Winter is finally here, with freezing temperatures and measurable snowfall expected Sunday night and Monday.

“We expect there will be a pretty severe storm,” said Matthew Kramar, a meteorologist with the National Weather Service in Moon.

The weather service is forecasting 2 to 5 inches of snow in the Pittsburgh region, with high temperatures remaining in the 20s throughout the week, according to its website.

A winter storm watch is in effect for eastern Westmoreland County from 1 p.m. Sunday to 7 p.m. Monday. According to the weather service website, up to 8 inches of snow could fall in the Laurel Highlands.

However, Kramar said on Saturday evening that the weather forecast remained unstable – little to no snow was also possible for the region and sleet or freezing rain could also be possible.

“It’s really a 50-50 coin toss going into this,” he said.

The snowstorm could begin as early as 7 p.m. Sunday in northern West Virginia, Kramar said, which would likely bring the storm into the western Pennsylvania region later Sunday evening.

“Somewhere tomorrow evening is the most likely time to see some snow,” he said. “The heaviest snow is likely to fall overnight into Monday morning.”

If warmer temperatures prevail, Kramar said there could be some ice Monday morning before snow returns for the rest of the day. In that scenario, the Pittsburgh area could see 1 to 3 inches of snow, he said.

“As you head south toward Morgantown, it gets bad pretty quickly,” Kramar said. “Be very careful about driving safety – be prepared to postpone or cancel travel plans.”

After Friday night’s snow squalls, the Pittsburgh region received a total of 1 to 4 inches of snow, and Westmoreland County received between 2 and 8 inches of snow, with totals higher in mountainous regions.

On Sunday, temperatures won’t rise much higher than the low to mid 20s, Kramar said.

Monday is the difficult day for forecasts for now.

“Temperatures could rise to above 20 or below 30 degrees, or it could stay a little colder,” Kramar said. “It could be almost freezing cold during the day on Monday, but we should be back to cold air by Monday evening.”

Beginning Sunday at 5 p.m., PennDOT will implement travel restrictions on some vehicles and roads. These restrictions mean that speeds on certain roads will be reduced and certain vehicles will be banned from the roads. Affected vehicles and roads include:

• Tractors without trailers

• Tractors pulling unloaded or lightly loaded closed trailers, open trailers or tankers

• Tractors pulling loaded tandem trailers without chains or alternative towing equipment

• Closed or lightly loaded trucks and vans that are considered commercial vehicles

• Passenger vehicles towing trailers

• Recreational RVs

• School, professional and travel buses

• Motorcycles

• Interstates 70, 79 and 279 and the Pennsylvania Turnpike, including extensions of Routes 43 and 66.

For details on restrictions, visit pa.gov.