Winter Storm Warnings are now in effect ahead of what promises to be the heaviest snowfall this winter for many across northern Illinois. Snow is expected to first begin across northwest Illinois late in the afternoon and then spread across the remainder of northern Illinois as the evening progresses. This will be a long duration event, with snow continuing through much of the day Friday and perhaps lingering into Saturday morning. Rates could exceed 1″/hr in the heaviest snowbands.

Recent runs of all the high res models continue to increase the amount of precipitation this system has available to it, some going as far as to suggest a foot of snow or more is possible in some areas. Another important thing to note is the indication of a very sharp cutoff line on the southern end of the system.

This is the remaining forecast challenge we’re currently trying to resolve is just where the heaviest band will setup and where that cutoff line could be. We are pretty confident in a high total snowfall event, now we just have to nowcast the finer details as the event begins to take shape. ISC will provide several updates as the day progresses and we encourage you to seek out the latest information. Either way, travel across northern Illinois will be discouraged this evening.

Detailed warning text from the NWS is shown below:


* WHAT…Heavy snow likely. Travel will be very difficult to
impossible at times, including during the morning commute on
Friday. Total snow accumulations of 6 to 10 inches are possible.
Localized areas may see snow in excess of one foot.

* WHERE…Portions of north central and northeast Illinois.

* WHEN…From 6 PM this evening to 6 PM CST Friday.

* ADDITIONAL DETAILS…Be prepared for significant reductions in
visibility at times.


A Winter Storm Warning for snow means severe winter weather
conditions are expected. If you must travel, keep an extra
flashlight, food and water in your vehicle in case of an