Impactful Snowstorm To Bring Up to 20-35cm of Snow to Southern Ontario Between Monday and Tuesday

What will likely be probably the biggest snowfall of the season for many regions across Southern Ontario is on the way between Monday and Tuesday. This same system is responsible for crippling snowfall and ice from Texas and all the way up into the Ohio Valley. The entire states of Texas, Oklahoma and Arkansas are under some form of winter advisory or warning! Here in Southern Ontario, For Southern Ontario, the snow will come in two separate waves starting with some light to moderate snow early Monday and throughout the day with the stronger second wave reaching our region late Monday evening. Very heavy snow and blowing snow is expected overnight into Tuesday morning. Travel should be avoided until later on Tuesday if possible. Widespread school bus cancellations across a wide swath of the region are almost certain which will further delay the return to in-person learning for some students.

We will actually see some lake effect snow around the southern shoreline of Georgian Bay overnight and early Monday morning in advance of this system. It doesn’t look particularly intense and is quite unorganized but locally 10-15cm can’t be ruled out around the Collingwood area even before we get started with the system. The first bands of system snow will spread across Southern Ontario by sunrise on Monday. The heaviest snow with the first round is expected to come down between 6-11 am on Monday with light snow continuing during the afternoon on Monday. Total accumulation by dinner time on Monday will range from 5-10cm just before the second round rolls into the region.

By Monday evening you might begin to think that this storm is amounting to nothing, but the worst is yet to come. Conditions will really begin the deteriorate late Monday evening and into the overnight hours as very heavy snow between 2-4cm per hour encompasses much of Southern Ontario. Strong wind gusts between 40-60km/h and stronger near the shorelines will likely result in blowing snow and localized blizzard-like conditions. Travel during this time will likely become almost impossible with near-zero visibility and rapid snowfall accumulation. If you do have to drive somewhere on Tuesday be sure to leave plenty of time to get to your destination and drive according to the conditions. The later in the day you can delay your trip the better as that will give time for the roads to be cleaned up. Snow will taper off around the noon hour although flurries and some drifting snow will continue to be an issue through the afternoon on Tuesday.

When we combine the accumulation from both rounds, we’re looking at widespread snowfall totals between 15-30cm across much of Southern Ontario by the end of Tuesday. A few localized pockets of between 30-40cm might be found south of Georgian Bay and through the Hamilton/Niagara region. Eastern Ontario will also see similar snow totals between 15-30cm with maybe near 35cm for the Kingston area. Areas to the north through Central Ontario and into Northeastern Ontario will see less snow from this system ranging from 10-20cm near Lake Simcoe and less than 10cm to the north of Parry Sound.

It’s important to note the factor of snow ratios that could affect the total accumulation we see from this system. In general, colder temperatures lead to more snow accumulation with the same amount of precipitation (we’re oversimplifying it here but it’s not important to get in the scientific details for this forecast). If temperatures were closer to the freezing mark with this system we’d be looking at accumulation closer to 10-20cm instead of the 20-35cm that we’re forecasting due to the colder temperatures. This is why some forecasts that use raw model data might be showing less snowfall accumulation than we’re forecasting. Regardless, we will see lots of snow - it looks like it will be closer to 25-30cm of light, fluffy snow instead of 10-15cm of heavy, wet snow.

Later in the week, we’re watching the potential for another system that could bring heavy snow to our region. It’s still several days in the future and lots could change. At this point, it appears to be following a similar track (maybe a little more to the west) with similar strength as the system on Monday/Tuesday. Slightly more moderate temperatures will result in lower snow ratios with this storm though so accumulation between 10-20cm is a fair bet at this point. We’ll continue to go over the latest data and keep you updated on that in the coming days. It’s certainly going to be a snowy week across Southern Ontario!