Warning categories on Aemet - No scientific basis for this, just experience of 4 years, yellow warnings for costal effects, waves and wind tend to be overplayed I've travelled to see the waves (on Amber warning days) at good locations like Cabo de Palos only to be disappointed, very similar to a normal day at Lands end, however rainfall I find can be underplayed, an Amber risk can be quite easily turn red and huge quantities of rainfall can amount