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

From: SIU Weather Processor <[email-masked]>
Date: Thu, 28 Oct 2010 21:28:08 -0500

WDPN32 PGTW 290300
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 660 NM
SOUTHWEST OF TOKYO, JAPAN, HAS TRACKED NORTHEASTWARD AT 11 KNOTS.
ANIMATED INFRARED SATELLITE IMAGERY AND A 282201 SSMIS MICROWAVE
IMAGE SHOW A SIGNIFICANT DECREASE IN DEEP CONVECTION AND LOSS OF THE
EYE WITHIN THE LAST 12 HOURS. STRATOCUMULOUS CLOUDS CAN BE SEEN IN
VISIBLE IMAGERY WRAPPING INTO THE SYSTEM FROM THE NORTHWESTERN SIDE
AND A TOTAL PRECIPITABLE WATER PRODUCT DEPICTS OVERALL DECREASING
MOISTURE CONTENT. THE CURRENT POSITION IS BASED ON A PGTW FIX AND
RADAR FIX FROM JAPAN WITH POOR CONFIDENCE. THE CURRENT INTENSITY IS
BASED ON PGTW, KNES, AND RJTD DVORAK ESTIMATES RANGING FROM 90 TO
102 KNOTS. ENVIRONMENTAL ANALYSIS INDICATES THE SYSTEM IS LOCATED IN
AN AREA OF HIGH VERTICAL WIND SHEAR (30 TO 35 KNOTS) AND MARGINAL
SEA SURFACE TEMPERATURES (26 DEGREES CELSIUS). TY 16W CONTINUES TO
MAINTAIN ENHANCED POLEWARD OUTFLOW INTO AN UPPER LEVEL MID-LATITUDE
TROUGH TO THE NORTHEAST. TY CHABA IS CURRENTLY TRACKING 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 16W WILL WEAKEN AS IT CONTINUES TO TRACK NORTHEASTWARD DUE
TO DECEASING OCEAN HEAT CONTENT AND INCREASING VERTICAL WIND SHEAR
ASSOCIATED WITH THE BAROCLINIC ZONE, JUST SOUTH OF MAINLAND JAPAN.
WITHIN 12 HOURS, TY CHABA IS FORECAST TO INITIALLY INTERACT WITH THE
MID-LATITUDE WESTERLIES AND BEGIN EXTRATROPICAL TRANSITION. AN UPPER
AIR SOUNDING FROM KAGOSHIMA, JAPAN (31.6N 130.6E) INDICATES VERY
STRONG UPPER LEVEL WESTERLIES. BY TAU 36, TY 16W SHOULD BECOME
ABSORBED BY THE BAROCLINIC ZONE, AND FULLY TRANSITION INTO AN
EXTRATROPICAL LOW. MODEL GUIDANCE IS IN GOOD AGREEMENT, EXCEPT FOR
GFDN, WHICH ERRONEOUSLY TRACKS THE SYSTEM NORTHWARD INTO THE MID-
LATITUDE FLOW. THIS FORECAST IS SOUTH OF MODEL CONSENSUS TO ACCOUNT
FOR THE GFDN TRACK ERROR AND IS FASTER THAN CONSENSUS TO ACCOUNT FOR
THE TENDENCY OF THE MODEL FORECAST TRACKS TO BE SLOW IN A
RECURVATURE SCENARIO.//

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