  A flexible spatio-temporal model is implemented to analyse extreme
extra-tropical cyclones objectively identified over the Atlantic and Europe in
6-hourly re-analyses from 1979-2009. Spatial variation in the extremal
properties of the cyclones is captured using a 150 cell spatial regularisation,
latitude as a covariate, and spatial random effects. The North Atlantic
Oscillation (NAO) is also used as a covariate and is found to have a
significant effect on intensifying extremal storm behaviour, especially over
Northern Europe and the Iberian peninsula. Estimates of lower bounds on minimum
sea-level pressure are typically 10-50 hPa below the minimum values observed
for historical storms with largest differences occurring when the NAO index is
positive.
