Freezing rain slated to stay in Allegheny County over the weekend crept northward into Butler County.

“The freezing drizzle that fell last night: it was fairly light, but it only takes a small amount of ice to cause problems,” said Bill Modzelewski, a meteorologist with the National Weather Service in Pittsburgh.

According to Butler County 911 reports, there were four vehicle accidents between 10:18 p.m. Saturday and 12:11 a.m. Sunday. There were also a handful of accident calls Sunday morning. Dispatchers also received a number of medical calls for falls and at least one sledding accident.

Butler State Police said they only received about two accident calls overnight between Saturday and Sunday, and neither appeared to be serious.

Modzelewski said freezing rain happens when warmer air remains aloft in the air, allowing for fluid rain, which then freezes as it hits the ground or near the ground level where temperatures are freezing.

“So once that hits the roads and cars, it froze on contact,” Modzelewski said.

PennDOT District 10 spokeswoman Tina Gibbs said freezing rain can create problems for her crews, especially if a hard rain washes away the salt and then freezes on the ground.

“Thankfully it was more of a drizzle (Saturday night,)” she said. “We monitored that throughout the whole night.”

While this weekend's icy conditions are in the rearview mirror, Gibbs said her crews are also preparing for another long night from Monday into Tuesday.

“We'll have crews out around the clock as usual,” she said.

According to Modzelewski, the forecast for Butler County shows a likelihood of between one to three inches of snowfall Sunday night into Monday morning.

“There's an area of low pressure that's going to be moving northeast across Ohio and Tennessee valley,” he said.

He said there will be a slight break from the snow during the day Monday before another storm comes through, which could drop between four and six inches of snow.

“For Butler, it looks like mostly snow,” Modzelewski said. “There could be some freezing rain early Monday night into Tuesday. That could make conditions even worse.”

Gibbs said some salt residue might still be on the ground from this weekend, but the crews will still have salt, anti-skid plows at the ready.

“It's important to remember that while the (precipitation) is falling, roads may not be bare, but we do the roads and get around as fast as we can get the trucks,” Gibbs said. “We just urge people to be cautious over the next couple days.”