Eastern Ontario and southern Quebec under storm threat
Monday, July 17, 2017, 4:15 PM - Lingering instability is giving way to thunderstorms across parts of Ontario Monday.
A cold front that moved through southern portions of the province Sunday has stalled south of the border and is expected to bring thunderstorms throughout the U.S. Eastern Seaboard, extreme eastern Ontario and southern Quebec.
"Cold air aloft with temperatures in the upper 20s ahead of the front will increase instability and bring the potential for large hail in the Eastern Townships," says The Weather Network meteorologist Kevin MacKay.
"Down sloping winds off the Adirondack Mountains may aid storm development south of Montreal this afternoon."
The Greater Toronto Area will see a cloudy start to the day, but conditions should clear out through the afternoon as high pressure pushes in from Lake Superior.
Meanwhile, northwestern Ontario is also under the risk of thunderstorms Monday, courtesy of a separate system.
"The cold front will reach lake of the Woods by this afternoon, coinciding with maximum daytime heating as temperatures south of the border will be pushing 40 degrees, and the southerly flow will be driving that instability northward," adds MacKay. "Higher moisture levels in Ontario will increase the potential for heavy rain and decrease the risk of large hail."
A heat warning has been issued in northwestern Ontario from Sandy Lake to Peawanuck as temperatures are expected to reach the 30 degree mark Monday afternoon across most of the region, according to Environment Canada.
"A cold front from the northern Prairie provinces will slide across the region and flush out the warm air tonight, bringing this heat to an end," says the weather agency.
Check back for updates as we continue to monitor the forecast.