WDXS31 PGTW 270300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 14S (VERNON) WARNING 
NR 005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.3S 87.4E
   INITIAL INTENSITY: 100 KTS
   GEOGRAPHIC REFERENCE: 934 NM EAST-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: NORTH-NORTHWESTWARD AT 05 KTS
   SIGNIFICANT WAVE HEIGHT: 45 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS THE
SYSTEM HAS MAINTAINED OVERALL CONVECTIVE SIGNATURE, SYMMETRY, AND
DEGREE OF WRAP. THE EIR LOOP ALSO INDICATES SUBSIDENCE ALONG THE
EASTERN PERIPHERIES CAUSED BY OUTFLOW FROM INVEST 93S, 120NM TO THE
SOUTHEAST. THE INITIAL INTENSITY IS PLACED WITH MEDIUM CONFIDENCE
BASED ON EXTRAPOLATION FROM A LOW LEVEL CIRCULATION FEATURE IN THE
262236Z SSMIS 91GHZ IMAGE. THE INITIAL INTENSITY IS ASSESSED HIGHER
THAN AGENCY AND AUTOMATED DVORAK ESTIMATES TO REFLECT THE SUSTAINED
EIR STRUCTURE. ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH THE
MODERATE VWS AND SUBSIDENCE ON THE EAST SIDE OFFSET BY WARM SST
AND STRONG POLEWARD OUTFLOW. TC 14S HAS BEEN SLOWED DOWN BY ITS 
BINARY INTERACTION WITH INVEST 93S AND HAS ENTERED A COL BETWEEN THE
SUBTROPICAL RIDGE TO THE SOUTHEAST AND THE NEAR EQUATORIAL RIDGE TO
THE NORTHWEST.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA 

CURRENT STEERING MECHANISM: SUBTROPICAL RIDGE (STR) TO THE
SOUTHEAST, NEAR EQUATORIAL RIDGE TO THE NORTHWEST, BINARY
INTERACTION WITH INVEST 93S.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T5.0 - 90 KTS
   FMEE: T4.5 - 77 KTS
   FIMP: T5.0 - 90 KTS
   CIMSS SATCON: 77 KTS AT 261928Z
   CIMSS ADT: 72 KTS AT 262115Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 20-25 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC VERNON IS EXPECTED TO BECOME
QUASI-STATIONARY UP TO TAU 24 AS IT REMAINS IN THE COL AREA AND IN
BINARY INTERACTION WITH 93S. AFTER TAU 24, THE STR TO THE SOUTHEAST
WILL RESUME STEERING AND DRIVE THE SYSTEM SOUTHWESTWARD FOR THE
REMAINDER OF THE FORECAST. AS THE CYCLONE TRACKS POLEWARD, THE HIGH
VWS, THEN THE INFLUX OF COOL DRY AIR IN THE LOWER LEVELS, AND
COOLING SST WILL CONTRIBUTE TO A GRADUAL WEAKENING - DOWN TO 65KTS
BY TAU 120. 

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT
WITH THE TRACK FORECAST. HOWEVER, THERE ARE DIFFERENCES IN THE
TIMING AS TO WHEN THE VORTEX WILL EXIT FROM THE COL AND BEGIN ITS
SOUTHWESTWARD TRACK. THIS UNCERTAINTY WILL ALSO AFFECT THE
INTENSITY FORECAST. IN VIEW OF THIS, THERE IS OVERALL MEDIUM
CONFIDENCE IN THE JTWC TRACK AND INTENSITY FORECASTS.

FORECAST CONFIDENCE:
   TRACK 0 - 72 HR: MEDIUM
   TRACK 72-120 HR: MEDIUM
   INTENSITY 0 - 72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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