Midweek System to Bring a Wintery Mix to Parts of Southern Ontario With Prolonged Freezing Rain and Heavy Snowfall
/updated fORECAST
Issued: Wednesday, January 4, 2023 - 1:30 PM
NOTE: You can click on the map to open a zoomable image which will be easier to read.
Based on the latest model data, there has been a shift in the location of the heaviest freezing rain due to the cold air not making it as far south as initially expected. We have updated our forecast to reflect these latest trends in the models.
This now puts the Ottawa Valley and northern parts of Central Ontario in the bullseye for the heaviest freezing rain accretion. The expected impact for the Kawartha Lakes and Kingston region will be lower as they will see more rain instead of prolonged freezing rain.
In addition to the shift in freezing rain risk, we have bumped up the expected ice accretion from 6-12mm to 8-16mm in the hardest-hit regions. This amount of ice is approaching the threshold that we would consider to be significant. However, the limited timeframe of 12-16 hours with freezing rain should limit the worst impacts compared to a more prolonged event. Power outages and icy road conditions will still be a big concern throughout the day and especially into the overnight hours when the freezing rain will be the most intense.
For those further north including Sudbury and North Bay, the story will be a mix of snow and ice pellets. And the rest of Southern Ontario will see between 15-30mm of rain by the end of Thursday.
PREVIOUS fORECAST
NOTE: You can click on the map to open a zoomable image which will be easier to read.
The rollercoaster of a season that has been this winter across Southern Ontario continues after the brief taste of weather we normally see in late fall or early spring rather than in January. This will come in the form of a messy winter system moving across our region over the next few days. Depending on the location, we could be looking at a fairly prolonged period of freezing rain late Wednesday into early Thursday morning for Central and Eastern Ontario. Further north, the story will be a mix of ice pellets and heavy snow with up to 10-25cm of total accumulation.
The impacts from this system will be less of a concern for Southwestern Ontario and the GTA where temperatures will stay above the freezing mark and keep the predominant precipitation type as rain. With rainfall totals ranging from 10 to 25mm, it could pose an issue in areas prone to flooding with the ground being partially frozen and unable to absorb a lot of moisture. This is especially true with all the rainfall that these areas have already received in the past week. There could even be the risk of an isolated non-severe thunderstorm towards the Lake Huron shoreline this evening.
Precipitation in the form of rain is already ongoing throughout the region as of Tuesday afternoon. As temperatures slowly drop late in the evening and overnight, we will see some areas transition over to freezing rain starting with the higher elevations of the Dundalk Highlands and over Algonquin Park. For the overnight and into Wednesday morning, the wintery precipitation will be primarily contained to those regions.
By the afternoon on Wednesday, the below-freezing temperatures will clash with the system over Eastern Ontario leading to the development of an expansive and heavy band of freezing rain. This will start with the Bancroft and Ottawa Valley area during the afternoon and expand southward towards the Kawartha Lakes and Kingston region by late Wednesday. Those on the northern edge of the freezing rain including Algonquin Park, Bancroft and Ottawa will see some ice pellets and wet snow mixing in with the freezing rain by the evening.
The heaviest freezing rain is expected to occur during the overnight hours on Wednesday and early Thursday morning through Peterborough and Kingston along with the Orangeville region. Precipitation will slowly come to an end by the late morning hours on Thursday as the system moves out of the province.
NOTE: You can click on the map to open a zoomable image which will be easier to read.
Here is an advertisement so we can pay other bills:
In terms of the overall impact of this system, it will likely be from the prolonged freezing rain in locations such as Shelburne, Orangeville, Peterborough, Tweed, Kingston and Brockville. Total ice accretion here will range from 6-12mm in the hardest hit regions although some ice pellets mixing in along the northern edge could reduce the actual accumulation. This amount of ice could lead to icy road conditions along with localized power outages and tree damage. Kingston and Brockville in particular could see the worst impact from the freezing rain with some models pointing to upwards of 15mm of ice accretion.
As you go further north, the focus will shift to ice pellets and heavy snow throughout Muskoka, Algonquin Park and the Ottawa Valley. Total accumulation will be hard to measure in this area due to the mix of precipitation but it certainly could cause some poor road conditions. Accumulating snow is possible for Northeastern Ontario with between 10-25cm of snow.
Those regions just to the north of the GTA around Lake Simcoe and into the northern shoreline of Lake Ontario could see some brief freezing rain with 2-6mm of ice accretion. The rest of Southern Ontario will stay on the warm side of this system seeing rainfall totals between 10-25mm.
