Subject: Pacific-NW: Subj/prognostic Reasoning For Typhoon 16w Warning Nr 29//

From: SIU Weather Processor <[email-masked]>
Date: Fri, 29 Oct 2010 08:01:09 -0500

WDPN32 PGTW 291500
MSGID/GENADMIN/NAVMARFCSTCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 16W WARNING NR 29//
RMKS/
1. FOR METEOROLOGISTS.
2. 12 HOUR SUMMARY AND ANALYSIS.
   A. TYPHOON (TY) 16W (CHABA), LOCATED APPROXIMATELY 460 NM
SOUTHWEST OF YOKOSUKA, JAPAN, HAS TRACKED NORTHEASTWARD AT 16 KTS
OVER THE PAST SIX HOURS. ANIMATED WATER VAPOR SATELLITE IMAGERY AND A
291051Z TRMM MICROWAVE IMAGE SHOW A STEADY DECREASE IN DEEP
CONVECTION AND ELONGATION IN THE NORTHEAST QUADRANT. THE CURRENT
POSITION IS EXTRAPOLATED FROM THE TRMM IMAGE. THE CURRENT INTENSITY
IS BASED ON PGTW, KNES, AND RJTD DVORAK ESTIMATES RANGING FROM 68 TO
90 KTS. ENVIRONMENTAL ANALYSIS INDICATES THE SYSTEM IS LOCATED IN AN
AREA OF HIGH VERTICAL WIND SHEAR (30 TO 35 KTS) AND MARGINAL SEA
SURFACE TEMPERATURES (26 DEGREES CELSIUS). TY 16W CONTINUES TO
MAINTAIN GOOD RADIAL OUTFLOW AS IT CURRENTLY TRACKS ALONG THE
NORTHWESTERN PERIPHERY OF A SUBTROPICAL STEERING RIDGE ANCHORED
SOUTHEAST OF JAPAN.
3. FORECAST REASONING.
   A. THERE IS NO CHANGE IN THE FORECAST PHILOSOPHY SINCE THE
PREVIOUS PROGNOSTIC REASONING MESSAGE.
   B.  TY CHABA WILL CONTINUE TO WEAKEN AS IT CONTINUES TO TRACK
NORTHEASTWARD INTO THE BAROCLINIC ZONE. IT HAS BEGIN EXTRATROPICAL
TRANSITION (ET) AND IS EXPECTED TO COMPLETE ET BY TAU 24. RECENT
ANIMATED MULTISPECTRAL IMAGERY SHOWS A ROBUST INFLUX OF COLD AIR
STRATOCUMULUS CLOUDS INTO THE LOW LEVEL CIRCULATION CENTER. MODEL
GUIDANCE IS IN SOLID AGREEMENT, EXCEPT FOR GFDN, WHICH CONTINUES TO
ERRONEOUSLY TRACK THE SYSTEM NORTHWARD INTO THE MID-LATITUDE FLOW.
THIS FORECAST IS TO THE RIGHT OF AND FASTER THAN MODEL CONSENSUS TO
OFFSET THE GFDN TRACK ERROR AND TO ACCOUNT FOR THE SLOW RECURVATURE
TENDENCY OF THE CONSENSUS.//

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