A storm called Friedhelm

  • The storm, named Friedhelm by the Free University of Berlin, explosively deepened as it neared northern Scotland. The "tail" of the cloud bears the hallmarks of what is called a "sting jet".

    At midday on Thursday the strongest winds were just approaching, marked in that area of very tightly packed isobars.

    By midday on Friday the storm will have moved east across southern Norway, with long-track NW'ly winds building big seas over the North Sea - significant height of 8 to 10 metres, maximum 12 to 16 metres. The cold flow will bring snow showers to Scotland and upland northern England.

    High waves batter the coastline at Helensburgh, Argyll and Bute. Photo: Danny Lawson/PA Wire

  • A storm called Friedhelm
    09.12.2011 09:41

    Computer models have come a long way in recent years. The fierce storm that crossed Scotland on Thursday was well marked long before the event, and forecast models hardly wavered in correctly forecasting its track or the strength of its winds.

    As a consequence some of the worst ramifications of such strong winds could be mitigated to a degree by careful and robust preparation. In October 1987 such finesse in the models would have been very welcome.

    But even the best forecasts cannot prevent the sort of structural damage, power outages or road and bridge closures that blighted parts of Scotland, Northern Ireland and northern England on Thursday.

    The storm, named Friedhelm by the Free University of Berlin, had its genesis as a depression in the Atlantic, and explosively deepened as it approached and crossed northern Scotland. The worst of its winds were across south, west and central Scotland, including the Central Lowlands; but it also delivered a string in its tail as it started to depart into the North Sea during Thursday evening, provoking potent north-westerly winds across northeast Scotland on its rearward flank.

    Wind gusts exceeded 70mph quite widely in the worst-affected areas, and reached 80 to 90mph in a number of exposed locations. In fact, 90mph was breached in a few spots while the uplands topped 100mph. At just 249 metres above mean sea level, Tulloch Moor gusted to 105mph at 1pm. Glen Ogle at 564 metres had gusts well in excess of that.

    The mountains are generally windier anyway but the gusts around the summit of Cairngorm, at an altitude of 1,237 metres, were notable to say the least. In the middle of the afternoon the automatic weather station near the peak recorded a gust of 165mph. It is a measure of the intensity of the storm that this is only just short of the highest gust ever recorded in Britain, which was 173mph on 20 March 1986 at the same place.

    Some recent comparable storms include:

    The Boxing Day storm of 1998, later named "Stephen" in Ireland. The strongest winds were across Northern Ireland and central Scotland, and Prestwick airport recorded a gust of 103mph. The Forth Road Bridge was forced to close for the first time in its history.

    The storm of 11-12 January 2005, when NW Scotland had gusts of 104mph and Cairngorm a gust of 135mph. At the centre of the storm the barometric pressure fell to 944mb.

    The Burns Day Storm of 25 January 1990, when the highest gust was 107mph at Aberporth, Ceredigion.

    The storm of 13 February 1989, when Fraserburgh in northeast Aberdeenshire recorded the highest ever lowland gust in the UK at 146mph.

    Finally, the most recent, lest we forget, was just this year on 23 May. This was not as strong in absolute terms but was an unusually strong storm for the time of year, and probably the worst May storm since 1962. With trees in leaf many were toppled because of the wind resistance. There were power cuts and the Forth Bridge was closed again. Inverbervie, Aberdeenshire, had a gust of 81mph while mountains sites recorded gusts over 100mph.

    By: Stephen Davenport