Nowcasting snow for airports at heterogeneous terrain

Kurzfassung

The forecast of snow events at airports is a major challenge in airport operation during winter time. In contrast to rain, snow has to be actively removed from aircraft or operation areas. Short term forecasting - or nowcasting - of snow events is required for airport operation. Airport stakeholders need to know the start and duration of snow events, but they need also an estimate of the snow accumulation during the event. Extrapolation techniques based upon weather radar observations are used to generate a probabilistic nowcast for airports. These techniques assume a linear propagation of the precipitation fields. In case of intensifying, decaying or non-linear propagation the forecast quality is considerably reduced. In this paper we show that lake effects along the coastlines or flow within the proximity of mountains degrade the forecast quality and the lead time for reliable nowcasts is shorter than for situations which are not affected by heterogeneous terrain.