Día tormentoso.

Tremendous thunderstorms all day. This is the view from the back window, as I was not tempted to go out lightning chasing as I may have in younger days. The village got off quite lightly, except for being closed off by a landslide on the main (only) road out, but the centre-island towns of Mercadal and Alaior were completely flooded as water flowed like a river down the streets, sweeping away cars and perimeter walls on its way. 16 people had to be rescued by helicopter from a farm roof, as the building was almost completely submerged. This is just gleaned from the online local news, as there was no way we were going out to look! I've not know weather like this in the years I have been here.
It seems this was caused by a DANA which is the acronym for “ Isolated High Level Depression ”.
A DANA is an isolated pocket of air, with a lower temperature than the one around it. The potential danger appears when this cold air encounters very warm surface temperatures and, especially, warm water surface temperatures in the Mediterranean .
When this happens, a large temperature difference is created in the different atmospheric layers, that is, a large thermal gradient . This creates a very unstable profile in the atmosphere, in which air masses rise very easily, become saturated with water vapor quickly and can give rise to strong storms with intense precipitation.
If we add to this contrast in temperatures the humidity and energy provided by a very warm Mediterranean after the summer months, the result is torrential rains , which frequently cause flooding in these areas.