With the IFS cycle 46r1 the Extreme Forecast Index (EFI) and Shift Of Tails (SOT) extend for fields are being extended to include 2-metre weekly mean temperature and weekly precipitation totals in the extended range forecast. The forecasts are provided twice every week - every Monday and Thursday - for the following forecast steps: T+0-168h, T+96-264h, T+168-336h, T+264-432h, T+336-504h, T+432-600h, T+504-672h, T+600-768h, T+672-840h, T+768-936, T+840-1008h and T+936-1104h.
For consistency with other extended-range products (e.g. anomalies, probabilities) these EFI/SOT forecasts share the same Model climate (M-climate) as the one used in the extended-range forecasts. Unlike the medium-range EFI/SOT M-climate, the extended-range M-climate is derived from a set of 3 (rather than 9) re-forecasts centred on the date of the real-time forecast initialisation. The climate sample size comprises of 660 values and therefore it is much smaller compared to than the 1980 values used in the medium range. Information about the M-climate used is coded in the GRIB header as well via the following GRIB keys:
| GRIB octets | GRIB keys (values shown are as used for extended range EFI/SOT) |
|---|---|
| 57-59 | numberOfReforecastYearsInModelClimate = 20 |
| 60-62 | numberOfDaysInClimateSamplingWindow = 7* |
| 63-65 | sampleSizeOfModelClimate = 660 |
* numberOfDaysInClimateSamplingWindow takes the closest odd number to the length (in days) of the time window in which all the re-forecasts are considered in the preparation of the M-climate, e.g. for the medium-range numberOfDaysInClimateSamplingWindow=31 as a month-long time window is used.
Corresponding Cumulative Distribution Functions (CDFs) of the M-climate and extended-range forecast anomalies complement the EFI/SOT forecasts. This allows for a more comprehensive interpretation of the extended-range forecasts. Each CDF plot displays all extended-range forecasts available for the the requested period together with the M-climate corresponding to the the latest forecast. Time The time evolution of the extended-range forecast together with the corresponding M-climate can be seen also on the extended-range ensemble meteograms.
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