Thermal runaway is a myth. That is all a forced pattern response.
Tropical forcing isn’t reminiscent of 2015 (yet) nor will the pattern be for the foreseeable future. But as we discussed a couple weeks ago, it is likely the pattern will trend warmer later in June into July in response to *sub*seasonal variability in tropical convection (combination of BSISO progression and onset of E-Hem monsoonal forcing).
But don’t make the same mistake everyone else does in reading too much into model guidance attempting to resolve sub-seasonal variability in the extended range.
SPC gets it up your way. I wouldn't be surprised to see a shift north into northern Illinois and Indiana just based off where the hot spots have been this year.