Radar-based Previous 24-h Accumulated Precipitation

Please note that this product is experimental and is not operationally supported, meaning that there may be some gaps in the availability on the EFAS web interface due to outages.

The Radar-based previous 24-h accumulated precipitation layer shows the 24 hour accumulated precipitation as estimated from gauge-adjusted OPERA radar composites from the pan-European OPERA radar rainfall network, in areas outside the radar coverage it is blended with short range precipitation forecasted by the ECMWF ensemble. This layer is generated at 00 and 12 UTC every day, the values refer to the total accumulated precipitation in the preceding 24 hours (Figure 1). Please note that the layer is only visible for observations during the previous 5 days, dates beyond this time range are not displayed on the web interface.

The layer is generated by summarising all the hourly blended radar and ECMWF forecast data over the previous 24 hours. The blending of the radar and ECMWF data is done at each hour by extracting from the most recently available ECMWF forecast the ensemble member which has the closest match to the radar observation. At locations where radar data are available, the blending gives greatest weight to the radar data, otherwise greater weight is given to the ECMWF data at locations which are further away from radar stations and in areas with no radar coverage. The areas of radar coverage are given in the Radar Coverage layer, values of 1 indicate complete radar coverage, values of 0 indicate no radar coverage, the blending of the radar and ECMWF precipitation data is done in the equation below.

Precipitation_Blend = (Precipitation_Radar * Radar Coverage) + (Precipitation_ECMWF * (1-Radar Coverage))

Figure 1. Radar-based previous 24 hour accumulated precipitation product on the 25th February 2025 at 12:00 UTC, a) when zoomed out at pan-European scale, b) when zoomed in to an area of interest - note the increased spatial detail