Severe thunderstorm watches and warnings end for GTA, southern Ontario

NATASHA RAMSAHAI | posted Wednesday, Sep 15th, 2021

Environment Canada’s severe thunderstorm watches and warnings have ended for southern Ontario, including Toronto and the GTA.

Tornado watches were also issued during the evening hours but ended around 10 p.m. Tuesday.

Meteorologist Natasha Ramsahai explains that a cold front in the region has been the trigger, setting off storms north of the GTA, including cottage country, on Tuesday afternoon. The environment was primed for storms in a warm sector, behind a warm front that increased temperatures and humidity through the day.

Once the cloud cleared in the afternoon, heating from the sun added extra energy to get the storms going to the north. This added energy helped to intensify the updrafts and downdrafts within the storms, resulting in very large hail.

Winds at the surface were coming out of a different direction than winds aloft. This was the “shear” needed to add the “twist” to some of these storm cells, resulting in tornado watches and warnings in the evening hours.

As the line of storms sinks south into the GTA through the night, there will be less daytime heating, but they will still pack a punch with rain and wind.

Gusts over 70 to 90 kilometres per hour are possible for the south GTA region and up to 100 kilometres per hour for the north GTA region as they pass through Tuesday night, especially if the line of storms starts to form a “bow echo,” which is a curved line on radar.

There is still a chance for hail in the GTA but it may be smaller than what we saw earlier in the day to the north.

Watch Meteorologist Natasha Ramsahai’s update as of 8:30 p.m. Tuesday night below:


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