Drought forecasting is based on forecasted discharge time series (EFAS driven by IFS-SEAS) for the whole of Europe and at regional scale. The discharge is at grid points of the major European rivers and collects all the runoff of the upstream grid cells (river and land). The threshold level method (TLM) is applied for the forecasting.
The TLM forecasts the river grid cells in drought, the onset, duration, and severity (deficit volume) of the drought in discharge in probabilistic terms. The drought occurs when the discharge is below the threshold. The probabilistic forecasts are presented as 25th percentile, median, and 75th percentile of the 51 ensemble members.