Researchers are expecting a moderate-to-large hypoxic zone this summer in the northern Gulf. A NOAA-sponsored ensemble of models has forecasted a ‘Dead Zone’ of 18,200 sq km. The NCSU/Obenour Lab model is part of this ensemble, and its prediction is for a hypoxic zone of 14,400 sq km, roughly the size of Connecticut and Rhode Island, combined. Our prediction is somewhat lower than the ensemble because our forecast considers both nutrient loads and flows from the Mississippi River Basin. This year, flows were relatively low, which may reduce water-column stratification, allowing more oxygen into bottom waters. At the same time, loads are above average, and moderately strong westward winds are expected to provide substantial delivery of nutrients and freshwater over the Louisiana-Texas shelf. Thus, despite the low flows, we still predict a moderately large hypoxic zone.
These predictions include substantial uncertainty due to summer hydro-meteorological variability. However, there is <1% chance that a record hypoxic zone (>22,700 km2) will be measured by the LUMCON shelfwide cruise this summer. It is also important to note that extreme weather can temporarily reduce the hypoxic zone, as in the case of Hurricane Hanna in 2020.