Sunday afternoon weather update: Storm threat increasing through the afternoon

With our severe threat ending, I'm going to take down the LIVE radar.  Should thunderstorms fire back up, I'll bring back the radar.

4:30pm Update: The thunderstorm that moved through southeastern Boone County and into McHenry County is now in Wisconsin with skies turning blue once again across Northern Illinois.  Thinking that over the next couple of hours our storm chance will greatly diminish heading into the overnight.  I'll still hold on to an isolated storm chance just with what's developing back west in Iowa, but I think what came through earlier is all we're going to get.



Was paying pretty close attention to the cell that quickly developed north of Kirkland and Kingston.  It did show signs of broad rotation for a little while, but has weakened slightly.  Garden Prairie now getting some pretty heavy rain.  Heads up Marengo.





Thunderstorm developing in and Kirkland, moving in south of Belvidere.  Frequent lightning and heavy downpours likely.







Radar update: Look for heavier rainfall south of Rochelle and west/southwest of Steward.  Still no lightning strikes with these, but with dew points in the middle and upper 60's, heavy downpours are likely.

2:30pm Update: Current check of radar shows not much has developed in N. IL and S. WI.  There have been a few heavier showers near Monroe in Wisconsin and south near Mendota that are now lifting into central Lee County.  While the instability is building, there isn't much 'lift' in the atmosphere to help generate thunderstorms.  This is mainly due to warmer air aloft.  It's not allowing the air to rise which is limiting storm growth.

There is, however, an isolated severe risk developing across Southern and Central Wisconsin.  Although, a watch is not anticipated at this time.  For a look at that, click on the latest discussion from the Storm Prediction Center.


A Slight Risk for severe thunderstorms remains in place across Northern Illinois and Southern Wisconsin as strong low pressure pulls through the upper Midwest. 

Now, many of you have asked if this is a set-up similar to what happened back in April, and no, not completely.  While there is a low end risk for tornadoes this afternoon, the greatest threat for those will be closer to where the warm front, low pressure and cold meet in southern Minnesota, Wisconsin and northern Iowa.  Our greatest storm threat will likely be strong winds. 

Skies have been clearing out since mid-morning today, and this has actually allowed instability to greatly increase across N. IL.  The image to the left is what we call CAPE, or Convective Available Potential Energy.  This indicates the amount of energy in the atmosphere thunderstorms would have available when they develop.  Numbers usually over 1,000 J/KG (Joules per Kilogram) are needed to build stronger storms.  Scattered thunderstorms are beginning to develop in western Iowa and southern Minnesota, and this activity will continue to develop throughout the afternoon.  Storm development for Northern Illinois and Southern Wisconsin could be as early as 2pm, but may hold off until after 3pm, as what's developing a little further north into Wisconsin may continue to develop further south into Northern Illinois.

As always, updates throughout the afternoon will continue so be sure to check back!