A significant winter storm is set to hit northern Illinois this weekend, with the National Weather Service upgrading its alert to a Winter Storm Warning from 3 a.m. Saturday through 6 a.m. Sunday. Forecasters say the region should prepare for 6 to 10 inches of snow, with locally higher totals possible northwest of a line from Ottawa to Aurora to Waukegan.

Snow is expected to begin developing in the early morning hours on Saturday, increasing in intensity shortly after sunrise. According to the National Weather Service, the storm will produce snowfall rates of up to 1 inch per hour, especially during the late morning and afternoon. That period, roughly noon to 6 p.m. Saturday, is highlighted as the window for the most hazardous travel.

In the more western portions of northern Illinois, including Whiteside and Bureau counties, the winter storm warning is in effect from midnight tonight through 6 a.m. Sunday.

A timeline released early Friday shows accumulating snow lasting all day Saturday before tapering off overnight. Snowfall will slow after sunset, but roads are expected to remain snow-covered and slick through Saturday night. The weather service warned that travel could become very difficult, with reduced visibility and rapidly deteriorating conditions during heavier bursts of snow.

Although temperatures may briefly climb enough to introduce a chance of drizzle later Saturday night, mainly south of I-80, forecasters say snow will remain the dominant precipitation type for most of the area. In northwest Indiana, a band of lake-effect snow could linger into Sunday morning, bringing additional travel impacts near the lakeshore.

The highest totals are expected in areas near and north of I-80, with the greatest confidence for 6 inches or more across McHenry, Lake, DeKalb, Kane, DuPage, northern Cook, and northern Will counties.

The storm arrives as many Illinois residents return home from Thanksgiving travel, prompting the National Weather Service to urge drivers to complete any final preparations Friday. Motorists should keep emergency supplies, such as a flashlight, food and, water, in their vehicles if travel is unavoidable.

Road conditions can be checked at GettingAroundIllinois.com.