The National Weather Service has upgraded Lake and McHenry counties to a winter storm warning and said seven inches of snow is possible in the area Saturday.
The National Weather Service (NWS) initially issued a winter weather advisory Friday afternoon and it went into effect at 9 a.m. Saturday.
The alert said accumulating snow and hazardous travel were expected for the Chicagoland area.
The weather service Saturday afternoon upgraded the advisory to a winter weather warning for Lake and McHenry counties and said the warning will expire at 3 a.m. Sunday.
A band of snow developed eastward into far northern Illinois Saturday morning, the NWS said.
The heaviest snowfall rates of up to one inch per hour are expected to occur through Saturday evening and then taper off from west to east into early Sunday morning.
The highest snow amounts will fall across far northern Illinois and southern Wisconsin.
Total snow accumulations of four to seven inches are expected with higher amounts possible, especially near the Wisconsin state line.
Northeast winds will gradually increase with gusts to 25 mph Saturday evening, which may result in patchy blowing snow, the NWS said.
Warmer air may result in a period of freezing rain south of Interstate 80 Saturday evening into the overnight hours.
The NWS said areas near and south of the Kankakee River have the highest chance of a glaze of ice occurring.
Motorists should plan on snow-covered roads and slippery travel, the NWS said. Visibility could be as low as one-half mile at times.
“If you travel, allow extra time to get to your destination, reduce speed and increase following distance,” the weather service said.