Updated: All you need to know to follow Thursday's storm

3:00 pm Update: Elevated thunderstorms moving into Northwest Illinois could produce small hail and heavy rain.  Another line of storms in Eastern Iowa will move east of the Mississippi River by 4pm.  Those, too, could produce heavy rain and small hail.

1:40 pm Update: Severe Thunderstorm Warnings have been issued for Eastern Iowa for elevated storms capable of producing quarter sized hail.  These storms are moving northeast at 60 to 65 mph and could clip Northwest Illinois within the next hour and a half.  Any storms that do move through this afternoon would mainly be hail producers as most would remain elevated and not rooted near the surface.  Reason: temperatures at the surface are in the 30's and we remain north of the warm front.

Noon Update: Rain with embedded thunderstorms will continue to shift east of I-39 with additional thunderstorms developing in central Iowa closer to an area of low pressure.  In fact, southeast of Des Moines, IA there have been a few severe thunderstorm warnings with heavy snow falling just to the north and temperatures in the 30's!  Impressive!  Once this second wave of rain moves out, we'll get a little break going into the afternoon until the main low and cold front move into Northwest Illinois.  With the third wave, additional thunderstorms will be possible going into the evening. 

One important issue we'll have to monitor going into the afternoon is just how far north the warm front will be able to travel until the cold front arrives.  Right now, the warm front remains in central Illinois (just look at the temperature contour contrast on the map to the left).  If that front stays to the south, then our temperatures will remain in the 30's.  If it's able to reach this far north, then we'll get close to the low 40's.  This could have an impact of how much snow we'll receive once the low passes tonight.








10:40 am Update: Additional showers will continue to track north/northeast into Northern Illinois through early afternoon as low pressure shifts east.  Showers will be heavier with a few elevated thunderstorms that could contain small hail.     





8:00 am update:




Temperatures this morning have held steady in the low to mid 30's as the first wave of moisture moved into Northern Illinois early this morning.  Anything from sleet, heavy rain, heavy/wet snow and thunder were reported.  The heavy, wet snow has created slush-filled roads so allow yourself a little extra time this morning.  Good news, the heaviest of the rain is done with only additional, lighter showers expected through the remainder of the morning.

Temperatures will stay in the mid-30's through the morning until a warm front, currently in Central Illinois, pulls north around Noon.  Along the front, there could actually be a few isolated thunderstorms as low pressure moves into Western Illinois.  Once the sun sets tonight, a strong cold front will begin to sweep across Northern Illinois and Southern Wisconsin with winds quickly switching around to the west and southwest.  Winds will increase to 30 mph with gusts approaching 50 mph through the overnight.  Colder air behind the front will allow snow to whip around with an additional inch of accumulation possible by Friday morning.