Thursday Storm Update

A Winter Weather Advisory will go into effect for Green, Rock and Walworth counties starting 3:00am Thursday.

A Flood Watch will go into effect for Lee and DeKalb counties starting 3:00am Thursday.

We're still on track to have a very strong storm system move through the Midwest Thursday before leaving late Thursday night.  Not much from the previous forecast has changed, although I do want to note that the NAM computer weather model has come in a little further south and east with it's track which would mean more of a wintry scenario for Northern Illinois.  Stay tuned for that one!

Wednesday's weather will be quiet with high pressure overhead and temperatures rising back into the upper 30's.  Additional snow melt will continue through this afternoon.  By tonight, likely well after midnight, a warm front will pull north into Central and Northern Illinois and then into Northern Illinois by 6am/7am Thursday morning.  Behind the front, a very moisture rich atmosphere (for February) will follow.  Temperatures at the surface and above will be very close to freezing (32 degrees) which gives the potential for any precip that falls to be more of a mixture of freezing rain or even snow.  With the front will also come the threat for elevated thunderstorms as instability will be slightly elevated through Thursday morning.  By early afternoon, low pressure will continue to strengthen and deepen through Northwest Illinois before moving into Michigan late Thursday night.  With the strengthening of the low, warmer air will be pulled into Southern Wisconsin helping to switch over any frozen precipitation to rain.  Rainfall amounts could reach close to 0.75" in parts of North-Central Illinois which, when combined with the snow melt, could cause some flooding issues especially in areas south of Rockford.

One thing to keep in mind is a further southern track would keep more of a wintry mix/snow threat for Southern Wisconsin and possibly Northern Illinois into the morning and then again Thursday evening.  Once the warm front passes, there may be a little lull in the activity until a powerful cold front moves through late afternoon.  As the front comes in a redevelopment of showers/storms will be possible southeast of Rockford.  Colder air will quickly move in behind the front across Northern Illinois with a transition to sleet/snow through the evening.  Winds will also significantly increase from the west once the front passes with gusts near 45 to 50 mph through Thursday night which could cause near blizzard-like conditions through Friday morning!

Needless to say, this storm is going to pack quite a bit of punch with tomorrow for the Midwest.  Whether it be all rain or a mix, Thursday's morning commute will be slow and likely the evening commute as well with the strong winds.