Christmas Winter Storm to Bury Parts of Southern Ontario in Up to 20-40cm of Snow; Prolonged Freezing Rain and Heavy Rain Through Eastern Ontario
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TIP: A ZOOMED-IN VERSION OF THE MAP CAN BE FOUND FURTHER DOWN THE ARTICLE.
TIP: A ZOOMED-IN VERSION OF THE MAP CAN BE FOUND FURTHER DOWN THE ARTICLE.
Santa won’t be the only one hard at work overnight into Christmas Day as Mother Nature is also expected to pay a visit to parts of Southern Ontario resulting in a very White Christmas as you wake up on Christmas morning. And it won’t be just a dusting… In fact, this will probably be the snowiest Christmas for Southern Ontario in recent memory! Current data indicating the potential for widespread snowfall totals between 10-25cm by the end of Christmas Day with up to 40cm through the snowbelts thanks to some lake effect snow that will develop later in the day. Unfortunately, this Christmas miracle won’t be seen in Eastern Ontario with prolonged freezing rain through the Bancroft area and heavy rainfall through the Ottawa Valley. The freezing rain threat could threaten holiday celebrations (within your own household) in the affected regions with the potential for power outages.
TIMING
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TIP: YOU CAN CLICK ON THE IMAGE TO OPEN IT IN A NEW TAB AND BE ABLE TO ZOOM INTO THE GRAPHIC.
TIP: YOU CAN CLICK ON THE IMAGE TO OPEN IT IN A NEW TAB AND BE ABLE TO ZOOM INTO THE GRAPHIC.
TIP: YOU CAN CLICK ON THE IMAGE TO OPEN IT IN A NEW TAB AND BE ABLE TO ZOOM INTO THE GRAPHIC.
Precipitation has already been occurring across Southern Ontario during the afternoon on Christmas Eve and many areas have transitioned over from the light rainfall to wet snow. At this point, accumulation has been quite light but that will change as we head into the evening and overnight. Heavier bands of precipitation will enter the region just after the dinner hour continuing past midnight and into the early hours of Christmas. Except for Eastern Ontario, the precipitation will come down in the form of heavy snowfall. Ice pellets may mix in through the Kawartha Lakes, Haliburton and Algonquin Park area early Christmas morning.
Eastern Ontario will mainly see heavy rainfall into Christmas Morning with the potential for several hours of freezing rain overnight through the Bancroft and Barry’s Bay area. Most of the precipitation will clear by late Christmas morning but will persist around Lake Huron and Georgian Bay as some lake effect snow develops. While we have snowfall occurring all day on our timing map for most areas, this doesn’t mean it will be occurring the whole time. We’re just showing the likely precipitation type if there is precipitation but the flurries will be scattered.
ACCUMULATION
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.Generally, we can expect around 15-25cm of snowfall accumulation from the storm which includes London, Kitchener/Waterloo, Western GTA into the Hamilton and Niagara region. Around Lake Huron and Georgian Bay is where the forecast becomes tricky because we start to mix in some lake effect snow (which could be quite intense in some areas) especially towards later in the day of Christmas Day. This could lead to locally up to 40cm and perhaps, even more, when you combine the system and lake effect snow totals.
The area that has the best chance for these totals include just to the northwest of London through Grand Bend and Strathroy along with the Northern Simcoe County and Muskoka regions. Not everyone within the 20-40cm zone will see the lake effect snow so they’ll just receive the general system snowfall around 20-25cm which is why we have such a large range. For the City of Toronto and Eastern GTA, we’ll see some ice pellets and wetter snow from this storm which will lead to lower snowfall totals around 10-15cm with even less as you head out into Oshawa and the Kawartha Lakes area.
Do note this is very dependent on temperatures and if it’s slightly colder then these areas will see more snow and get way more snowfall accumulation than forecasted. Extreme Southwestern Ontario like Windsor and Sarnia will see less snowfall as well ranging from 5-10cm although it’s possible that they even see less than 5cm depending on the track of the system. Lake effect snow will likely linger into the weekend so we’ll be continuing to monitor that and issue more forecasts as needed.
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Further east, the story will become the heavy freezing rain risk that extends from northeast of Oshawa through Bancroft and into the Barry’s Bay Area. Between 6-12 hours of heavy freezing rain is possible in this region which may lead to power outages and ice to accrete on untreated surfaces. Total ice accretion ranging from 6-12mm is expected in the hardest-hit regions and the impacts of this ice build-up will likely extend into the weekend with little potential for melting afterwards. Thankfully, the wind is expected to be fairly light so this ice storm should be fairly insignificant compared to what this area has seen in the past. could cause some issues if you were planning on cooking Christmas Dinner and there is no power due to the freezing rain.
More details on how to prepare for an ice storm can be found here:
Eastern Ontario will be asking ‘what storm?’ as they’ll experience a much different Christmas than the rest of the province with heavy rainfall ongoing and expected to continue into Christmas Day. Rainfall totals will range from 30-50mm which is a pretty significant amount in the middle of winter so flooding is possible in some areas.
From the Instant Weather team, we wish you a happy and safe Christmas and holiday season. We will be here over the next few days bringing you all the updates you’ll need to stay informed during this storm!
