The First Snowstorm of the Season Takes Aim at Parts of Northern Ontario This Weekend (Oct 16–18) With Up to 20cm of Snow Possible

It was only the beginning of the month when we were talking about Northern Ontario’s first snowfall and Mother Nature isn’t wasting any time in bringing wintery weather to the province. The first appreciable snowfall event is quite likely over the weekend with a combination of lake effect snow and an Alberta Clipper that could bring widespread snow totals between 10-15cm and locally up to 20cm.

Brief heavy bursts of flurries have already developed Friday afternoon east of Lake Superior and is expected to become more organized as we head into the evening and overnight hours. These bands of snow will be focused on an area between Sault Ste. Marie and Wawa along the Trans-Canada Highway into Saturday before tapering off before noon due to the approaching Alberta Clipper from the south. Total accumulation from the lake effect snow could approach 15-20cm in the hardest-hit area but it will be extremely localized. The surrounding region can expect maybe a few centimetres at most.

As the Alberta Clipper slides into the region, we’ll begin to see light to moderate snowfall develop during the early afternoon on Saturday. This will continue throughout the day and into the overnight hours with the heaviest precipitation extending from Thunder Bay through to Geraldton. The system will slowly move out of the province and over James Bay early Sunday morning with snowfall ending starting with those along the US border and fully done by Sunday afternoon.

As far as accumulation, we believe the highest totals will be found in the Thunder Bay and Geraldton region with between 12-20cm possible by the end of the day on Sunday. Other nearby regions including Atikokan, Armstrong and Marathon can expect between 6-12cm with some localized areas coming close to 15cm. The rest of Northern Ontario (excluding the above-mentioned lake effect zone) will see less than 5cm from this system. Keep in mind that temperatures are very close to the freezing mark and that can have big implications on how much snow sticks to the ground. Our forecast assumes no melting so in some areas the actual accumulation may be lower than the forecast.