The December Storm

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  • One of the five bungalows in Hemsby, Norfolk which fell into the sea on Thursday as the storm surge and high tide caused the cliff to break up. Photo: Ben Kendall/PA Wire

    A tree lands on a car in Davidsons Mains, Edinburgh after Scotland is hit by strong winds. Photo: David Cheskin/PA Wire

    Map showing the maximum gust in knots between 6 and 7am on Thursday morning.

  • The December Storm
    07.12.2013 14:57

    Gale force winds and even stronger gusts battered the UK on Thursday morning, with western Scotland being the worst affected. Two people have died. A storm surge, combined with high tides, then brought the worst flooding to eastern England since 1953.

    About the storm

    The storm was caused by a rapidly deepening low pressure system which swept in from the west, travelling across the Shetland Islands and swinging down through the North Sea and into southern Scandinavia. Although the UK saw worse conditions than it would in most winter storms, this type of weather system is not especially unusual. A cold front moved south across the UK, bringing frequent lightning strikes and over 40mm of rain to north-west Scotland and smaller amounts elsewhere.

    Strong winds
    There were sustained winds of around 50mph during the early hours of the morning in northern Scotland. The strongest recorded gust was 142mph at Aonach Mor in Invernessshire at an elevation of 1130m. However, winds gusted to well over 80mph across many lowland areas too, and 82mph was recorded in Edinburgh shortly before 9am. As the storm tracked south, southern parts also became windy with gusts of close to 50mph in London. Scottish Hydro reported that they were working to restore power to 1,500 customers after power was cut by damage to power lines, mainly by the wind. 64,000 homes had their power disrupted by the storm.

    Flooding
    As the storm caused a build up of water along the east coast of England (a storm surge, see below), this coincided with a high tide and thousands of homes were evacuated. In Hemsby, Norfolk, three houses fell into the sea and insurance claims are expected to reach hundreds of millions of pounds. Coastal areas of north Wales were also flooded later that day.

    How did the storm surge form?
    As an area of low pressure moves over the ocean, it pushes down on the ocean less than the surrounding areas of higher pressure do. This causes the surface to “bulge up”. This is unnoticeable far from the coastline. As the depression tracked in from the west, it brought with it water from the Atlantic which was then channeled down into the North Sea. Strong north-westerly winds reinforced the movement of the water towards southern parts of the North Sea by what is known as Ekman transport. This is where the direction of water movement is to the right of the wind direction due to the coriolis force. As the North Sea gets shallower and narrower further south, sea surface levels were forced to rise.

    Europe
    The storm later moved on to leave 400,000 without power and three deaths in Poland, as well as one in Sweden, and one in Denmark. A gust of 99mph was recorded at Torsminde on the west coast of Denmark at around 4pm.

    By: Ben Windsor