Thunderstorms are expected to affect southwestern Ontario this morning and into this afternoon. Any thunderstorms that do develop will have the potential to produce torrential rainfall. The threat of thunderstorms will diminish late this afternoon as the upper level disturbance responsible moves away from the region. Heavy downpours can cause flash floods and water pooling on roads. Lightning kills and injures Canadians every year. Remember, when thunder roars, go indoors! Severe thunderstorm watches are issued when atmospheric conditions are favourable for the development of thunderstorms that could produce one or more of the following: large hail, damaging winds, torrential rainfall. Emergency Management Ontario recommends that you take cover immediately, if threatening weather approaches. Please continue to monitor alerts and forecasts issued by Environment Canada.