WDPN31 PGTW 060300
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 26W
/WARNING NR 09//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 060000Z6 TO 110000Z2 OCT 2004.
   A. TROPICAL STORM (TS) 26W (MA-ON), LOCATED APPROXIMATELY 460
NM SOUTHEAST OF OKINAWA, JAPAN, HAS TRACKED WEST-NORTHWESTWARD AT
09 KNOTS OVER THE PAST 06 HOURS. THE WARNING POSITION IS BASED ON
052230Z2 MULTISPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS
BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 55 KNOTS.
   B. TS 26W HAS BEGUN TO TRACK NORTHWESTWARD UNDER THE INFLUENCE
OF AN INTENSIFYING ANTICYCLONE ANCHORED TO THE NORTHEAST. THIS
RIDGE IS FORECAST TO CONTINUE BUILDING THROUGH THE NEXT 36 HOURS,
BEFORE IT WILL BE WEAKENED BY AN APPROACHING SHORTWAVE TROUGH. AS
THE SHORTWAVE TROUGH ERODES THE RIDGE, THE TRACK WILL TURN MORE
POLEWARD AND PICK UP SPEED. THE AVAILABLE DYNAMIC AIDS CONSISTING
OF NOGAPS, COAMPS, NCEP GFS, GFDN, JGSM, JTYM, UKMET EGRR, WBAR
AND TCLAPS ARE IN FAIR AGREEMENT WITH THIS SCENARIO. THIS FORECAST
IS BASED ON A CONSENSUS OF ALL AVAILABLE DYNAMIC AIDS.
   C. TS 26W WILL CONTINUE TO INTENSIFY AS IT IS FORECAST TO
CONTINUE TRACKING THROUGH AN ENVIRONMENT OF WEAK VERTICAL WIND
SHEAR AND FAVORABLE UPPER LEVEL DIVERGENCE ALONG THE SOUTHWEST
QUADRANT OF THE SUBTROPICAL RIDGE. THE INTENSITY IS FORECAST TO
TO WEAKEN AFTER 48 HOURS AS TS 26W CRESTS THE RIDGE AXIS AND BEGINS
TO ENCOUNTER MARGINAL VERTICAL SHEAR FROM INCREASED FLOW FROM THE
SOUTHWEST.
   D. CURRENT WIND RADII ARE BASED ON A 052053Z5 QUIKSCAT PASS.
FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZED
SYSTEM.
   E. TS 26W IS FORECAST TO INTERACT WITH A SHORTWAVE TROUGH EXITING
ASIA IN THE EXTENDED FORECAST. LAND INTERACTION, INCREASED VERTICAL
WIND SHEAR, DRIER AIR AND COLDER SEA SURFACE TEMPERATURES WILL CAUSE
THE SYSTEM TO WEAKEN AFTER 72 HOURS. EXTRATROPICAL TRANSITION IS
FORECAST TO BEGIN IN 96 HOURS AS TS 26W INTERACTS WITH THE BAROCLINIC
ZONE. THE DYNAMIC AIDS AVAILABLE FOR THE EXTENDED FORECAST PERIOD ARE
IN POOR AGREEMENT WITH THIS SCENARIO, AND AS A RESULT, CONFIDENCE IN
THE EXTENDED FORECAST TRACK REMAINS SOMEWHAT LOW.
3. FORECAST TEAM: GRUBER/BOWER/HEATH/VOHS//

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