WDPN31 PGTW 201500
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON (TY) 20W (KETSANA)/
WARNING NR 08//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 201200Z5 TO 251200Z0 OCT 2003.
   A. TYPHOON (TY) 20W (KETSANA), LOCATED APPROXIMATELY
775 NM SOUTHWEST OF IWO JIMA, HAS DRIFTED NORTHEASTWARD 
AT 03 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION
IS BASED ON 201130Z7 MULTISPECTRAL SATELLITE IMAGERY. 
THE WARNING INTENSITY IS BASED ON SATELLITE CURRENT 
INTENSITY ESTIMATES OF 55 AND 65 KNOTS. 200MB ANALYSIS 
DEPICTS GOOD EQUATORWARD AND POLEWARD OUTFLOW ALONG WITH
WEAK VERTICAL WINDSHEAR CREATING A FAVORABLE ENVIRONMENT 
FOR INTENSIFICATION. 
   B. TY 20W CONTINUES IT'S SLOW MARCH TOWARD THE NORTHEAST ALONG THE 
WESTERN PERIPHERY OF THE MID-LEVEL STEERING RIDGE. TY 20W IS EXPECTED TO 
CONTINUE TO SLOWLY TRACK IN A PREDOMINANTLY NORTHEASTWARD DIRECTION 
FOR THE NEXT 12 TO 24 HOURS. AFTER 24 HOURS, TY 20W WILL SPEED UP
AS THE STEERING RIDGE BUILDS IN FROM THE EAST AND THE SYSTEM IS FULLY 
INFLUENCED BY THIS RIDGE. THE AVAILABLE DYNAMIC AIDS CONSISTING OF THE 
UKMET (EGRR), JGSA, JTYM, AND AVN (GFS) MODELS ARE IN GOOD AGREEMENT. 
THE NOGAPS MODEL HOLDS TY 20W QUASI-STATIONARY AND THEN HAS THE SYSTEM DRIFTING
SOUTHWESTWARD FOR THE REMAINDER OF THE FORECAST PERIOD DUE TO 
INTERACTION WITH A WEAK CIRCULATION (TD 21W) TO THE NORTHEAST OF TY 20W. THIS 
FORECAST IS BASED ON A CONSENSUS OF AVAILABLE MODELS WITH EXCEPTION 
OF THE NOGAPS MODEL.
   C. TY 20W IS EXPECTED TO INTENSIFY AT A NEAR CLIMATOLOGICAL RATE 
THROUGH TAU 72. AFTER THIS TIME, TY 20W WILL START TO WEAKEN DUE TO BEING 
STEERED INTO AN AREA OF HIGHER VERTICAL WIND SHEAR AND SLIGHTLY COOLER SEA 
SURFACE TEMPERATURES. 
   D. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED 
SYSTEM.
3. FORECAST TEAM: DAMRON/KLINZMANN/BIRD/CHITWOOD//

NNNN