Snow covers a lilac bush and apple tree in the southeast community of Chaparral. Snow covers a lilac bush and apple tree in the southeast community of Chaparral. (Submitted by J. Moore)

Calgarians are scrambling to cover their plants and gardens as another spring storm is forecast to bring 10 to 20 centimetres of snow to the area overnight into Friday morning.

Several Environment Canada weather warnings and advisories were in place Thursday, including a severe thunderstorm watch for the Cypress Hills area.

Thunderstorms moving north from Montana could bring large hail and damaging winds, said Environment Canada.

Rain on Thursday turned to snow, which started to accumulate in the afternoon on highways south of Calgary.

A car skidded on Highway 1 near Airdrie on Thursday and was hit by a semi.A car skidded on Highway 1 near Airdrie on Thursday and was hit by a semi. (RCMP)

The RCMP reminded people to slow down on the slick roads after a car lost control on Highway 2 in Airdrie and was hit by a tractor-trailer. The car's driver was taken to a Calgary hospital with non-life threatening injuries.

A power outage on Seventh Avenue halted downtown C-Train service at suppertime and Calgary Transit scrambled to set up shuttle buses for commuters.

A rainfall warning is in effect for Brooks, Strathmore and Lethbridge while the snowfall warning covers Calgary, Okotoks, Cochrane, Sundre, Banff, Kananaskis, Cardston and Crowsnest Pass areas.