P6.4 Severe thunderstorm forecasting program in Finland

Wednesday, 8 November 2006
Pre-Convene Space (Adam's Mark Hotel)
Ari-Juhani Punkka, Finnish Meteorological Institute, Helsinki, Finland; and J. Teittinen

In every summer, there are several days when severe thunderstorms have locally a large impact on society in Finland. In July 2002, a derecho hit Eastern Finland and devastated a million cubic meters of trees. In August 2004, a strong F2 tornado cut down a hundred thousand cubic meters of trees and demolished several buildings on its 20 km long track. In previous years, the forecasters at Finnish Meteorological Institute (FMI) have carried out the same scheduled duties despite the severity of the weather. This has resulted in situation where, in case of severe weather, the forecaster is overwhelmed by the work tasks and is unable to cope with any extra duties.

In order to tackle the work load problem, a severe weather forecasting program has been tested at FMI since January 2005. Currently, seven Warning Weather Service forecasters are involved in the program. One extra forecaster is in duty every weekday and he or she will work in the weather room, as long as needed, up to from 9 AM to 9 PM. The main objectives of the program are to provide emergency authorities and other forecasters with information on severe weather risk 0-48 h before the event hits and to improve operational severe weather warnings. The program also aims to improve forecasting tools together with the developers and to learn more on severe weather forecasting in and around Finland. The main means of communication is a severe weather outlook issued by the preparedness forecaster. The outlook typically contains a picture of the area at risk and a written severe weather outlook.

The preparedness forecasters have acted as test users for several new nowcasting tools. During the summer 2006 they tested two Vaisala lightning tracking softwares, a hydrometeor classification algorithm and a meteorological workstation extension which makes possible to overlay real-time storm damage reports from the emergency response centers with meteorological data. Since 2005, a sounding tool with hodographs, numerous convection parameters and fully adjustable temperature and moisture profiles has also been tested.

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