Another day, another wintry mess! Thursday's culprit is a fast moving low pressure that will streak out of Missouri on a track through Illinois late in the day. You can watch the low move from St Louis to Milwaukee below.
This is a classic track for heavy snow in my area if sufficient cold air is in place. However, that's not the case over the SE third of Iowa and NW Illinois where a wedge of warm air aloft exists. That means freezing rain, sleet, and snow will all be players before Thursday comes to an end around much of my area. You can see the different precipitation types in the animation above. These are the NWS advisories in effect at the time of this post. They could be altered by morning as the storm shows its hand.
Timing the transition from mixed types to snow is a difficult challenge and it makes it harder than usual to forecast snow amounts when such a conversion is involved. A delay of 2-3 hours in some cases can lower snow amounts 1-2". Be that as it may, here are some ice and snow forecasts from late Wednesday night.
Let's start with ice. You can see a trend where the threat is greatest from Missouri into eastern Iowa and extreme NW Illinois into Wisconsin.
The 3k NAM
The snowfall forecasts show the threat for accumulation greatest NW of a line from Ottumwa to Iowa City and on to Dubuque. I prefer the EURO and GFS solutions over the other 2 models.
The 3k NAM
As the storm advances into Illinois winds will increase to 35 mph with falling temperatures through the afternoon. Here's the projected temperatures at 6:00 am.
By 6:00 pm look whats happened.
Friday morning wind chills are 20 to 35 below!
Like it or not, the next 24-36 hours are not going to be pretty. Another punch from winter! Roll weather...TS