The weather could turn quite stormy for some Monday late morning and early afternoon as thunderstorms ride along the outer edge of a strong heat dome currently building across the middle of the country. A SLIGHT RISK for severe thunderstorms is in place for northern Illinois and southern Wisconsin for the risk of thunderstorms producing significant damaging winds, large hail and isolated tornadoes.
For the rest of Sunday night, skies will remain partly to mostly cloudy. Temperatures did warm into the upper 70s, to near 80 degrees, once the fog lifted and clouds cleared. It actually felt a little humid as the dew point temperature reached near 70 degrees in some locations. But an east wind will help to scour out some of the moisture, lowering dew point temperatures and making it feel much more comfortable. Tonight, Sunday night, will likely be the last ‘windows open’ night as temperatures are expected to rise quickly in the days to follow.
A stationary boundary located south of the Stateline will be pulled back north as a warm front Monday morning and afternoon. But just how far north through the region is just one, of many, questions that’ll help determine what occurs Monday afternoon. Another is with a storm complex that will likely develop over the High Plains Sunday late evening, racing east/southeast into the Midwest Monday morning. It’s part of that storm complex that could impact us through early Monday afternoon, if it shifts this far to the southeast.
The storm complex would remain mostly to the north of the warm front Monday, as the environment south would likely have a strong cap – or lid – on the atmosphere preventing storms from developing. If the front clears the Stateline Monday morning it would bring the highest storm risk more into southern Wisconsin, shifting it across northeast Illinois and eventually into Indiana. If, however, the front stalls out over northern Illinois then that highest storm threat would be placed right over the Stateline. Unfortunately at this point, Sunday night, it’s hard to determine exactly where that boundary sets up and just how the storms over the Plains will evolve later Sunday night.
Having said that, the risk is there for damaging wind gusts, hail and isolated tornadoes in northern Illinois as early as 11am and lasting through 2pm/3pm. Please remain weather aware during the day Monday! Over the next 12 hours we should get a better picture on what may occur during the day Monday. Be sure to stay updated with the forecast as these storms would move in quick, and leave quick! Following the thunderstorms will be the heat and humidity. For some, it’ll arrive Monday late afternoon. For most, temperatures will rise Monday night, peaking Tuesday and Wednesday.