Borrasca historica que provoco la mayor nevada en Madrid en mas de 50 anos, con espesores de hasta 60 cm en el centro peninsular.
Mas de 1.400 millones de euros en danos, 4 fallecidos, colapso de transportes durante una semana.
Filomena was not a deep depression: it was a coincidence. A mass of Arctic air had been sitting over the peninsula for days when the depression, arriving from the southwest laden with subtropical moisture, slid underneath it. The warm, humid air rose over the cushion of freezing air and unloaded as snow over central Spain for almost two days straight. That is the mechanism that turns an ordinary depression into the heaviest snowfall Madrid had seen in half a century: an exceptional pressure was not required, what was required was that the cold already be there. After the snow came the worst of the episode, a cold spell with the snow on the ground acting as a mirror and radiating the heat away to a clear sky.
The figures that follow are not estimates and have not been copied from any bulletin: they were computed on ERA5, the European Centre’s reanalysis, at a point representative of the area affected — Madrid — and compared with the 27 complete years of the series. What matters is not the number but the rank.
| Variable | During the episode | Rank in the series |
|---|---|---|
| Minimum pressure | 1,003.5 hPa | falls in the most extreme 5 % of the series of the 236,688 hours measured |
| Maximum 10 m wind | 25 km/h | falls in the most extreme 1 % of the series of the 236,688 hours |
| Rainfall over 6 days | 39.8 mm | falls in the most extreme 5 % of the series of the 9,857 6-day windows |
| Minimum temperature | -7.3 °C | falls in the most extreme 0.1 % of the series of the 236,688 hours |
At this point, what was exceptional about Filomena was the cold. The other variables stayed within what this place sees with some regularity. To place the rainfall: the wettest 6-day episode recorded at Madrid in the whole series was 90.4 mm, on 17 December 1996.
ERA5 works with cells of about 28 kilometres and smoothed terrain. It describes the air mass well and allows one storm to be compared with another on the same yardstick, which is precisely what cannot be done with station records that have changed site. What it does not see is the detail: a storm that unloads over one particular ravine is averaged across a cell of 800 square kilometres, and that is why its totals are always lower than those of a well-sited rain gauge. For the official figures of an episode, AEMET is the authority.
Data: ERA5 · Copernicus Climate Data Store, CC-BY licence. Sources and methodology →
