Preliminary polarimetric analysis of a winter storm causing catastrophic traffic problems

A winter storm, which occurred on the 17th of March 2005 in Southern Finland, caused the worst traffic chaos ever seen in the greater Helsinki area. First test measurements made by the University of Helsinki new research radar setup, consisting of a coherent polarimetric radar and a vertically pointing conventional magnetron Doppler radar (both C-band), showed distinct differences around th 15 minute period when the most serious traffic preoblems occurred, compared to the general appearance of the storm. Although the installation of the new polarimetric radar was not complete and the whole radar setup was still about to enter to very first tests, the results were encouraging giving high resolution falling velocity spectra of precipitation with polarimetric signatures supporting in situ observations of freezing precipitation.