Evening Storm Update

11:35 PM UPDATE: The thunderstorms across the Stateline are continuing to weaken and move away from the area aside from one stronger storm in Rock County. We have gotten numerous reports of hail -- even hail covering the ground -- and a few reports of tree branches down in Ogle County. These photos show some storm damage near Stillman Valley where strong winds likely brought these branches down as the severe thunderstorm moved through.


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11:15 PM UPDATE: A Severe Thunderstorm Warning is in effect until 11:45 PM for Rock and Walworth Counties for hail to the size of quarters and wind gusts upwards of 60 MPH. The storm has exhibited some rotation, which suggests it is very mature and strong. For that reason, the storm should have no issues remaining strong to severe as it traverses across Rock County and into Walworth County.
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10:50 PM UPDATE: A Severe Thunderstorm Warning is in effect until 11:15 PM for hail to 1" in diameter, or the size of quarters. It is moving very slowly towards the south and east. Torrential rainfall with this storm, in addition to others, will create the potential for flash flooding in low-lying areas and areas near water.



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10:00 PM UPDATE: A Severe Thunderstorm Warning is in effect until 10:45 PM for southwest Winnebago County and northern Ogle County for half dollar size hail. The storm is moving slowly to the south and east.


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9:15 PM UPDATE: A Severe Thunderstorm Warning has been issued for Winnebago County until 10 PM for hail to the size of half dollars. Vivid lightning is also occurring with this storm as it slowly moves off to the southeast.





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8:20 PM UPDATE: A Severe Thunderstorm Warning has been issued for Green and Rock Counties in Wisconsin until 9 PM. The storm is being warned for 1" diameter (quarter size) hail. It is located 11 miles northeast of Monroe and it is moving east very slowly at 25 MPH. Areas that will be affected include Brodhead, Janesville, Orfordville, Monticello, Albany, Footville, and Hanover.
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7:40 PM UPDATE: A Severe Thunderstorm Warning has been issued for Stephenson County until 8:30 PM for quarter size (1") hail. Trained weather spotters have confirmed reports of 1" hail with this storm as it heads east southeast at 20-30 MPH. The storm will affect Cedarville, Freeport, Dakota, and potentiall Winnebago County as it continues its movement ESE. Any storms that develop this evening could turn strong to severe and pose a hail threat.
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Our first "strong thunderstorm" has developed in northwestern Rock County as of 6:30 PM. According to the National Weather Service, dime size hail, winds to 40mph, and lightning are all possible as it moves towards Janesville, Orfordville, Footville, Magnolia, and Afton. This trend will likely continue through the evening as we have seen some minor destabilization (energy in the atmosphere) take place along and north of U.S. 20 as the sun has popped out. That, along with the warm front that is essentially sitting over the region now and modest bulk shear in place, will allow for thunderstorms to continue popping up and maturing this evening into the overnight hours.

 The warm front is essentially the focal point for the thunderstorms this evening. Wherever that boundary is located is where the storms will likely develop. Models have continued suggesting this to be JUST northeast of Rockford along a Madison, McHenry, Chicago line. However, some of the most recent model guidance has pushed storm development closer to Rockford. With the storms that do develop and mature, there is the risk for a few strong to severe storms with hail and gusty winds.

So the bottom line is we have a few rain showers in the southwest corner of the Stateline in Lee and Whiteside Counties. That will continue dissipating as additional thunderstorms redevelop across portions of the region. That development is occurring now and will last through the evening as storms move slowly eastward overnight. Again, the areas with the best chance of seeing the storms this evening include: Belvidere, McHenry, Walworth, Lake Geneva, Rockton, Janesville, Beloit, Milton, Roscoe, Poplar Grove, Capron, Marengo, Harvard, and Lake Summerset. However, other regions do have the chance to see a few storms.