Hi @ironbar - Thanks for your patience. It seems you figured this out from the responses in our other thread.
And yes, in general @Galeros93 is also right about additional data sources like this. Additional data can be explored during model training, but only approved sources are allowed for generating predictions during real-time evaluation. The description on the website and the data request form includes what is required for an additional source to be considered, including a demonstration that the source adds clear value beyond existing approved sources (like the HRRR climate data source). Again, in this case it seems you tracked down the answer already.
Good luck!