Warmer than average sea surface temperatures are predicted through the spring of 2020 for the Gulf of Alaska. Fisheries scientists are giving the Eastern Bering Sea ocean waters 50 to 55 percent odds of neutral conditions for the upcoming winter and a 30 percent chance of El Nino.
Fisheries scientists note that the unusual warm conditions in the Gulf came in the wake of the extreme marine heat wave of 2014–2015, popularly known as “The Blob” before returning to more typical temperatures in 2017 and 2018. In September of 2018, sea surface temperatures in the western Gulf of Alaska shelf area crossed a temperature threshold to become a marine heat wave and have largely remains in heat wave status since then.
Sea level pressure patterns from late 2018 through last summer resulted in high pressure over the Gulf, suppressing storms and contributing to development of warm sea surface temperatures, particularly during the summer. Similar temperatures were observed during the previous 2014–2016 “Blob” heat wave.
While the total number of days in heat wave status in 2019 was similar to that of 2015, there was proportionally more heat during the 2019 summer, and those warm temperatures extended down the water column, especially in the western Gulf.
The coastal Gulf also featured warmer than normal air temperatures and lower than usual precipitation, resulting in drought conditions in areas accustomed to summer rain. Those warm temperatures had extensive impacts of populations of carnivorous fish such as Pacific cod, who in their larval stage eat phytoplankton bloom, which did not show up until June.
The eastern Bering Sea meanwhile experienced a second year of low sea ice conditions in 2018–2019 winter due to residual heat in the Chukchi Sea and anomalous winds from the south in February 2019 causing ice to retreat. The 2018–2019 mean sea ice extent was the second lowest on record, with only the winter of 2017-2018 being lower.