Toronto is in the midst of getting hit by a massive rain storm, with totals reaching as high as 75mm of precipitation (some reports have as much as 90mm fallen at Pearson Airport). A procession of powerful thunderstorms is currently working its way through the GTA, causing localized flooding, power outages, and frowns all round.

Right now, the TTC says the subway system holding in key areas due to a series of signal and flooding issues. There are pockets which remain in use on the YUS line and the Bloor-Danforth line is running between Jane and Kennedy, but much of the system is shut down. There are also widespread reports of flooding at Union Station.

Streetcar service may be affected due to surface flooding but there are no reports of any issues with power. There are also reports of flooding on the DVP, 401, and several other major roads, including Lake Shore and Esplanade.

Widespread power outages have been reported in Toronto, while reports indicate that 70 per cent of Mississauga is without power. Both Square One and and Sherway malls have been evacuated due to flooding.

Pictures began to surface almost immediately of cars stranded in flooded underpasses, burst storm drains spewing geysers, and general soaking misery for thousands of rush-hour commuters. Here are some preliminary photos of the storm, with more to come shortly.

Add your photos of the storm to Instagram with the hashtag #drenchedTO.

UPDATE: 19:36

TTC: Yonge-University-Spadina line is closed Davisville to St. Clair West, Osgoode to Bloor, Lawrence to Finch, Bloor-Danforth is down from Ossington to Kipling, and there's no service on the Sheppard line.

ROADS: Disaster, frankly. Too many local floods to count. DVP is closed south of the Bloor/Bayview exit and cops are turning cars around, Allen Road is closed at Eglinton, Lake Shore is a mess, Bayview is closed south of Pottery Road, King is reportedly bad around Atlantic Ave., and a large portion of Highway 427 is a lake.

HYDRO: Current estimates are 300,000 without power in the GTA.

WEATHER: Rain is easing right now but more is in the forecast. Here are some current rainfall levels: 92 mms at Pearson, 90mm downtown, 107 mm reported in places. The one-day record is 121 mm at Pearson and the CBC says that could go with this next wave.

UPDATE: 19:55

Reports now of a trapped GO train south of Pottery Road on the Richmond Hill line. Pictures show water rising through the train. Pictures below.

Toronto Police, not surprisingly, are advising people avoid traveling and warn to steer clear of rivers and streams. Waters are extremely unpredictable.

UPDATE: 20:15

Rob Ford on CBC Radio: "We have to batten down the hatches and do the best we can." Says call 311 for non-emergencies, 911 for emergencies. "I don't want to say this is scary but it's getting very uncomfortable right now," he added after seeing some flood damage. "It's a major concern."

"Stay at home and take care of people who might be vulnerable"

UPDATE: 20:20

Pictures now emerging of commuters swimming away from GO train trapped in the Don Valley. Marine unit responding.

More rain on the radar - weather reports say it won't be as heavy, possibly another 10-20 mms. Should be here in around 30 to 40 minutes.

UPDATE: 20:33

TTC: No service on Yonge-University-Spadina from Downsview to St Clair West, Osgoode to Bloor, Lawrence to Finch. Bloor-Danforth down Ossington to Kipling, Sheppard Line still shut. Shuttle buses on routes. TTC's Brad Ross: "It will be slow."

GO TRANSIT: Reports of trains trapped in several locations. Staff say avoid the service until further notice.

AIRPORTS: Porter has cancelled all flights out of Billy Bishop this evening. Some cancellations at Pearson though getting there will be one of the biggest issues for travelers.

ROADS: Avoid, avoid, avoid. DVP closed south of York Mills, floods on Highway 427, 401, and Allen Road. Still lots of local floods, too. Traffic lights are out at numerous intersections across the city - treat these intersections as a four-way stop.

POWER: Toronto Hydro says around 300,000 still without power. Crews assessing damage.

UPDATE: 20:56

FORD: 30 minutes ago the Toronto Sun's Don Peat reported the mayor was in his SUV with the AC running. Power is out at his Etobicoke home.

UPDATE: 21:00

TTC: Service is back on the Bloor-Danforth line west to Jane. Problems on the Yonge-University-Spadina and Sheppard lines still as reported earlier. 501 Queen streetcar is turning back at the Humber loop due to flooding at Parklawn. 504 King is out between Roncesvalles and Shaw due to flooding. 65 shuttle buses in service right now.

ELSEWHERE: Drake Hotel's Calgary Flood benefit is cancelled due to flooding, says @SallySalmon on Twitter.

UPDATE: 21:10

ELSEWHERE: Doug Ford is directing traffic at Dixon and Islington, reports CBC's Steven D'Souza on Twitter. Picture below.

UPDATE: 21:14

WEATHER: It's still raining steadily in the GTA - no sign yet of any issues related to the predicted next wave of storms. Here's the latest radar image. In short, more rain to come.

UPDATE: 21:25

GO TRANSIT: The Toronto Police Marine Unit is helping evacuate passengers off that stranded GO train near Pottery Road. Here's what their website has to say:

"Lakeshore West Passengers: A portion of the track west of Long Branch is completely under water, making us unable to operate trains along the Lakeshore West line. We are investigating alternatives and an update will be provided as information becomes available."

"As our trains run from west to east, Lakeshore East Passengers will experience delays and possible cancellations this evening. Updates will be provide as they become available."

"Weather conditions and the resulting traffic delays are affecting our GO Buses this afternoon. GO Buses are experiencing delays of up to 60 minutes."

UPDATE: 21:50

TTC: CEO Andy Byford speaking on CP24 says the TTC will "do its damnedest to get everyone to work tomorrow." Signals and other electrics need to be inspected before subway service can resume. Looks like the commute could be rough in the morning.

GO TRANSIT: Marine Unit still helping EMS workers evacuate passengers in the Don Valley. No reports of any injuries though there's plenty of frustration. The train has been stuck for more than four hours.

WEATHER: Severe thunderstorm watch for the GTA has now ended. Rain still in the forecast.

UPDATE: 22:06

POWER: The lights are starting to come back on in Mississauga and Vaughan. Hooray!

UPDATE: 22:19

GO TRANSIT: Despite CP24's best efforts to amp up the drama (they have seriously likened the train to the Titanic) most of the people being ferried off the stranded cars by dinghy are in good spirits. There were reports earlier that a water snake was seen on the train but that appears to be the height of the action.

UPDATE: 22:28

WEATHER: Things seem to be settling down so now seems to be a good time to take stock of some rainfall numbers as of 10:30:

PEARSON: 123 mms

CITY: 91 mms

ISLAND: 84 mms

OSHAWA: 4 mms

Some perspective: During Hurricane Hazel, Toronto's Pearson Airport (or Malton as it was then) experienced 107 mms in the first 12 hours (it would eventually see 137 mms, according to Environment Canada).

Wettest. Day. Ever. Let's see what tomorrow brings...

Lead photo by Ann Darby (deftonia11)