Could be. I remember back in the early/mid 90s the models tended to move the dry sector too far east, so a lot of Day 2's erred too far east. David Hoadley wrote a Stormtrack article on this around 1993. I think these problems are gone, though, but maybe a trace of this eastward bias still persists.
It is interesting that Colorado has been upgraded a lot, but only downgraded once.
Looking just at the upgrade graphic, I think I see a slight correlation with the radar hole maps that were previously discussed in another thread. The absence of nexrad coverage probably has little or no impact on the SPC deciding whether or not to upgrade an outlook, but isn't there other data gathered at those sites besides radar, the absence of which just might be significant to the SPC? Or am I just seeing things... I admit the correlation between the maps is vague at best.
I don't know what to make of the downgrade map, I can't think of any reason why those areas would be prone to downgrade.
Interesting topic, though. What were your criteria for downgrade and upgrade? Were you looking at the actual percentages or just the categories of Slight, Medium, and High? I assume the later. What about days they raised the risk and then lowered it again? I know I've seen a few of those over the years, although probably nowhere near enough to be significant to something like this. And how about the different risk factors? It might be interesting to look at up/down-grades to just the Tornado risk, or Hail or Wind... Well OK, let's not get carried away. But hey, isn't it great just to have this kind of data to play around with? :wink: