(CNN) — A winter storm will hit the Mid-Atlantic and northeastern United States on Saturday.

The first storm will dump a foot of snow and significant ice through Sunday and cause travel disruptions. Millions of people are now on alert A winter storm.

Transportation crews began preparing the area's roads on Friday.

In central and northern Pennsylvania, where up to 6 inches of snow is forecast, transportation crews are treating roads to ensure “roadways are passable and not completely cleared of snow and ice,” according to a Department of Transportation statement.

Parts of Pennsylvania will bear the brunt of the storm, along with parts of Appalachia and parts of northeastern and interior New England, including west of Boston.

Major disruptions are rare in Philadelphia, Baltimore, New York and Washington. A storm track and adequate cold air combined to slightly reduce snow chances.

But other cities, especially in New England, have a higher chance of snow. Several inches of snow are forecast for Boston. It may not be on par with past blizzards, but it could be the city's heaviest snowfall in a single storm since 8 inches fell on February 25, 2022.

If the predictions come true in Hartford, Connecticut, it will be the city's biggest snowstorm since 11 inches fell on February 1, 2021.

Boston crews also prepared the streets, which were expected to be open. Drivers and 800 pieces of equipment are kept ready in case of need.

“Our goal is to be on top of the storm to keep the streets clear and passable,” Jaska Franklin-Hodge, Boston's chief street officer, said at a news conference Friday.

“In general, though, when there's weather like this, people should be careful, if they're going out they should drive carefully.”

An even more powerful and menacing storm

Another big and more powerful storm will arrive by mid-week with all the possible dangers: snow, ice, strong winds, tornadoes and heavy rain.

It will begin to strengthen rapidly on Monday as it moves across Central America toward the Great Lakes, bringing snow and possible blizzards to colder northern regions along its path.

The exact location and amount of snow will vary depending on the storm's track, which is still uncertain, but the Northeast Plains, Great Lakes, Midwest, and Interior regions are most likely to see heavy snowfall.

The storm will take advantage of warmer, more humid air south from the Gulf of Mexico, increasing the risk of severe storms including some strong tornadoes and damaging winds and rain flooding near the Gulf Coast. The risk of strong storms will increase Monday and Tuesday across southern parts of the Southeast, including Florida.

As the storm moves northeast, rain and strong winds will cause widespread flooding and power outages across much of the eastern United States.

Scattered showers will occur in areas soaked and snowed by the first storm.

Heavy rain alone can cause flooding, but snowfall increases the risk because warm rain melts the snow and releases its water quickly into aquifers.

The same devastating story played out in December, when a powerful storm caused deadly flooding in inland New England after its rain melted snow.

CNN's Amy Simonson contributed to this report.