February 20, 2020 — It looked big. It looked bad. But the marine heat wave that threatened much of the West Coast in the fall of 2019 has mostly dissipated, at least at the surface.
The Northeast Pacific Marine Heatwave of 2019, or NEP19, lasted 225 days and at its peak covered about 3.2 million square miles. It was the second longest-lasting and second-largest such event ever recorded in the northern Pacific Ocean over the past 39 years, according to a blog post by the National Oceanic and Atmospheric Administration (NOAA).
The disturbance decreased below the agency’s classification threshold for a heat wave as of Jan. 5, said Chris Harvey, a fisheries biologist at the agency’s Northwest Fisheries Science Center, on Tuesday.
But while NEP19 is mostly gone, it’s not forgotten: Scientists caution that it is not clear the heat wave is entirely dissipated, or that it will not return. The deep ocean is still retaining significant amounts of heat. Monitoring of sea surface temperature readings from multiple platforms, including satellites, ships and buoys will continue.