The severe thunderstorm that barrelled through the Long Beach Island area early Tuesday evening, generating a confirmed waterspout over the Barnegat Bay and destructive winds, also likely spawned a ”meteotsunami,” a coastal researcher said.
According to Gregg Sakowicz, a Rutgers University researcher who operates water-monitoring sensors for the Jacques Cousteau National Estuarine Research Reserve (JCNERR) in Tuckerton, a meteotsunami is caused by a weather event, not seismic activity.
The event was captured on sensors that he operates for JCNERR, as well as those operated by the organization’s partners, including the National Oceanic and Atmospheric Administration and the United States Geological Survey, within the Great Bay, Barnegat Bay, Absecon Inlet, and at other locations, according to the researcher.
“We are awaiting official confirmation of this event as a meteotsunami by the National Weather Service. Based on our experiences with the 2013 event, we are quite confident it will be,” Sakowicz said.
In June 2013, a meteotsunami impacted the Barnegat Inlet, shocking an experienced fisherman and washing two people off the Barnegat Light jetty. Read the JSHN report here.
So how did this week’s event happen?
According to Sakowicz, Tuesday’s severe thunderstorm system was similar to the event on June 13, 2013, consisting of extreme weather and a “precipitous drop” in barometric pressure.
“Also like that event, when this system ejected off the coast, it presumably caused enough of a localized pressure differential to create what is called a barotropic wave,” he says.
“When the atmospheric pressure in the middle of a storm decreases, so does the downward force on the surface of the water, which actually causes the water to bulge upwards in the middle of the storm. In some cases, as the storm quickly moves away, this bulge settles back down, displacing a large mass of water and generating a (small) tsunami.”
A water monitoring station at US Coast Guard Channel Marker 126 that broadcasts live data detected the anomaly, as well as USGS tidal sensors at the Little Egg Inlet and Barnegat Light and a NOAA water-level sensor in Atlantic City, according to Sakowicz.
The researcher says that the meteotsunami continued to reverberate throughout coastal waters yesterday, “manifesting itself as a ‘seiche’ — or a wave within a basin that reverberates – within local waters like those of Great Bay and possibly the continental shelf itself, sloshing around and interfering with the normally-predictable-and-smooth tidal pattern as seen towards the right side of this plot.”
He explains that it takes a long time for a seiche to subside because it continues to reverberate within the waterbody.
“The example I like to use is how it is difficult to walk across a room with a full coffee cup because the wavelength of the wave in the cup, created by your gait, matches the resonance frequency (a factor of its diameter and depth) of the cup, so when the wave falls on one side of the cup it fuels the rise of water on the other side,” he says. “The wave sloshing from side to side experiences minimal interference because of resonance and maintains most of its energy rather than lose it to dampening.”
Sakowicz says that more information will become available after the National Weather Service analyzes the data.
You can see Sakowicz’s full explanation, with sensor images, here.