Changes in MJO Teleconnections in the Southeast U.S. Under Global Warming in the CESM2 Large Ensemble

Abstract We examined projected changes in Madden–Julian Oscillation (MJO) teleconnections over North America using 90 ensemble members from the Community Earth System Model Version 2 Large Ensemble (CESM‐LENS2) under the SSP370 scenario. In the warmer climate, the classic PNA‐like teleconnection strengthens and shifts eastward, with large ensemble member consistency. An additional Rossby wave source emerges over the southeastern U.S. (SEUS), generated largely by an eastward‐extended MJO in concert with the subtropical jet, providing a more direct pathway for tropical variability to influence SEUS weather. These changes nearly double SEUS precipitation anomalies and substantially increase extremes, with 82% of members projecting growth in persistent extreme events. Results highlight greater subseasonal extreme risks in a warmer climate and emphasize the importance of both MJO variability and the background state in shaping future teleconnections.