Sudden stratospheric warming predicts the cold snap

January 7, 2013 — 3 Comments

Meteorology is complicated! Changes in the atmosphere a very long way from Reigate have an impact on our weather. For example, a relatively new finding by meteorologists has been that sudden warming of the stratosphere (10-50,000 metres) above the North Pole frequently heralds and may even cause cold winter weather in the northern hemisphere at our latitude. These “sudden stratospheric warming” events, one of which occured recently (see the red line going up steeply on the graph), weaken the usual polar vortex winds circulating round the pole and this allows cold polar air to sink into middle latitudes. Blocking HIGH pressure takes the place of the usual string of Atlantic LOWS and this cuts off our prevailing warm westerly winds allowing chilly air to arrive from the Poles. When the cold weather arrives this weekend think of the warming stratosphere about 20km above the North Pole!  (Actually, it’s not that warm, still -55°C!!). Some are predicting that the cold snap may well last for a while: but models are still uncertain.  Northerly and easterly winds from a cold continent will follow a LOW pressure crossing the south east on Friday (rain) with possible snow on Saturday.  Also: a tentative forecast of snow depth on Saturday (see above).  See these links on SSWs for more detail:

http://met-monkey.co.uk/2013/01/05/sudden-stratospheric-warming-will-it-turn-colder/

http://forum.netweather.tv/topic/74587-stratosphere-temperature-watch-20122013/


3 responses to Sudden stratospheric warming predicts the cold snap

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Trackbacks and Pingbacks:

  1. From ice sheet to high street! « Reigate Grammar School Weather Station - January 12, 2013

    [...] for a while, though at the moment forecasts are uncertain beyond a few days ahead due to the “sudden stratospheric warming” which is taxing every super-computer weather forecasting model including our own UK met [...]

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