WDPN31 PGTW 091500
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (YINXING) WARNING NR 026//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.1N 113.6E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 356 NM EAST-NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 48 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AS INDICATED IN ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY, 
TYPHOON (TY) 24W HAS MAINTAINED ITS OVERALL CONVECTIVE STRUCTURE WITH 
A 10NM RAGGED EYE AND A SYMMETRIC EYEWALL. ENVIRONMENTAL CONDITIONS 
REMAIN FAVORABLE WITH RADIAL OUTFLOW AND LOW VERTICAL WIND SHEAR. THE 
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EIR 
IMAGERY. THE INITIAL INTENSITY OF 110 KNOTS IS ASSESSED WITH MEDIUM 
CONFIDENCE, WITH OBJECTIVE AND SUBJECTIVE ESTIMATES RANGING FROM 102 
TO 117 KNOTS.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

CURRENT STEERING MECHANISM: DEEP-LAYERED SUBTROPICAL RIDGE (STR)
POSITIONED TO THE NORTH AND NORTHWEST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   DEMS: T6.0 - 115 KTS
   CIMSS ADT: 117 KTS AT 091130Z
   CIMSS AIDT: 108 KTS AT 091130Z
   CIMSS D-PRINT: 108 KTS AT 091200Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: STRONG RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TY 24W HAS SLOWED SIGNIFICANTLY AND IS EXPECTED 
TO TURN WEST-SOUTHWESTWARD TO SOUTHWESTWARD AS IT TRACKS ALONG A 
NARROW EXTENSION OF THE STR. A MAJOR SHORTWAVE TROUGH PROPAGATING 
OVER SOUTHEAST CHINA WILL WEAKEN THIS STR EXTENSION BRIEFLY BEFORE 
FILLING AND TRANSITING INTO THE EAST CHINA SEA BY TAU 24. AFTER TAU 
24, THE STR EXTENSION WILL REBUILD TO THE NORTHWEST ACCELERATING THE 
SYSTEM SOUTHWESTWARD OVER VIETNAM. TY 24W IS EXPECTED TO ENCOUNTER 
SIGNIFICANT DRY AIR ENTRAINMENT AND SLIGHTLY COOLER SST (26C),
WHICH WILL SERVE TO RAPIDLY WEAKEN THE SYSTEM THROUGH TAU 72.
ADDITIONALLY, INCREASING VERTICAL WIND SHEAR (20-25 KNOTS) AND 
INTERACTION WITH LAND WILL AID IN WEAKENING THE SYSTEM AFTER TAU 48. 
TY 24W WILL MAKE LANDFALL SOUTH-SOUTHEAST OF DA NANG AT APPROXIMATELY 
TAU 60, WITH DISSIPATION EXPECTED BY TAU 72.  

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE REMAINS IN FAIR AGREEMENT, 
WITH AN 85NM CROSS-TRACK SPREAD IN SOLUTIONS AT TAU 48 DIVERGING TO 
120NM AT LANDFALL. BOTH THE 090000Z EPS AND THE 090600Z GEFS 
ENSEMBLES SUPPORT THE JTWC TRACK AND INTENSITY FORECAST WITH MEDIUM 
CONFIDENCE THROUGH THE FORECAST PERIOD. RELIABLE INTENSITY GUIDANCE 
INDICATES RAPID WEAKENING AFTER TAU 12, WITH DISSIPATION FORECAST 
NEAR TAU 72.  

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