NWS Response to the Atlantic Coast Meteotsunami of 15 May 2018

AMS Conference – 2019

99th AMS Annual Meeting

Lewis Kozlosky¹ and Michael Angove²

(1) NOAA / NWS / Tsunami Program Physical Scientist

(2) NOAA / NWS / Tsunami Program Lead, Physical Scientist

NWS Response to the Atlantic Coast Meteotsunami of May 15, 2018

Meteotsunamis have the same characteristics as earthquake-generated tsunamis, but are caused by barometric pressure forcing associated with intense, fast moving mesoscale convective systems (MCS) such as squall lines. Development of a meteotsunami depends on several factors such as the intensity, direction, and translational speed of the disturbance as it travels over a water body with a depth that enhances wave amplification due to resonance.

On May 15, 2018, the National Weather Service’s (NWS) National Tsunami Warning Center (NTWC) in Palmer, Alaska detected a tsunami wave signal on Deep Ocean Assessment and Reporting of Tsunamis (DART) buoy 44402 off the northeast Atlantic coast. Using a draft protocol that was developed after the meteotsunami event of June 13, 2013, the NTWC contacted coastal NWS Weather Forecast Offices (WFO), which then issued products to warn of possible coastal impacts.

The system moved across northern New Jersey, southern Connecticut, Long Island, and into the open ocean. The greatest pressure rises were over southern Connecticut with 5.1mb rise in 12 min and a 3.3mb rise in 6 min over the far eastern portion of Long Island. This implies the meteotsunami may have been generated south of Long Island. The meteotsunami generation and movement toward the DART buoy in relationship to Atlantic Shelf orientation apparently played a role in how much energy was reflected back towards shore. Less energy made it back to the coast during this event, and wave heights at the shore were significantly lower than the 2013 event.

NTWC began contacting the WFOs about 45 minutes before they issued their products. Coordination also took place with the NWS Eastern Region Regional Operations Center. NTWC spent about 10 minutes talking with each of 3 WFOs.

This presentation will review the circumstances of this event and will summarize the current state of the U.S. meteotsunami detection, forecast, and warning capability, and efforts underway to improve these capabilities.