1. Pierre Eckert Daniel Cattani MétéoSuisse
Extrem Forecast Index
Pierre Eckert
Daniel Cattani
MétéoSuisse

2. EFI: definition
Scores and verification
Precipitations
Wind gust
Conclusion

3. p
Ff(p)

4. An Extreme Forecast Index
Takes values from –1 (all members break climate minimum records) and +1 (all beyond climate maximum records)
For a single value (e.g. deterministic) forecast with climate rank Q: EFI3=(Q-50%) [1+4(Q-50%)2]
Q=95%, EFI3=0.81
Q=98%, EFI3=0.92
Q=99%, EFI3=0.96

5. Verification parameters (1)
Precipitations (nov.2001-apr.2003)
Predictands: 2nd max prec. / 24h of climatological regions (W, E, S)
Predictors: EFI max over regions
Thresholds
10 mm/24h
20 mm/24h
50 mm/24h

6. Verification parameters (2)
Gusts (nov.2001-apr.2003)
Predictands: 2nd max gust / 24h of climatological regions (W, E )
Predictors:
EFI max over regions
EFI max over all the domain ( °N; °E)
Thresholds
50 km/h
75 km/h
100 km/h

7. Verification: scores Forecasted : EFI gt given value
Event
Observed
Not Observed
Forecasted A B
Not Forecasted C D
Forecasted : EFI gt given value
Hit Rate = A / (A+C)
FAR = B / (A+B)

8. Precipitations : Switzerland West
Hit = 0,5
EFI = 0,3 T+66h
EFI = 0,2 T+90h
EFI = 0,2 T+114

9. Precipitations : Switzerland West

10. Precipitations : Switzerland West

11. Precipitations : Switzerland South

12. Precipitations : Switzerland South

13. Precipitations : Switzerland South

14. Gusts : Switzerland West
50km/h
75km/h

15. Gusts : Switzerland West
50km/h
75km/h

16. Gusts: Switzerland West

17. Gusts: Switzerland West (ref region)

18. Conclusion: precipitations
T+42-66h
Hit=0.6
Prec ge 10mm
Prec ge 20mm
Prec ge 50mm
EFI
FAR
West
0.2
0.6
East
0.3
0.7
South
0.5

19. Conclusion: Gusts Gust ge 75 km/h Hit=0.5 T+36-60h T+60-84h T+84-108h
EFI
FAR
West (ref region)
0.3
0.7
0.5
0.2
0.8
West (ref domain)
0.9