Heavy Snowfall Europe - 7 to 11 March 2010

Conclusion

Upper level cold core lows have high potential for development but also for difficulties in the forecasts. If the ULL is detached from the large-scale upper air flow, computing of the further track is very difficult for the NWPs. If the cold core reaches, like in this case, the relatively warm Mediterranean Sea intense cyclogenesis is generated. A 5b track (similar 5b in this case) of a Mediterranean Low can bring heavy precipitation all over Austria. But the intensity and the snowline is still difficult to predict for the NWP's. So it is on the forecaster to question the model output and advance the forecasts by his expert knowledge and actual measurements. In general the event was not poor predicted, but some small details in the height of the snowline and the regional diversity of the precipitation intensity can have big impacts for some end-users. In this special event the Aladin-LAEF Model realized the situation for Austria better than other NWP's. The real measured TEMP's, maybe in combination with Wind and TA forecasts, can help for a better estimation of the snowline in Austria in such tricky situations. The relative rough, but often used, aproximation that 1mm precipitation is equivalent to 1cm snow was approximately verified by this event.