The storm tearing through the UK today threatens widespread damage, especially in South Wales and southern England, with winds expected to gust up to around 130km/h (80mph) in exposed coastal areas.

An added danger is the threat of spring tides, which are especially high at this time of year in the run-up to the spring equinox. The Met Office cautions that the combination of the storm and high tides could bring significant flooding along the western and southern coasts of the UK.

It could also produce a large Severn Bore, expected around 8.30am today. The bore is Britain’s most spectacular natural phenomenon – a tidal wave that rushes in from the sea up the River Severn for up to around 32km (20 miles).

The Severn estuary has some of the highest tides in the world, and they are especially high around the equinoxes. This tidal surge is squeezed up the funnel-shape of the estuary until it rides over the River Severn as a wave of seawater. The bore can reach some 2m (6.6ft) high, and although today’s bore was not expected to be particularly large, it will be greatly boosted by strong southwesterly winds. Viewing conditions, though, will be extremely bleak in the high winds and torrential rain.