  We investigate the statistics and dynamics of extreme heat waves over
different areas of Europe. We find heatwaves over France and Scandinavia to be
associated with recurrent wavenumber three teleconnection patterns in surface
temperature and mid-tropospheric geopotential height. For heatwaves with return
times of 4 years these teleconnection patterns and their dynamics are robustly
represented in a hierarchy of models of different complexity and in reanalysis
data. For longer return times, reanalysis records are too short to give
statistically significant results, while models confirm the relevance of these
large scale patterns for the most extreme heatwaves. A time series analysis
shows that heatwave indices defined at synoptic scale are fairly well described
by Gaussian stochastic processes, and that these Gaussian processes reproduce
well return time plots even for very rare events. These results suggest that
extreme heatwaves over different areas of Europe show recurrent typical
behaviours in terms of long-range spatial correlations and subseasonal-scale
temporal correlations. These properties are consistently represented among
models of different complexity and observations, thus suggesting their
relevance for a better understanding of the drivers and causes of the
occurrence of extreme midlatitude heatwaves and their predictability.
