February 16th-18th Late Tonight - Monday Morning Accumulating Snow Event Update #4

Our snow system for the latter half of this weekend is slowly approaching and developing to our west this evening across the plains. Everything for the most part looks on track as it will move into portions of Illinois later tonight and early tomorrow morning, bringing the next round of accumulating snow to the region as the active pattern roles on.

I dig into the latest below along with radar, satellite, and an updated TAM/expected snowfall totals...

Taking a look at a water vapor satellite image this evening, we can see our system, that looks fairly impressive tonight across the plains as it slowly approaches the Midwest. It will be quite the slow mover, taking nearly all of tomorrow to move through our region. 

Next, we can take a look at radar across the region, showing blossoming precipitation/snow to our west (boxed in orange) across the central plains and now making its way into and through portions of Iowa and Missouri. This will then nose into western and northwest Illinois around or just after the midnight hour tonight. 

Now taking a look at high resolution model guidance of how this system evolves late tonight and through all of tomorrow, we can watch the loop below. You can initially see snow moving into western and northwest Illinois overnight tonight and then spreading eastward across the rest of central and northern Illinois by the predawn/early morning hours. There could be some low level dry air across northeast Illinois that could delay snow onset by a bit, but continued saturation should overcome that by the morning hours. As the broad area of low pressure slowly makes its way through southern Illinois and up through the Ohio River Valley, the northern half of the state will be in a favorable location for continued snow through the entire day tomorrow, even though it will be falling at a light rate and not accumulating very fast. 

The loop below runs from late this evening all the way until late Monday morning, showing the entire evolution of this system. Even though snow will be mostly light to occasionally moderate, snow will continue through the late evening hours tomorrow and quite possibly into Monday morning for portions of Illinois. 

Lastly, there is also a hint of some lake effect snow that brushes the western shores of Lake Michigan in northeast Illinois late Monday morning, including downtown Chicago. This could lead to some additional snow accumulations across the area outlined in orange overnight Sunday night into and through Monday morning. 

Below is our latest expected snowfall amounts between late tonight through Monday morning.