WDXS31 PGTW 020900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (INDUSA) WARNING NR 
002//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 12.0S 73.5E
   INITIAL INTENSITY: 40 KTS
   GEOGRAPHIC REFERENCE: 300 NM SOUTH OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 04 KTS
   SIGNIFICANT WAVE HEIGHT: 17 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS A
CONSOLIDATING, COMPACT TROPICAL CYCLONE (TC) 29S (INDUSA) SLOWLY
TRACKING SOUTHWESTWARD UNDER THE INFLUENCE OF A DEEP-LAYER
SUBTROPICAL RIDGE (STR) CENTERED TO THE SOUTHEAST. AFTER A BRIEF
PERIOD OF INTENSE CONVECTION PRODUCING A CENTRAL DENSE OVERCAST (CDO) 
FEATURE, THE SYSTEM NOW DISPLAYS A MORE PRONOUNCED CONVECTIVE BANDING 
WRAPPING INTO THE LOW-LEVEL CIRCULATION CENTER (LLCC). SOME DRIER AIR 
IS ENTERING THE CORE OF THE VORTEX, SLIGHTLY SLOWING DOWN DEVELOPMENT, 
WHILE OTHER ENVIRONMENTAL PARAMETERS REMAIN HIGHLY FAVORABLE FOR RAPID 
INTENSIFICATION - SEA SURFACE TEMPERATURES ARE VERY WARM (29-30 C), 
VERTICAL WIND SHEAR (VWS) IS LOW (5-10 KTS) AND UPPER LEVEL OUTFLOW 
REMAINS STRONG, PRIMARILY IN THE POLEWARD DIRECTION. THE INITIAL 
POSITION IS PLACED WITH MEDIUM CONFIDENCE BASED ON THE WRAPPING OF THE 
CONVECTIVE BANDING OBSERVED IN THE VISIBLE SATELLITE IMAGERY LOOP, IN 
LINE WITH THE EXTRAPOLATION FROM AN EARLIER (020149Z) F16 SSMIS PASS. 
THE INITIAL INTENSITY OF 40 KTS IS ASSESSED WITH MEDIUM CONFIDENCE 
BASED ON AN EARLIER (020052Z) RCM-3 SAR PASS SHOWING A COMPACT SYSTEM 
WITH 35-40 KTS WIND SPEED BANDING ALMOST FULLY ENCIRCLING THE LLCC.

INITIAL WIND RADII BASIS: A 020052Z RCM-3 SAR DATA

CURRENT STEERING MECHANISM: A DEEP-LAYER SUBTROPICAL RIDGE (STR)
CENTERED TO THE SOUTHEAST

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T2.5 - 35 KTS
   FMEE: T3.0 - 45 KTS
   CIMSS ADT: 47 KTS AT 020600Z
   CIMSS D-MINT: 36 KTS AT 020328Z
   CIMSS D-PRINT: 43 KTS AT 020630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: HIGHLY FAVORABLE
   VWS: 5-10 KTS
   SST: 29-30 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 INDUSA IS FORECAST TO CONTINUE TRACKING
ALONG THE NORTHWESTERN PERIPHERY OF A STR CENTERED TO THE SOUTHEAST
UNTIL AT LEAST TAU 48. THE ENVIRONMENT IS EXPECTED TO REMAIN HIGHLY
FAVORABLE RESULTING IN STEADY, NEAR-RAPID INTENSIFICATION
THROUGHOUT THIS TIMEFRAME. THERE IS A POSSIBILITY THAT THE SYSTEM
WILL REACH INTENSITY BEYOND THE CURRENTLY FORECASTED PEAK OF 85 KTS
SHORTLY AFTER TAU 48, BUT PRIOR TO TAU 72, WHICH THE CURRENT
WARNING GRAPHIC IS NOT ABLE TO VISUALIZE. AS THE SYSTEM ROUNDS THE
AXIS OF THE RIDGE AROUND TAU 72, IT IS EXPECTED TO BEGIN INTERACTING 
WITH A TAIL END OF AN UPPER LEVEL JET, RESULTING IN A WEAKENING TREND 
AND BEGINNING OF AN EXTRATROPICAL TRANSITION (ETT). THE ENVIRONMENT 
WILL THEN BECOME INCREASINGLY LESS FAVORABLE, WITH DRY AIR ENTERING 
THE SYSTEM FROM THE NORTH AND WEST, MULTIPLIED BY RAPIDLY INCREASING 
VERTICAL WIND SHEAR AND COOLING SEA SURFACE TEMPERATURES. BEFORE TAU 
120, THE CIRCULATION IS EXPECTED TO INCREASE IN SIZE AND BECOME 
SIGNIFICANTLY LESS SYMMETRIC, WITH THE CORE WIND SPEEDS DECREASING. TC 
29S IS EXPECTED TO COMPLETE THE ETT JUST PRIOR TO TAU 120, AS IT 
POSITIONS ITSELF UNDERNEATH THE STRONG, UPPER-LEVEL WESTERLIES.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN OVERALL GOOD
AGREEMENT THROUGHOUT THE FORECAST WITH VERY TIGHT INITIAL GUIDANCE
ENVELOPE, AS WITNESSED BY A 75 NM CROSS-TRACK SPREAD AT TAU 72,
INCREASING TO 250+ NM BY THE END OF THE FORECAST. THE PRIMARY
OUTLIER IS NAVGEM, WHICH PREDICTS A SHARPER TURN AROUND THE WESTERN
PERIPHERY OF THE RIDGE AND FASTER EXTRATROPICAL TRANSITION.
ALONG-TRACK SPREAD ALSO INCREASES TOWARDS THE END OF THE FORECAST,
WITH NAVGEM BEING THE PRIMARY OUTLIER AGAIN PROJECTING A MUCH
FASTER, EASTWARD TRACK. JTWC OFFICIAL INTENSITY GUIDANCE IS LAID
WITH MEDIUM CONFIDENCE, SLIGHTLY ABOVE THE CONSENSUS MEAN,
INCLUDING THE RAPID INTENSIFICATION AIDS, AND CLOSE TO THE
PROJECTION FROM HAFS. WHILE ALL AVAILABLE MODELS AGREE ON GENERAL
TIMELINE OF INTENSIFICATION AND WEAKENING, THE PEAK INTENSITY
SPREAD IS CURRENTLY ESTIMATED AT 40 KTS, WITH DETERMINISTIC GFS
ONLY SHOWING PEAK OF 60-65 KTS, OPPOSING COAMPS-TC RI-AID AND
COAMPS-TC ENSEMBLE MEAN SHOWING 95-100 KTS WIND MAXIMUM.

FORECAST CONFIDENCE:
   TRACK 00-72 HR: HIGH
   TRACK 72-120 HR: MEDIUM
   INTENSITY 00-72 HR: MEDIUM
   INTENSITY 72-120 HR: MEDIUM//
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