Just saw this nice new tool - http://tidesandcurrents.noaa.gov/inundation/
From the User Guide
The inundation analysis tool provides frequency and duration of inundation statistics above a specified threshold elevation at a given location using observed data from the NOAA Center for Operational Oceanographic Products and Services’ tide stations. The analysis uses six-minute interval time series, with observed times and heights of high waters (tides). Initially developed by the CO-OPS Coastal Oceanographic Applications and Services of Tides and Lakes (COASTAL) Program for the purposes of marsh restoration and planning, the program potentially has broader applications for the coastal engineering and mapping community, including analyzing return frequencies for coastal flooding threshold elevations and/or user specified datum elevations.Here is a snippet from Sewells Point for early 2014 using MHHW as the reference.
This might be useful for engineers and planners.