Ice storm continues to slam into southern Ontario

April 15, 2018

This weekend's ice storm is spreading across the region, with widespread power outages, hundreds of cancelled flights, localized flooding and treacherous travel conditions, it makes sense it's being labelled as "historic," by Environment Canada.

By early Sunday morning, southern Ontario was under widespread freezing rain warnings. However, rainfall warnings were being issued from Windsor through the Greater Toronto Area.

At the height of the storm, over 15,000 Hydro One customers were without power. The Ontario Provincial Police reported the responded to over 400 crashes in the GTA, according to OPP Sgt. Kerry Schmidt. Winds were powerful enough in Hamilton to knock over a large commercial sign and seriously injure a man. He was rushed to a hospital where he remains in critical condition, according to CBC Toronto.

The storm, which brings with a myriad of concerns across higher flows and water levels, may result in potential flooding and hazardous conditions. The shoreline of Lake Ontario is another concern as large waves, some of 2 metres in height, and biting east winds will bring the surge to areas, especially on the western end of the lake. It is advised to avoid shorelines at all costs.

Highlights

1. Across southern Ontario, freezing rain warnings are in effect. We expect these to continue throughout today.

2. Rainfall warnings are also in effect for Sunday night throughout the southern Ontario from Windsor to the GTA.

3. Through the worst-hit areas, 20 mm of freezing rain is expected to wreak havoc. This total has been upped from our last report.

4. Along with the freezing rain, strong winds — combined with ice-laden trees and power lines — will likely result in widespread power outages.

5. Travel is inadvisable for many regions across Sunday. As we said, please avoid unnecessary travel today. Toronto Mayor John Tory said it himself, "if you don’t need to travel today, please stay in or take transit."

6. Heavy rain will likely move into the region on Sunday evening — and possibly overnight. It is raising major flooding concerns.

7. Potential snow on the back edge of the system could mean a fairly messy Monday morning commute for the region. More on that below.

Sunday

It gets better after Sunday. We promise.

The worst of the storm is expected on Sunday. This is due to an influx of moisture straight from the Gulf of Mexico, which is super-charging the core of the system, as it slides through southern Ontario. Freezing rain and ice pellets will surge back into the region through the morning — while winds remain strong — and will cause widespread power outages.

The Weather Network is forecasting that a changeover to rain is expecting to begin in southwestern Ontario through the late morning hours of Sunday. It is expected to creep its way through to the Niagara region — and the Golden Horseshoe — by around noon. Entrenched cold air, which is away from the lakeshore, however, is raising concerns over how fast the changeover happens further inland from Lake Ontario.

"We are increasingly concerned that the temperature will really struggle to climb above zero north of the 401 corridor, especially above the escarpment," The Weather Network's Dr. Doug Gillham said. "If the temperature does not rise above 0ºC in these areas until tonight, we will see substantial ice accumulation and a heightened threat for damage to trees and power lines. In addition, the east wind will be gusting 60 to 80 km/h through the day, adding to the strain on trees and power lines," he added.

Sunday Night

Although it may seem that the freezing rain would never stop. It will.

Freezing rain will likely give way to heavy rain, sweeping into the GTA through the evening hours, while continuing for the southwest. Thunderstorms are possible at times, mainly from Windsor to London, while this will serve to enhance rainfall totals, they are not expected to be severe in nature, however, this may change. (Cold air from the north and warmer air from the south will play a game of tag; attempting to cause unstable conditions in the atmosphere, which will be conductive to some strong thunderstorms.)

The soaking rain, however, is causing concerns regarding flooding. This is particularly a concern in low-lying areas and along waterways. The Toronto Region Conservation Authority has issued a flood watch for the city of Toronto, in effect until Tuesday.

In cottage country, warm air will continue to eat away at the cold throughout the overnight hours, making way for an eventual changeover to rain for Grey-Bruce and Barrie, however, it may take until Monday morning for the frozen precipitation to stop entirely, particularly over high terrain areas such as the Oak Ridges Moraine and the Kawartha Highlands.

Monday

The flow of moisture, from the Gulf of Mexico, will likely start to ease through the overnight hours, with the coming of the cold front, with rain expected to taper off over extreme southwestern Ontario by dawn, and with drier air moving into the London area by mid-morning.

With the coming cold front, we're watching another return to cold air from the northwest. This cold could clip the remaining moisture eating out of the GTA and central southern Ontario and make a quick blast of snow on the back edge of the system. Any accumulations will be light, however, a quick return to the cold air could mean icy roads and poor driving conditions for the afternoon commute for parts of the GTA — particularly north of Toronto — and the Niagara region.

Central, Eastern Ontario

As southern Ontario deals with this significant storm system, a nasty swath of snow is expected to persist across much of central and eastern Ontario into Quebec. (The Weather Network has issued a specific forecast for this region here.)

With files from The Weather Network.

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