Our stormy winter – records continue to tumble

By meteorological convention, ‘winter’ consists of the calendar months of December, January and February. Few will regret the passing of the ‘climatological’ winter of 2013/14, as records continued to tumble right up until the last day …

Wettest February on record – with 117 mm of rainfall (no snow fell during the month), this was the wettest February since the university’s records began in 1908. It was only the fifth February in that period to surpass 100 mm, and the month’s total was almost three times the normal February normal fall of 41 mm.

A stormy month – the above-normal rainfall was the result of a continuation of the passage of low pressure systems across the British Isles that had been experienced during the preceding six weeks. The average mean sea level pressure at the University during February was just 997.6 hPa, almost 20 hPa below normal and the lowest on record for any month. Initial studies suggest that this value is lower by 1.1 hPa than the lowest value recorded for any month in London’s records back to 1692 (Cornes, R. C., Jones, P. D., Briffa, K. R. and Osborn, T. J. (2011) A daily series of mean sea-level pressure for London, 1692-2007. International Journal of Climatology. doi: 10.1002/joc.2301), although typically the air pressure in London might be expected to be about 0.5 hPa greater than that in Reading.

A mild and wet (and yet sunny) winter – no air frost was recorded at the university’s atmospheric observatory during February: the last time this happened was back in 1990. Normally in February we would expect the lowest minimum temperature to be -4.5 °C. (There was, however, an air frost on Saturday 1 March.)

In terms of rainfall, the winter has been unprecedented on the university’s 100+ year record – the total fall of 375 mm making this the wettest season of any name yet recorded. The wettest season up to this year was the autumn of 2000, which received 353 mm, and was also notable for extensive and persistent flooding episodes.

Each month this winter was warmer than normal, with the average temperature for the season of 6.5 °C making it the mildest winter since 2005/6 when 7.0 °C was the average temperature. The lowest temperature recorded this winter was -3.8 °C on 12 January – this was the only morning when the air temperature fell to -2 °C or below. There were only 10 mornings with air frost (air temperature drop below 0 °C), the fewest occasions since just 8 mornings in 1989/90.

 

Acknowledgements: the daily weather observations during the current winter have been made, almost exclusively, by the University’s meteorological observer Mike Stroud.

References
Cornes, R. C., Jones, P. D., Briffa, K. R. and Osborn, T. J. (2011) A daily series of mean sea-level pressure for London, 1692-2007. International Journal of Climatology. doi: 10.1002/joc.2301

 

 

This entry was posted in Climate, Weather. Bookmark the permalink.