• Up to 7 inches of heavy snow forecast for region.

Up to 7 inches of snow on the way

A winter storm warning has been issued for southwestern Pennsylvania beginning Wednesday morning.

A forecast of about 6 to 8 inches of snow was made at 6:30 p.m. Tuesday as a new storm system moves into the Pittsburgh region, according to the National Weather Service in Moon.

The winter storm warning is in effect from 7 a.m. Wednesday to 7 a.m. Thursday for Allegheny, Butler, Washington, Westmoreland, Greene and Fayette counties, with the heaviest snowfall to occur between 3 p.m. and 10 p.m., said Weather Service Meteorologist Fred McMullen.

A winter storm warning is in effect for the higher elevations east of Pittsburgh.

Mr. McMullen said downed trees and power lines are possible due to the wetness of the incoming snow and wind gusts may reach up to 25 mph.

Weather Service meteorologist Myranda Fullerton anticipates “a good snow event,” no matter the accumulation bands on the map.

“We’ll have a 24-hour window with accumulating snow,” she noted, with the first flakes falling late Wednesday morning before picking up in intensity through the afternoon and evening hours. “There will be plenty of moisture associated with this storm as well,” making for some heavy, wet snow, Ms. Fullerton said.

She added predicted snowfall totals could shift and meteorologists will be closely tracking the storm over the next few hours to see if there’s any deviation in the current weather model.

“It depends on how much warm air will work its way into the system,” she said.

AccuWeather chief meteorologist Bernie Rayno said its team has adjusted the 6-inch line farther west.

“We’ve taken it back toward the Pittsburgh area because of the strength of the cold air, and the upward motion means this is going to be a larger storm,” he said.

The storm is expected to impact the Wednesday evening commute, so people are advised to stay off the roads if they can. AccuWeather’s models are showing the storm moving out by 7 or 8 a.m. Thursday.

Temperatures will slowly rise from the 20s Wednesday morning to 33-34 degrees by the afternoon, Ms. Fullerton said. Wind gusts of up to 20 mph are forecast.

Pennsylvania’s storm

warning stretches into Central and Eastern Pennsylvania, where a broad swath of 12 to 18 inches of snow is forecast to fall across parts of Eastern Pennsylvania, New Jersey and New England. Some areas could receive more than 2 feet, according to AccuWeather.

The news prompted Gov. Tom Wolf on Tuesday to sign a emergency declaration.

“The commonwealth’s emergency preparedness teams have spent a great deal of time and energy over the last several months supporting efforts to mitigate the COVID-19 pandemic and help the commonwealth weather this public health emergency and ensure vaccines are delivered as planned,” Mr. Wolf said. “This proclamation makes it easier for all of those involved in vaccine delivery and keeping people safe to do their jobs.”

In preparation for the storm, Allegheny County plans to deploy 26 salt trucks beginning just before dawn Wednesday, Public Works Director Stephen Shanley said in a statement.

“Drivers will be kept over the end of their shifts to provide continual coverage until the snow stops and county roadways are clear,” said Mr. Shanley, adding the county will continue to monitor the weather and will adjust its plans based on the latest forecasts.

Roads will likely be slick during the afternoon rush hour due to the heavy snow, and Mr. Shanley cautioned drivers to slow down during their commute and to plan on giving themselves more time to get to their destination.

Also, “leave extra space between their vehicle and the ones in front of them, and please give our salt truck drivers plenty of room to navigate,” he said.

In the city, 75 trucks will be treating the road and plowing snow between 6 a.m. and 2 p.m., according to a release. Later, between 2 p.m. and 10 p.m., 69 trucks will be available. A night crew will work from 10 p.m. through 7 a.m. Thursday, the city said.

PennDOT officials said they are well stocked with supplies and equipment to handle snowstorms this year. Last year’s relatively mild winter left the department with some surplus.

PennDOT and Pennsylvania Turnpike Commission officials on Tuesday night also encouraged motorists to avoid all unnecessary travel during the storm and said they anticipate some truck and larger vehicle restrictions to take effect on Wednesday at 1 p.m., which reflects Tier 1 of the commonwealth’s weather event vehicle restriction plan.