Comparing the OUNWRF to the current radar as of 1915Z on Thu shows the model is too slow on initiation since there are already echoes. But, the placement of the echoes as you move ahead in time looks almost spot on. The other issue with the model is that it takes 1.5-2 hrs for radar echoes to develop into a mature supercell. Based on what happened yesterday with a similar environment, it would take no more than an hour for a supercell to evolve.