KNMI weather radar in Herwijnen disrupted by trees and bats

The KNMI weather radar in Herwijnen, Netherlands, is experiencing persistent inaccuracies due to a row of fast-growing poplar trees. The obstruction affects precipitation forecasts in a corridor stretching from Herwijnen toward Germany, passing through areas between Arnhem and Nijmegen and via Doetinchem.

Local authorities in the West Betuwe municipality cannot immediately prune or remove the trees due to environmental protection laws. Ecological research is currently underway to determine if the trees serve as a protected foraging area or flight route for bats. Until the results of this study are released, no intervention can take place.

To mitigate the errors, the KNMI is using higher-altitude radar scans that look over the trees, as well as data from radars in Belgium and Germany, specifically the radar in Essen. While these corrections help, the KNMI stated that minimizing interference remains a priority.