WDPN31 PGTW 091500
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 091200Z2 TO 121200Z6 OCT 02.
    A. TROPICAL DEPRESSION (TD) 26W, LOCATED APPROXIMATELY 335 NM 
NORTH OF THE ISLAND OF CHUUK, HAS TRACKED WEST-NORTHWESTWARD AT 16 
KNOTS OVER THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 
090530Z7 ENHANCED INFRARED SATELLITE IMAGERY. THE WARNING INTENSITY 
IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 25 KNOTS. A 
090911Z0 TRMM PASS AND A 091001Z1 SSM/I PASS DEPICT THE DEEP 
CONVECTION IN THE NORTHEASTERN AND SOUTHWESTERN QUADRANTS. ANIMATED 
INFRARED IMAGERY SUGGESTS THAT THE LOW LEVEL CIRCULATION REMAINS 
ELONGATED AND CONTINUES TO BE INFLUENCED BY THE MONSOON TROUGH.
    B. A LONGWAVE TROUGH SITUATED OVER JAPAN IS EXPECTED TO 
PROPAGATE EASTWARD, WEAKENING THE LOW TO MID-LEVEL SUBTROPICAL RIDGE 
EAST-SOUTHEAST OF JAPAN BY 72 HOURS. TD 26W IS EXPECTED TO TRACK 
NORTHWESTWARD THROUGH THE PERIOD ALONG THIS SUBTROPICAL RIDGE. THE 
AVAILABLE DYNAMIC AIDS, CONSISTING OF NOGAPS, NCEP AVIATION (AVN), 
UKMET GLOBAL (EGRR), AND THE JAPANESE GLOBAL (JGSM) AND TYPHOON 
(JTYM) MODELS ARE IN FAIR AGREEMENT WITH THIS SCENARIO. THE MODELS 
HAVE CONSISTENTLY INITIALIZED A LARGE SYSTEM, RESULTING IN A 
POLEWARD BIAS EARLY IN THE PERIOD. OUR FORECAST IS BASED ON A BLEND 
OF PERSISTENCE AND THE MEDIUM AND FULL BETA ADVECTION MODELS THROUGH 
36 HOURS. AFTER 36 HOURS, THE FORECAST IS BASED ON A BLEND OF ALL 
AVAILABLE DYNAMIC AIDS.
    C. THE APPROACHING LONGWAVE TROUGH IS EXPECTED TO ENHANCE THE 
OUTFLOW OF THE SYSTEM. TD 26W IS EXPECTED TO INTENSIFY AT A 
CLIMATOLOGICAL RATE THROUGH THE FORECAST PERIOD AS IT TRACKS IN A 
FAVORABLE UPPER LEVEL ENVIRONMENT.
    D. FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE-
SIZED SYSTEM.
3. FORECAST TEAM: WINGEART/KENDALL/KUMAGA/STATEN//
NNNN