WDPN33 PGTW 120300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 10W WARNING NR 17//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
    A. TROPICAL STORM (TS) 10W (ETAU) HAS TRACKED GENERALLY EASTWARD
AT OVER 20 KNOTS ALONG THE NORTHERN PERIPHERY OF A MID-LEVEL SUB-
TROPICAL RIDGE (STR) TO THE SOUTH. ANIMATED MULTISPECTRAL SATELLITE
IMAGERY SHOWS THE SYSTEM HAS BECOME ASYMMETRICAL AND THE LOW LEVEL
CIRCULATION CENTER (LLCC) PARTIALLY EXPOSED. THE CURRENT POSITION AND
INTENSITY ARE BASED ON DVORAK FIXES FROM PGTW AND RJTD AND ON SHIP
OBSERVATIONS NEAR THE LLCC. UPPER LEVEL ANALYSIS INDICATES TS 10W HAS
CROSSED INTO THE POLEWARD SIDE OF THE RIDGE AXIS, EXPOSING IT INTO
STRONGER WESTERLY WINDS. DESPITE THE INCREASED VERTICAL WIND SHEAR,
THE CYCLONE WILL MAINTAIN A 30-KNOT INTENSITY AFTER TAU 12 AS IT
TRANSITIONS INTO AN EXTRA-TROPICAL (ET) LOW PRESSURE SYSTEM.
3. FORECAST REASONING
    A. THE FORECAST PHILOSOPHY HAS NOT CHANGED SINCE THE LAST
PROGNOSTIC REASONING BULLETIN.
    B. TS 10W WILL CONTINUE TO TRACK EASTWARD UNDER THE INFLUENCE OF
THE STR DESCRIBED IN PARA 2.A. AFTER TAU 12, THE EASTERN EXTENSION OF
THE STR, ORIENTED NORTHEAST TO SOUTHWEST, WILL NUDGE THE SYSTEM TO A
MORE NORTHEASTWARD TRACK BEFORE IT BECOMES FULL ET BY TAU 24. ALL
AVAILABLE NUMERIC GUIDANCE ARE IN CLOSE AGREEMENT WITH THIS TRACK
FORECAST.
FORECAST TEAM: ALPHA//
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