Monitoring A Severe Weather Threat

A very nice Saturday is in store for the area with a dominant area of high pressure in control. That will keep humidity values low, temperatures in the upper 70s, and will deliver mainly sunny skies. Late Saturday night the high moves east, allowing winds to turn southwesterly. That means heat and humidity will be on the increase by Sunday. That also opens up a path for some disturbances to swing through the Midwest in the form of rain and thunderstorms. Our first chance of precipitation will come on Sunday well before sunrise with an approaching complex of rain and storms. They will be in their weakening phase as the nocturnal low-level jet begins to lose its punch as we approach sunrise on Sunday morning. Nonetheless, rain and a few storms are likely to start the day Sunday.

Some of those could continue into the afternoon hours as well before becoming much more scattered to isolated in nature. Then our eyes turn to later Sunday evening into Sunday night. This is when a secondary shortwave (or a disturbance in the upper-level flow) moves through. That will trigger showers and storms somewhere in the vicinity of the yellow shaded area above. That is the "Slight Risk" zone for severe weather on Sunday. That does include the entirety of the Stateline, which means severe weather is a real possibility on Sunday, mainly late in the day.

It all depends on where and if the storms develop. At this time, it does look like there will be enough "umph" in the atmosphere to ignite thunderstorms near the Rockford area sometime later in the Sunday, but how strong will they get? That is something we have to continue monitoring.

Then all focus shifts to a potentially dangerously hot heat wave late next week. A strong upper-level ridging pattern will take aim at the Central Plains and Midwest/Missouri Valley areas. Underneath that ridge will exist very hot weather with temperatures soaring into the 90s in Illinois and Wisconsin. Highs in the 100s are likely just to our west. Heat index values will approach and likely exceed 100° at some point late next week IF all of the potential thunderstorm activity does end up stay north. If the ridge is slightly further west, then we will have a higher probability of seeing rain late next week, thus lowering our chances of seeing significant heat.