Storms holding off yesterday could mean greater coverage/intensity today

I was a little surprised to see a genuine lack of thunderstorms yesterday.  Some rain popped up, but otherwise it stayed relatively quiet as the warm surface air was unable to overcome the cap.  Today, however, should be a different story.

SBCAPE as forecasted for 5PM today by the NAM4KM's 2am run.  Instability should skyrocket as temperatures soar into the low 90s and dewpoints approach 70°F.

VERY unstable conditions are forecast to exist by the short term models, and a couple areas of intense thunderstorms are forecast to develop this afternoon in the Thumb and some areas of SE Michigan in particular.

NAM4KM currently shows limited coverage but high intensity in the thunderstorms it forecasts to develop.

Note that I'm agreeing with the SPC's "Marginal" risk assignment right now only due to lack of wider coverage indicated by the model.  Conditions where storms pop up should be good for intense storms to develop as there will be ample fuel.  Combined with some not-totally-anemic wind profiles and the dynamics of lake breezes, this could create some fireworks.  

1 hour max updraft helicity as forecasted by the NAM4KM.  This parameter forecasts how much rotation will exist in any storms that develop.

These storms should also make an abrupt right turn from moving east to almost due south; when storms turn right, they tend to rotate. 1km EHI - the index used to forecast a combination of rotation and instability in the first 1000 meters above ground - is forecasted to get above 4 in some locations, and 1 hour max updraft helicity (rotation of updrafts where the model detects them) indicates that there is a slight tornado risk, particularly in the Thumb and counties near the bay.

Where storms pop up and when is going to have everything to do with how big they become.  Right now the NAM4KM is suggesting storms in the Thumb, Saginaw Valley and in and around the I-69 corridor to the south of the Saginaw Bay.  This can change with different runs, and should coverage look like it's going to increase, there's no doubt in my mind that the SPC will upgrade the categorical outlook.