By Paul Homewood
With all the data in for last year, I thought I would revisit the South Yorkshire floods in November.
The trigger for the floods was exceptionally heavy rainfall on 7th November. Excluding upland sites, the heaviest rainfall that day was in Sheffield, which recorded 63.8mm. However that total was much less than the Sheffield daily record rainfall of 119.2mm in 1973 .
Largely as a consequence, November rainfall for Sheffield was much higher than average at 200mm. However monthly totals of this level are by no means unprecedented in Sheffield:
https://www.metoffice.gov.uk/research/climate/maps-and-data/historic-station-data
In fact, the root cause of the flooding was that the ground was already saturated following above average rainfall in September and October. Autumn rainfall was more than 170% of average across a region consisting of S Yorks, Lincolnshire and Nottinghamshire. By contrast most of the rest of the country had rainfall close to average.
https://www.metoffice.gov.uk/research/climate/maps-and-data/uk-actual-and-anomaly-maps
The area affected lies within the Central Region, as defined in the Met Office’s UK Regional Precipitation series. Autumn rainfall was 66% above average for the region, but as the chart below shows was certainly not unprecedented. Indeed the wettest autumn was in 1875.
https://www.metoffice.gov.uk/hadobs/hadukp/
It is clear from the data that the floods were merely the result of a combination of natural meteorological factors, which affected only that part of the country.
The rainfall which resulted was not unprecedented, and neither is there any indication whatsoever that such events are becoming more common.
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February 24, 2020 at 08:14AM
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