Tornado watch issued for parts of Northern Illinois and Southern Wisconsin

7:45PM: The tornado watch was cancelled, and our severe threat has come to an end tonight.

 5:15PM UPDATE: The tornado watch was expanded to include Ogle, Lee, and DeKalb counties, which remains in effect until 10PM. We still think locally the highest threat with any storm will be primarily with large hail and damaging winds. Be sure to heed any warnings that are issued!

5:00PM UPDATE: A new severe thunderstorm warning has been issued for portions of Carroll and Whiteside County until 6PM. This storm is capable of producing 60 mph wind gusts and quarter sized hail as it moves Northeast at 40 mph.

4:50PM UPDATE: Additional thunderstorms have begun to develop along the dryline to our West, pulsing up very quickly within the last 20-30 minutes. While not severe yet, they likely could turn severe quickly with extreme instability ahead of them. Storms moving Northeast at 40-50 mph.

4:45PM UPDATE: A severe thunderstorm warning has been issued for NE Ogle County, SE Winnebago County, and Boone County until 5:30PM. This storm is capable of producing 60 mph winds and quarter sized hail as it moves Northeast at 50 mph.

It is a very hot and humid afternoon in the Stateline with temperatures reaching into the low 90s for some. Dew point values meanwhile are in the mid to upper 60s, helping to provide some of that surface moisture to develop strong storms.

With the heat and humidity in place, there is a LOT of energy, or instability, for these storms to work with. This will allow for any storm that develops to quickly turn strong to severe. This indicated by the bright colors shown below.

A few showers and storms are at least trying to develop across portions of Southwestern Wisconsin, likely showing we are getting the initiating point of our storm development within this extreme instability. These showers will likely rapidly develop into mature thunderstorms, tracking Northeast. Additional storm development may be possible South of these between 3-4PM.

A tornado watch has been issued for far Northern Illinois and Southern Wisconsin, effective until 10PM Thursday. While the main threat with these storms is not tornadoes, an isolated tornado cannot be ruled out given the moisture near the surface.

The highest chance for any severe storms will be primarily along and East of I-39, given a little more time for storms to mature. This will likely begin to occur between 4-5PM, with storms then moving East through 7-8PM before exiting the area. After that, the threat will quickly diminish. Storms will not congeal into a line around here, they will remain relatively scattered. So that means not everyone will see a storm at all. It is likely some if not many will remain completely dry. That said, those who do see storms will likely see storms with significant impacts. The strongest storms will be capable of producing large to destructive hail, with a secondary threat of strong winds, followed by tornadoes. Storms will only last over one particular area for an hour or two at a time.

There is a level 3/5, or enhanced risk for severe storms across most of the Stateline this evening, per the latest outlook from the Storm Prediction Center. The highest threats will be further East where storms have a longer time to mature. Further South and West, the window for storms is much shorter, hence the lower overall risk. Be sure to stay tuned for updates through this afternoon and evening!