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The extratropical storm tracks cause much of the high-impact weather in the midlatitudes, and thus it is of interest to examine the weather impacts of projected storm track change. Here, a framework for quantifying storm track impact on precipitation over Europe developed in Part I for winter is extended to all four seasons and applied to estimate the precipitation impacts of CMIP5 and CMIP6 model projected storm track change under the high-emission scenarios. For autumn and winter, a significant portion of the projected decrease in precipitation over southern Europe and the Mediterranean Sea region can be related to a projected decrease in storm track activity over these regions. In winter, the projected increase in storm track activity near the British Isles accentuates the precipitation increase over that region. In summer, a projected storm track decrease over northern Europe is expected to give rise to a decrease in precipitation that expands the projected drying region poleward and reduces the impact of the projected high-latitude precipitation increase related to the increase in atmospheric moisture. CMIP6 models project stronger drying than CMIP5 models over central and northern Europe in summer and autumn. Part of this increased drying can be related to an enhanced decrease in storm track activity projected by CMIP6 models. Apart from multimodel mean projections, different model projected storm track change patterns can give rise to very different regional precipitation impacts, and account for the model spread in precipitation projection in many regions. What causes such model diversity should be further examined. [ABSTRACT FROM AUTHOR]

Large-scale analysis of the dynamic and thermodynamic properties of landfalling atmospheric rivers (ARs) over western Europe is performed utilizing 38 years of the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), reanalysis dataset. A climatology of landfalling ARs from 1980 to 2017 is developed using a combination of integrated water vapor transport (IVT) calculations and a detection algorithm, which identified 578 ARs over the study period. Examination of the upper-level potential vorticity (PV) fields shows that 73% of these AR events are related to anticyclonic Rossby wave breaking (RWB), a dynamic feature which has been shown to play a role in AR strength and structure. Atmospheric river variability is also found to be closely tied to jet-stream latitude modulation by the North Atlantic Oscillation (NAO), such that during a positive NAO the North Atlantic jet is shifted north, creating an environment that is more favorable for anticyclonic RWB and AR landfalls over northern Europe, and during a negative NAO it is shifted south, creating such an environment over southern Europe.Through the use of linear regression analysis, AR strength is shown to be dependent on atmospheric moisture availability, which is found to increase as sea surface temperatures (SSTs) increase. Therefore, in a warming climate warmer SSTs leading to higher atmospheric moisture availability will result in an increase in the average strength and intensity of ARs over western Europe—a trend that has already been observed. [ABSTRACT FROM AUTHOR]