Record-breaking rainfall

20.11.09 15:09

The torrential and persistent rain that inundated many areas in northwest Britain and brought particularly devastating floods to Cumbria is on its way into the record books.

A rain gauge at Seathwaite in the Fells filled with 372mm in the space of 30 hours, and 314.4mm in 24 hours up to 00:45 on Friday.

It is probably safe to say, given the additional rain that fell in the hours outside these measurements, that the previous 48-hour record for rainfall in the British Isles has also been consigned to history. That was 315mm, also measured at Seathwaite, which has a fair claim to be England’s wettest location.

If the figures are verified as correct then it would be fair to state that this huge amount of rainfall stands as the new one-day record in the UK by quite a distance; and rainfall has been measured in the UK since 1727.

The previous record was 279.4mm in 24 hours at Martinstown, Dorset, on 18 July 1955. Interestingly, that and the next three highest 24-hour totals occurred during the summer months, when massive slow-moving thunderstorms can build to give high totals in concentrated areas. Such storms accounted for the floods in Boscastle, Cornwall, on 16 August 2004.

It is quite remarkable that a slow-moving front and its widespread rain should produce so much rain, although a very similar situation produced 211mm of rain in Rhondda and Glamorgan on 11 November 1929. That total now lies eleventh in the new list of highest daily rainfall in the UK.

 

Amount (mm)	Location	Date
314*	Seathwaite, Cumbria	19 Nov 2009
279.4	Martinstown, Dorset	18 Jul 1955
242.8	Bruton (Sexey’s School), Somerset	28 Jun 1917
241.3	Upwey (Friar Waddon), Dorset	18 Jul 1955
238.8	Cannington, Somerset	16 Aug 1924
238.4	Loch Sloy Main Adit, Strathclyde	17 Jan 1974
228.6	Long Barrow, Devon	15 Aug 1952
228.6	Upwey (Higher Well), Dorset	18 Jul 1955
215.4	Bruton (King’s School), Somerset	28 Jun 1917
213.1	Timberscombe, Somerset	28 Jun 1917
211.1	Rhondda (Lluest Wen Reservoir), Glamorgan	11 Nov 1929
211.1	Upwey (Elwell), Dorset	18 Jul 1955
208.3	Kinlochquoich, Highland	11 Oct 1916
204.0	Seathwaite, Cumbria	12 Nov1897
203.2	Camelford, Cornwall	08 Jul 1957
200.7	Bruton (Pitcombe Vicarage), Somerset	28 Jun 1917
200.7	Wynford House, Dorset	18 Jul 1955
200.4	Otterham, near Boscastle	16 Aug 2004

By: Stephen Davenport and Michael Dukes