WDXS31 PGTW 290300
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 11S (ELEVEN) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.5S 76.3E
   INITIAL INTENSITY: 35 KTS
   GEOGRAPHIC REFERENCE: 394 NM SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 12 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM
CONTINUED TO STRUGGLE AS THE LOW LEVEL CIRCULATION CENTER (LLCC)
REMAINED MOSTLY EXPOSED AND STATIONARY WITH THE CENTRAL CONVECTION
SHEARED WESTWARD. HOWEVER, IN THE LAST THREE HOURS, THE LLCC HAS
BEGUN TO TRACK SLOWLY SOUTHWESTWARD INTO THE CONVECTIVE CANOPY. THE
INITIAL POSITION IS PLACED WITH HIGH CONFIDENCE BASED ON THE EXPOSED 
LLCC. THE INITIAL INTENSITY OF 35KTS IS PLACED WITH MEDIUM CONFIDENCE 
BASED ON THE HIGH END OF AUTOMATED INTENSITY ESTIMATES AND REFLECTS 
THE MOSTLY SUSTAINED CONVECTIVE SIGNATURE OVER THE LAST 12 HOURS. 
ANALYSIS INDICATES A MARGINAL ENVIRONMENT WITH WARM SST AND STRONG 
POLEWARD OUTFLOW OFFSET BY MODERATE TO STRONG VWS.

INITIAL WIND RADII BASIS: SCATTEROMETER DATA. 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.0 - 30 KTS
   KNES: T2.0 - 30 KTS
   CIMSS SATCON: 36 KTS AT 282300Z
   CIMSS ADT: 35 KTS AT 282330Z
   CIMSS AIDT: 35 KTS AT 282330Z

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

ANALYSIS CONFIDENCE:
   INITIAL POSITION: HIGH
   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 11S WILL CONTINUE SOUTHWESTWARD UNDER THE
STEERING INFLUENCE OF THE STR TO THE SOUTHEAST. AFTER TAU 36, THE
STEERING MECHANISM WILL TRANSITION TO A SECONDARY STR BUILDING IN
FROM THE SOUTHWEST, SLIGHTLY ALTERING THE TRACK TO A MORE
WEST-SOUTHWESTWARD TRAJECTORY. AFTER TAU 72, THE CYCLONE WILL AGAIN
TRACK TO A SOUTHWESTWARD DIRECTION AS THE SECONDARY STR RECEDES
EASTWARD. THE MARGINALLY FAVORABLE ENVIRONMENT WILL, AT BEST,
MAINTAIN THE INTENSITY IN EQUILIBRIUM AT 35KTS. AFTER TAU 72, THE
VWS WILL RELAX VERY SLIGHTLY, RESULTING IN A MINIMAL
INTENSIFICATION TO 40 KTS, SUSTAINED UP TO TAU 120. 

MODEL DISCUSSION: THE AVAILABLE NUMERICAL MODELS ARE IN VERY GOOD
AGREEMENT WITH A GRADUAL AND EVEN SPREAD TO 148M BY TAU 72 THEN TO
277NM BY TAU 120. HOWEVER, THE INTENSITY GUIDANCE IS WIDELY SPREAD
OUT WITH A VARIANCE OF 25KTS AT TAU 72 AND 35KTS AT TAU 120. IN
VIEW OF THESE, THERE IS ONLY A MEDIUM CONFIDENCE IN THE JTWC TRACK
AND INTENSITY FORECASTS FOR THE 5-DAY DURATION.

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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