Extratropical cyclone activity over Eurasia has exhibited a weakening trend in the recent decade. Extratropical cyclones bring precipitation and hence supply fresh water for winter crops in the mid‐ and high‐latitude regions of Eurasia. Any changes in extratropical cyclone activity over Eurasia in the future may have a critical impact on winter agriculture and the economies of affected communities. However, potential future changes in regional storm activity over Eurasia have not been studied in detail. Therefore, in this study, we investigate anticipated changes in extratropical storm activity by the end of the century through a detailed examination of the historical and future emission scenarios from six different models from CMIP5. A statistical analysis of different parameters of storm activity using a storm identification and tracking algorithm reveals a decrease in the number of storms over mid‐latitude regions. However, intense storms with longer duration are projected over high latitude Eurasia. A further examination of the physical mechanism for these changes reveals that a decrease in the meridional temperature gradient and a weakening of the vertical wind shear over the mid‐latitudes are responsible for these changes in storm activity.

An increased frequency and intensity of winter and spring storms have recently manifested over a broad area of North America—along the east coast of the U.S. especially, though global mean storm tracks are suggested to shift northward. To understand these changes, we have conducted atmospheric model experiments, examining the response of North American storm activity to the elevated tropical Pacific sea surface temperature (SST) associated with El Niño. The results indicate that, when tropical Pacific SST increases, there are more numerous intense storms over southwestern, southeastern, and northwestern North America, but fewer weaker storms over the northeast. Transient eddy analysis of the general circulation demonstrates consistent changes, suggesting systematic changes from large‐scale general circulation to synoptic‐scale storms. These changes can be attributed to enhanced lower tropospheric baroclinicity, to which the southward shift and an intensification of extratropical jet streams make a major contribution.

No abstract