A potent winter storm is expected to sweep across northern Illinois this weekend, with the National Weather Service warning of heavy snowfall, hazardous travel, and the potential for more than 6 inches of accumulation across much of the region.

The National Weather Service issued a Winter Storm Watch from late Friday night through late Saturday night for nearly all of northern and central Illinois, including the Sauk Valley, DeKalb, McHenry, Kane, DuPage, Kendall, Grundy, La Salle, Kankakee and Livingston areas, as well as Cook and Will counties. Portions of northwest Indiana are also included.

Forecasters say snow will develop after midnight Friday, intensify quickly, and continue through the day Saturday. The heaviest snow is expected Saturday morning through Saturday evening, with snowfall rates potentially reaching up to an inch per hour at times.

NWS graphics show much of the region in the higher-probability zone for at least 6 inches of snow, including areas along and north of Interstate 80. Locations farther south, including parts of Livingston, Ford and Iroquois counties, could see slightly lower totals depending on how far north a rain-snow mix sets up.

A period of light rain or drizzle is possible Saturday night, mainly south of I-80, as warmer air briefly noses into the system. Even so, the NWS says snow should remain the dominant precipitation type for most of the area.

Winds are not expected to be as strong as those seen earlier in the week, but visibility could still be sharply reduced during heavier bursts of snow, and roadways may become snow-covered and slick through the day Saturday. Travel could be difficult, especially during the storm’s peak.

Snow is likely to taper off overnight Saturday, though forecasters say some light, lingering snow may continue into Sunday morning. The chance for additional accumulation on Sunday appears low.

Ahead of the storm, Friday will feature partly cloudy skies and highs in the low to mid-30s, with temperatures falling into the 20s by evening.

The National Weather Service urges residents to monitor updated forecasts and be prepared for difficult travel conditions during one of the busiest travel weekends of the year.