WDPN32 PGTW 061500 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL DEPRESSION 20W (NARI) WARNING 
NR 03//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 061200Z9 TO 091200Z2 SEP 01.
   A. TROPICAL DEPRESSION (TD) 20W (NARI), LOCATED APPROXIMATELY
85 NM WEST OF OKINAWA, HAS TRACKED NORTHEASTWARD AT 07 KNOTS DURING 
THE PAST SIX HOURS. THE WARNING POSITION IS BASED ON 061130Z1 
INFRARED SATELLITE IMAGERY AND RADAR IMAGERY. THE WARNING INTENSITY 
IS BASED ON CURRENT SATELLITE INTENSITY ESTIMATES OF 25 AND 30 
KNOTS. ENHANCED I/R DEPICTS A VERY WEAK, DIFFUSE SYSTEM. RADAR 
IMAGERY REVEALS A POSSIBILITY THAT A PARTIALLY EXPOSED LOW-LEVEL 
CIRCULATION CENTER STILL EXISTS NEAR A NEW ISOLATED BURST OF 
CONVECTION.
   B. TD 20W IS SITUATED WITHIN A WEAKNESS IN THE SUBTROPICAL RIDGE. 
THE UKMET-O GRID-POINT, JMA GLOBAL AND TYPHOON MODELS, NOGAPS AND 
THE KMA GLOBAL ALL AGREE WITH A SLOW DRIFTING MOTION EARLY IN THE 
PERIOD ALONG THE TAIL END OF A WEAK FRONTAL SYSTEM. THEN, EROSION OF 
THE WEAK PERIPHERAL RIDGE BY LARGER, TY 19W (DANAS) WILL CAUSE TD 
20W TO DRIFT TOWARD THE CHINA COAST WITHIN THE LOW/MID FLOW OF A 
RIDGE EXTENDING OVER THE COAST THROUGH THE REMAINDER OF THE PERIOD. 
THE JTWC FORECAST IS BASED ON THE AFOREMENTIONED MODELS AND 
SCENARIO.
   C. LITTLE INTENSITY CHANGE IS FORECAST THROUGH THE PERIOD AS THE 
SYSTEM SLOWLY TRACKS NORTH OF THE SUBTROPICAL RIDGE.
   D. TD 20W CURRENTLY DOES NOT MEET CRITERIA FOR WIND RADII.  
FORECAST TEAM: ROBERTS/BALDINGER/HARRISON//