WDPN31 PGTW 100300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TYPHOON 24W (YINXING) WARNING NR 028//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.0N 113.2E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 333 NM EAST-NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 01 KTS
   SIGNIFICANT WAVE HEIGHT: 46 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE SYSTEM 
HAS SLOWLY EXITED THE COL AREA AND BEGUN TO GRADUALLY WEAKEN AS
EVIDENCED BY COOLING CONVECTIVE TOPS IN THE SYMMETRICAL COLD CENTRAL 
COVER AND UNRAVELING OF FEEDER BANDS. THE EYE, ALTHOUGH STILL 
DISCERNIBLE, HAS BANDED AND BECOME CLOUD-FILLED. THE INITIAL POSITION 
IS PLACED WITH HIGH CONFIDENCE BASED ON THE DEFINED BANDING EYE. THE 
INITIAL INTENSITY IS ALSO ASSESSED WITH HIGH CONFIDENCE BASED ON THE 
OVERALL ASSESSMENT OF CLOSELY-CLUSTERED AGENCY AND AUTOMATED DVORAK 
FIXES AND REFLECTS THE DEGRADATION IN THE 6-HR EIR-BD LOOP. ANALYSIS 
INDICATES THE ENVIRONMENT HAS BECOME UNFAVORABLE WITH MEDIUM VWS AND 
MODERATE OUTFLOW OFFSET BY COOLING ALONG-TRACK SST AND INCURSION OF 
CONTINENTAL DRY AIR FROM SOUTHWESTERN CHINA.

INITIAL WIND RADII BASIS: PERSISTENCE.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.5 - 102 KTS
   RJTD: T5.5 - 102 KTS
   RCTP: T5.5 - 102 KTS
   CIMSS ADT: 99 KTS AT 092330Z
   CIMSS AIDT: 93 KTS AT 092330Z
   CIMSS DPRNT: 94 KTS AT 092330Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 15-20 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: MODERATE POLEWARD AND EQUATORWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TYPHOON YINXING WILL CONTINUE TO TRACK
SOUTHWESTWARD AND SLOWLY ACCELERATE TOWARD SOUTHERN VIETNAM UNDER
THE STEERING INFLUENCE OF THE STR TO THE WEST. THE UNFAVORABLE
ENVIRONMENT, IN ADDITION TO DIMINISHING POLEWARD OUTFLOW, THEN 
EVENTUAL LAND INTERACTION, WILL CONTINUE TO GRADUALLY WEAKEN THE
SYSTEM TO DISSIPATION BY TAU 72, POSSIBLY SOONER, AFTER IT MAKES
LANDFALL OVER CENTRAL VIETNAM, JUST SOUTH OF DA NANG.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT,
GRADUALLY SPREADING OUT TO 163NM BY TAU 72; HOWEVER, DUE TO THE
UNCERTAINTY IN THE STORM MOTION AS THE CYCLONE MOVES AWAY FROM THE
COL AREA, THERE IS ONLY MEDIUM CONFIDENCE TO THE JTWC TRACK AND
INTENSITY FORECASTS.  


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