Decadal Predictability of Late Winter Precipitation in Western Europe through an Ocean–Jet Stream Connection

The characteristics of the North Atlantic jet stream play a key role in the weather and climate of western Europe. While much of the year to year variability in the jet stream arises from internal atmospheric processes that are inherently unpredictable on timescales beyond a few days to weeks, any low frequency variability or long term trends that can be considered forced by slowly varying boundary conditions, offers the potential for extended range predictability of climatological conditions in western Europe. Here, it will be demonstrated that the observational record displays pronounced multi-decadal variability in precipitation in western Europe during the late winter in connection to Atlantic jet stream variability. It is found that both the precipitation and jet stream variability are strongly connected to low frequency sea surface temperature (SST) variability in the North Atlantic. While the connection between SST variability and the jet stream/precipitation does not seem to be well represented in General Circulation Models (GCMs), the SST variability in the region of interest is well predicted in initialized decadal prediction experiments. Combining the information from these model predicted SSTs with the observed relationship between precipitation and SST, it will be shown that there is great potential for skillful decadal predictions of late winter precipitation in western Europe.