We were there.
Luckily DD1 was in line for coffee at 6 a.m. and learned that one of the lodges had been evacuated at 2 a.m. and that the northern entrance had already been closed. So we rousted the family, children, spouses and grandchildren, and fled to the western exit.
Our biggest impediment was a large herd of bison, more than 100 strong, running toward us on the highway and swerving around us like a herd of cattle in a western movie. I guess the massive flooding pushed the herd up onto the highway. We got some cool photos.
Other than the 8 hour drive to SLC airport followed by a 5 hour flight home, we got off easy,