Subject: Pacific-NW: Subj/prognostic Reasoning For Typhoon 16w Warning Nr 35//

From: SIU Weather Processor <[email-masked]>
Date: Fri, 29 Oct 2010 21:46:17 -0500

WDPN32 PGTW 300300
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W WARNING NR 35//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TYPHOON (TY) 16W (CHABA), LOCATED APPROXIMATELY 225 NM SOUTH-
SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 19 KNOTS
OVER THE PAST SIX HOURS. ANIMATED MULTI-SPECTRAL IMAGERY (MSI) SHOWS
THAT THE EYE HAS COLLAPSED OVER THE PAST FEW HOURS WITH DEEP
CONVECTION SHEARING NORTHEAST OF A PARTIALLY-EXPOSED LOW-LEVEL
CIRCULATION CENTER (LLCC). MSI ALSO DEPICTS FRONTAL CHARACTERISTICS
WITH INCREASING ENTRAINMENT OF COOLER AIR INTO THE WESTERN FLANK OF
THE SYSTEM AND A WARM FRONT EXTENDING SOUTH OF THE KANTO PLAIN. TY
16W IS TRACKING UNDER STRONG (50+ KNOTS) VERTICAL WIND SHEAR
AND HAS BEGUN TO DE-COUPLE. THE 34-KNOT WIND RADII ARE BASED PARTLY
ON OBSERVATIONS FROM JAPANESE COASTAL STATIONS AND OFF-SHORE ISLANDS
REPORTING GALE FORCE WINDS. THE CURRENT INTENSITY IS BASED ON AN
AVERAGE OF DVORAK ESTIMATES RANGING FROM 65 (RJTD, KNES) TO 77 KNOTS
(PGTW).
3. FORECAST REASONING.
    A. THERE IS NO CHANGE TO THE FORECAST PHILOSOPHY.
    B. TYPHOON 16W IS EXPECTED TO COMPLETE TRANSITION TO A STORM
FORCE EXTRA-TROPICAL LOW DURING THE NEXT 12 HOURS. VERTICAL WIND
SHEAR WILL INCREASE TO NEAR 100 KNOTS BY 35N AND WILL ACT TO
COMPLETELY DECOUPLE THE SYSTEM. TYPHOON 16W IS EXPECTED TO MAINTAIN
A NORTHEASTWARD BEARING THROUGH THE DURATION OF ITS TRANSITION TO AN
EXTRA-TROPICAL CYCLONE. WITH THE EXCEPTION OF GFDN, THE NUMERICAL
MODELS ARE IN GOOD GENERAL AGREEMENT WITH THIS SCENARIO. THE
FORECAST TRACK IS SLIGHTLY TO THE RIGHT AND SLIGHTLY FASTER THAN
CONSENSUS. THE SPEED OF TRANSLATION IS BASED ON PERSISTENCE WITH A
SLIGHT INCREASE DUE TO INCREASED INTERACTION WITH THE STRONG MID-
LATITUDE SOUTHWESTERLIES.//

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