WDPN31 PGTW 281500 
MSGID/GENADMIN/NAVPACMETOCCEN PEARL//JTWC//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 23W (LEKIMA) 
WARNING NR 27//
RMKS/
1. FOR METEOROLOGISTS.
2. PROGNOSTIC REASONING FOR 281200Z3 SEP 01 TO 011200Z4 OCT 01.
   A. TROPICAL STORM (TS) 23W (LEKIMA), LOCATED APPROXIMATELY 20 NM 
SOUTHEAST OF TAIPEI, TAIWAN, HAS TRACKED NORTHWARD AT 03 KNOTS. THE 
WARNING POSITION IS BASED ON 281130Z5 INFRARED SATELLITE IMAGERY, 
SYNOPTIC DATA, AND RADAR DATA. THE WARNING INTENSITY IS BASED ON 
SATELLITE CURRENT INTENSITY ESTIMATES OF 25 KNOTS AND SYNOPTIC 
REPORTS NEAR 35 KNOTS. ANIMATED INFRARED SATELLITE IMAGERY DEPICTS 
DECREASING ORGANIZATION AND WEAKENING DEEP CONVECTION OVER THE PAST 
6 HOURS. HOWEVER, 281200Z3 SYNOPTIC ANALYSIS AND RADAR DATA DEPICT 
TWO 30-35 KNOT LOW-LEVEL CIRCULATION CENTERS (LLCC). IN ADDITION TO 
THE STORM CENTER, THERE IS AN APPARENT LLCC NEAR 23.0N5 120.6E9, 
OVER SOUTHERN TAIWAN. SEA LEVEL PRESSURE ANALYSIS SHOWS A BROAD 
AREA OF NEAR 1000.0 MB PRESSURES ACROSS TAIWAN. RADAR SHOWS A BROAD 
AREA OF CONVECTION WITH THE NORTHERN LLCC, AND ISOLATED CONVECTION 
WITH THE SOUTHERN LLCC. 
  B. TS 23W IS SITUATED WITHIN A WEAKNESS IN THE LOW TO MID-LEVEL 
SUBTROPICAL RIDGE. THE DYNAMIC AIDS ARE IN POOR AGREEMENT AND 
CONSIST OF THE JMA TYPHOON (JTYM) AND GLOBAL SPECTRAL 
(JGSM), UK-MET OFFICE (EGRR), AND NOGAPS (NGPS) MODELS. THE JGSM, 
JTYM, EGRR, AND AVN MODELS OVER-DEVELOP THE SYSTEM, TRACK THE SYSTEM 
RAPIDLY NORTHEAST AFTER 24 HOURS, AND MERGE WITH A MID-LATITUDE 
TROUGH. THE NGPS MODEL TRACKS THE SYSTEM WEST-NORTHWESTWARD SLOWLY 
AND DISSIPATES IT AFTER 36 HOURS. THE OFFICIAL FORECAST IS BASED ON 
PERSISTENCE AND THE NUMERICAL CONSENSUS TRACK. HOWEVER, THE OFFICIAL 
FORECAST FAVORS A SLOWER TRACK SPEED DUE TO AFOREMENTIONED PROBLEMS 
WITH THE DYNAMIC AIDS. THERE IS LOW CONFIDENCE IN THE FORECAST TRACK 
DUE TO THE POOR AGREEMENT OF THE DYNAMIC AIDS, THE COMPLEX 
INTERACTION OF THE SYSTEM WITH LAND AND THE LLCC TO THE SOUTH, AND 
THE WEAK STEERING ENVIRONMENT. 
   C. TS 23W IS EXPECTED TO GENERALLY MAINTAIN INTENSITY THROUGH THE 
FORECAST PERIOD, BUT REMAIN WITHIN A MARGINAL ENVIRONMENT.
   D. TS 23W DOES NOT MEET WIND RADII CRITERIA.
FORECAST TEAM: BARLOW/LEEJOICE/WAUGAMAN/SHERRY//