It was a meteotsunami, which is exactly what it sounds like — a tsunami triggered by the weather.
According to NOAA, meteotsunamis are possible in many lakes, seas and oceans around the world when conditions are right. Some have even been observed to reach six feet or higher. That being said, they still tend to be smaller than true tsunamis, which are usually triggered by earthquakes.
Storms that moved across the area yesterday ended up creating a meteotsunami across the Mid-Atlantic & up into the SNE coastline. You can see the meteotsunami in the water fluctuations from area tidal gauges, esp in the New Haven gauge. Learn more here: https://t.co/o7GgowMUI2 pic.twitter.com/tble00XnNN— NWS Boston (@NWSBoston) May 16, 2018
Meteotsunamis happen when air pressure jumps rapidly. We see them a lot when fast-moving thunderstorms blow out over the ocean, like derechos or the line of storms that swept across the Northeast on Tuesday night. The storm generates a wave, NOAA says, which moves toward the shore and gets amplified when it hits shallow water.
We’ve seen several meteotsunamis off the East Coast in the past few years, including during the 2012 derecho and a similar storm in 2013. Tuesday night, abnormal tides were recorded through the evening. On the gauges, it looked like large waves rolling onto the shore.
It’s still difficult to predict when a meteotsunami will happen, but it’s not impossible, especially since we now have a better idea of what causes them. Eventually we will see meteotsunami warnings along the coast during severe weather situations.
Strong pressure jump caused by a line of very heavy storms has generated a meteo-tsunami on the DE/NJ coast. Abnormal tides and strong currents are possible through the night. Swimmers should avoid the water /boaters should take extra care for sudden strong currents. pic.twitter.com/14DnJL45Ig— Dan Satterfield (@wildweatherdan) May 16, 2018