WDPN31 PGTW 202100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (KOPPU) WARNING NR 
32//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.
   TROPICAL STORM (TS) 24W (KOPPU), LOCATED APPROXIMATELY 276 NM 
NORTH OF MANILA, PHILIPPINES, HAS TRACKED EAST-NORTHEASTWARD AT 03 
KNOTS OVER THE PAST SIX HOURS. ANIMATED ENHANCED INFRARED SATELLITE 
IMAGERY DEPICTS A RAPIDLY WEAKENING SYSTEM WITH A BROAD, ILL-DEFINED 
CENTER POSITIONED JUST OFF THE NORTHERN COAST OF LUZON. BASED ON THE 
WEAKENING CONVECTIVE STRUCTURE AND LACK OF RELIABLE IMAGERY, THERE 
IS LOW CONFIDENCE IN THE INITIAL POSITION. THE INITIAL INTENSITY HAS 
BEEN DECREASED TO 35 KNOTS BASED ON THE LACK OF DEEP DEFINING 
CONVECTION AND LLCC. WHILE PREVIOUS ASCTA DOES SHOW HIGHER WINDS AT 
THE PERIPHERY OF THE SYSTEM, THESE ARE ATTRIBUTED TO FUNNELING 
AFFECTS OF THE LUZON TERRAIN AND TAIWAN. ENVIRONMENTAL CONDITIONS 
REMAIN MARGINAL MODERATE EASTERLY VWS AND A WEAKENING POLEWARD 
OUTFLOW CHANNEL. TS 24W IS CURRENTLY TRACKING ALONG THE NORTHERN 
SIDE OF A NER TO THE SOUTH AND AN INDUCED RIDGE TO THE EAST (BETWEEN 
TS 24W AND TY 25W).
3. FORECAST REASONING.
   A. DUE TO THE OVERALL WEAKNESS, ILL-DEFINED NATURE AND BROADNESS 
OF THIS SYSTEM, IN ADDITION TO LAND INTERACTION AND POOR STEERING 
ENVIRONMENT, IT IS ASSESSED THAT THIS SYSTEM IS PROBABLY NO LONGER 
TROPICAL IN NATURE.
   B. TS 24W IS FORECAST TO SLOWLY TRACK EASTWARD TO NORTHEASTWARD 
UNTIL THROUGH TAU 48 AS THE STEERING MECHANISM CHANGES FROM 
PRIMARILY THE NER TO THE INDUCED RIDGE. THIS RIDGE BEGINS TO TAKE ON 
CHARACTERISTICS OF A STR ALONG 19 NORTH. AS THE SYSTEM TRACKS 
POLEWARD, IT WILL CONTINUE ITS SLOW TRACK SPEED AND WEAKEN IN 
INTENSITY. TS KOPPU IS EXPECTED TO BE COMPLETELY DISSIPATED BY TAU 
48. OVERALL, THERE IS LOW CONFIDENCE IN THE JTWC FORECAST DUE TO THE 
COMPLEX STEERING ENVIRONMENT AND LARGE SPREAD IN MODEL SOLUTIONS.//
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