WDPN32 PGTW 240900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (RAGASA) WARNING NR 024//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 21.6N 112.6E
   INITIAL INTENSITY: 105 KTS
   GEOGRAPHIC REFERENCE: 98 NM WEST-SOUTHWEST OF HONG KONG
   MOVEMENT PAST 6 HOURS: WEST-NORTHWESTWARD AT 12 KTS
   SIGNIFICANT WAVE HEIGHT: 38 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A NEARLY
FULLY FILLED EYE FEATURE OF TYPHOON (TY) 24W (RAGASA) AS IT
APPROACHES THE SOUTHERN COASTLINE OF CHINA. SPIRAL BANDS OF DEEP
CONVECTION ARE MOSTLY PRESENT THROUGHOUT THE SOUTHERN SEMICIRCLE OF
THE SYSTEM, AS THE NORTHERN PORTION BEGAN TO INTERACT WITH LAND.
RADIAL OUTFLOW ALOFT AND WARM (28-29 C) SEA SURFACE TEMPERATURES
REMAIN FAVORABLE, HOWEVER THE SYSTEM IS BEGINNING TO BE CUT OFF
FROM ITS FUEL SOURCE, WHILE IT APPROACHES LANDFALL. OVERALL 
UNFAVORABLE CONDITIONS ARE AMPLIFIED BY FRICTIONAL EFFECTS OF LAND 
INTERACTION, PARTICULARLY THROUGHOUT THE NORTHERN PORTION OF THE
WIND FIELD. THE INITIAL POSITION IS PLACED WITH MEDIUM CONFIDENCE
BASED ON A COMBINATION OF RADAR AND VISIBLE SATELLITE IMAGERY. THE
INITIAL INTENSITY OF 105 KTS IS ASSESSED WITH MEDIUM CONFIDENCE
BASED ON THE AGENCY DVORAK AND OBJECTIVE ESTIMATES LISTED BELOW,
ALL EXHIBITING WEAKENING TRENDS.

INITIAL WIND RADII BASIS: PERSISTENCE 

CURRENT STEERING MECHANISM: EXTENSION OF A SUBTROPICAL RIDGE (STR)
CENTERED TO THE NORTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T6.0 - 115 KTS
   RJTD: T6.0 - 115 KTS
   KNES: T5.5 - 102 KTS
   DEMS: T6.0 - 115 KTS
   CIMSS ADT: 112 KTS AT 240540Z
   CIMSS AIDT: 105 KTS AT 240540Z
   CIMSS D-PRINT: 110 KTS AT 240640Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG RADIAL
   OTHER FACTORS: FRICTIONAL EFFECTS OF LAND INTERACTION

ANALYSIS CONFIDENCE:
   INITIAL POSITION: MEDIUM
   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 FORECAST TO CONTINUE TRACKING
WEST-NORTHWESTWARD AND IS QUICKLY APPROACHING LANDFALL. THE
EXTENSION OF THE STEERING STR TO THE NORTHEAST REMAINS IN PLACE AS
A PRIMARY MECHANISM, THEREFORE TY RAGASA IS FORECAST TO BEGIN
GRADUAL WEAKENING AS IT APPROACHES THE LEIZHOU PENINSULA. LAND
INTERACTION EXTENT WILL DETERMINE THE RATE AND TIMELINE OF
DISSIPATION, WHICH IS CURRENTLY FORECAST TO OCCUR BETWEEN TAU 36
AND 48 NEAR THE BORDER OF LAOS AND NORTHERN VIETNAM.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN FAIR
AGREEMENT AS WITNESSED BY A 35 NM CROSS-TRACK SPREAD AT TAU 12,
EXTENDING TO 75 NM 12 HOURS LATER. SOME UNCERTAINTY REMAINS IN
REGARD TO THE POTENTIAL OF TY RAGASA RE-EMERGING OVER WATER NEAR
TAU 24, HOWEVER WELL-INITIALIZING DETERMINISTIC GFS, AS WELL AS
MAJORITY OF OTHER MODELS INDICATE TRACK SOLELY OVER LAND. ECMWF
ENSEMBLE IS CURRENTLY THE ONLY OUTLIER, SUGGESTING A TRACK FURTHER 
SOUTH. JTWC OFFICIAL TRACK IS THEREFORE LAID CLOSE TO THE MULTI-MODEL
CONSENSUS WITH MEDIUM CONFIDENCE. INTENSITY GUIDANCE IS IN GOOD
AGREEMENT WITH NEARLY ALL MODELS PREDICTING GRADUAL WEAKENING AND
DISSIPATION AT OR NEAR TAU 36, RESULTING IN HIGH CONFIDENCE OF THE 
INTENSITY FORECAST. 

FORECAST CONFIDENCE:
   TRACK 00-72 HR: MEDIUM
   INTENSITY 00-72 HR: HIGH//
NNNN