WDPN31 PGTW 071500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 14W (KOINU) WARNING NR 033//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.3N 115.1E
   INITIAL INTENSITY: 95 KTS
   GEOGRAPHIC REFERENCE: 78 NM SOUTHEAST OF HONG KONG
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 02 KTS
   SIGNIFICANT WAVE HEIGHT: 40 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM
HAS BECOME QUASI-STATIONARY, AND MAINTAINED A COMPACT CENTRAL DENSE
OVERCAST AND A SHARPLY-OUTLINED 8-NM PINHOLE EYE. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PINHOLE EYE IN
THE EIR LOOP THAT IS CONCENTRIC WITH A DEFINED EYE FEATURE IN A
COMPOSITE RADAR LOOP. THE INITIAL INTENSITY IS ASSESSED WITH MEDIUM
CONFIDENCE BASED ON OVERALL ASSESSMENT OF AGENCY AND AUTOMATED
DVORAK ESTIMATES AND REFLECTS THE 6-HR SUSTAINED CONVECTIVE
STRUCTURE.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: DEEP LAYER SUBTROPICAL RIDGE (STR) TO
THE NORTHWEST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   KNES: T5.0 - 90 KTS
   DEMS: T6.0 - 115 KTS
   CIMSS ADT: 90 KTS AT 071130Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: MARGINALLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON KOINU WILL SLOWLY DRIFT
WEST-SOUTHWESTWARD THEN SOUTHWESTWARD UNDER THE STEERING STR. THE
MARGINALLY FAVORABLE ENVIRONMENT WILL PROMOTE A SLOW WEAKENING TO
60KTS BY TAU 48. AFTERWARD, DRY AIR INTRUSION FROM MAINLAND CHINA
PLUS LANDFALL INTO HAINAN, SPLASH BACK INTO THE GULF OF TONKIN,
THEN FINAL LANDFALL INTO CENTRAL VIETNAM, WILL ERODE THE SYSTEM AT
A FASTER RATE TO 25KTS, POSSIBLY DISSIPATED, BY TAU 120 AS IT
CROSSES INTO CAMBODIA.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH AN EVEN SPREAD TO 182NM BY TAU 72, THEN MORE ERRATICALLY TO
365NM BY TAU 120, LENDING MEDIUM CONFIDENCE TO THE JTWC TRACK AND
INTENSITY FORECAST UP TO TAU 72 THEN LOW CONFIDENCE AFTERWARD. 


FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: LOW
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: LOW//
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