Landspouts at lake breeze fronts in southern Ontario

The authors have undertaken a project to update the tornado climatology for Ontario. This involves revising and updating the current tornado database and analyzing the resulting data. One emerging aspect of the updated climatology is the frequent occurrence of landspouts in southern Ontario when thunderstorms develop and rapidly intensify at lake breeze fronts. Such landspouts have had tracks less than 10 km, lasted from 5 to 15 minutes, and resulted in F0 - F2 damage. In several cases, the landspout moved along the lake breeze front against the mean tropospheric flow. There are also cases in which multiple landspouts were observed. In all cases, tornadoes appear not to be associated with a mesocyclone aloft but rather with the intensification of vertical vorticity along the lake breeze front. Landspouts, known to occur frequently in parts of Colorado and Florida, may make up a large portion of the weak tornadoes that occur in southern Ontario each year.