WDPN31 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 14W (KOINU) WARNING NR 
041//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.1N 112.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 119 NM SOUTHWEST OF HONG KONG
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE
SYSTEM CONTINUED TO RAPIDLY DETERIORATE AS THE CENTRAL CONVECTION 
ERODED AND FEEDER BANDS UNRAVELED. THE INITIAL POSITION IS PLACED 
WITH LOW CONFIDENCE BASED EXTRAPOLATION OF A RAGGED REMNANT OF THE 
LOW LEVEL CIRCULATI0N ON A COMPOSITE RADAR LOOP. THE INITIAL 
INTENSITY IS ASSESSED WITH LOW CONFIDENCE BASED ON OVERALL ASSESSMENT 
OF AGENCY AND AUTOMATED DVORAK ESTIMATES AND REFLECTS THE 6-HR 
DEGRADED CONVECTIVE STRUCTURE.

INITIAL WIND RADII BASIS: PERSISTENCE

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE WEST.


AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   RJTD: T3.0 - 45 KTS
   KNES: T2.5 - 35 KTS
   CIMSS ADT: 34 KTS AT 091130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE POLEWARD
   OTHER FACTORS: DRY AIR INTRUSION FROM CHINA AND LAND
INTERACTION. 

ANALYSIS CONFIDENCE:
   INITIAL POSITION: LOW
   INITIAL INTENSITY: LOW
   INITIAL WIND RADII: MEDIUM

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TS KOINU WILL DRIFT SOUTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR TO THE WEST. THE UNFAVORABLE
ENVIRONMENT, EXACERBATED BY LANDFALL INTO LEIZHOU PENINSULA THEN
FINALLY INTO HAINAN WILL RAPIDLY ERODE THE SYSTEM TO DISSIPATION BY
TAU 36.

MODEL DISCUSSION: NUMERICAL MODELS ARE WIDELY SPREAD AND ERRATIC,
LENDING LOW CONFIDENCE TO THE JTWC TRACK FORECAST.


FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM//
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