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Ontario: Thunderstorm risk, and what's beyond it

Thursday, March 14th 2019, 10:11 pm - Severe thunderstorm risk spilled somewhat into Ontario Thursday, courtesy of a Colorado low that also sent temperatures soaring

Ontario enjoyed its warmest day in weeks Thursday, though also marked by periods of rain, and a thunderstorm risk that sparked some severe storms in the evening for parts of the southwest. We break down what you need to know about what's beyond this dynamic system below, plus a look at the "significant interruption" to the milder pattern coming next week.

Visit our Complete Guide to Spring 2019 for an in depth look at the Spring Forecast, tips to plan for it and much more


WEATHER HIGHLIGHTS

  • Rain largely tapers off by Friday morning across the south
  • Chance of late-night thunderstorms for the southwest
  • Cooler air arrives late Friday, chance of a few flakes here and there
  • Keep on top of severe weather warnings here.

WATCH BELOW: PRECIPITATION OUTLOOK

MID-MARCH THUNDERSTORM THREAT

The combination of the Colorado low and strong cold front that will pass Thursday night may also fuel something uncommon for mid-March: A few rumbles of thunder!

SevereriskON

Most storms that spark are expected to be non-severe in nature, though the threat of an isolated severe storm, and indeed severe thunderstorm warnings were issued for communities on and around the Bruce Peninsula after 8 p.m., and the Goderich area after 9 p.m.

"Damaging winds will be the primary threat with this type of set-up," Hamilton says.

Though the rain will have largely ended by Friday morning across most of Ontario aside from some pockets of the north, the moderate amounts that did fall, combined with temperatures above zero, may make for localized flooding to close out the week, particularly in watersheds prone to ice jams.

"10-20 mm of rain may not seem like a lot, but when you have the amount of snow on the ground like the Ottawa Valley and parts of eastern Ontario currently do, it's definitely raising a few red flags for what could be a significant flooding season," Weather Network meteorologist Tyler Hamilton says.

HEAVY SNOW IN THE NORTH, SOUTHERN ONTARIO NOT IN THE CLEAR EITHER

Snowfall warnings were in effect for parts of northwestern Ontario Thursday, with 20+ cm expected, along with local blowing snow. There will still be a few flakes to fall by Friday morning for areas furthest north.

"Prepare for quickly changing and deteriorating travel conditions," warns Environment Canada. "Visibility may be suddenly reduced at times in heavy snow."

Baron Ontario Snow 19-03-13

The snowfall totals will vary quite a bit due to the rain and warm air around Lake Superior, but the heaviest amounts will fall in areas north of Armstrong.

COOLER WEATHER RETURNS

After the two days of milder weather to end March Break, a significant interruption to this spring-like pattern is expected.

"By Friday afternoon, the snow is back in the picture for southern regions," Hamilton says. "So you go from mid-teens back to snow showers in this dynamic spring-like set up in Ontario."

ONSaturday

A cooler pattern will continue through much of next week, although most places will still be nearly 10 degrees milder than the first 10 days of the month.

"While consistent warmth has been delayed, we still expect a milder pattern will develop for the final week of March and trend even milder for the first half of April," adds Michael Carter, another meteorologist at The Weather Network.

GET THE KIDS OUT: A MARCH BREAK AT ONTARIO PLACE MIGHT BE THE TICKET

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