A look at driving rain spells at three cities in Great Britain

In this article, driving rain spell amounts are calculated from hourly wind and rainfall data for three cities in Great Britain, and comparisons are made with average annual driving rain values, also from hourly wind and rainfall data. The results show that the maximum observed driving rain spell intensities versus wall angles are qualitatively similar to angular distributions of annual driving rain both at and between the stations. For driving rain spell intensity expressed as the average number of exceedances of a threshold spell intensity value versus wall angle, results are both qualitatively and quantitatively very similar to angular distributions of annual driving rain. This suggests that average annual driving rain might be useful as a proxy measure of spell driving rain intensity in situations where relative risk of repeated penetration of masonry walls in building facades is of interest but quantitative spell data are not available.