After what has been quite a dry and generally anticyclonic last fortnight across much of the UK, we must be to an absolute drought in some parts of the country, which is very surprising as many parts of England where covered in flood waters less than seven weeks ago. The definition for absolute drought was introduced by the British Rainfall Organisation back in 1887 but is frowned upon now by the Met Office for some reason, and I had to dig back to find a reference to it. I can’t guarantee that I’ve captured all the SYNOPs for the last 14 days, and so I can’t guarantee that the above chart is complete, but I do my best with SYNOP observations that I download from the wonderful OGIMET site.
Drought: Dryness due to lack of RAINFALL. Certain definitions have been adopted inMeteorological Glossary 1963
order to obtain comparable statistical information on the subject of droughts.
Thus an ‘absolute drought’ is a period of at least 15 consecutive days, to none of
which is credited 0.01 in., or 0.2 mm, or more of rainfall. A ‘partial drought’ is a
period of at least 29 consecutive days, the mean daily rainfall of which does not
exceed 0.01 in., or 0.2 mm. A ‘dry spell’ is a period of at least 15 consecutive days
to none of which is credited 0.4 in., or 1.0 mm or more of rainfall. During the
62 years 1858-1919, there were 69 absolute droughts and 163 dry spells at Camden
Square, London. The definitions of absolute drought and partial drought were
introduced in British Rainfall (1887) while that of dry spell was first used in
British Rainfall (1919).