It's not JUST snow this time...

... not that that's necessarily good news.

10:45 p.m. update: Radar echoes are reaching the northern tiers of counties of Illinois. However, I haven't seen any reports of anything reaching the ground quite yet, but I doubt that it'll take more than an hour. We're sitting at 32 as I write this... however, our dew point is 24. As the rain falls into that dry air, it evaporates and cools the air. I expect our temperatures to come down a few degrees as we start getting rain to finally reach the ground. We can't afford to cool the temperature at the surface since it's already at 32... but we'll have to deal with freezing rain anyway. Freezing rain will continue until our temperatures get back above 32, which I believe will happen as the more moist air - and warmer air - gets here in the early morning hours. In fact, I suspect we'll get a changeover to rain earlier than I was originally expecting. Regardless, the ice we do receive will still be hazardous.

I feel as though I've downplayed the flooding problem. With some 12-20" of snow on the ground and rain falling on top of it, that water will have absolutely nowhere to go. I wouldn't be surprised to see some local urban flooding where storm drains are blocked, quick rises on some waterways, and standing water in low spots.

As always, stay alert.

-J

At 7 p.m., precipitation is spreading northward through western Illinois. Unfortunately, temperatures at the surface are below freezing and warmer air is riding above it aloft. The area is looking at freezing rain issues for tonight as temperatures at the surface remain below freezing. As the system pulls northward overnight, warm air will become wrapped in at the surface, changing things over to good old-fashioned rain. Right now, it appears that up to 0.25" of ice and the changeover to rain will be what people wake up to Sunday morning. As you can well imagine, the rain - which may be heavy at times - along with the new ice and the snowmelt will make getting around pretty tricky. If you're heading out to church, brunch, or any of the memorial services in DeKalb, allow for extra travel time and drive at the appropriate speed.

Early afternoon is when I expect the rain to switch over to snow, and it should be a quick transition as the cold air pushes southward behind the cold front. Temperatures will plummet with strong northwest winds. Snow accumulations are pretty tricky to pinpoint with these precip-changing events, but I'm thinking 3 or 4" in Rockford with amounts quickly increasing to the northwest (where the warm air won't make as great a surge) with quickly decreasing amounts to the southeast (where warm air will be in place longer). Blowing snow will be an issue Sunday afternoon.

Of course, any change in the timing of when the precipitation changes from one type to another and the eventual track of the low will alter how things all shake out. To recap, here's what I'm thinking right now: up to 0.25" of ice overnight... changing to all rain, which may be heavy at times and cause some flooding issues, around dawn... changing to snow in the early afternoon with accumulations of generally 3-4" in Rockford.

I'll post another update or two later.