Forecasters are watching a winter storm that could impact 100 million people in the eastern United States, including Indiana and multiple other counties from the tri-state area around Pittsburgh toward the Eastern Seaboard.

“The storm will strike the Appalachians in a fast and furious nature, leaving many areas buried under more than a foot of immobilizing snow,” AccuWeather senior meteorologist Alex Sosnowski said Friday.

National Weather Service offices in Pittsburgh and State College issued winter storm watches late Friday morning that will be in effect from Sunday afternoon through Monday afternoon.

Forecasters said between 1 p.m. Sunday and 1 p.m. Monday that 8 to 12 inches of snow can be expected in Indiana Borough and areas to the north and west in Indiana County, while 6 to 8 inches can be expected elsewhere.

In nearby counties, 8 to 12 inches is expected in Armstrong, Cambria, Clarion Clearfield and Jefferson, as well as the northwest corner of Westmoreland, with 6 to 8 expected in the rest of that county.

The National Weather Service advised travel could be very difficult, with hazardous conditions impacting the Monday morning commute, specifically along Interstate 80.

“The Pennsylvania Emergency Management Agency is actively monitoring the weekend forecast and projected snow accumulations,” Emily Demsey, Gov. Tom Wolf’s deputy press secretary, said Friday afternoon. “PEMA is actively working with PennDOT, state police and the turnpike to prepare for the snowfall. As the weather system gets closer, the administration will provide an update to Pennsylvanians as to what to expect and how to prepare.”

Speaking of PennDOT, a spokeswoman for Pennsylvania Department of Transportation District 10 said crews are ready throughout its five-county area.

“We have been very closely monitoring the storm,” District 10 Community Relations Coordinator Tina Gibbs said Friday. “Crews will be out all weekend doing pre-treatment work on the roadways.”

Gibbs said PennDOT typically runs three shifts during winter, “so essentially we have 24-hour coverage planned.”

That includes the use of stockpiles in each county (Indiana, Armstrong, Butler, Clarion and Jefferson), with 44 trucks available for Indiana County.

“Our staffing looks good, our supplies look good and our trucks look good,” Gibbs said.

What crews do depends on what the roads are like in advance of a snowstorm.

“It doesn’t look like where we are will will have rain before the snow,” Gibbs said.

Efforts on roads with heavier volumes involve a salt brine, a mixture of water and salt. Where traffic is at a lower volume, there may be less salt and more of an anti-skid compound of crushed limestone and salt.

“Motorists should know before they go what to expect,” the District 10 spokeswoman said.

“While the storm is several days away, we encourage everyone to take advantage of this time to make sure they have what they need at home and in their cars to stay safe,” Demsey said. “Free downloadable checklists for home and vehicle emergency kits are available on the website. Once snow arrives, Pennsylvanians can monitor traffic, possible restrictions or incidents, and snow plows on public roads by visiting”

Also late Friday, PennDOT and the Pennsylvania Turnpike Commission advised motorists to avoid unnecessary travel during the storm and said they anticipated implementing various speed and vehicle restrictions throughout the storm.

Beginning Sunday at 3 p.m., Tier 2 of the commonwealth’s weather event vehicle restriction plan will kick in for all interstates south of Interstate 80, as well as the Pennsylvania Turnpike and, locally, U.S. Route 22.

Under Tier 2 restrictions, the following vehicles are not permitted on affected roadways:

• Tractors without trailers;

• Tractors towing unloaded or lightly loaded enclosed trailers, open trailers or tank trailers;

• Tractors towing loaded tandem trailers unless there are chains or another approved Alternate Traction Device on board;

• Enclosed cargo delivery trucks that meet the definition of a CMV;

• Passenger vehicles (cars, SUVs, pickup trucks, etc.) towing trailers;

• Recreational vehicles/motorhomes;

• School buses, commercial buses and motor coaches; and motorcycles.

After 7 p.m. Sunday, Tier 2 restrictions will be extended north of I-80, while Tier 3 restrictions will kick in for I-70 and I-99, followed at 11 p.m. by Tier 3 restrictions for other interstates including I-380 in the Pittsburgh area.

Tier 3 restrictions mean Tier 2 restrictions continue, while also no commercial vehicles will be permitted except loaded single trailers with chains or approved alternate traction devices.

Authorities said drivers also should prepare or restock emergency kits with items such as nonperishable food, water, first-aid supplies, warm clothes, a blanket, cellphone charger and a small snow shovel. They said motorists should tailor their kits to any specific needs that they or their families have such as baby supplies, extra medication and pet supplies.

On its Facebook page Friday afternoon, White Township said its road crew foremen and drivers were prepared for the worst that the storm may deliver, with a barn full of salt, a mountain of antiskid material, 10 trucks and a team of drivers ready to clear more than 80 miles of township-owned roads.

For youngsters throughout the area, Monday already was an off-day because of the federal holiday marking the birth of the Rev. Dr. Martin Luther King Jr., but many area public school districts have Act 80 or in-service days for teachers, including the Indiana County Technology Center.

Among parochial schools, St. Bernard of Clairvaux in White Township also has an Act 80 Day Monday. Monday is listed as “no school” for Seeds of Faith Christian Academy in Creekside and New Story School in Indiana also is closed for the King holiday.

Staff at Indiana Wesleyan School in Dixonville said they planned to have classes but have canceled school for Monday.

Keys Montessori School in Indiana, Indiana County Head Start, Kiski School in Loyalhanna Township, Indiana University of Pennsylvania and Westmoreland County Community College also have no classes Monday because of the holiday.

Calvary Baptist Academy is scheduled to have classes Monday.