WDPN31 PGTW 240300
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON (TY) 20W (KETSANA)/
WARNING NR 22//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 240000Z6 TO 280000Z0 OCT 2003.
       A. TYPHOON (TY) 20W (KETSANA), LOCATED APPROXIMATELY 500
NM WEST-SOUTHWEST OF IWO JIMA, HAS TRACKED NORTHEASTWARD 
AT 04 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION 
IS BASED ON 240000Z6 MULTI-SPECTRAL SATELLITE IMAGERY. THE 
WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY 
ESTIMATES OF 102 AND 115 KNOTS. RECENT MICROWAVE IMAGERY
REVEALS TY 20W HAS AN EASTERLY SHEAR COMPONENT. ANIMATED
MULTI-SPECTRAL SATELLITE IMAGERY REVEALS A 16 NM EYE.
       B. TY 20W CONTINUES TO TRACK NORTHEASTWARD ALONG THE 
WESTERN PERIPHERY OF THE MID LEVEL STEERING RIDGE LOCATED TO 
THE EAST OF THE SYSTEM. TY 20W IS NOW POLEWARD OF THE RIDGE 
AXIS AND IS EXPECTED TO PICK UP SPEED AS IT INTERACTS WITH THE 
SHORTWAVE TROUGH APPROACHING FROM THE WEST. TY 20W IS NOW 
ENTERING THE BAROCLINIC ZONE AND HAS COMMENCED EXTRA-TROPICAL 
TRANSITION. ANIMATED SATELLITE IMAGERY REVEALS COLD DRY AIR 
ENTERING THE SYSTEM FORM THE NORTHWEST.TY 20W IS FORECAST TO 
BE AN EXTRA-TROPICAL SYSTEM BY TAU 48. THE AVAILABLE DYNAMIC 
AIDS, CONSISTING OF NOGAPS, UKMET (EGRR), JGSM, GFDN, AND NCEP 
GFS ARE IN FAIR AGREEMENT WITH THIS SCENARIO THROUGH TAU 72.
THIS FORECAST IS BASED ON A CONSENSUS OF AVAILABLE AIDS.
       C. TY 20W WILL SLOWLY WEAKEN IN INTENSITY OVER THE NEXT 12
HOURS AS THE POLEWARD OUTFLOW IS DECREASED AND THE SYSTEM ENTERS A
HIGHER VERTICAL SHEAR ENVIRONMENT. THE INTENSITY WILL DECREASE AT A 
FASTER RATE AFTER TAU 24 AS IT ENCOUNTERS CONFLUENT FLOW ALOFT AND 
HIGHER VERTICAL WIND SHEAR ALONG WITH SLIGHTLY COOLER SEA SURFACE 
TEMPERATURES. 
       D. CURRENT AND FORECAST WIND RADII ARE BASED ON CLIMATOLOGY 
FOR AN ABOVE-AVERAGE SIZED SYSTEM.
       E. THE EXTENDED FORECAST EXPECTS TY 20W TO CONTINUE ON 
A NORTHEAST TRACK AND TRANSITION COMPLETELY TO AN EXTRATROPICAL 
SYSTEM BY THE 72 HOUR FORECASTED POSITION.
3. FORECAST TEAM: MOHAMMED/JACOBS/NUTONGLA/SCHULTZ//

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