High pressure remains in place today, but as a warm front moves into the forecast area tomorrow a couple of clusters of storms will be possible. The first looks to organize across northern Illinois and move southeast Thursday afternoon into the evening.
The second cluster is forecast to develop Thursday night into Friday across northern Indiana, northern Ohio, and southern Michigan then move south/southeast across zone 1.
Areas of heavy rainfall will be likely with these clusters of storms. The NAM 4km shows as much as 4-5″ of rainfall locally under these clusters. While this may be on the extreme side of things, rain totals of 2-3″ will be more common. Keep in mind, these clusters often have vert sharp cut-offs with rainfall. One part of the county may get a few inches while another side gets little to no rainfall.
Through the end of the week into the weekend the upper-level ridge will build into the region. This will allow heat and humidity to expand across zones 1 and 5.
With temperatures in the 90’s and high levels of humidity heat indexes will warm into the mid to upper 90’s in many places. Across zone 5 heat indexes could be in the upper 90’s to low 100’s! So if you have outdoor plans stay hydrated and cool!