Bob and Susie,
Sounds like a nice trip. We moved to VA from Minneapolis, MN and the upper MIssissippi is the only scenic part worth seeing. Taking the TennTom also sopunds the better route
as well. Should be lots to see and nice folks along the way too.
I wouldn't worry about the flooding so much as the debris. Logs
and assorted can stuff pose the greatest danger
and something to watch for the whole trip. The dams tend to keep the current
from getting out of hand until Cairo. Tornadoes are not anything you'll see coming or be able to out run. Hopefully your locking skills will be developed fast.
Wabasha has some current
to deal with but at least you'll be able to power through and keep steerage and it's just a very short stretch. Downtown St Paul has the strongest current on the entire river and it is far behind you.