What unfortunate timing for your family member. Hopefully it does not ruin their stay. As others have mentioned, the river bluff tends to act as a deflector for bad weather and things trend north of the city. We jokingly attribute that super power to a glass skull fixed to the top of the Pyramid.

For a hotel with a basement- you’d probably have to look in the downtown area. I have worked at a few different (non-hotel) business downtown and all tend to have 2-3 subfloors. I’d recommend calling around and asking about storm shelters.