Drop your rake and grab your shovel: Up to a half-metre of snow is expected to pound some areas of southern Alberta this weekend.

Environment Canada says snow is likely to start blanketing the southern half of the province on Friday afternoon and could continue right through to Monday.

Though Environment Canada hadn't issued any winter storm watches for Calgary by noon on Thursday, it had for nearby communities, including Okotoks, High River, Bragg Creek, the Tsuu T'ina First Nation, Canmore, Nanton, Claresholm and Priddis.

Kyle Fougere, a meteorologist with Environment Canada, told CBC News that "drastic changes" in the weather are coming.

"There is a very potent fall low-pressure system, and it does have the potential to produce significant amounts of snowfall, especially up along the higher terrain of the foothills and parts of extreme southwestern Alberta," he said.

Much of southern Alberta could see up to 15 to 30 centimetres of snow by Monday.

Some areas in the southwest of the province that are at higher terrain may be walloped by 50 centimetres — though Fougere said temperatures could impact these levels.

Calgarians may see thunderstorms on Thursday evening, with the temperature dipping to –1 C overnight with a risk of frost.

Temperatures are expected to quickly drop on Friday night, Fougere said.

"On Saturday and Sunday, accumulations become a little bit more likely," he said. "Calgary's right on the edge of where we're expecting the accumulations to really be, so we're going to have to see the exact track of the system to see where the accumulations are going to happen."

The agency said that travel is expected to be hazardous due to reduced visibility, while highways, roads and walkways are expected to be icy and slippery.

"The conditions are really going to deteriorate this weekend," Fougere said. "If anyone has any travel plans, especially if they are heading south out of Calgary or west on Highway 3 down by Lethbridge, they should really pay attention to the weather."

The areas hit by the heaviest snowfall may also see trees' branches snap under the weight.

Calgary says it's ready to clear roads

In Calgary, city officials said they were prepared for the snowfall, with a plan to clear roads with higher levels of traffic first.

"Crowchild, Glenmore, those are the roads we'll be clearing first," Jim Fraser with the city's roads department said at a news conference mid-day Thursday.

"Some of the other pieces of infrastructure, like the cycle tracks downtown, they'll receive the same priority as the major roads."

Jim Fraser, middle, with Calgary's roads department said the city will once again follow the city's seven-day snow plan. (CBC News)

Fraser said the city would again follow its seven-day snow plan, which prioritizes various roads and sidewalks for snow removal within a weekly timeframe.

"That hasn't changed, with the exception of some of the infrastructure that's been added into the plan, including the cycle tracks," he said.

According to data from Environment Canada, between 1884 and 2011 Calgary saw the greatest snowfall the weekend of Sept. 27 in 1925, when snowfall ranged between 6.6 and 19.8 centimetres.

For an up-to-date list of public weather alerts, visit the agency's website.