Winter Storm Jonas is underway, spreading a swath of snow and ice, some of it heavy, from the Appalachians into the Mid-Atlantic and Northeast.

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If you plan to hit the road now through the weekend, you should stay informed on the latest forecast. With some planning, you may be able to avoid driving in dangerous winter weather conditions.

To help you plan, we've put together forecasts for four major interstate highway corridors that will be affected by the storm: Interstate 95 in the Northeast megalopolis, Interstate 81 in the interior Mid-Atlantic region including the Shenandoah Valley, Interstate 64 from Kentucky to Virginia, and Interstate 40 from Tennessee to North Carolina.

Interstate 95

Winter Storm Jonas Forecast: Interstate 95

(Forecast temperatures and wind speeds at 8-hour intervals for major cities along Interstate 95 in the Northeast.)

Conditions will vary greatly along the I-95 corridor from Boston to Washington. For Boston, only a few inches of snow are expected; from New York to Washington, this will be a crippling blizzard.

The National Weather Service has issued blizzard warnings for Washington, D.C., Baltimore, Philadelphia, New York City and southern Connecticut. All of the blizzard warnings are now in effect.

Snowfall rates will exceed 1 inch per hour through much of Saturday in the Washington, Baltimore and Philadelphia areas. Sustained northeasterly winds will approach 30 mph at times, and gusts will be higher, leading to blizzard conditions with near-zero visibility. I-95 and other roadways will likely be forced to shut down. Road crews simply won't be able to keep up with the snowfall and it will be too dangerous to allow motorists onto limited-access highways given the conditions.

Total snowfall accumulations may top the 2-foot mark in the Baltimore-Washington corridor. Amounts of a foot or more are likely from northern Delaware through Philadelphia, much of New Jersey and into New York City. Winds in these areas will also be strong, leading to blizzard conditions.

Driving conditions are likely to be treacherous during the storm from northern Delaware to southern Connecticut, and speed restrictions – if not outright closures – are likely along this stretch of I-95 as well as the non-Interstate portion of the New Jersey Turnpike.

Travel on Interstate 95 through southern New England will be toughest in southern Connecticut, where snowfall totals of more than 6 inches are likely and a blizzard warning has been issued. A plowable snowfall of 3 to 6 inches is expected along most of the interstate in Rhode Island, though travel conditions should improve quickly north of Providence.

The heaviest of the snow will pass south of Boston, so I-95 from Boston northward should be less problematic for drivers. However, as we've seen many times this winter, even light wintry precipitation can lead to serious problems when drivers don't adjust their speeds for the conditions. Use caution driving when snow or slush is on the road, even in small amounts.

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Interstate 81

Winter Storm Jonas Forecast: Interstate 81

(Forecast temperatures and wind speeds at 8-hour intervals for major cities along Interstate 81 from the Tennessee-Virginia border to Harrisburg, Pennsylvania.)

Interstate 81, a favorite alternate route for many Southerners driving to the Northeast, is not a good road to be on during Winter Storm Jonas.

Most of Virginia's Shenandoah Valley is in line for a crippling snowstorm with amounts exceeding – and in some cases possibly doubling – the one-foot mark. Snowfall rates into early Saturday will reach or exceed 1 inch per hour. Similar conditions are expected on the stretch of I-81 passing through the Eastern Panhandle of West Virginia as well as near Hagerstown, Maryland.

Travel will quickly become treacherous north of the Mason-Dixon Line separating Pennsylvania from Maryland. Snowfall exceeding 6 inches is expected as far north as Wilkes-Barre/Scranton area – a marked northward shift from earlier forecasts. Snowfall totals should dwindle rapidly as you head north from Scranton to the New York state line.

All along the I-81 corridor, winds should not be as strong as they will be along the I-95 corridor, reducing the risk of blizzard conditions.

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Interstate 64

Winter Storm Jonas Forecast: Interstate 64

(Forecast temperatures and wind speeds at 8-hour intervals for major cities along Interstate 64 from Kentucky to Virginia.)

East of the Appalachians in Virginia, conditions on I-64 will vary significantly as a variety of snow, sleet and rain impacts the area, heavy at times. There may also be lulls in the precipitation, only to be followed up by additional bursts of heavy snow, ice or rain.

The transition zone has set up between Richmond and Norfolk, leaving Richmond in line for a mixture of heavy snow and sleet. Meanwhile, Norfolk saw a brief period of snow and ice on Friday before quickly changing to rain Friday night – and then back to light snow Saturday morning.

Although the heaviest snow has ended along I-64 from western Virginia into West Virginia, occasional snow showers and blowing snow can still result in tough travel conditions Saturday morning.

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Interstate 40

Winter Storm Jonas Forecast: Interstate 40

(Forecast temperatures and wind speeds at 8-hour intervals )

Difficult travel conditions will slowly improve on I-40 from Tennessee to central North Carolina through the day on Saturday.

Significant amounts of snow ice impacted much of the stretch of interstate on Friday, but as precipitation has tapered off, roads should gradually become cleared and passable later Saturday.

A few lingering snow showers cannot be ruled out on Saturday, but the majority of the precipitation has ended.

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Additional Snowfall Forecast

(Forecast snowfall accumulation through Sunday, Jan. 24.)

Stay with The Weather Channel and weather.com as we continue to update the forecast for Winter Storm Jonas.