Friday, September 7, 2018, 7:08 PM
The relief from the heat and humidity has arrived across southern Ontario with temperatures struggling to reach the 20°C mark by Saturday. Hold off on swapping in the fall wardrobe however, as the return to a late summer pattern returns by next week.
More on how hot things get, below PLUS a look at how the remnants of deadly Tropical Storm Gordon threatens parts of the weekend with gusty winds and locally heavy rain.
(COMING SOON: 2018 FALL FORECAST AND A SNEAK PEEK AT WINTER. DON'T MISS THIS ALL DAY EVENT ON MONDAY, SEPTEMBER 17)
After more heat records were smashed across parts of southern Ontario this week, a break in the humidity arrived with a passing cold front on Thursday, and Friday featured low humidity and near-seasonal temperatures in the low to mid 20s. By Saturday, things will feel even cooler.
"Saturday will be mostly sunny with temperatures on the cool side of seasonal," says Weather Network meteorologist Dr. Doug Gillham. "High temperatures will struggle to reach 20°C in the GTA and temperatures will remain in the teens across Cottage Country. Quite a contrast to last weekend!"
Despite a quiet start so far, the Atlantic hurricane season is starting to ramp up as we approach the climatological peak, which falls around September 10. After making landfall over the Gulf states earlier this week, the remnants from what was once Tropical Storm Gordon could bring widespread rainfall and gusty winds through parts of Ontario this weekend.
Environment Canada issued a special weather statement Friday covering most areas on and a little inland of lakes Ontario and Erie, including the entire Greater Toronto Area.
"Sunday will start out dry, however, the remnants of Tropical Storm Gordon will approach our region during the day with a rather brisk east wind off of Lake Ontario," Gillham says. "The exact timing is still uncertain, but a widespread soaking rain will develop from south to north across our region. The rain will develop midday near Lake Erie and slowly spread north during the afternoon and evening."
The rain will be heavy at times Sunday evening and overnight, especially across Niagara and the GTA. There's the potential for 25-50 mm of rain for parts of southwestern Ontario and into the Niagara Peninsula through Monday. Winds gusts through Ontario are also expected to gust between 50-70 km/h Sunday evening.
While Gordon's impact on southern Ontario and Quebec is unlikely to be particularly impressive, it's not the first storm to make the journey from the Gulf to our part of the world, and the same can't be said about them. As the map of historical tropical storm and hurricane tracks, below, shows southern Ontario and Quebec see their fair share of leftovers when it comes to tropical activity, even though the region isn't at risk of the direct strikes we sometimes see in Atlantic Canada.
Historical tropical system tracks. Image courtesy NOAA/NHC.
The grey lines in the image represent portions of the track where the storm in question had already diminished to an extra-tropical state, with blue indicating tropical depression strength, and green -- the highest we see here for Ontario -- representing tropical storm strength systems. Note that this map shows only tracks for those storms that came within 200 nautical miles (370 km) of southern Ontario.
Some of the more significant storms to sweep into southern Ontario from the Gulf Coast were Arlene and Dennis, both products of 2005's merciless hurricane season. Another thing these two storms had in common was a stronger starting point; Dennis was a category 3 storm when it made landfall in the Florida Panhandle. Even so, the path across the entire contiguous United States is a rough one for any tropical system, and Dennis was classified as a remnant low by the time it crossed the border near Sarnia, with winds of only around 10 knots (about 18 km/h).
It's no coincidence that the strongest and most memorable tropical systems (or their remnants) that have impacted Ontario and Quebec have been those that made landfall along the Atlantic Coast rather than in the Gulf of Mexico. While the lows have to scale the Appalachians to reach us on this track, it's still a much shorter distance to travel over land, giving storms a better shot to retain their strength, and occasionally even some of their tropical characteristics, by the time they reach the Lower Great Lakes.
Image courtesy NOAA/NHC
Image courtesy NOAA/NHC
Image courtesy NOAA/NHC
The last post-tropical system to skim past southern Ontario was 2017's Nate, which sped by south of lakes Erie and Ontario in early October. That system brought a widespread 15 to 30 mm of rain across southern Ontario.
Check back for updates as we continue to monitor the forecast.
With files from Weather Network meteorologist Caroline Floyd