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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