We continue to watch this weather system closely and confidence is slowly increasing that a winter storm with potentially significant impacts could affect portions of the state this coming weekend. Now, not all of Illinois will see wintry weather and as of right now, model guidance continues to favor northern and portions of western Illinois for wintry weather with the rest of the state remaining too warm and therefore seeing just plain rain. Let's dig into the latest below.....
If you remember from a couple days ago, our weather system of interest was well out over the western northern Pacific Ocean but over the last 48 hours or so, it has continued steadily eastward and at this time, is now located off the coast of British Columbia and the Pacific Northwest (circled in blue). By tomorrow morning, it will be ashore the western United States and this is when we should start to see a clearer picture on what exactly to expect from this system. Once it is over land, it will be able to be sampled by weather balloons and that data will be ingested into the computer models we look at.
Even though we continue to see disagreement among model guidance, we are slowly starting to shrink the circle of possible outcomes, as you can see below. This is again an ensemble model forecast showing possible surface low locations at noon on Saturday with a decent cluster across southern Illinois. So yes, even though the exact track isn't set in stone yet, we are slowly getting closer. If the track ends up through southern Illinois, you can almost bet on significant wintry weather impacting northern portions of the state, as what current thinking is.
Looking at one model and one possible scenario, the evolution follows as this...
1. Widespread rains spread into much of Illinois Friday afternoon and evening with portions of northern Illinois seeing a mix of sleet, freezing rain, and snow as colder low level air will be available. This first round would last into Saturday morning. Some guidance suggests a lull in activity while others suggest wintry precipitation will continue right through much of Saturday.
2. As the surface low moves northeast during the afternoon and evening hours, a renewed area of precipitation looks to develop on the west and northwest side of the surface low. This is the period to look out for a more widespread shot at snow accumulations, some possibly significant if the storm system takes a favorable track.
**We continue to stress that this remains a tricky and complex setup and forecast and trying to pinpoint the snow and ice zones remains difficult at this stage. We can however say that confidence is increasing for a winter storm affecting northern and western portions of the state Friday afternoon/evening through Saturday night**
Our current thoughts regarding placement of snow and snow/ice zones are as followed below along with best guess on a storm track at this time but, both of these things are subject to change. **If you are looking for exact expected snowfall totals at this time, you're in the wrong place and we are not confident enough in that just yet**.
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