Severe Thunderstorm watch issued for Cornwall, Lancaster

Weather conditions are favourable for the development of severe thunderstorms this afternoon in Cornwall and Lancaster. The main threats are damaging winds, large hail and torrential downpours. The humid tropical air mass has arrived as expected.

PHOTO CREDIT - TheWeatherNetwork.com

Cornwall - Jul. 21, 2011 - Weather conditions are favourable for the development of severe thunderstorms this afternoon. The main threats are damaging winds, large hail and torrential downpours. The humid tropical air mass has arrived as expected. The strong July sun will quickly cause the mercury to soar well into the middle and upper thirties this afternoon. Combining the record setting temperatures with the high humidity in this sultry tropical air mass will result in oppressive humidex values in the low to mid forties across all of Southern Ontario by this afternoon. There will be some local relief from the high humidex values immediately along the shorelines of the Great Lakes and large inland lakes.

Current indications suggest that a weak front will slip through tonight. However in the wake of the front it will continue to be hot on Friday with temperatures in the low to mid thirties but somewhat less humid. Well above normal temperature will continue into the weekend for most of Southern Ontario with temperatures reaching the low thirties again on Saturday. It will be the combination of the duration of the high heat along with warm overnight conditions which makes this heat event particularly significant. During times of high heat and humidity, it is critical to stay properly hydrated by drinking Plenty of fluid like water or juice. Strenuous outdoor activities should be scheduled during the early morning or evening hours. Wear loose fitting, light weight clothing and spend as much time as possible in air conditioned places. Stay out of the sun and never leave elderly, children or pets unattended in a car refer to your local public forecast for further details.