Storm Gloria

Map plotting the track of Gloria according to the Ocean Prediction Center

The system that would eventually become Storm Gloria was first noted as a developing complex of low-pressure systems over the central United States on 9 January; the strongest of these organised sufficiently to be named Winter Storm Isaiah by The Weather Channel later that day. A large trough associated with Isaiah dug into the Southwestern United States from 10 January, providing a path for cold air that had been settled over Canada to move southwards and clash with warm, moist air moving northward from the Gulf of Mexico.[5] In the warm sector of the system, severe thunderstorms and tornadoes developed across the south-central United States on the morning of 10 January. Isaiah continued to develop and intensify as it moved eastwards across the United States before exiting into the north Atlantic on 13 January.[6]

After stalling off the coast of North America for several days, the system was first noted as Cyclone Ilka by the Free University of Berlin – who name all low-pressure areas affecting Europe – on 17 January,[4] while moving steadily eastwards across the open Atlantic. AEMET, the Spanish meteorological agency, began issuing warnings on Storm Gloria on 18 January as the system was approaching the Iberian Peninsula. After turning southeastwards and entering the Bay of Biscay, Gloria subsequently made landfall close to Santander in northern Spain on 19 January.[7]

Gloria quickly passed over northern Spain as a weak cyclone and then emerged into the western Mediterranean Sea, where it stalled for several days.[7][8][9] After remaining nearly stationary near the Balearic Islands for around 48 hours, Gloria began to slowly drift southwards and then westwards, passing over the Strait of Gibraltar and northern Morocco on 22 January[10] before emerging into the far eastern Atlantic on 23 January. After looping for several days offshore to the south and west of Portugal,[11] Gloria dissipated on 25 January off the country's southern coast.[12]

Storm Gloria set numerous meteorological records in Spain across a range of categories. Between 19 and 23 January, seven separate weather stations across the country recorded more than 300 mm (12 in) of rain. During this time period the station at Barx set the highest total of 433 mm (17.0 in), more than four times the total monthly average rainfall for the month of January at this location.[21] At Málaga Airport, 21 mm (0.83 in) of rainfall was recorded in one hour, and 265 mm (10.4 in) in total between 22 and 25 January.[21] Storm Gloria set new rainfall records at the Daroca and Tortosa weather stations that were more than double the previous record.[21]

On 20 January, significant wave heights in the western Mediterranean Sea – a measure of the mean height of the highest third of any set of waves – reached 8.44 m (27.7 ft) at a buoy off the coast of Valencia, breaking the previous record significant wave height for the entire Mediterranean of 8.15 m (26.7 ft) registered near Mahón in January 2003.[21] Since this is a mean value, individual wave heights were even higher – a buoy near Dragonera recorded a maximum wave height of 14.2 m (47 ft) during the storm.[21]

At Vilafranca, 86 cm (34 in) of snow fell on 21 January alone, breaking the Spanish national record for the heaviest recorded snowfall in a 24-hour period; this previously stood at 80 cm (31 in) at the same site, recorded on 7 March 1968.[21] Also on 21 January, there were 3,035 recorded lightning strikes in the Valencian Community alone, the highest-ever daily lightning strike count for that province.[21]

• Storm Filomena (2021), a similarly slow-moving extratropical cyclone which affected the Iberian Peninsula with record snowfall one year after Gloria.
• Similar flood events in southern Europe:
  • 1957 Valencia flood
  • Autumn 2000 Western Europe floods
  • Hurricane Vince (2005)
  • 2018 European floods
  • Storm Alex (2020)