Monday Afternoon Weather Update: Severe Thunderstorm Watch Issued

9:45pm Update: A Severe Thunderstorm Warning had been issued for parts of Ogle, Lee and DeKalb counties earlier Monday evening.  The storm quickly strengthened as it moved into DeKalb County, likely producing strong wind gusts south of Malta and DeKalb.  The Severe Thunderstorm Warning has expired as the storm has fallen below severe limits.


Additional thunderstorms continue to develop over southeast Iowa and central Illinois along a stationary boundary.  This will likely be the focus for additional thunderstorms during the overnight.  Heavy rainfall will be our biggest concern.




7:15pm Update: The bulk of the storm activity is done but isolated showers and thunderstorms are still likely as the atmosphere holds on to a little instability through the evening.  A line of showers and thunderstorms have developed from near Forreston, southwest into Carroll County.  The storm cell just southwest of Forreston could contain smaller hail with it.  These storms are moving to the east/northeast.













6:05pm Update: Just in: The Severe Thunderstorm Watch has been canceled for northern Illinois.  While a few isolated showers/storms may continue for the next hour or two, the threat for severe weather continues to decrease this evening.


The image on the left shows estimated rainfall totals from storms earlier Monday morning and afternoon.  Locally 2-3 inches of rain came down over far NW Illinois before sunrise.  Most of the thunderstorms Monday afternoon missed northwest Illinois.





5:30pm Update: Severe Thunderstorms developed mostly south of Rockford Monday afternoon in an area that had developed better instability.  Severe Thunderstorm Warnings were issued for Lee and DeKalb counties, but have since expired as those storms have moved well east of the area.  The storm over DeKalb County did show some mid-level rotation, but with the environment not supportive of tornadoes the storm likely produced large hail and even a possible wet microburst.
There are some additional light showers developing over Rochelle, but our severe threat will be decreasing through the evening.

A Severe Thunderstorm Watch has been issued for Winnebago, Boone, Ogle, Lee, DeKalb, McHenry and Whiteside counties until 10pm Monday evening.  Thunderstorms have developed southwest of Rockford Monday afternoon, closer to where a warm frontal boundary is located.  Instability has increased quite a bit over Ogle, DeKalb and Lee counties this afternoon.  Thunderstorms capable of large hail, strong winds and heavy rainfall will be likely through roughly 7pm-9pm.  Storm threat will then shift east into the early overnight before additional rain showers/embedded thunder will be possible.