NOAA GFDL - Geophysical Fluid Dynamics LaboratoryGFDL - Geophysical Fluid Dynamics Laboratory

Experimental Seasonal Forecasts

  • April 2026 Northwest Atlantic Predictions

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    Andrew Ross

    The experimental seasonal outlook for the Northwest Atlantic Ocean predicts widespread warm surface conditions this summer and fall. Along the Northeast U.S. continental shelf, cooler than normal bottom temperatures will persist in deeper parts of the Gulf of Maine and Mid-Atlantic Bight, while an inflow of warmer than normal water is predicted from the Scotian Shelf into the Eastern Gulf of Maine.

    Warmer than average surface conditions, indicated by positive sea surface temperature (SST) anomalies, are expected to continue across the central portion of the Northwest Atlantic region in the next 3 months, while patches of cooler than usual water are present in the north and northwest regions. By late summer, positive anomalies are predicted throughout the majority of the Northwest Atlantic. Towards the end of the year, an extensive region of warm conditions is predicted near the Northeast US shelf, with cooler water to the south, suggestive of a northward tendency in the Gulf Stream.

    Focusing on the Northeast U.S. shelf region, cooler than usual bottom waters are expected to persist through spring and summer in the western Gulf of Maine and Mid-Atlantic Bight. A pulse of warm bottom water is predicted to flow from the western end of the Scotian Shelf into the eastern Gulf of Maine from spring through fall. Strong anomalies are not predicted next winter, though prediction skill is lower at this long lead time.

    Here we show predicted bottom temperatures, rather than anomalies, along the Northeast U.S. For reference, lines marking shallow (30 m depth) and deep (150 m depth) regions have been added. In spring, shallow regions of the Gulf of Maine are predicted to remain cool, while the coastal Mid-Atlantic Bight (MAB) is much warmer. In summer, the MAB cold pool is evident as a region of water predicted to be colder than 10 °C in the central MAB surrounded by much warmer water along the coast and shelfbreak. The warm water predicted to enter the Gulf of Maine has temperatures near 12 °C, which is characteristic of Warm Slope Water that lies between the shelfbreak and Gulf Stream. Note that these panels show temperatures averaged over 3-month seasons, but temperatures will vary throughout the months and may be warmer or cooler than the average shown here on any particular date.

    These figures show data from GFDL’s regional ocean model of the Northwest Atlantic, MOM6-NWA12. This model is based on the Modular Ocean Model version 6 (MOM6) and features 1/12° resolution. To produce year-long seasonal forecasts, MOM6-NWA12 is run using atmospheric forcing fields from GFDL’s SPEAR global prediction system. An ensemble of 10 simulations is run, using a different ensemble member from SPEAR for each, and the results are averaged for the figures shown here. New seasonal forecasts are run four times per year, in January, April, July, and October. Note that these experimental predictions are not official NOAA forecasts.