Table 1.

Overview of predictors and associated data used for model building, together with their relation to EWP

Predictor data sets and period used	Relation to EWP
CET 1767–2002 (Manley, 1974; Parker et al., 1992)	Warm winters tend to be wetter winters through enhanced advection.
WI 1767–2002 (Barriopedro et al., 2014); Wheeler et al., 2010)	Measure of the persistence of westerly winds beneath the exit zone of the North Atlantic extratropical jet stream.
PL 1767–2002 (Cornes et al., 2013)	Measure of westerly air flow over Northwest Europe. Used as an indicator of the state of the NAOI.
LSLP 1767–2002 (Cornes et al., 2012a)	MSLP for the city of London. High pressure is associated with lower precipitation totals.
Leading EOF of reconstructed gridded SLP (KEOF) 1767–2002 (Küttel et al., 2010)	Surrogate for the NAOI from independent SLP reconstructions
Average of correlated grids from reconstructed gridded SLP (KAVG) 1767–2002 (Küttel et al., 2010; Baker et al., 2018)	SLP for area representing 50o–60oN, 10oW–5°E high pressure associated with lower precipitation totals.

Note: Full details of each predictor are provided in the Section 2.