First Aemet Report on the DANA: 'An Extraordinary Episode with Historic Accumulations'

On October 29, 2024, an extraordinary rainfall event affected the eastern coast of Spain, causing historic accumulations in the Valencian Community, exceeding 300 litres per square metre in a large area of the interior of Valencia province. This is detailed in the first preliminary report published by the State Meteorological Agency (Aemet) on its social media this Friday, a month after the great tragedy, reviewing the chronology of its predictions and warnings issued both on the day of the DANA and in previous days.

The Agency highlights in this report "the great intensity and persistence of the observed precipitation" in Turís (Valencia), which recorded 185 litres in just one hour and 621 litres in six hours (equivalent to the average annual rainfall in Spain), setting new records measured at Aemet's network stations. According to the document, these 185 litres triple the 60-litre value used to define torrential rain.

The institution admits that it is still too early to analyse the climatic context and the ranking position of the episode in terms of accumulated precipitation and impacts caused, but indicates that everything suggests it is "the largest flood caused by a DANA in the 21st century in our country, comparable to other historic events in the Valencian Community during the 1950s and 1980s."

Aemet will present "in the coming weeks" a more comprehensive study covering the entire episode.

The document titled 'Report on the Meteorological Episode of Torrential and Persistent Rainfall Caused by a DANA on October 29, 2024' details the chronology of its predictions and recalls that on Sunday 27, a special warning was issued (when an adverse episode is expected) indicating that Tuesday 29 was expected to be the peak day of the DANA, with the highest probability of these intense rains in the Mediterranean area of the peninsula (less likely in Barcelona and Girona) and around the Strait, and to a lesser extent, in the centre and southern half. "It is likely that in parts of the Valencian Community and Murcia, more than 150 l/m2 will be exceeded in 24 hours," the special warning noted.

On Monday 28, the special warning was renewed along the same lines, and on the 29th at 07:36, Aemet issued a red level warning (the most severe as it poses a danger to life) for accumulations of 90 l/m2 in one hour in the southern Valencian coast. This red warning was repeated at 12:00 for accumulations of 180 l/m2 in twelve hours, and from this time, the orange level warnings of 50 and 140 l/m2 remained in effect until the end of the day. Finally, at 16:24, the Agency issued a new red warning for accumulations of 90 l/m2 in one hour, valid until 18:00, with the orange level continuing from that time until the end of the day.

Regarding the northern interior of Valencia, on the 29th, at 08:59, Aemet updated the warning for accumulations in one hour, maintaining the orange level. At 09:41, the warnings were raised to red level, for accumulations of 90 and 180 l/m2 in one and twelve hours, respectively. These warnings were in effect from that time until 18:00, with the orange level continuing from that time until the end of the day.

In the southern interior of Valencia, the report notes that on the 29th, at 06:36, the orange warning for accumulations in one hour was updated, bringing its start forward to 06:00 with validity for the entire day.

Despite the red and orange warnings, the Valencian Government did not activate the ES-Alert system (which sounds on all mobile phones asking the population to avoid unnecessary travel) until 20:11, which has been heavily criticised. The DANA, which affected nearly 80 Valencian towns, resulted in 222 fatalities and material damage (30,000 buildings damaged, 120,000 cars destroyed) worth billions of euros.