As of 2030Z, storms have already initiated near Pierre SD in the KABR forecast area.

Both PHS and the HRRR appear to be too slow on forecasting convective initiation in this area.

The first image is PHS comp reflectivity (overlaid on PHS SBCAPE) valid at 22Z.

The image below is HRRR comp reflectivity valid at 22Z. Both PHS and HRRR are depicting convective initiation between 21Z-22Z, but as mentioned, storms have already initiated as of 2030Z. PHS and HRRR both show initiation in slightly different locations, but in real life, initiation occurred near both indicated locations.

Both PHS and HRRR also depict that stronger cells will develop near the SD/ND border in the 23Z-00Z time frame. The next two images show this in the parameter space. The first image shows Sig Tor Parameter on PHS (valid 23Z) and the second image is the same thing, but with PHS comp reflectivity overlaid on top.

Of most note is the simulated storm northwest of Ashley ND, which not only has the highest simulated comp reflectivity value, but also significantly impacts the storm-scale environment (as depicted in the model by an unrealistic significant localized bullseye of STP). As a forecaster, although I recognize these STP values (~10) are likely spurious, I can use their presence as a proxy to the fact that the storm simulated by PHS in this location is likely very strong and modifying its environment in a way that only significant supercells are able to do.

— Insolation