Chicago ice threat timeline: Freezing rain to create hazardous travel conditions, what to know

CHICAGO - Chicagoland is bracing for hazardous travel conditions as freezing rain and freezing drizzle move into the area this evening.

Chicago Weather Alert

What we know:

The National Weather Service has issued a Winter Weather Advisory for the city, beginning at 6 p.m. and lasting until 6 a.m. Thursday.

Meanwhile, an advisory for the south suburbs began at 4 p.m.

While road salt will be effective with temperatures in the upper 20s to low 30s, any untreated surfaces are expected to become icy quickly.

The freezing precipitation will be scattered at first, primarily affecting the southern suburbs in the late afternoon before expanding northward into the evening. The heaviest precipitation is expected tonight before tapering off overnight.

Timeline:

• As of 4 p.m., precipitation had begun moving into the far southern suburbs (LaSalle, Grundy, Kankakee, Newton, Jasper).
• At 6 p.m., a Winter Weather Advisory will begin for the following counties: McHenry, Lake (IL), DeKalb, Kane, DuPage, Cook, Lake (IN), Porter, LaPorte, Will, and Kendall.
• By 7 p.m., conditions are expected to deteriorate as untreated roads and sidewalks turn icy.
• By 8 p.m., freezing rain and drizzle will extend northward to the Wisconsin border.
• The freezing rain will continue overnight but gradually taper off after midnight, clearing from west to east.

While most areas will receive less than a tenth of an inch of ice, even a thin layer could cause hazardous travel conditions.

By Thursday morning, temperatures will rise into the lower 40s, allowing any lingering ice to melt by midday.

Freezing rain impact

Slippery roads, bridges and overpasses are a major concern during this winter storm.

Authorities are advising commuters and motorists to prepare for travel delays and road closures during their commutes through Thursday morning.

Chicago’s Department of Streets and Sanitation deployed salt spreaders to treat city streets early on Wednesday.

The Illinois Tollway is reminding drivers to slow down and stay alert. They’ll have a full fleet of nearly 200 plows de-icing roads.

In addition, South Shore train lines issued an advisory saying ice can adversely impact tracks, overhead wires and other mechanical components. As a result, icebreaker trains were being sent out.

Train operations, however, are expected to proceed as scheduled.

ComEd is also adding additional crews, preparing for ice that could potentially interrupt power lines.

What's next:

Drivers and pedestrians are urged to use caution tonight and early Thursday morning.

Roads, sidewalks, and bridges may remain slick until temperatures rise. Authorities recommend allowing extra travel time and checking conditions before heading out.