Wednesday, October 28th 2020, 8:49 pm - We couldn't quite get through October without some first flakes of the season, and now the coldest air in months is set to spread into southern Ontario.
After an early-season appearance, cottage country and eastern Ontario face the lingering threat for more snow and lake-effect flurries as temperatures plunge even further by Thursday. In fact, these will be some of the coldest conditions since May, with the potential to set records for the frigid weather early next week. More on the blast of frosty air, plus a look at the track of Zeta and its tropical influence on the region, below.
- Broad upper trough over the Great Lakes maintains instability over the region
- Remnant moisture from Zeta approaches southern Great Lakes Thursday, chance for some showers in the Niagara region.
- Chance for snow squall event Sunday night into Monday
THURSDAY: NORTHERN EDGE OF ZETA REMNANTS APPROACH THE SOUTHERN GREAT LAKES, LIMITED IMPACT
Hurricane Zeta made landfall along the central Gulf Coast of the U.S. as a Category 2 hurricane Wednesday late afternoon. Beyond, it will rapidly lose strength as it tracks inland toward the northeastern U.S. Thursday and Friday.
Initial models showed some chance the storm's remnants would deliver some moisture to southern Ontario. The latest forecast now has the remnants of Zeta remaining further south than initially expected, though we can't rule out the chance of rain showers scraping extreme southern sections of the province, most likely along the shores of Lake Erie and into the Niagara region, through the day.
Given the temperatures, we also cannot rule out the chance of a rain/snow mix for those areas Thursday night into early Friday.
FRIDAY: COLDEST TEMPERATURES SINCE MAY
Clouds look to give way to sunshine from west to east across southern Ontario Friday morning, but to indoor observers, it will be deceptive. Blustery conditions, driven by a gusty north wind, will bring the coldest air of the season so far.
A northeast flow off of Lake Ontario Friday could also stir up some lake-effect flurries across the Niagara region through parts of Friday.
Overnight lows on Friday will dip below freezing, the first time for major cities including Toronto and Hamilton. In fact, a low temperature of -3°C hasn't been reported at Toronto's Pearson Airport since May 13 of this year.
Temperatures will rebound slightly into Saturday, making for a sunny, but still chilly, Halloween day.
TWO TROUGHS SET TO STIR UP TROUBLE IN THE ATMOSPHERE, RARE EVENTS EXPLAINED
SUNDAY INTO MONDAY: ANOTHER COLD FRONT WITH BANDS OF LAKE-EFFECT SNOW
The origin of what could be the first widespread shot of lake-effect snow for southern Ontario's traditional snow belts is already brewing in the West: A low-pressure system gradually tracking toward Ontario through the late week.
It's set to bring rain and snow to the northwest and Nickel Belt, while its cold front will pass through southern Ontario. Showers will be relatively widespread through the day Sunday, but the cold front looks likely to trigger the lake-effect snow machine, bringing bands of snow streaming inland from Lake Huron and Georgian Bay Sunday night through Monday.
This set-up could have quite an impact on travel through the snow belts, especially if the squalls sit over one area for an extended period of time.
WARMING THROUGH EARLY NOVEMBER
Next week will start on another cold, and potentially record-breaking note, as cold air crosses the Great Lakes Sunday night and into Monday. Temperatures aloft will be more typical of mid-to-late December, with a record cold high temperature of just 2°C forecast for Monday in Toronto.
It won't take long, however, for the warmer weather to nudge back in.
"An extended period of near to above seasonal temperatures are expected through the second week of November with temperatures more typical of mid-October," says Weather Network meteorologist Dr. Doug Gillham.
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