The National Weather Service has issued a winter weather advisory for Allegheny County, expected to bring between 2 to 4 inches of snow by this evening.
Rain Sunday night is expected to turn to snow around daybreak today. Accumulation is less likely in river valleys and more possible in higher elevations. Wind gusts could reach up to 40 mph.
The weather service also issued a winter storm warning for areas north and east, which could bring between 4 to 6 inches of snow, and up to a foot in the mountains.
Snow will often melt on roadways this time of year, as a late April sun can warm pavement even through clouds, said National Weather Service meteorologist Brad Rehak, who noted that heavy, wet snow can snap tree limbs and bring down power lines.
To be sure, this type of weather is atypical this late in the month.
"Heavy snow is pretty common in early April but becomes very rare mid-to-late April," Mr. Rehak explained.
Pittsburgh's record snowfall in April is 12.7 inches on April 3, 1901. A list of the heaviest Pittsburgh snowfalls after April 15 on the National Weather Service website includes 2 inches April 23-24, 2005; 3.1 inches May 9, 1966; and 2.1 inches April 30 to May 1, 1963.
Mr. Rehak said while wind gusts can reduce visibility, this snowfall will be heavy and is "not so much of a blowing snow."
Temperatures will be in the mid-30s today, drop to the low 30s tonight and rise to the mid-40s Tuesday.
This weather is due to a storm system from the Great Lakes region, with Canadian air, colliding with a system coming up along the East Coast from the south.
"It's like a nor'easter you'd have in February, but we're having it in April."
The nor'easter was expected to bring mostly rain and heavy winds along the East Coast today. In addition to Western Pennsylvania, Ohio, West Virginia and some western parts of New York may see between 4 to 12 inches of snow.
In New York City, 2 1/2 to 3 1/2 inches of rain and gusts of 25-30 mph were expected. There and in Washington, pro baseball games were postponed and the scheduled arrival for the space shuttle Enterprise has been moved.
Philadelphia, New York City and southern New England could see up to 4 inches of rain. Light rain fell over Baltimore and Washington metro areas Sunday and was expected to fall harder throughout the day, causing potentially low visibility and slick conditions.
Precipitation totals in many parts of the Northeast are below normal for this time of year. Some areas were expecting flooding.
Molly Born: firstname.lastname@example.org or 412-263-1944. The Associated Press contributed.