Jan 17th-18th Accumulating Snow And Ice Event (Update #2)

We continue to watch with a close eye a system that will be eventually pushing into the heart of the central U.S. by the start of the weekend and one that looks to bring a round of wintry precipitation, including accumulating snow and ice to portions of the Midwest and potentially here in Illinois. The latest follows below....​

Our system of interest late this afternoon and early this evening is moving over southern Alaska and the Aleutian Islands and will continue south and eventually southeast, making a turn towards the west coast of the United States. It is forecast to come ashore tomorrow afternoon and evening across southern Canada and then continuing mostly east towards the Rockies and the plains. If you recall from the last two articles, not much has changed with the overall track. One thing that does look to have changed is the speed of the system has slowed down some. 

The general idea and evolution hasn't changed much with widespread precipitation developing Thursday afternoon and evening well to our southwest across the southern and central plains. It will then steadily continue east and northeast overnight into Friday and through much of the day on Friday, changing over to snow, freezing rain, and sleet as it encounters colder air to the northeast. The tricky forecast at this time remains to be trying to pin point areas that remain all snow, areas that see more of a freezing rain threat (ice) and areas that could see a mixture of everything. It does look like further downstate will stay warm enough to only experience rain. The animation below runs from 3pm Thursday through midnight Friday night/Saturday morning. This is also not a set forecast, just showing the general evolution of things. 

Using one ensemble forecast to look at **potential** snowfall amounts...this is for Dekalb, IL which is just about smack dab in the middle of northern Illinois. The mean is right around 3" (black line) but we can also infer a cluster of solutions of 4-6" and then lower than the mean a of maybe a dusting to an inch. This goes to show you that forecasts are not at all set in stone yet and won't be for another few days. 

Be sure to stay tuned for continued updated forecast articles as this remains a tricky forecast trying to pin down the zones of specific precipitation types. Right now, areas across the northern portions of the state are favored for accumulating snow and areas just south, say I-80 and into central Illinois could see more of a freezing rain threat. Could these areas change? Of course but that is the best guess right now.