The National Oceanic and Atmospheric Administration has updated its most recent report to refine predictions about high-tide flooding. The upshot: we can expect a dramatic increase in flooding that happens on days when there’s no storm to blame.
High-tide flooding, also known as “sunny day” flooding or nuisance flooding, is becoming increasingly common because of sea level rise. It happens in low-lying areas when tides reach 1.75 to 2 feet above the daily average high tide. This typically causes streets to flood or storm drains to overflow.
NOAA has high tide gauges installed in a small number of locations in Massachusetts: Boston, Woods Hole, Chatham, Nantucket, and Fall River.
In a February 2022 report, the administration predicted that the East Coast of the U.S., including Cape Cod and the Islands, would get 25 to 75 days of sunny day flooding by 2050.
Earlier this month, NOAA updated this report with a more precise figure for 2050. It now expects 40 to 70 days of sunny day flooding in our area by mid-century.
NOAA’s prediction for three to seven days of sunny day flooding each year was accurate for Nantucket and Woods Hole over the last year. Nantucket saw five days, Woods Hole had four.
“The flooding is growing in leaps and bounds,” NOAA oceanographer told CAI. “It’s not just a smooth, gradual change that’s going to occur, [where] we’re going to flood a little bit each year. The flooding is going to really start to take hold. It will get deeper, more severe, more widespread.”
