WDPN31 PGTW 071500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 08W (CHATAAN) WARNING 
NR 39//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 071200Z0 TO 101200Z4 JUL 02.
   A. TYPHOON (TY) 08W (CHATAAN), LOCATED APPROXIMATELY 535 NM 
SOUTHEAST OF OKINAWA, HAS TRACKED WEST-NORTHWESTWARD AT 13 KNOTS 
OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 071130Z2 
ENHANCED INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY IS BASED 
ON SATELLITE CURRENT INTENSITY ESTIMATES OF 115 AND 127 KNOTS. 
ANIMATED ENHANCED INFRARED SATELLITE IMAGERY SHOWS THE SYSTEM HAS A 
WELL DEFINED 24 NM DIAMETER EYE.    
   B. A RIDGE IS FORECASTED TO MOVE OFF MAINLAND CHINA INTO THE 
NORTHERN PORTION OF THE SEA OF JAPAN, REINFORCING THE SUBTROPICAL 
RIDGE CAUSING IT TO BE ORIENTATED IN A NORTH TO SOUTH DIRECTION. TY 
08W IS FORECAST TO TRACK NORTHWESTWARD THROUGH 36 HOURS AND THEN 
TURN POLEWARD FOLLOWING IN BEHIND THIS HIGH. THE AVAILABLE DYNAMIC 
AIDS CONSISTING OF AVN, NOGAPS, GFDN, COAMPS, THE UK-MET GLOBAL 
(EGRR), AFWA MESOSCALE (MM5), AND THE JAPANESE GLOBAL (JGSM) AND 
TYPHOON (JTYM) MODELS ARE IN EXCELLENT AGREEMENT THROUGH THE FIRST 
48 HOURS. AFTERWARDS, THE MODELS DIFFER IN DIRECTION AND SPEED WITH 
EGRR HAVING THE MOST EASTWARD FORECAST TRACK AND FASTEST SPEED. OUR 
FORECAST IS BASED ON A BLEND OF ALL THE DYNAMIC AIDS WITH LESS 
EMPHASIS BASED ON EGRR.    
   C. TY 08W IS EXPECTED TO MAINTAIN ITS INTENSITY THROUGH 36 HOURS 
AS THE SYSTEM APPROACHES THE UPPER LEVEL RIDGE AXIS. AFTERWARDS, TY 
08W WILL SLOWLY WEAKEN AS IT ENCOUNTERS COOLER SEA SURFACE 
TEMPERATURES AND INCREASING VERTICAL SHEAR.   
   D. WIND RADII ANALYSIS BASED ON A 070930Z9 QUIKSCAT PASS. 
FORECAST WIND RADII BASED ON CLIMATOLOGY FOR AN AVERAGE SIZE SYSTEM. 
3. FORECAST TEAM: LEEJOICE/AYALA/HARRISON/BOSTIC//

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