Jan 17th-18th Wintry Weekend System Could Bring Accumulating Snow (Update #1)

Not a whole lot has changed over the last 24 hours or so regarding an interesting looking late week/early weekend system that has potential to bring a wide array of wintry weather to the Midwest and Illinois. This certainly includes the potential for freezing rain (ice), sleet, and accumulating snow as well. 

Our system of interest is still out over the northern Pacific Ocean this morning and will continue to dive southeast over the next 12-18 hours before coming ashore California later tonight and early Thursday. Beyond that, it is forecast to move into the Four Corners region, eventually crossing the Rockies into the plains. Once onshore, model guidance should start getting a better handle on this system and developing more of a consensus on what to expect. 

Taking a different approach this time around, lets look at an ensemble forecast instead of just one models given output/solution. The image below is showing 20 different possible solutions, valid at noon on Friday across the Midwest. As you can see, most of them show the general idea of widespread precipitation developing across the plains Thursday night and then moving northeast into the Midwest by Friday morning and early afternoon. Do they all agree? Of course not. They do however mostly agree on the general evolution of things but this goes to show you that several details still have to be worked out and this is more so to show some disagreement still exists and the spectrum of solutions possible. Some are slower while some are faster moving precipitation into the state. Some show more snow than others. All of them do show snow in some fashion along with a "mixing zone" of freezing rain and sleet between the snow and rain. 

Again, using an ensemble forecast when looking at **potential** snowfall amounts...the image below is averaging out 50 different ensemble members (50 different outcomes/scenarios) and creating a mean forecast. Below is showing the percentage chance of a greater than 3" snowfall across the region in a 24 hour period from 6am Friday to 6am Saturday. As of right now, the highest chances for a 3" or greater snowfall exist across the northern portions of the state.  Obviously this is still subject to change and probably will but as of right now, northern Illinois stands the best chance for meaningful snowfall from this system. 

Questions still remain but the northern portions of the state stand the best chance for accumulating snow at this juncture. Stay tuned for more updates and forecast articles as we get closer to Friday and the start of the weekend. ​