02/27/2023
**February 27-28 WINTER SYSTEM UPDATE**
ISSUED: Sunday, Feb. 26, 2023 - 11:30 PM
Déjà vu, anyone? After reviewing the latest model data on the upcoming system for Southern Ontario, it looks like the colder air will win over across much of the region. We have adjusted our forecast moving the heavy snow zone further south into Central and Eastern Ontario. The freezing rain risk now covers an almost identical area as last week's storm with the heaviest icing expected across Sarnia through London and into the Hamilton/Niagara region. For the rest of Southwestern Ontario and into the GTA, we are looking at a mixed bag of precipitation including brief freezing rain, ice pellets and snow.
The timeframe of this winter storm is fairly similar to our initial forecast with precipitation expected to start during the late morning hours in Deep Southwestern Ontario and spreading northward throughout the afternoon. It will likely begin as freezing rain in the Windsor/Chatham region before transitioning over to rain as temperatures rise above the freezing mark by the dinner hour. As mentioned, those in the Sarnia, London and Hamilton corridor will see more prolonged freezing rain during the afternoon and evening where the cold air is expected to hold on.
We are also looking at a big impact on the evening commute as heavy snow and ice pellets affect the Golden Horseshoe starting during the late afternoon and continuing through the evening. There is still some disagreement on the exact temperature in this area, especially closer to the shoreline of Lake Ontario which would dictate the main precipitation type. Current indications suggest it should start as some heavy wet snow before transitioning over to ice pellets and even some freezing rain. Later in the evening and overnight, there is the potential that temperatures climb above the freezing mark around the shoreline leading to a transition over to rain.
For Central and Eastern Ontario, snowfall will start during the early evening hours, continuing throughout the overnight and into Tuesday morning. Strong to damaging wind gusts may also accompany this system with gusts expected to reach 60-80km/h by late Monday and may even come close to 90km/h east of Lake Huron. This could lead to power outages in the areas that received heavy freezing rain earlier in the day and blowing snow for those further north.
Everything will come to an end by Tuesday afternoon as the system moves out of our region. Total snowfall accumulation across Central and Eastern Ontario is expected to range from 10 to 15cm with some localized pockets (especially in the Ottawa Valley) picking up to 20cm.
The icing from this event isn't expected to come near what we saw last week, but up to 4-8mm of ice accretion is possible in the hardest-hit region. Those in between the snow and freezing rain including much of Southwestern Ontario into the GTA will see a bit of everything so the exact totals are difficult to predict depending on the exact temperature.
- Brennen P.
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