Isolated storms continue another day...Rain lingers but it won't last

The greatest instability within the atmosphere has remained down south and that's where it's going to stay for the next couple of days.  However, we have had a few storms roll through as low pressure spins in the middle of the country.  Low pressure currently southwest of the Quad Cites will lift a warm front into northeast Illinois over the next couple of hours with temperatures rising into the low 60's.  North and northwest of the front clouds will keep temperatures in the 50's during the afternoon.  While scattered showers are almost a sure bet in northern Illinois and southern Wisconsin, thunderstorms will also be possible as the upper low swings through later today. 

Temperatures usually decrease with height and the colder the temperature is above the surface, the stronger the lapse rate will be.  Lapse rate is simply a change in temperature with height.  The greater the difference, the steeper the lapse rate.  This is just one, of many, factors in developing thunderstorms.  Clouds have thinned out mainly south and east of Rockford as drier air wraps in around the low.  This clearing will allow surface temperatures to rise into the low 60's.  As the colder upper level low moves over the relatively warmer surface, the air will quickly rise causing it to become unstable and generate thunderstorms.  If those storms were to form, hail would be the primary threat.  However, a few funnels have been reported in eastern Iowa and there was a report of a brief tornado in Shannon (Carroll County).  Any storms that do develop will have the possibility of hail and could also begin to rotate being close to the low pressure system.  Storms would then decrease in coverage once the sun sets this evening with just showers lingering into the overnight.

This low pressure system will continue to weaken and move into the eastern Great Lakes by the end of the week.  Even though we'll see a daily chance for rain it will decrease in coverage the closer we get towards the weekend.