WDXS31 PGTW 032100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 29S (INDUSA) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 17.8S 71.6E
   INITIAL INTENSITY: 65 KTS
   GEOGRAPHIC REFERENCE: 644 NM SOUTH OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: SOUTH-SOUTHWESTWARD AT 14 KTS
   SIGNIFICANT WAVE HEIGHT: 21 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
TC 29S HAS STEADILY INTENSIFIED OVER THE PAST TWELVE HOURS.
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY DEPICTS
INCREASING ORGANIZATION, INCLUDING DEVELOPMENT OF A ROBUST
CONVECTIVE BAND WRAPPING INTO THE CIRCULATION ON FROM THE EAST AND
APPEARANCE OF A DIMPLE NEAR THE CENTER OF THE CIRCULATION
CORRESPONDING TO A NASCENT EYE. THE INITIAL POSITION IS PLACED WITH
MEDIUM CONFIDENCE BASED ON A 031411Z SSMIS PASS AND MULTI-AGENCY
SATELLITE FIXES. THE INITIAL INTENSITY OF 65 KTS IS ASSESSED WITH
MEDIUM CONFIDENCE BASED ON A CONSENSUS OF SUBJECTIVE DVORAK AND
AUTOMATED INTENSITY ESTIMATED LISTED BELOW.

INITIAL WIND RADII BASIS: OBJECTIVE BEST TRACK 

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

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T4.0 - 65 KTS
   DEMS: T3.5 - 55 KTS
   FMEE: T4.0 - 65 KTS
   FIMP: T4.0 - 65 KTS
   CIMSS ADT: 55 KTS AT 031800Z
   CIMSS AIDT: 62 KTS AT 031700Z
   CIMSS D-MINT: 54 KTS AT 031543Z
   CIMSS D-PRINT: 64 KTS AT 031800Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 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 29S WILL CONTINUE TRACKING GENERALLY
POLEWARD AROUND THE PERIPHERY OF THE CURRENT STEERING RIDGE THROUGH
TAU 24 AND IN THE GRADIENT BETWEEN THIS RIDGE AND A DEEP-LAYER
TROUGH APPROACHING FROM THE WEST THEREAFTER. ENVIRONMENTAL
CONDITIONS INCLUDING A STRONG POLEWARD OUTFLOW CHANNEL AND LOW
VERTICAL WIND SHEAR FAVOR NEAR-TERM INTENSIFICATION. ALTHOUGH THE
CURRENT FORECAST ANTICIPATES A PEAK INTENSITY OF 75 KNOTS AT TAU
12, A HIGHER PEAK IS CERTAINLY POSSIBLE GIVEN THE FAVORABLE
ENVIRONMENT AND COMPACTNESS OF THE CIRCULATION. WESTERLY TO
NORTHWESTERLY UPPER-LEVEL FLOW AHEAD OF THE APPROACHING TROUGH WILL
INDUCE VERTICAL WIND SHEAR BY TAU 24, ALLOWING THE SYSTEM TO BEGIN
ENTRAINING DRIER AIR FROM THE WEST AND INITIATING A WEAKENING
TREND. HOWEVER, FAVORABLE BAROCLINIC INTERACTION WITH THE TROUGH
WILL OFFSET THE WEAKENING TREND AND INDUCE A FAIRLY RAPID
EXTRATROPICAL TRANSITION THAT IS EXPECTED TO BE COMPLETE BY TAU 48.

MODEL DISCUSSION: NUMERICAL MODEL TRACK GUIDANCE IS IN EXCELLENT
AGREEMENT FOR THE ENTIRETY OF THE FORECAST PERIOD. THE CURRENT
FORECAST TRACK IS SITUATED NEAR THE MULTI-MODEL CONSENSUS AND
PREVIOUS FORECASTS WITH HIGH CONFIDENCE. INTENSITY GUIDANCE,
INCLUDING BOTH DYNAMICAL AND STATISTICAL-DYNAMICAL MODELS, BROADLY
INDICATE MARGINAL (5-10 KNOT) INTENSIFICATION OR A STEADY STATE
OVER THE NEXT 12 TO 24 HOURS FOLLOWED BY SLOW WEAKENING. RAPID
INTENSIFICATION (RI) GUIDANCE PRIMARILY INDICATES MUTED
PROBABILITIES OF RI, BUT FAVORABLE NEAR-TERM ENVIRONMENTAL
CONDITIONS AND A PRIMED STORM STRUCTURE PRESENT NOTEWORTHY
POTENTIAL FOR AT LEAST A BIT MORE INTENSIFICATION THAN REFLECTED IN
THE CURRENT FORECAST, CONTRIBUTING TO ONLY MODERATE CONFIDENCE IN
THE INTENSITY FORECAST DESPITE BROAD AGREEMENT IN THE EXPECTED
TREND AMONG CURRENT MODEL FORECASTS.

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