WDXS32 PGTW 112100
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/PROGNOSTIC REASONING FOR TROPICAL CYCLONE 13S (DINGANI) WARNING 
NR 006//
RMKS/
1. FOR METEOROLOGISTS.
2. 6 HOUR SUMMARY AND ANALYSIS.

SUMMARY:
   INITIAL POSITION: 15.9S 77.3E
   INITIAL INTENSITY: 55 KTS
   GEOGRAPHIC REFERENCE: 599 NM SOUTH-SOUTHEAST OF DIEGO GARCIA
   MOVEMENT PAST 6 HOURS: WEST-SOUTHWESTWARD AT 09 KTS
   SIGNIFICANT WAVE HEIGHT: 25 FEET

SATELLITE ANALYSIS, INITIAL POSITION AND INTENSITY DISCUSSION:
ANIMATED ENHANCED INFRARED (EIR) SATELLITE IMAGERY SHOWS A COMPACT
SYSTEM THAT HAS AN IMPROVED OVERALL CONVECTIVE SIGNATURE WITH THE
CENTRAL CONVECTION SLIGHTLY SHEARED WESTWARD FROM AND PARTIALLY 
EXPOSING THE LOW-LEVEL CIRCULATION (LLC). THE INITIAL POSITION IS 
PLACED WITH HIGH CONFIDENCE BASED ON THE PARTLY EXPOSED LLC IN THE 
EIR LOOP. THE INITIAL INTENSITY IS ALSO PLACED WITH HIGH CONFIDENCE 
BASED ON THE MAJORITY AND HIGH END OF AGENCY AND AUTOMATED DVORAK 
ESITMATES AND CONSISTENT WITH THE 12-HR CONVECTIVE IMPROVEMENT. 
ANALYSIS INDICATES A FAVORABLE ENVIRONMENT WITH MODERATE POLEWARD 
OUTFLOW OFFSET BY MODERATE VERTICAL WIND SHEAR AND TEPID SSTS.

INITIAL WIND RADII BASIS: PERSISTENCE.

CURRENT STEERING MECHANISM: LOW- TO MID-LEVEL SUBTROPICAL RIDGE
(STR) TO THE SOUTHEAST.

AGENCY DVORAK AND AUTOMATED FIXES: 
   PGTW: T3.0 - 45 KTS
   KNES: T3.5 - 55 KTS
   DEMS: T3.0 - 45 KTS
   FMEE: T3.5 - 55 KTS
   CIMSS ADT: 3.3 KTS AT 111600Z

FORECASTER ASSESSMENT OF CURRENT ENVIRONMENT: FAVORABLE
   VWS: 5-10 KTS
   SST: 27-28 CELSIUS
   OUTFLOW: MODERATE RADIAL

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

3. FORECAST REASONING.

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

FORECAST DISCUSSION: TC DINGANI WILL TRACK GENERALLY SOUTHWESTWARD
UNDER THE STEERING STR. VWS IS EXPECTED TO RELAX A BIT AND THE
POLEWARD OUTFLOW TO INCREASE, FUELING A GRADUAL INTENSIFICATION
PHASE TO A PEAK OF 70KTS AT TAUS 36-48. AFTERWARD, COOLING SST AND
RAPIDLY INCREASING VWS WILL ERODE THE SYSTEM AND BY TAU 120, WILL BE 
REDUCED TO 35KTS AS IT PASSES TO THE SOUTH OF RODRIGUES ISLAND, 
MAURITIUS. THERE IS A DISTINCT POSSIBILITY THAT TS 13S WILL DISSIPATE 
SOONER THAN TAU 120 DUE TO THE HIGH VWS AND COOL SSTS.   

MODEL DISCUSSION: NUMERICAL MODELS ARE IN OVERALL GOOD AGREEMENT UP
TO TAU 24; AFTERWARD, THE MEMBERS SIGNIFICANTLY, ALBEIT EVENLY,
SPREAD TO 270NM BY TAU 120, LENDING OVERALL MEDIUM CONFIDENCE TO
THE JTWC TRACK FORECAST THAT IS LAID OVER THE MODEL CONSENSUS. THE
INTENSITY FORECAST IS AT MEDIUM CONFIDENCE UP TO TAU 72, THEN LOW
AFTERWARD. 

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