Improving the Representation of Tropical Variability and its Large-Scale Teleconnections in NOAA's Unified Forecast System

Atmospheric variability in the tropics is primarily driven by equatorial waves interacting with moist convective processes. These "convectively coupled" equatorial waves are important not only for the tropics, but for global sub-seasonal to seasonal predictions due to tropical-to-extratropical teleconnections. However, convectively coupled equatorial waves have been a major modeling challenge from weather to climate scales because the onset and propagation of these waves depends on processes that are only partially accounted for in global prediction systems. We here present research aimed at improving the coupling between cumulus convection and equatorial waves within NOAA's Unified Forecast System (UFS) that has been transitioned to the UFS operational prototypes of GFSv17 and GEFSv13 - these updates to the convective parameterizations include representation of sub-grid convective organization, improved moisture coupling, stochasticity and prognostic evolution. We then use experimental versions of the UFS with improved tropical variability to discuss the imprints of these advancements for predictions outside the tropics, with a particular focus on the interaction between the Madden Julian Oscillation (MJO) and Atmospheric River landfall off the coast of North America.