winter storm timeline

Timeline: When This Week's Winter Storm Will Impact the Chicago Area

NBCUniversal Media, LLC

As a powerful storm system approaches the Chicago area, we are learning more about how the nasty weather will unfold in the coming days.

The storm will start out as a rain event, then will transition to ice and mixed precipitation before turning completely to snow by Thursday afternoon.

Here is what we know so far as the system approaches the region.

Wednesday Afternoon:

The storm system will begin to move its way into the Chicago area in the afternoon, bringing with it plenty of rain and windy conditions, according to forecast models.

That rain is expected to bring 1-to-2 inches of rain to the area, with localized heavier amounts possible, causing potential flooding and slippery road conditions.

Wednesday Night:

Temperatures will begin to drop Wednesday night, with select locations seeing rain transition to freezing rain around midnight, according to forecasts.

The transition will likely occur from northwest to southeast due to strong northerly winds, meaning that rain is expected to continue overnight Thursday in many locations.

Overnight Thursday:

Slowly but surely, rain will transition to freezing rain across the area, starting in the northern suburbs and slowly making its way down through Chicago and then ultimately into the southern suburbs.

Rain may continue in LaSalle, Grundy and Kankakee counties after sunrise before transitioning to freezing rain once temperatures cool enough.

In far northern Illinois, snow could potentially begin before sunrise, with the icy mix transitioning to snow in Lake and McHenry counties by the time the sun comes up.

Thursday Morning:

Thursday morning should see snow become more widespread across the area, with the intensity picking up as the morning moves along.

The only places it likely won’t snow before noon are in the far southern suburbs, where freezing rain and mixed precipitation are expected to fall through the early afternoon.

Thursday Afternoon:

By afternoon, snow will be falling area-wide, with winds picking up and causing limited visibility and hazardous travel conditions throughout the afternoon.

It is not known at this time where the heaviest snowfall amounts will occur, but widespread travel issues are expected, with snow tapering off in the evening hours.

The European Model is showing several inches of snow across the area, but the Global Model forecast paints a much more serious picture of potential snowfall, with more than 10 inches of snow possible south of Interstate 80.

According to the NBC 5 Storm Team, that model could misinterpret precipitation as snow, meaning that totals could wind up being lower than what is being forecasted.

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