Researchers are expecting moderately severe hypoxia this summer in the Northern Gulf of Mexico.  A NOAA-sponsored ensemble of models has forecasted a ‘Dead Zone’ of 13,900 sq km. Similar to last year, the best estimate from the NCSU/Obenour Lab model is 13,200 sq km, nearly the size of the state of Connecticut. This estimate reflects below-average flow and nutrient loading from the Mississippi River this spring, coupled with moderate westward winds to deliver nutrients and freshwater over the Louisiana-Texas shelf.

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.

As part of a Sea Grant funded project, we are forecasting above-average oxygen levels for the Neuse Estuary this summer (July-August).  The forecast is based on substantial estuary flushing over the winter and early spring, and low streamflow conditions (and nutrient load) in May.  Forecasted oxygen levels are less conducive to fish kills than normal, though meteorological variability make such events difficult to predict.  The following Sea Grant post shows the 2021 forecast as well as a retrospective assessment of least year’s (2020) forecast.

Summer 2021 Hypoxia Forecast: Fish Kills Less Likely Than Usual in the Neuse River Estuary

Researchers are expecting moderately severe hypoxia this summer in the Northern Gulf of Mexico.  A NOAA-sponsored ensemble of models has forecasted a ‘Dead Zone’ of approximately 12,600 sq km. The best estimate from the NCSU/Obenour Lab model is 13,350 sq km, nearly the size of the state of Connecticut. This estimate reflects below-average flow and nutrient loading from the Mississippi River this spring, coupled with moderately strong westward winds to deliver nutrients and freshwater over the Louisiana-Texas shelf.

These predictions include substantial uncertainty due to summer hydro-meteorological variability.  However, there is <0.5% 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.

As part of a Sea Grant funded project, we are forecasting moderately low mean oxygen levels for the Neuse Estuary this summer (July-August).  The forecast is based on moderate estuary flushing over the winter and early spring, and moderate streamflow conditions (and nutrient load) in May.  Forecasted oxygen levels are conducive to fish kills, though meteorological variability make such events difficult to predict in advance.  The following Sea Grant post shows the 2020 forecast as well as a retrospective assessment of least year’s forecast.

Midsummer Neuse River Forecast Shows Greater Potential for Fish Kills

Researchers are expecting severe hypoxia this summer in the Northern Gulf of Mexico.  A NOAA-sponsored ensemble of models has forecasted a ‘Dead Zone’ of 6700 sq mi, substantially larger than the state of Connecticut. The best estimate from the NCSU/Obenour Lab model, which is included in the NOAA ensemble, is 17,200 sq km (6600 sq mi). This estimate reflects above-average flow and nutrient loading from the Mississippi River this spring (as determined by USGS), coupled with average westward wind velocities that deliver nutrients and freshwater over the Louisiana-Texas shelf.

Model forecasts are compared to observations from the midsummer LUMCON shelfwide cruise. Considering typical weather variability and other system uncertainties, we estimate less than a 5% chance of observing a record (>22,700 sq km) hypoxic area this year. There is almost no chance of observing a hypoxic area of less than 5000 sq km (management goal), unless a major storm disrupts the hypoxic zone prior to the monitoring cruise.