Severe thunderstorm radar signatures of 5 July 2002 derecho in Finland

On 5 July 2002 a bowing squall line moved over eastern Finland causing wind damage over a distance of 450 km. This mesoscale convective system had a strong reflectivity gradient in the leading line which was followed by a stratiform precipitation region. The rear inflow notch was visible in radar pictures as a weak echo region behind the leading line. The most intense damage was situated near the location of the rear inflow jet. Merging of a bow echo moving northward at 21 m/s and slower moving isolated cells in front of it resulted in the development of very intense thunderstorms embedded in the squall line. These storms were responsible for the microbursts that caused the most intense (F2 strength) burst swaths over the damage area. Many of these damage causing storms had elevated reflectivity cores.