The Weather Network – A major threat of spring snow targets Ontario this week


Sunday, April 18, 2021, 10:13 p.m. – Forecasters are closely monitoring a low pressure system that has the potential to bring wet snow to much of Ontario by midweek.

Forecasters are closely monitoring an atmospheric pattern that could provide heavy snowfall in April in parts of southern Ontario just as the first buds of the season are approaching flowering.

There are two factors that contribute to this late season snow. The first is a strong cold front that will push south through the region late Monday through early Tuesday morning, putting the risk of scattered showers in southern Ontario.

Temperatures ahead of the front on Monday afternoon are likely to reach the upper adolescence for much of the GTA and the southwest. However, cold arctic air will build up over the region and send temperatures below the season for Tuesday before the main system brews in the United States.

As we head into Tuesday night, the system will begin to move south of the lower Great Lakes. With the help of the cooler air in place, this system will have the potential to release snow, possibly significant amounts, in parts of southern Ontario.

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Many factors will determine which communities end up in the thickest strip of snow. Terrain is a major consideration, as areas along the escarpment and at higher elevations will have the potential to see greater amounts of snow. The other factor will be whether the trajectory of this low is shifting and redirecting precipitation.

The trajectory of the low will be essential in determining who will suffer the greatest impacts from this winter system. There are many forecast models that The Weather Network monitors closely to estimate which areas will see the most snow. Here are two notable scenarios to consider.

As of Sunday, Scenario A indicates that the heaviest snow could fall near and north of the Highway 401 corridor.


Alternatively, Scenario B takes the heaviest snow across the Niagara region and the southwestern parts of the GTA. Both models indicate that the heaviest snowfall amounts will vary from 5cm to over 10cm by Wednesday morning.


Given the variation in forecasting models, it is too early to determine the amounts of snow for each city that will be impacted by precipitation. However, temperatures will support the potential for wet snow accumulation on the ground until Wednesday morning, which is bad news for anyone who has been cradled early in their gardens by the unusually warm temperatures of recent weeks.

“Some orchards are already in bloom in Niagara. This could be devastating for many orchards, especially apricots and maybe cherries,” said Dr Doug Gillham, meteorologist at The Weather Network.

We will be watching this potentially snowy system very closely as it approaches. Check back for updates in the meantime.

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