Difficult travel days as more lake-effect snow targets Ontario, risk of 30+ cm
Locally heavy snowfall with total accumulations of 30 to 40+ cm kick off the work week in Ontario. Snow squall warnings are in effect
Several systems and the Great Lakes will work together to generate multiple bouts of snow across Ontario this week. Prepare for some travel delays and deteriorating conditions, with the risk for 30-40+ cm of snow in some of the harder-hit areas.
A stalling low over Lake Superior will give big totals downwind of some of the Great Lakes. Meanwhile, a stubborn low will linger over Lake Ontario into Tuesday, bringing periods of unsettled weather at times.
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Expect slower, slippery commutes this week, even with the lighter amounts expected across the Greater Toronto Area (GTA).
With most of the Great Lakes free of ice, the warmer surface water continues to provide instability to sustain low-pressure systems, keeping them borderline stationary.
The stronger jet stream remains farther south, so Lake Superior will continue to inject heat and moisture into the atmosphere, making the low appear anchored over the area.
More squalls pick up Tuesday through Wednesday
On Tuesday, lake-effect snow will continue thanks to the colder air overhead, spilling into Wednesday.
As a trough moves through and shifts the winds from west to northwesterly, the snow squalls will be pushed south Tuesday afternoon, which could bring a burst of flurries to parts of the GTA, as well.
Snow squalls will then continue off Georgian Bay and Lake Huron, targeting some different areas. Meaford to Wasaga Beach will see squalls off of Georgian Bay, and then from Grand Bend to the Saugeen shores off of Lake Huron.
The worst impacts will be largely in the snowbelts and across northern Ontario, where travel will be locally challenging.
"Snow squalls cause weather conditions to vary considerably; changes from clear skies to heavy snow within just a few kilometres are common," says Environment and Climate Change Canada (ECCC) in the snow squall warning. "Rapidly accumulating snow could make travel difficult over some locations."
Temperatures will become quite cold for the middle of this week, but then will rebound late week and on the weekend to near-seasonal values.
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A rather cold, wintry pattern is expected into the fourth week of January, but a much milder pattern should develop for the first two to three weeks of February, potentially starting during the final few days of January.
