Cold front with strong gusty winds over southwestern Finland: 29 September 2009
A particular strong wind event took place on 29 Sepetmber 2009. The event was characterized by a mesoscale convective line which was not reflected in any of the operational models.
A cold air outbreak took place in Finland on September 29, 2009. The most interesting part of this particular cold air outbreak was unexpectedly strong wind gusts. Operational models, except one, did not give a hint about strong wind gusts. The strongest observed gust was 30 m/s but fortunately no hazards or problems were reported from the sea areas around Finland. Newspapers reported some fallen trees and observations of roofs being blown off properties in southwest Finland. In this article, this particular event is evaluated and presented together with observational and operational model data.
Strong wind gusts also affected the standard measured 10 minute average wind speeds, so that the forecasted maximum was 12 m/s and the observed 20 m/s, which is close to official storm wind speed threshold in Finland. Operational forecaster on duty corrected forecasts quickly after observations showed higher than forecasted wind speeds.