The GTA is poised for its biggest snowstorm in five years and a painful Friday morning commute. The beginnings of the storm had already hit Toronto Thursday afternoon just in time for rush hour.

The snow tapered off later in the evening, but a second, stronger wave is expected to hit overnight.

Winter storm and snowfall warnings are in effect for the GTA, and CityNews meteorologist Natasha Ramsahai said between 25 and 40 centimetres of snow could fall by the time the system dissipates by Friday evening.

The City of Toronto has issued an extreme weather alert and opened up more shelter beds for the city’s homeless.

City crews are ready with 10,000 pounds of salt expected to be sprayed on our streets. Crews will focus on the major roads and expressways fist before dealing with side streets.

“We’ll be doing multiple rounds of plowing during the day…we’ll be busy through the weekend with this amount of snow,” said the City’s Peter Noehammer.

Ramsahai says the heaviest snow will arrive early Friday morning and will come down at a rate of two to four centimetres per hour for about eight hours.

“This is going to be big,” she said.

“The system bringing the snow continues to get stronger and has a lot of moisture with it, which is why we’re forecasting such high snowfall amounts.”

The heaviest snow, according to Environment Canada, will affect the Highway 401 corridor between London and the GTA.

The weather agency’s winter storm warnings are in effect for Hamilton, Burlington, Oakville, Mississauga and Brampton. Snowfall warnings are in effect in Peel, York and Durham regions, including Halton Hills, Milton, Caledon, Vaughan, Richmond Hill, Markham, Pickering and Oshawa.

GO Transit has set up a GO in the snow page for service updates and information.  GO confirmed late Thursday that it would running on an adjusted schedule.

Porter Airlines, WestJet and Air Canada are advising travellers to check their flight status before heading to the airport Thursday night and Friday. Air Canada is waiving change fees for customers who want to rebook their flights. Greyhound also said delays and cancellations were expected.

And downtown hotels — including the Sheraton Centre Toronto Hotel, Hilton Toronto, InterContinental Toronto Centre and Holiday Inn Express — have slashed their rates by $20-$180 for those who’d rather stay in the city than commute in or who get stuck in the city on Friday.

But the Maritimes and the U.S. east coast will likely have it worse.

Some forecasters are calling for a historic blizzard in eastern Canada, Boston and New York, with between 30 and 60 centimetres of snow.

The biggest one-day snowfall recorded at Pearson International Airport was 39.9 centimetres on Feb. 25, 1965.

Check the full forecast