WDPN32 PGTW 181500 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 20W (NARI) WARNING 
NR 51//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 181200Z2 TO 211200Z6 SEP 01.
   A.TROPICAL STORM (TS) 20W (NARI), SITUATED JUST OFF THE CENTRAL 
EASTERN COAST OF TAIWAN, HAS REMAINED STATIONARY OVER THE PAST SIX 
HOURS. THE WARNING POSITION IS BASED ON 181130Z4 INFRARED SATELLITE 
IMAGERY AND SYNOPTIC REPORTS. THE WARNING INTENSITY IS BASED ON 
SATELLITE CURRENT INTENSITY ESTIMATES OF 30 KNOTS AND SYNOPTIC 
REPORTS.
   B. THE SYSTEM IS FORECAST TO TRACK WESTWARD UNDER THE STEERING 
INFLUENCE OF A LOW TO MID LEVEL RIDGE BUILDING OVER SOUTHERN CHINA. 
NOGAPS, GEOPHYSICAL FLUID DYNAMIC NAVY (GFDN), UK-MET OFFICE (EGRR), 
JMA GLOBAL (JGSM) AND THE TYPHOON (JTYM) MODELS ARE IN GOOD 
AGREEMENT TRACKING THE SYSTEM WEST-SOUTHWESTWARD THROUGH THE PERIOD. 
OUR FORECAST IS BASED ON PERSISTENCE AND THE NUMERICAL CONSENSUS OF 
THE FIVE DYNAMICAL AIDS.
   C. TS 20W IS EXPECTED TO WEAKEN SLIGHTLY AS IT CROSSES TAIWAN. 
SLIGHT INTENSIFICATION IS EXPECTED THROUGH 36 HOURS AS THE SYSTEM 
MOVES OVER THE SOUTH CHINA SEA. THE SYSTEM SHOULD SLIGHTLY WEAKEN 
AGAIN AS IT BEGINS TO INTERACT WITH THE SOUTHERN COAST OF CHINA.     
   D. THE WIND RADII ARE BASED ON CLIMATOLOGY FOR AN AVERAGE SIZE 
SYSTEM.
FORECAST TEAM: CANTRELL/VILPOS/WAUGAMAN/SHERRY//