I'd say we don't have enough data. Look at some of the convection allowing ensemble suites that are available for North America. We have a handful of deterministic CAMs to take a look at but they are limited in true value, I think. Especially for those that like to chase on a day like yesterday. I think there are also some misconceptions on how these models work, how many people realise that the WRF is not just one model? There are many flavours out there and most of them are initiated from the GFS, Netweather's NMM for example, Manunicast's WRF (very rarely gets mentioned here) or the WRF at modelzentrale.de, all with different physics. I'd love to have more data, but then I'm a storm/model junkie