I would like to suggest adding a couple more stats to your evaluation. Depending on one (HSS) is typically dangerous when trying to conclude from a single score.  It would be great to actually show the graphic with the actual HSS over the US at a minimum.  In my past career doing forecast evaluation, each score has it's good and bad points, and only when all available stats point to the same result provided the good answers to folk footing the bill ($$; experience in modeling stats, severe weather and aviation forecast evaluation).  But nice to see a group provide some look back into what happened...sort of an outlier in NOAA/NWS.  

Mary Cairns

NOAA/NWS/FAA Retired