Widespread Snowfall With Strong Winds and Frigid Temperatures on the Way for Southern Ontario; Up to 6-12cm Possible Between Thursday and Friday
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A Colorado Low is expected to impact Southern Ontario beginning Thursday evening bringing with it the threat of widespread accumulating snowfall to some parts of the region. General snowfall accumulation ranging from 6-12cm is expected by the end of Friday. Lower amounts are expected around Lake Erie and Lake Ontario shoreline due to some rain mixing in as temperatures temporarily rising above the freezing mark early Friday morning. We will also see strong wind gusts develop early Friday morning particularly around the Georgian Bay and Lake Huron shoreline reaching as high as 60-80km/h. Blowing snow and reduced visibility is possible throughout the day on Friday.
This system will also serve as a preview of what will dominate the weather story across Southern Ontario the next week starting with bone-chilling Arctic air flowing in behind the system as it moves out by late Friday into Saturday. Very cold temperatures combined with the Great Lakes that are still mostly ice-free will provide the optimal environment for snow squalls to impact the typical snowbelts starting Saturday morning. Current indications suggest these squalls could be quite prolonged and could last all the way into the middle of next week.
The precipitation associated with this Colorado Low will start to enter the province from Michigan sometime late Thursday evening just before midnight. As is usual, Windsor and Sarnia will be the first to be affected which is expected to come down as mainly snow although some data suggest some brief freezing rain could also occur. Precipitation will continue on its eastward trek encompassing all of Southern Ontario south and east of Lake Simcoe around midnight with snowfall continuing throughout predawn on Friday.
As mentioned, temperatures will be very close to the freezing mark as the system ushers in some warmer air just for Friday morning. So some areas mainly through the GTA and Niagra region may see some rain mix in which would reduce the potential snowfall accumulation. This system will also be weakening as it moves across Southern Ontario so by the time it reaches Eastern Ontario around sunrise of Friday, it will mostly be just light snow or flurries. For Southwestern Ontario into the GTA, we’ll see the snow start to taper off late Friday morning with it linger through Central and Eastern Ontario until around the lunch hour. The worst conditions will be found early Friday morning where strong wind gusts could result in some blowing snow and drifting snow. Be sure to leave plenty of time for your commute on Friday, but major impacts like school bus cancellations aren’t expected at this time.
Most areas throughout Southern Ontario will end up with total accumulation between 6-12cm and a few localized pockets picking up as much as 15cm. However, there are a few exceptions such as along the Quebec border, the GTA/Niagara region and around Georgian Bay which will likely not reach the 6cm mark due to the lack of moisture or rain mixing in. Those areas can expect around 2-6cm although those right near the lakeshore may even struggle to get up to 2cm if it comes down as mostly rain.
In the wake of the system, we’ll see temperatures plunge well below the freezing mark overnight Friday setting the stage for a very cold weekend. Many areas will see lows over the weekend flirt with the -20°C mark especially on Sunday and into next week. Extremely cold wind chills will likely be found on several mornings making it feel like below -30°C.
This will all set the stage for what could be a pretty prolific snow squall outbreak off the Great Lakes beginning on Saturday. The threat for squalls will continue on and off all next week as well with the current data pointing to a consistent southwesterly and westerly flow during this time. This would mean areas east of Georgian Bay (Muskoka, Parry Sound) along with northern sections of Grey-Bruce counties will likely be the hardest hit from these squalls. Snow totals this weekend and all next week could exceed 75-100cm in some of these areas although that may change and it depends on if the squalls lock in for a prolonged time. Squalls off Lake Ontario and Erie will mostly affect Upstate New York but with a southwesterly flow, they may drift far enough north to affect the Niagara and Kingston region at times. Wouldn’t be surprised to see some of those areas pick up 10-25cm of snow over the next 5 days.
Of course, the lake effect snow event is still several days away and there’s still a lot of details to work out so this is subject to change. We’ll have a more precise forecast in the coming days including forecast maps but we thought it was significant enough to give a heads up so you can plan accordingly.
