Severe thunderstorms moving across southwestern Ontario Tuesday afternoon are expected to bring heavy rain, strong winds and possible hail before a cold front ushers in cooler temperatures, according to meteorologist Julie Atchison. “A severe thunderstorm watch was in effect from Windsor through Chatham, while Sarnia was under a severe thunderstorm warning. The watches and warnings will shift as these storms push their way through," she said. Storms producing torrential downpours were moving through Lambton County and were expected to reach the London area within about an hour [2:30 p.m.]. There is a sharp cold front pushing through southern Ontario, behind the front, winds are expected to shift to the northwest, bringing significantly cooler air into the region. “The main storms will be through the area by 7 p.m., and then overnight, we will see cloudy conditions, just the chance for showers. But as the winds shift northwest, it will generate some off-lake rainfall," said Atchison. Temperatures are expected to fall noticeably behind the front, with a forecast high of 21 C on Wednesday. Conditions are expected to improve later in the week, with sunshine returning Thursday and Friday and highs of 23 C and 26 C, respectively.