More rain on the way could mean more flooding for recovering Toronto

Toronto residents were bracing themselves for a possible repeat of Monday's wild weather today, as all of southern Ontario is was under a Severe Thunderstorm Watch, and the watches were being upgraded to warnings as storms moved into the province from Michigan.

After the deluge of rain on Monday night, that caused flash flooding throughout the GTA, there was a bit of a break on Tuesday and through most of the day today, which let the metro area at least start to pick itself up and dry off. However, with the ground still saturated and waterways still swollen from all the rain, word of more storms on the way was not welcome news to those still trying to recover.

Environment Canada had issued Severe Thunderstorm Watches for regions right across the southern part of the province this morning, from Windsor to Ottawa and north into the Parry Sound/Muskoka and Algonquin areas. However with most of the activity sticking to southwestern Ontario and along Lake Ontario into eastern parts of the province, most of the watches further north were called off this afternoon.

With both bands of storms and individual storm cells tracking across southwestern Ontario — moving from the shores of Lake Huron to Lake Erie and Lake Ontario — the watches were progressively upgraded to Severe Thunderstorm Warnings as these storms make their way through. Regions around Windsor, London and Kitchener-Waterloo, Hamilton and Niagara, and even parts of the GTA have gone from a watch up to a warning, and then back down to a watch after the storms passed, but the threat for more still remains.

As of this evening, the storms have moved off into eastern Ontario and southwestern Quebec, with the severe thunderstorm warnings following along, and the weather watches being called off in southwestern and central Ontario.

Severe thunderstorm warnings are currently in regions from north of the eastern end of Lake Ontario, through Gananoque and Cornwall, and into regions around the Montreal metro area and north to Lac-Saint-Jean.

Residents in the Ottawa area were treated to some impressive views of the coming storms:

The watches and warnings are advising of the possibility for heavy downpours that could deposit up to 50 mm of rain in just an hour, powerful winds of up to 100 km/h and hail stones from 2 cm to 4 cm wide (about marble-sized to ping-pong-ball-sized).

Reports of rain and hail came in over Twitter , and some storm damage has been reported in the Guelph area, as strong winds brought down some utility poles:

[ Related: Toronto storm sets rainfall record amid flash flooding, traffic chaos ]

The city broke records on Monday, including the all-time daily rainfall record, that had stood since Hurricane Hazel slammed the city with days of rain back in October of 1954. 126 mm of rain fell at Pearson Airport on Monday night, beating out Hazel's day-long contribution of 121 mm from 59 years ago. The other weather stations in the Toronto area recorded between 68 mm of rain (at the G. Ross Lord Dam, on the Don Valley River) and 97 mm (at Toronto City station near Queen's Park).

Dave Phillips, Environment Canada's senior climatologist, told The Canadian Press: "It is really, probably the most intense, wettest moment in Toronto’s history. It's almost like Toronto was a target with a bull's-eye."

These record rainfall amounts set off flash flooding that made the evening commute a nightmare, stranding vehicles on roads suddenly turned into rivers and lakes, and trapping over a thousand passengers on a GO Train for nearly 7 hours.

Blackouts across the GTA made the situation even worse, and Toronto Hydro is reporting that approximately 300,000 were without power at the peak of the event, and there are still an estimated 600 customers still without power as of this evening. Rolling blackouts made life difficult for around 50,000 of their customers on Tuesday, though, as Toronto Hydro responded to a Hydro One request. Those rolling outages were lifted Tuesday night, but it's possible they may need to resume if demand stays high.

Toronto Hydro is still requesting that residents of the GTA limit their power usage. They recommend turning off all non-essential lighting, setting thermostats at 25°C (or higher if you're not going to be home), and closing curtains and blinds to keep the sun out. They also recommend cooking outdoors on the barbeque, or using a microwave oven (as that draws less energy than a stove top or conventional oven). Especially helpful is saving activities like as clothes drying and dishwashing until after 8 p.m., when demand is lower (as well as rates!). They also remind that since most electronic devices still draw power when they're plugged in ('stand-by mode'), unplugging any non-essential electronic devices will go a long way towards helping the situation.

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Some relief from the heat and humidity is in sight now, as forecasters are expecting this passing cold front to bring cooler, drier conditions behind it. The front is expected to pass through southwestern Ontario this afternoon, and be moving through eastern Ontario by this evening.

(Photo courtesy: REUTERS/Mark Blinch)

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