Stifling temperatures, humidity in Ontario courtesy of 'heat dome'
Humidex values will approach or hit the low-40s in many southern Ontario locales by Sunday.
A heat dome -- a ridge of high pressure stationed in the upper atmosphere, acting as a vault to trap heat in -- is in place above much of eastern North America, including Ontario, which saw heat reach uncomfortable levels Friday, rising even higher into the weekend. By Sunday, humidex values approaching or hitting the 40s will be commonplace. The next opportunity for thunderstorms in the south will come Monday. Details and timing, below.
WEATHER HIGHLIGHTS:
Heat dome will create uncomfortable temperatures through the weekend
Severe storm risk possible Saturday in the northwest
Next storm chance in the south will be Monday morning
Keep an eye on weather ALERTS in your area
SATURDAY/SUNDAY: HEAT DOME IN PLACE, STORM RISK IN NORTH
Scorching July temperatures gradually crept back in Friday thanks to that heat dome in the U.S., and they were a harbinger for what looks to be an even hotter weekend.
On Saturday, daytime highs are expected to hit or exceed the 30-degree mark across the south, though will feel more like the mid-30s with the humidity. Overnight showers in southwestern Ontario will linger a little through the morning.
On Sunday, temperatures look to be even warmer, with humidex values approaching or in the low-40s in many locales.
While most of the weekend will be dry in the south, a trough moving into northwestern Ontario will bring the risk for thunderstorms in the pre-dawn hours Saturday morning.
The risk for severe storms near Lake Superior will continue during the day once the initial round of storms moves eastward in the afternoon. Hazards include heavy rain, small hail and strong wind gusts.
Sunday looks calmer, and beyond the weekend, the next chance of a storm risk in southern Ontario will come courtesy of a cold front filtering in Monday morning. The heat will also continue, with temperatures not expected to cool off until mid-week.
THE SCIENCE BEHIND A HEAT DOME
Check back as we continue to monitor the forecast.