Could a foot of lake-effect snow fall in the Chicago area? What to know

Lake-effect precipitation is expected to hammer the Chicago area Thursday and Friday, but could eye-popping snowfall totals occur?

The Details

Bands of lake-effect snow could potentially impact parts of the Chicago area late Thursday and into Friday, with some eye-popping accumulations possible.

Some models are suggesting that the heaviest bands of lake-effect snow could produce localized snowfall totals of 10 or more inches, but there is still plenty up in the air as the weather pattern begins to shift in the area, according to the NBC 5 Storm Team.

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What is known on Thursday afternoon is that there are several key ingredients that could be present that would allow for lake-effect snow to form. Those include blustery winds out of the northeast, which are already churning up large waves on Lake Michigan, and warm temperatures over the lake itself, which can help provide fuel to precipitation that is expected to form in the coming hours.

Those factors, combined with dry air present over the Chicago area, could lead to the formation of snow even if air temperatures are slightly above freezing, and that could ultimately lead to some significant accumulations if enough factors come together.

However, there is plenty that can still impact the forecast. The first is how quickly the air will cool in the impacted areas, which will impact when precipitation transitions from rain to snow. According to the NBC 5 Storm Team, the earlier that happens the higher the potential accumulations could get, as mixed precipitation or rain would prevent much accumulation from happening.

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As of Thursday afternoon, it appears precipitation could start to form in the late evening hours, starting out as rain and then slowly transitioning to mixed precipitation and then to snow over parts of the area.

Air travel

Why FAA says it issued a ground stop for airports nationwide Federal Aviation Administration More than 250 flights delayed at O'Hare, Midway amid nationwide FAA ground stop Unlike earlier in the week when forecast models were showing areas of Porter County were expected to receive the heaviest snow, that has now shifted to the west, with areas right along the Illinois-Indiana state line at the highest chance of significant accumulations.

Like in other lake-effect snow events however, the disparity in snowfall over small distances could be dramatic. Lake-effect bands tend to be very narrow, and snowfall totals can vary wildly in very short distances, according to the NBC 5 Storm Team.

What’s more, lake-effect snow bands typically oscillate, meaning they could move back and forth between areas, which could also prevent the largest accumulations from falling.

Regardless, residents in northwest Indiana and eastern Illinois will have to keep their guard up late Thursday night and into Friday morning, with a winter weather advisory in effect for southern Cook County, eastern Will County and most of Lake County in Indiana, according to the National Weather Service.

We will continue to update this story with the latest forecasts as the lake-effect precipitation begins to form and fall.