The stage is set for wild weather across Southern Ontario. Details here.

Ontario: Sunday Storm, Wicked Cold and Shut-down Squalls

Find Your Forecast Search for a location

Chris Scott

Chief Meteorologist

Sunday, January 5, 2014, 2:34 PM -

The stage is set for wild weather across Southern Ontario that will include a Sunday snow/slop storm followed by near historic cold and possible road-closing snow squalls.

The storm

An area of low pressure will develop across Arkansas Sunday morning and move rapidly into Ohio by Sunday evening, spreading heavy precipitation into Southern Ontario later Sunday afternoon into the evening. While some snow will already be falling Sunday morning, the main event is slated to begin Sunday afternoon for southwestern Ontario and Sunday evening for central and eastern regions.

This storm is a guarantee, but the amount of snow vs mix/rain is extremely difficult to forecast for areas close to where the low pressure centre is expected to track. This track will be very close to the GTA and Ottawa meaning that the forecast for cities like Hamilton, Toronto and Ottawa may fluctuate leading up the storm. Whatever the exact outcome in terms of snow vs freezing rain or rain, there will be a hangover into Monday morning’s busy commute in the big cities, so leave plenty of extra time for your drive to work.

The heaviest snow will fall in a stripe from Windsor through London to Barrie and north to Petawawa. Amounts in excess of 20 cm are likely in the hardest hit places – not an epic snowfall by any means, but still significant. The snow shield will extend northwest through the Bruce Peninsula towards Sudbury and North Bay.

To the east is where the messy mix is likely. At this point, the Niagara Peninsula is likely to see snow changing to rain. There may be some freezing rain as well, particularly east of Trenton along the 401 corridor through eastern Ontario into southern Quebec. Fortunately, this will not be an ice storm. Freezing rain is typical with these types of systems, particularly in locations like Kingston, Ottawa and Montreal, but it generally lasts only for only a few hours.

Areas that see the mixed precipitation will not escape the driving impact Monday. Except some icy road conditions to develop by early Monday morning across the GTA as cold air quickly wraps in on the backside of the system. While road crews will have some time to clear and treat roads after the heaviest precipitation falls, it’s likely some roads will still be treacherous for the Monday a.m. commute given the plummeting temperatures.

The cold

The severity of the arctic mass that will follow this storm has prompted school cancellations for Monday across some Midwestern States. While all of Ontario and Quebec will receive this wicked blast of air that is currently descending across the Prairies, the hardest hit region in terms of departure from normal will be southwestern Ontario.

It appears this multi-day cold air outbreak will be among the coldest ever seen in southwestern Ontario as measured by daytime high temperatures and wind chills. The U.S. National Weather Service office in Detroit is suggesting this will be the coldest batch of air in 20 years, and among the top 5 coldest blasts on record.

Wind chills will be severe, particularly Monday pm through Tuesday. Windsor’s all-time wind chill record is -42; this record could be in jeopardy Monday evening. All regions of southern Ontario will be experiencing dangerous wind chills through the day on Tuesday will bitterly cold air and knifing westerly winds. Some relief is expected by later Wednesday as winds ease.

The squalls

Snow Squalls will set up in the traditional snow belts of southern and central Ontario Monday as westerly winds crank behind the departing low pressure system. The hardest hit regions will be east of the Lake Huron and Georgian Bay shorelines from Huron-Perth through Grey-Bruce/Dufferin towards Midland, Gravenhurst and Bracebridge. While significant snow is expected, the main concern is for strong winds which will cause whiteout conditions. Given the extremely cold temperatures, this will become a very dangerous situation in the snow belts, particularly Monday night into Tuesday. Road closures are a strong possibility.

Squalls will linger into Wednesday morning before easing later in the day.