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The Iberian nations are again battling the aftermath of extensive flooding following Tempest Claudia unleashed torrential downpours and strong winds the previous week.

Claudia's Genesis and Journey

This weather system formed from a low-pressure zone that had beforehand caused early season cold and snowy conditions through eastern parts of the Canadian territory and the American north-east in early November.

Claudia tracked eastwards across the Atlantic Ocean in the middle of the second week of November before slowing and stalling to the north-west of the Iberian region, caught in the trough of an progressively more wavy jet stream.

Impact on Spain and Portugal

Spain's Galicia area in the northwest was the first affected, with 80-150mm of rain coming down along its Atlantic coast in just one full day up to the evening of Wednesday as a slow-moving band of rain crawled across western parts of the peninsula.

More downpours and stormy weather on the following Thursday led to floods to Portuguese localities where an elderly couple died in the capital Lisbon after rising waters from the bursting Tagus River invaded their residence as they were asleep.

Tempestuous weather persisted into the weekend, with a tornado ripping through a outdoor lodging area and a nearby hotel in Albufeira in southern Portugal on the weekend's Saturday, killing an 85-year-old British woman and harming 28 individuals.

Wider Effects across Europe

Claudia had more extensive impacts across Europe's western part. By pulling tropical air from the subtropics, the system contributed to thermometers climbing in southwestern France to nearly 30 degrees Celsius, the nation's all-time high November temperature.

By Friday, this tropical air mass met a cold air mass across the northern regions of the continent, generating a band of rain stretching from the west of Ireland to Russia.

In the UK, this halting system of rain produced exceptionally large precipitation amounts, leading to significant waterlogging in Wales.

As this weather phenomenon loses strength early this week, the frigid air will push south, delivering to Europe its first taste of colder weather.

Parallel Events in California, USA

The US state of California encountered a so-called atmospheric river the previous week, delivering heavy rain and powerful winds that resulted in rapid flooding and debris flows in areas scarred by wildfires in the recent past.

Over two inches of rain was recorded in the southern region of the state on last Friday, with a further 50mm across extensive areas of California on the subsequent Saturday.

More than 100mm of rain was deposited on coastal parts of Southern CA in all, reaching a full 200 millimetres in areas of elevated terrain.

An atmospheric river is a plume of tropical, saturated air stemming from the tropics or subtropics.

Locations with fire damage including the Pacific Palisades area and Altadena region endured the worst of the flash flooding and earth movements, leading to evacuations.

Elsewhere in California, a 71-year-old man died after his vehicle was carried away from a inundated overpass, and a seven-year-old girl and her parent were pulled into the ocean by large waves on the Central Coast.