WDXS31 PGTW 030900
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (INDUSA) WARNING NR 
005//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.2S 72.9E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 939 NM EAST-NORTHEAST OF PORT LOUIS,
MAURITIUS
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 11 KTS
   SIGNIFICANT WAVE HEIGHT: 18 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS TROPICAL
CYCLONE (TC) 29S (INDUSA) STILL STRUGGLING WITH DRY AIR INTRUSION
THROUGHOUT THE CIRCULATION PUTTING A HOLD ON ANY SIGNIFICANT
INTENSIFICATION. THE OTHERWISE FAVORABLE ENVIRONMENT IS CHARACTERIZED 
BY WARM (28-29 C) SEA SURFACE TEMPERATURES (SST), LOW (5-10 KTS) 
VERTICAL WIND SHEAR (VWS), AND ROBUST POLEWARD OUTFLOW. DESPITE THE 
COMPACT STRUCTURE OF THE SYSTEM, IT FAILED TO OPPOSE THE DRY AIR 
ENTRAINMENT AND THEREFORE REMAINED STAGNANT AT 55 KTS OVER THE LAST 12 
HOURS. THE INITIAL POSITION IS ASSESSED WITH HIGH CONFIDENCE, DERIVED 
FROM THE CURVATURE OF CONVECTIVE BANDING IN THE VISIBLE SATELLITE 
IMAGERY LOOP AND SUPPORTED BY A 030434Z METOP-B ASCAT PASS. THE 
INITIAL INTENSITY OF 55 KTS IS ALSO ASSESSED WITH HIGH CONFIDENCE, 
CORROBORATED BY DVORAK ESTIMATES FROM MULTIPLE AGENCIES AND OBJECTIVE 
INTENSITY ESTIMATES LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.5 - 55 KTS
   FMEE: T3.5 - 55 KTS
   FIMP: T3.5 - 55 KTS
   CIMSS ADT: 55 KTS AT 030600Z
   CIMSS AIDT: 45 KTS AT 030500Z
   CIMSS D-MINT: 48 KTS AT 030316Z
   CIMSS D-PRINT: 47 KTS AT 030630Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 28-29 CELSIUS
   OUTFLOW: STRONG POLEWARD

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

3. FORECAST REASONING.

SIGNIFICANT FORECAST CHANGES: PEAK INTENSITY HAS BEEN LOWERED SINCE 
LAST FORECAST, FROM 90 KTS TO 70 KTS, DUE TO CONSISTENTLY LOWER
INTENSITY GUIDANCE AND LACK OF RAPID INTENSIFICATION AIDS WITHIN
THE 030600Z AID SUITE.

FORECAST DISCUSSION: TC 29S IS FORECAST TO MAINTAIN ITS TRAJECTORY
ALONG THE NORTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE THROUGH
TAU 36. THE ENVIRONMENT IS EXPECTED TO REMAIN GENERALLY FAVORABLE,
SUPPORTING A PERIOD OF SUSTAINED INTENSIFICATION, CONTINGENT UPON
THE CORE REMAINING INSULATED FROM DRY AIR ENTRAINMENT. IF THE
SYSTEM IS NOT ABLE TO MAINTAIN A MOIST CORE AND SYMMETRICAL
STRUCTURE, INTENSIFICATION MAY BE SLOWED DOWN SIGNIFICANTLY OR
HALTED ENTIRELY. PEAK INTENSITY IS CURRENTLY FORECAST TO REACH 70
KTS AROUND TAU 36, IMMEDIATELY PRECEDING A RECURVATURE TOWARDS THE
SOUTH-SOUTHEAST AND AROUND THE RIDGE AXIS. POST-RECURVATURE, TC INDUSA
WILL BEGIN TO INTERACT WITH AN UPPER-LEVEL JET, INITIATING A
WEAKENING TREND AND THE ONSET OF EXTRATROPICAL TRANSITION (ETT). THE
SYNOPTIC AND OCEANIC ENVIRONMENT WILL BECOME INCREASINGLY HOSTILE,
CHARACTERIZED BY PERSISTENT DRY AIR ADVECTION, RAPIDLY INCREASING
VERTICAL WIND SHEAR, AND COOLING SEA SURFACE TEMPERATURES, REACHING
22-23 C BY TAU 72. AROUND THAT TIME, THE WIND FIELD OF TC 29S IS
EXPECTED TO EXPAND AND BECOME INCREASINGLY ASYMMETRIC AS CORE WIND
SPEEDS DECREASE FURTHER. TC 29S IS ANTICIPATED TO COMPLETE THE ETT 
AROUND TAU 72 AS IT BECOMES EMBEDDED WITHIN THE DEEP-LAYER MID-
LATITUDE WESTERLIES AND WEAKENS TO 35 KTS.

MODEL DISCUSSION: NUMERICAL WEATHER PREDICTION GUIDANCE DEMONSTRATES 
VERY GOOD AGREEMENT IN REGARD TO THE TRACK THROUGHOUT THE CURRENT 
FORECAST PERIOD, EVIDENCED BY A MINIMAL CROSS-TRACK SPREAD OF ONLY 85 
NM AT TAU 72. THE OFFICIAL JTWC TRACK FORECAST IS LAID NEAR THE MULTI-
MODEL CONSENSUS WITH HIGH CONFIDENCE. THE INTENSITY FORECAST IS ISSUED 
WITH MEDIUM CONFIDENCE, POSITIONED SLIGHTLY ABOVE THE GUIDANCE MEAN, 
FAVORING THE POTENTIAL FOR SLIGHT INTENSIFICATION GIVEN THE SUPPORTING 
ENVIRONMENT. ALTHOUGH MODELS CONCUR ON THE GENERAL INTENSIFICATION AND 
DECAY TIMELINE, A 25 KT SPREAD IN PEAK INTENSITY EXISTS. DETERMINISTIC 
GFS AND STATISTICAL-DYNAMICAL MODELS PROJECT A PEAK OF 60-65 KTS, 
CONTRASTING WITH THE COAMPS-TC AND HAFS STILL EXPECTING AN INCREASE TO 
80-85 KTS. CONSIDERING THE LACK OF RAPID INTENSIFICATION AIDS 
TRIGGERING DURING THE MOST RECENT MODEL RUN, THE OFFICIAL JTWC 
INTENSITY FORECAST CALLS FOR A PEAK 5-10 KTS BELOW THE HAFS 
PROJECTION, BUT SLIGHTLY ABOVE THE OVERALL CONSENSUS MEAN AND IS 
ASSESSED WITH OVERALL MEDIUM CONFIDENCE.

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