October 2014 – typical and atypical

By Ross Reynolds

Apart from a hiccup with the cooler than average August, October was the ninth warmer than average month for the UK this year. This was reported on the Met Office website by Emma Boorman, one of our recent MSc Applied Meteorology graduates. In addition, this year is currently heading to being one of the warmest on record for the UK.

The autumn of course is the time of year when the risk of a battering from ex-tropical cyclones is highest with ‘Gonzalo’ keeping up the tradition. The storm swept across the country on the 21st with the high winds leading unfortunately to two fatalities in the south-east, extensive high winds including a gust of 108 mph (94 kn, 48 m/s) on Cairngorm and more than 30 mm of rain in parts of western Scotland and North Wales.

Less than a week later, prolonged, heavy rain of an orographically-enhanced nature affected parts of upland north-west Britain. The totals of some 250-260 mm from a mid-latitude frontal system over four days in parts of the Scottish Highlands produced significant flood damage. Although notable, this pales into insignificance compared to the UK record two day fall of 396 mm in November 2009 at Seathwaite, Cumbria (well known to rainfall buffs). This total benefited from the seeder-feeder mechanism too.

The month’s end witnessed the rarest event – of extreme warmth for Halloween; Gravesend in north Kent and Kew Gardens both reported a maximum of 23.6°C, way clear of the previous high of 20.0°C for the date. The extensive southerly flow and sunny conditions were part of the story, as is very likely the background increase in greenhouse gas concentration. Interestingly, other highs above 20°C occurred on the north coasts of Norfolk and Wales; similar to the location of the UK’s record highest January maximum of 18.3°C in northern Scotland and North Wales.

A high of 21.7°C was recorded at our Atmospheric Observatory on 31st. I checked the frequency of October days with maxima at or above 21.7°C on campus by using the recently improved (thanks to Roger Brugge) Reading weather web pages. It turns out that over more than 40 years of daily data, on average it was equalled or exceeded on about 1 day in 80 or getting on for once every 3 years. But that’s for the whole month of October of course; the incidence of such warmth at Halloween will clearly be very much lower. To put it in a climatological context, the average maximum at the Observatory declines during October from around 17°C at the beginning of the month to just 13°C at the end.

In a spell of some ten days the UK experienced significantly high winds, high temperatures and large rainfall amounts, but the Met Office handled each of these varied events very well, both in terms of lead times and their location and magnitude.

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