UPDATE: The National Weather Service downgraded its winter storm watch to an advisory Sunday afternoon, but still warns that a heavy, wet snowfall will impact the area.
Rain that develops Sunday evening will change to snow overnight.
The winter weather advisory for snow is in effect from 5 a.m. Monday to 2 a.m. Tuesday, which means snowfall will cause travel difficulties.
The weather service warns travelers to be prepared for snow-covered roads and limited visibility.
"Strong low pressure is forecast to move northward through eastern Pennsylvania tonight," the National Weather Service states on its website. "This system will spread rain across the area later this evening that will change to snow late tonight and Monday morning."
The snow could become heavy at times, especially Monday morning, with the largest accumulations likely in the higher elevations east of Pittsburgh, states the weather service.
The heavy, wet snow combined with strong winds might bring down tree limbs, which could in turn cause power outages, according to the weather service.
EARLIER STORY PUBLISHED SATURDAY:
If April showers bring May flowers, what does a winter storm watch bring in late April?
Well, there's that. It also brings a forecast for a combination of a heavy wet snow and strong winds for late Sunday night through Monday that could bring down tree limbs and power lines, the National Weather Service says.
"A winter storm watch means that snow ... sleet ... or ice accumulation may severely impact travel," the weather service website states. "Visibilities may be reduced below one-quarter of a mile in the heaviest snowfall Monday morning."
Rain will change to snow after midnight Sunday and become heavy at times through Monday morning, the weather service predicts.
Northwest winds could gust up to 45 mph and temperatures will drop into the lower 30s.
"A very strong system is forecast to move northward through central Pennsylvania, leaving western Pennsylvania, northern West Virginia and far western Maryland on the cold side of the track of the system," according to the National Weather Service statement.