Weekend winter storm update

As we get closer and closer to the weekend we're beginning to gain a little better idea of what will occur with our next winter storm.  The main storm system has been onshore for about 24 hours now and this has helped models come into a little better agreement on track, intensity and amount of moisture.  While there will still be a few adjustments over the 36 hours, here's the current thinking and greatest impact you can expect going into the weekend.

Surface low pressure looks to track from Texas to Missouri by Saturday night and into Indiana by Sunday morning and near southeast Michigan by Sunday afternoon.  A situation similar to what we've experienced today may unfold Saturday afternoon and evening as warmer air above moves in over cooler air at the surface.  It's still a question as to just how far that warm air lifts north.  Because of this, we're forecasting a mix of sleet, freezing rain, snow and possibly just rain through the evening Saturday until the low swings southeast of the Stateline by Sunday morning.  Depending on how quickly the cold air wraps into the system will determine how quickly the mix will switch over to snow.  Right now, it looks like that transition will occur after midnight from west to east and continue through Sunday morning.

Now, if more warm air becomes wrapped into the storm system Saturday evening this will reduce the potential for significant snow in Northern Illinois Sunday.  However, if the low tracks a little further south Saturday this means the colder air in place will be able to support more snow causing totals to increase through mid-morning Sunday.

Right now, there looks to be a swath of roughly 4"-8" from South-Central Wisconsin to Northern Illinois, including Rockford and down towards the Quad Cities.  Again, should this track shift a little bit either north or south the snowfall totals, and potential accumulating ice, amounts will change.

The greatest timing impact appears to be after 6pm Saturday through the overnight into Sunday morning.  This is when conditions are expected to be at their worst until the system pulls to the northeast by Sunday afternoon.   Now, this isn't going to be the February Groundhog Day blizzard like we experienced a couple years back, but it will have a big impact on travel.  So best advice, if you don't have anywhere to be Saturday evening or Sunday morning I would just stay home. 

We will be on a conference call with the Chicago National Weather Service at 2pm this afternoon to discuss this weekend's storm.  Any further updates from that call will also be provided here.