Regarding deleting the old grids: Perfect! Yeah in my experience I would expect the tool to delete all previous grids for the selected time range when I choose to run the tool, so that change would make sense. Glad it sounds like it's an easy fix!
Regarding the POP/Frost: Yeah I can maybe see some cases where you have a slight chance of showers, but if showers don't happen there could be frost. I think the cases are far and few between, though. Locally we have "clear skies" as part of our frost advisory/freeze warning criteria, and the NPW directive at least suggests clear skies be a requirement. I know the Kentucky Frost flowchart (attached from our previous discussions for others to see) only gives a minor penalty for "scattered" clouds (which is coded as <= 69 sky cover), but in my mind anything more than say, 30%, seems like it would prevent strong enough radiational cooling to form frost. I realize sky cover is a tiny part of the dew check, and thus it isn't much of a factor if sky cover is <= 69%, but maybe that threshold should be lowered? This isn't a critical issue, of course, so maybe after the growing season ends the team can gather feedback to evaluate and possibly make changes to this code.
And finally regarding the separate PoWT tools: On behalf of those of us who have been with ya on the PoWT bandwagon for many years, we really appreciate having the tools available outside the FB procedure! Thank you!