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Portugal and Spain are once more battling the aftermath of extensive inundation after Storm Claudia brought torrential downpours and powerful gusts last week.

The Storm's Formation and Trajectory

This weather system formed from an area of low pressure that had previously caused early season cold and snowy conditions through the eastern regions of the Canadian territory and the American north-east in early November.

This storm journeyed east across the Atlantic during the second weekend of November before slowing and stalling to the north-west of the Spanish and Portuguese landmass, trapped within a trough of an progressively more wavy air current.

Effects in the Iberian Peninsula

The northwestern Spanish region of Galicia was the first affected, with three to six inches of rain pouring down along its western coastline in just 24 hours up to the evening of Wednesday as a slow-moving band of rain drifted across the western areas of the Iberian peninsula.

Further showers and thunderstorms on the following Thursday caused inundations to parts of Portugal where an older couple died in the city of Lisbon after rising waters from the bursting Tagus River flooded their dwelling as they slept.

Stormy conditions lasted through the weekend, with a violent whirlwind ripping through a campsite and a nearby hotel in Albufeira in the south in Portugal's south on Saturday last week, claiming the life of an British woman aged 85 and wounding 28 people.

Broader Impacts across the European continent

Claudia had broader repercussions across the western European nations. By drawing warm air from the warmer regions, the system assisted in raising temperatures in southwestern France to nearly 30 degrees Celsius, the country's highest recorded autumn temperature.

By the following Friday, this warm and humid air mass met a cold air mass across the northern regions of the continent, creating a precipitation zone extending from western Ireland to Russia.

In the UK, this halting system of rain produced very high rainfall totals, resulting in significant waterlogging in the principality of Wales.

As this weather phenomenon progressively weakens early this week, the cold air mass will advance southward, giving Europe its premier experience of winter.

Parallel Events in California, USA

California encountered a so-called atmospheric river last week, bringing torrential rain and strong winds that resulted in sudden inundations and mudslides in regions impacted by blazes previously in the year.

In excess of 50 millimetres of rain was recorded in southern California on the week's end, with a further 50mm broadly over the state on the subsequent Saturday.

In excess of 100 millimetres of rain fell over coastal parts of the state's south in aggregate, attaining eight inches in total in locations at higher elevations.

An atmospheric river is a concentrated stream of hot, humid air originating from the equatorial or near-equatorial zones.

Locations with fire damage including Pacific Palisades and Altadena suffered the most severe the rapid inundations and landslides, prompting evacuations.

In other parts of the state, a man in his seventies lost his life after his vehicle was carried away from a submerged bridge, and a young girl aged seven and her parent were dragged into the Pacific by powerful waves on the the state's central shoreline.