I just called Roundtop to figure out the NASTAR race schedule for the remainder of the season, but the operator sounded only to know generic plan. Does anyone know the schedule for sure? I'd like to try couple of runs on Feb 22 evening, but also want to make sure it will be available for the time before driving all the way up there. If I can't do it, no reason for going there.

NASTAR is scheduled for Friday Evening 2/22, I plan to go myself, of course, if the weather starts affecting the course, that would be a factor.

If they cancelled NASTAR they would very likely put it on the front page of their website, notifying everyone.

I plan on doing it myself both this
Friday and next Friday too.
I only drive 1hr 15 minutes or so, but I can appreciate that if you have a long drive it would be a concern whether they cancelled.

All I can tell you is that so far this year there was one Friday night they cancelled and it was on front page of website.
And there was one other Friday early in the season, where it was raining a bit and I went up and thought they could've had it anyway, but didn't, but with that weather what do I know about making sure the racecourse is safe etc..

As long as the weather holds up you should be fine, hopefully it will stay cold, and watch their website that day.