A reconstruction of the August 1st 1674 thunderstorms over Holland

Abstract. On August 1st 1674 an active cold front moved over the low countries. The accompanying thunderstorms along the squall line were abnormally active, leading to large-scale damage in Europe, from northern France to the northern parts of Holland where damages were particularly severe. Using reported and pictured observations of damages, a reconstruction of this storm is made and an interpretation using modern meteorological concepts is given. The velocity of this exceptionally severe squall line and its orientation, including a developed bow-echo structure, are reconstructed. An estimate of the wind speeds associated with this event and an estimate of the return time of this event is given. This storm is compared to a more recent storm which was similar in dynamics but much less devastating. Special attention is given to the city of Utrecht which was hit hardest, and where the impact of this storm is still recognisable in the cityscape.