WDPN31 PGTW 230300
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 21W WARNING NR 
03//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 230000Z5 TO 260000Z8 AUG 02.
   A. TROPICAL STORM 21W, LOCATED APPROXIMATELY 300 NM NORTH-
NORTHWEST OF ENEWETAK ATOLL, HAS TRACKED WEST-NORTHWESTWARD AT 11 
KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 
222330Z2 MULTISPECTRAL SATELLITE IMAGERY. THE WARNING INTENSITY IS 
BASED ON SATELLITE CURRENT INTENSITY ESTIMATES OF 35 AND 45 KNOTS. 
   B. THE LOW TO MID-LEVEL SUBTROPICAL RIDGE NORTH OF THE SYSTEM IS 
EXPECTED TO BUILD AND SLOWLY PROPAGATE WESTWARD. TD 21W IS FORECAST 
TO TRACK WEST-NORTHWESTWARD ALONG THIS SUBTROPICAL RIDGE THROUGH THE 
FORECAST PERIOD. THE AVAILABLE DYNAMIC AIDS, CONSISTING OF NOGAPS, 
UKMET OFFICE (EGRR), AND THE JAPANESE GLOBAL MODEL (JGSM), ARE IN 
FAIR AGREEMENT WITH THE TRACK DIRECTION. THE MODELS ARE VERY POOR IN 
INITIALIZING THIS SYSTEM, CHOOSING TO FOCUS ON A WEAK CIRCULATION 
LOCATED TO THE THE WEST AT 12.7N0 155.3E4. THE MODELS CONTINUE TO 
MERGE THE TWO CIRCULATIONS, RESULTING IN A FASTER CONSENSUS TRACK. 
OUR FORECAST IS BASED ON A BLEND PERSISTENCE AND THE BLEND OF THE 
BETA ADVECTION MODELS.  
   C. THE UPPER LEVEL LOW NORTHEAST OF THE SYSTEM IS NOW LOCATED 
NEAR 21.8N1 174.1E4.  IT HAS CONTINUED TO ENHANCE THE OUTFLOW OVER 
THE SYSTEM OVER THE LAST 12 HOURS. CURRENTLY, TS 21W HAS DUAL 
OUTFLOW CHANNELS AND THEREFORE EXPECTED AT AN AB0VE CLIMATOLOGY RATE 
OVER THE NEXT 48 HOURS. AFTERWARDS, DEVELOPMENT SHOULD BE AT A 
CLIMATOLOGY RATE AS THE UPPER LEVEL FILLS. 
   D. THE FORECAST WIND RADII ARE BASED ON CLIMATOLOGY FOR AN 
AVERAGE-SIZED SYSTEM.
FORECAST TEAM: LEEJOICE/MORRIS/DUKES/BOSTIC//

NNNN