLOW IS FAVORABLE. TD 17W IS ACCELERATING NORTHEASTWARD
ALONG THE NORTHWEST PERIPHERY OF THE DEEP-LAYERED SUBTROPICAL
RIDGE (STR).
3. FORECAST REASONING.
   A. THIS PROGNOSTIC REASONING MESSAGE SETS THE FORECAST
PHILOSOPHY.
   B. TD 17W IS FORECAST TO ACCELERATE AND TRACK POLEWARD OF THE
STR WITHIN THE NEXT 12 HOURS, AND WILL TURN EASTWARD AS IT TRACKS
WITHIN THE MIDLATITUDE WESTERLIES. TD 17W IS FORECAST TO UNDERGO
EXTRA-TROPICAL TRANSITION (ETT) WITHIN THE NEXT 12 HOURS AND WILL
COMPLETE ETT BY TAU 24 AS IT GAINS FRONTAL CHARACTERISTICS. TD 17W
IS NOT EXPECTED TO INTENSIFY AND WILL REMAIN AT TROPICAL DEPRESSION
STRENGTH THROUGH THE FORECAST PERIOD. DYNAMIC GUIDANCE IS LIMITED
BUT GENERALLY SUPPORTS THE FORECAST TRACK WITH HIGH CONFIDENCE.//
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