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Once again, Portugal and Spain find themselves recovering from widespread inundation after Storm Claudia unleashed heavy rain and powerful gusts last week.

The Storm's Genesis and Journey

The storm system formed from a region of depressed atmospheric pressure that had previously ushered in unseasonably early chilly and snowy weather through the eastern sectors of the Canadian territory and the north-eastern US in early November.

This storm journeyed east across the Atlantic over the second weekend of November before losing momentum and stopping to the north-west of the Spanish and Portuguese landmass, snared in a dip of an ever more meandering atmospheric river.

Consequences for Spain and Portugal

Spain's Galicia area in the northwest was initially impacted, with a substantial 80 to 150 millimetres of rain pouring down along its west coast in just 24 hours up to the evening of Wednesday as a leisurely moving system of rain crawled across western parts of the region.

Further showers and thunderstorms on Thursday led to floods to areas in Portugal where an older couple lost their lives in the city of Lisbon after water from the overflowing Tagus River flooded their dwelling as they rested.

Stormy conditions continued into the weekend, with a twister devastating a campsite and a nearby hotel in Albufeira in the south in southern Portugal on Saturday last week, fatally injuring an 85-year-old British woman and wounding two dozen and eight persons.

Broader Impacts across Europe

The storm produced more extensive impacts across the western European nations. By drawing warm air from the subtropics, the system contributed to thermometers climbing in southwestern France to 29.8C (85.6F), the country's highest recorded November temperature.

By last Friday, this tropical air mass met a frigid air system across the northern regions of the continent, generating a band of rain running from western Ireland to the Russian Federation.

In the United Kingdom, this stalling band of rain produced exceptionally large precipitation amounts, leading to severe flooding in Wales.

As the storm progressively weakens early this week, the chilly atmospheric system will push south, providing the continent its premier experience of winter.

Parallel Events in the state of California

The Golden State experienced an "atmospheric river" the previous week, delivering torrential rain and high-velocity gusts that provoked flash flooding and debris flows in areas impacted by wildfires previously in the year.

More than 50mm of rain fell in the southern region of the state on the week's end, with a another 50 millimetres broadly over the state on Saturday last.

More than 100mm of rain was deposited on coastal parts of southern California in total, attaining a full 200 millimetres in locations at higher elevations.

Such a weather system is a narrow band of warm, moist air coming from the tropics or subtropics.

Burn scar areas including Palisades and Altadena endured the most severe the flash flooding and mudslides, leading to evacuations.

Elsewhere in California, a 71-year-old man lost his life after his vehicle was washed off a inundated overpass, and a child of seven years and her parent were swept into the sea by powerful waves on the the state's central shoreline.