The Martinstown Flood, 18 July 1955

[Nick F]

Between 14.30 h on 18 July and 5 h on the 19th, 279 mm (11 in) of rain fell at Martinstown, 3 miles SW of Dorchester. This occured in a month that was very sunny and warm, where some places had no rain at all during the month.

On the afternoon of 17th July, temperatures reached 28-29C in Dorset, while colder air arrived aloft in the rear of a depression to the South and thunderstorms broke out over Northern France and Southern England. On the 18th of July, an active storm crossed the coast and ground to a halt, so that rain that would normally have moved on and fell over a wider area instead fell over one small area in Dorset.

The floods that occured in Weymouth, Dorchester and Bridport areas caused damage to cars, submerged caravans and covered roads in mud and boulders. There was less loss of life than the Lynmouth disaster, with two people drowned. Although the rainfall was more concentrated in area than in the Lynmouth disaster, the porous chalk in this area of Dorset soaked up large quantities of water, so Martinstown suffered delayed-action floods, so the worst flood was to come the evening after the storm, with a little river bordering Martinstown to Winterborne Steepleton road turning the road into a 4 metre-wide river.

The Martinstown 279 mm fall was the highest 24-hour total so far recorded in the UK:

http://www.metoffice.com/climate/uk/extremes/index.html

[summer blizzard]

Here is the chart for that day, i am suprised that so much rain was produced.