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

EFI: definition Scores and verification Precipitations Wind gust Conclusion

p Ff(p)

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

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

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 (45-48.5°N; 5-11.5°E) Thresholds 50 km/h 75 km/h 100 km/h

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)

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

Precipitations : Switzerland West

Precipitations : Switzerland West

Precipitations : Switzerland South

Precipitations : Switzerland South

Precipitations : Switzerland South

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

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

Gusts: Switzerland West

Gusts: Switzerland West (ref region)

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

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