Characteristics of Mesoscale Precipitation Bands in Southern Finland

Abstract

A large amount of observational material, consisting of more than 3000 hours of radar measurements from about 1 50 cyclones has been analyzed to discover the characteristic features of banded structures in extratropical cyclones in southern Finland. All previously classified types of rain- and snowbands have been observed. The most common rainband types were warm frontal aloft, postfrontal, warm sector and occluded warm frontal bands. The average size parameters of different rainband types showed only slight variations from type to type. A distinct annual variation in the echo top height, rainband width and wavelength has been found. The average echo top heights were 3 and 6.5 km, the wavelengths 29 and 77 km, and the widths 18 and 35 km in winter and summer, respectively. The monthly values of the ratio of wavelength to height were relatively constant. They varied between 6 and 14, averaging 11.