WDXS31 PGTW 162100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 20S (BILLY) WARNING 
NR 007//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 19.6S 92.6E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 507 NM SOUTH-SOUTHWEST OF COCOS ISLANDS
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 06 KTS
   SIGNIFICANT WAVE HEIGHT: 14 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS THE DEEP
CENTRAL CONVECTION HAS SHEARED 70+ NM TO THE SOUTHEAST, EXPOSING
THE LOW LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS PLACED
WITH HIGH CONFIDENCE BASED ON THE EXPOSED LLC IN THE EIR LOOP. THE
INITIAL INTENSITY OF 40KTS IS BASED ALSO WITH HIGH CONFIDENCE ON THE
161558Z ASCAT BULLSEYE PASS SHOWING A LARGE SWATH OF 40-KT WIND
BARBS ALONG THE SOUTHWEST QUADRANT. ANALYSIS INDICATES AN
UNFAVORABLE ENVIRONMENT WITH WARM SST AND STRONG POLEWARD OUTFLOW
GREATLY OFFSET BY STRONG (40KT+) VWS. THE CYCLONE IS TRACKING ALONG
THE NORTHWEST PERIPHERY OF THE STR TO THE SOUTHEAST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA.

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE TO THE SOUTHEAST. 

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   CIMSS SATCON: 47 KTS AT 161503Z
   CIMSS ADT: 45 KTS AT 161430Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: UNFAVORABLE
   VWS: 40+ 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: THERE ARE NO SIGNIFICANT CHANGES TO
THE FORECAST FROM THE PREVIOUS WARNING.

FORECAST DISCUSSION: TC BILLY WILL CONTINUE ON A SOUTH-SOUTHWESTWARD
TRACK UNDER THE STEERING STR AND DISSIPATE BY TAU 24, POSSIBLY
SOONER, DUE TO THE UNFAVORABLE ENVIRONMENT MAINLY CAUSED BY STRONG
VWS. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN TIGHT AGREEMENT AT LEAST
UP TO TAU 24, LENDING HIGH CONFIDENCE IN THE JTWC TRACK AND
INTENSITY FORECASTS. 

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