A Winter Storm Warning was issued for the entire Chicago area and northwest Indiana Thursday, as the biggest snowstorm of the season so far descened on the region.
The exclamation point on a week of wintry weather could leave more than a foot of accumulation total across some parts of the region by Sunday.
The National Weather Service upgraded an existing Winter Storm Watch with a Winter Storm Warning overnight, meaning severe winter weather conditions are not only likely, but expected.
The warning for DuPage, Cook, La Salle, Kendall, Grundy, Will counties in Illinois, and Lake and Porter counties in Indiana, is scheduled to go into effect at 6 p.m. on Thursday and last through Friday at noon.
The warning in place for McHenry, Lake, DeKalb, Kane counties in Illinois is scheduled to go into effect at 6 p.m. on Thursday as well, but is expected to last through Friday at 9 a.m.
Steady, moderate to heavy snow is likely across the entire area during this time frame.
The snow began to fall Thursday evening, and was expected to leave several inches of accumulation by dawn.
Steady snow continues Friday, moderate to heavy at times through the day, with the NWS warning that heavy snowfall will make driving conditions difficult, particularly during Friday morning's rush hour.
Friday's snowfall will likely taper off and end in the evening, but the winter weather won't be done just yet.
Saturday morning will start overcast and cold, with more light snow possible throughout the day, mainly from the city, west along I-88 and areas south with a few inches of accumulation possible.
Any light snowfall on Sunday will likely taper off in the morning before clouds break for sun in the afternoon - though it will still be cold with highs in the upper 20s.
Overall, by the end of the weekend, parts of the Chicago area could see a total of more than a foot of snow on the ground over the course of the week, including the 1 to 3 inches of accumulation from the snowfall late Tuesday night into Wednesday - though snow totals will likely fluctuate as the system continues to move into the area.