Showers possible later today; Maybe even some hail

12:30pm Update:  Instability showers with a few thunderstorms have blossomed across Minnesota and northern Wisconsin.  From the storms that have formed in Wisconsin reports of quarter sized hail as well as funnel clouds have been reported.  Scattered showers, as well as thunderstorms, will move into southern Wisconsin and northern Illinois by mid to late afternoon.  With the very cold air above and a weak area of surface convergence it's likely we'll have small hail and possibly even a few cold air funnels this afternoon!   Cold air funnels rarely turn into tornadoes, but it may be a sight to see later this afternoon!

The cloud cover we had this morning is no more as mostly sunny skies are found.  Skies should remain mostly sunny, however later this morning you'll start to notice a few of the puffy cumulus clouds in the sky.

A few showers and maybe a thunderstorm or two could develop as an upper level low moves through and it's possible that some of those showers may contain small hail.  Now, you may be asking if any severe weather is in the forecast and the answer is "no".  So then your next question may be: "Why the hail"? 

To answer that question we need to talk about cold air aloft and lapse rates.  I'm sure you already know what cold air aloft means, but you may be wondering about lapse rates.  Simply put, lapse rate is the changing of temperature with height.  The colder the air is above the quicker the air at the surface will move upward when it's heated with the sun.  This is often referred to as a steep lapse rate.  As long as the air that is being lifted is warmer than the surrounding air it's going into, the air will continue to rise.  This is how clouds and thunderstorms form.  When the low currently in Minnesota moves closer to the area later this afternoon the colder air associated with it will allow for the air parcels to quickly rise which could produce what we call 'instability showers'.  It's also possible that if a few of the updrafts grow quick enough and strong enough a few short-lived thunderstorms may develop.

Now, let's talk about hail.  When there is colder air aloft the freezing level (point in the atmosphere where the temperature is 32° or below) lowers.  This means the water molecules in the clouds only have a short distance to travel before they freeze and fall to the ground.  This set-up will be very similar to what will happen later today.  Forecast soundings from Minnesota show the temperatures where this low is located at to be roughly -20°C to -25°C. 

On the opposite end, when there is warmer air above the air at the surface has a harder time trying to lift because it's entering into an airmass that is the same temperature, or in some cases warmer temperature, of the actual parcel.  This type of set-up we tend to see more during the summer months.  So later today if there are a few showers that do form don't be surprised if small hail occurs as well.  However, if the showers don't form until closer to evening the threat for any thunderstorms or hail will diminish because we will have lost the heating of the daytime.