The Finish Floor Elevations established after Floyd were based on the NGVD 1929. The new flood gauge predictions will be based on the NGVD 1988.
Therefore, if your finish floor elevation shows 19.5 ft. (above mean sea level) you will need to SUBTRACT 1.5 ft. from that which would make it 18.0 Ft.
If the new flood gauge prediction shows that the Blackwater River will crest at 17. Ft. then you should be ok however things on the floor should be elevated to be safe.
These are only predictions and property owners should take extra precautions if they feel it necessary!