WDPN31 PGTW 102100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL STORM 24W (YINXING) WARNING NR 
031//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 18.2N 112.0E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 250 NM EAST-NORTHEAST OF DA NANG, VIETNAM
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 22 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE COLD
CENTRAL COVER (CCC) WAS SWIFTLY DECAPITATED BY HIGH SOUTHWESTERLY
VERTICAL WIND SHEAR, PARTLY EXPOSING THE LOW LEVEL CIRCULATION
(LLC) THAT HAS ACCELERATED SOUTHWESTWARD. THE DEEP CONVECTION OVER
THE CCC HAVE RAPIDLY ERODED AND SHEARED NORTHEASTWARD. THE INITIAL
POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE PARTLY EXPOSED 
LLC THAT LINED UP VERY WELL WITH THE BULLSEYE IN THE 101430Z ASCAT 
PASS. THE INITIAL INTENSITY IS ALSO ASSESSED WITH HIGH CONFIDENCE 
BASED ON THE ASCAT PASS THAT SHOWED MAX OF 45-KT WIND BARBS, 
SUPPORTED BY THE RAPIDLY WEAKENING TREND IN AGENCY AND OBJECTIVE 
DVORAK ESTIMATES, AND ALSO REFLECTS THE RAPID DEGRADATION IN THE 6-HR
EIR-BD LOOP. ANALYSIS INDICATES THE ENVIRONMENT HAS BECOME HIGHLY 
UNFAVORABLE WITH THE STRONG POLEWARD OUTFLOW GREATLY OFFSET BY HIGH 
RELATIVE VWS, COOL SST AND INCURSION OF CONTINENTAL DRY AIR FROM 
SOUTHWESTERN CHINA.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   RJTD: T4.0 - 65 KTS
   RCTP: T3.5 - 55 KTS
   CIMSS DPRNT: 41 KTS AT 1730Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY UNFAVORABLE
   VWS: 25-30 KTS
   SST: 26-27 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: RAPID DISSIPATION EXPECTED.

FORECAST DISCUSSION: TROPICAL STORM YINXING WILL CONTINUE TO TRACK
SOUTHWESTWARD UNDER THE STR TO THE WEST. THE HIGHLY UNFAVORABLE
ENVIRONMENT, IN ADDITION TO DIMINISHING POLEWARD OUTFLOW, WILL
CONTINUE TO RAPIDLY ERODE THE SYSTEM TO DISSIPATION IN THE SOUTH
CHINA SEA BY TAU 24.

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT, GRADUALLY 
SPREADING OUT TO A MERE 73NM BY TAU 24, LENDING HIGH CONFIDENCE TO 
THE JTWC TRACK AND INTENSITY FORECASTS.  

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