Maryland

Maryland's tidal geography is among the most contrasted on the East Coast. The Atlantic shore — Ocean City and the barrier islands of the lower shore — runs semidiurnal tides with about 1.0 m mean range, moderate surf, and a navigated inlet that serves both recreational and commercial traffic. That's roughly 30 miles of oceanfront. Everything else is Chesapeake Bay. With 9,600 km of tidal shoreline — more than the entire US Pacific coast — the Chesapeake is the largest estuary in North America by watershed area. But it is microtidal: mean range at Annapolis is approximately 0.4 m, and at the upper bay it narrows further still. Wind direction and barometric pressure can move water levels as much as 0.6 m in 24 hours, swamping the astronomical tide signal entirely. This means that on a strong northeast blow, a 'high tide' can arrive hours early and run a foot above predicted. For mariners, anglers, and paddlers, this wind-dominated system demands a different situational awareness than coastal tidal work. NOAA CO-OPS stations at Annapolis, Baltimore, and Cambridge provide real-time gauge data that is the ground truth for bay planning. The Atlantic coast stations follow the standard NOAA tidal prediction model with the tighter confidence expected for semidiurnal ocean coasts.