WDPN31 PGTW 090900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (YINXING) WARNING NR 025//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.9N 114.1E
   INITIAL INTENSITY: 110 KTS
   GEOGRAPHIC REFERENCE: 375 NM EAST-NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: WESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
AS INDICATED IN ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI),
TYPHOON (TY) 24W HAS RESTRENGTHENED OVER THE PAST SIX HOURS, WITH A
15NM OBLONG EYE AND AN EYE TEMPERATURE OF PLUS 11.8C (BRIEFLY). 
CONSEQUENTLY, SUBJECTIVE DVORAK INTENSITY ESTIMATES INCREASED AND NOW 
RANGE FROM T5.5 TO T6.0 (102-115 KNOTS). A 090534Z AMSR2 89GHZ COLOR 
COMPOSITE MICROWAVE IMAGE SHOWS A COMPACT SYSTEM WITH A SYMMETRIC 
EYEWALL SURROUNDING A ROUND MICROWAVE EYE FEATURE, AND SPIRAL BANDING 
LOCATED PRIMARILY OVER THE EASTERN SEMICIRCLE. THE INITIAL POSITION IS 
PLACED WITH HIGH CONFIDENCE BASED ON THE MSI AND MICROWAVE IMAGERY. 
THE INITIAL INTENSITY OF 110 KNOTS IS ASSESSED WITH MEDIUM CONFIDENCE, 
WITH OBJECTIVE AND SUBJECTIVE ESTIMATES RANGING FROM 103 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: T5.5 - 102 KTS
   RJTD: T6.0 - 115 KTS
   RCTP: T5.5 - 102 KTS
   KNES: T5.5 - 102 KTS
   DEMS: T5.5 - 102 KTS
   CIMSS SATCON: 104 KTS AT 090630Z
   CIMSS ADT: 117 KTS AT 090600Z
   CIMSS AIDT: 109 KTS AT 090600Z
   CIMSS DPRINT: 103 KTS AT 090630Z

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 IS EXPECTED TO TRACK WESTWARD THROUGH
TAU 12 THEN TURN SHARPLY 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. THIS WILL LIKELY SLOW THE SPEED OF ADVANCE BY TAU 12. AFTER
TAU 24, THE STR EXTENSION WILL REBUILD TO THE NORTHWEST DRIVING 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.  

MODEL DISCUSSION: BOTH THE 081800Z EPS AND THE 090000Z GEFS ENSEMBLES 
SUPPORT THE JTWC TRACK AND INTENSITY FORECAST WITH MEDIUM CONFIDENCE 
THROUGH THE FORECAST PERIOD. THE 090000Z COAMPS-TC ENSEMBLE (GFS 
VERSION) ALSO SUPPORTS THE JTWC TRACK FORECAST AND SHOWS A TROPICAL 
DEPRESSION STRENGTH SYSTEM AFTER TAU 60. 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//
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