Flash flood · Eastern Spain
Valencia's DANA: a year's rain in a day
On 29 October 2024 thunderstorms formed again and again over the same hills west of Valencia. Turís measured 772 mm of rain, more than the city usually gets in a year, and 184.6 mm of it in a single hour, a Spanish record. In the evening the Poyo ravine, dry most of the year, sent a wall of water through Paiporta, Catarroja and the towns south of the city, where most of the rain had not even fallen. More than 220 people died.
29–30 October 2024 · Valencia, Spain · ERA5
90mm
ERA5 near Chiva, 29 Oct
The Lab's grid point in the catchment: about a ninth of what Turís measured.
What happened
In Spain such storms are called a DANA, a depresión aislada en niveles altos: a low cut off from the jet stream, cold aloft, which can sit in one place for days.N1 At the end of October 2024 one lay over the Strait of Gibraltar. On its eastern side warm, moist air from the Mediterranean was driven west into the coastal hills of Valencia, and thunderstorms grew, drifted inland and were replaced by new ones over the same ground.
29 Oct, morning
Storms build over the hills around Chiva and Turís; rain falls at more than 100 mm an hour.N2
29 Oct, afternoon
The Magro river and the Poyo ravine rise rapidly; the alert reaches mobile phones only in the evening.
29 Oct, evening
The flood from the Poyo reaches Paiporta, Catarroja and the suburbs south of Valencia, under clear skies.N3
30 Oct
Thousands of cars are piled in the streets; more than 220 people have died.N3
The low and the wind
The upper-air map shows the cut-off low south-west of Iberia. At 850 hPa an easterly wind blows from the Balearic Sea straight onto the coast of Valencia, the moisture feed for the storms.
What the grid sees
1/9
ERA5's 90 mm near Chiva on 29 October, against 772 mm at Turís, 15 km away. Storms that stand still over one valley are a few kilometres across; the 28 km grid spreads them out, and its model rains less.
The Mediterranean was unusually warm that autumn, and October 2024 was the wettest October in Spain's records.N2 A warmer sea adds moisture to the air that such storms feed on.
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References
News
- N1Royal Meteorological Society, MetMatters. Cut-off lows, cold drops and DANA. November 2024.What a DANA is and how this one formed.
- N2AEMET. Resumen climatológico de octubre de 2024. November 2024 (in Spanish).Turís's records and October 2024 as Spain's wettest October.
- N3NASA Earth Observatory. Valencia floods. November 2024.Satellite views of the flood and its toll.