An investigation of the feasibility of predicting icing episodes using numerical weather prediction model output

Icing on power lines due to supercooled water droplets in saturated air is a potential hazard in Norway, as well as in many other countries, every winter. For this reason, there is a strong desire to improve the predictions of icing episodes. In order to develop a new method, we have selected a few icing episodes for which verifying measurements are available. The measurements were made using rotating multicylinder instrument at the top of a hill in northern Finland. We then ran the weather prediction model HIRLAM for these cases, and extracted information on temperature, wind conditions and cloud water content. By comparing the modelled values of cloud water content with the measured values, we studied the feasibility of using numerical weather prediction model output directly for prediction of icing episodes.