Assessing multi-year-drought vulnerability in dense Mediterranean-climate forests using water-balance-based indicators

•Water stress is expressed based on precipitation (P) minus evapotranspiration (ET).•Cumulative P–ET relates to vulnerability reflected by moisture loss and mortality.•Dense lower-elevation forests are more vulnerable during multi-year droughts.•An LSTM model predicts ET (testing r2 = 0.72) and water availability (r2 = 0.99).•Historical-minimum annual P–ET portends water stress in multi-year droughts.