WDPN31 PGTW 160300 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL HARBOR HI/JTWC// 
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 20W WARNING NR/ 
03// 
RMKS/ 
1. FOR METEOROLOGISTS. 
2. PROGNOSTIC REASONING FOR 160000Z7 AUG TO 190000Z0 AUG 02. 
   A. TROPICAL DEPRESSION (TD) 20W, LO9CATED APPROXIMATELY 466 NM 
SOUTH OF HONG KONG, CHINA, HAS TRACKED NORTHEASTWARD AT 06 
KNOTS OVER THE PAST 6 HOURS. THE WARNING POSITION IS BASED ON 
152330Z4 VISIBLE SATELLITE IMAGERY AND A 152219Z0 QUIKSCAT PASS. THE 
WARNING INTENSITY IS BASED ON SATELLITE CURRENT INTENSITY ESTIMATES 
OF 25 KNOTS. ANIMATED VISIBLE SATELLITE IMAGERY REVEALS A FULLY 
EXPOSED LOW LEVEL CIRCULATION CENTER (LLCC) WITH CONVECTION 
DISPLACED 90 NM TO THE SOUTH-SOUTHWEST OF THE LLCC. 
   B. TD 20W IS EXPECTED TO TRACK SLOWLY TO THE NORTHEAST AND THEN 
NORTHWARD UNDER RELATIVELY WEAK STEERING FLOW IN THE SOUTH 
CHINA SEA. THE AVAILABLE DYNAMIC AIDS CONSISTING OF NOGAPS, UKMET 
(EGRR), JAPANESE GLOBAL (JGSM) AND AVIATION (AVN) MODELS AGREE WITH 
THIS SCENARIO. OUR FORECAST IS BASED ON A BLEND OF PERSISTENCE, 
CLIMATOLOGY, AND THE AVAILABLE AIDS. 
   C. TD 20W IS FORECAST TO DEVELOP AT A LESS THAN CLIMATOLOGICAL 
RATE THROUGHOUT THE FORECAST PERIOD WITH ONLY MINIMAL 
INTENSIFICATION AS IT TRACKS SLOWLY IN THE SOUTH CHINA SEA WITH 
STRONG WESTERLIES AND MODERATE VERTICAL WIND SHEAR TO THE SOUTH. 
   D. SYSTEM DOES NOT MEET WIND RADII CRITERIA.
FORECAST TEAM: MAZANY/RONSSE/SCHAEFER/TON//

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