
Der ExtremeForecastIndex des ECMWF liest sich folgendermassen
ohne grad mit konkreten mm-Zahlen um sich zu werfen (disclaimer).EFI magnitudes of 0.5 - 0.8 (irrespective of sign) can be generally regarded as signifying that "unusual" weather is likely whilst magnitudes above 0.8 usually signify that "very unusual" weather is likely