It has been a very dry May so far in many places across IONA, but particularly so in the southeast of England, where Benson in Oxfordshire has only reported a trace of rainfall in the first 22 days of the month. Technically a number of stations are already experiencing an ‘absolute drought’.
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).
Looking at the latest NWP for the next ten days, anticyclonic conditions are forecast to predominate, so it maybe that southern area will see little or no addition to the meagre accumulations they already have right through to the start of June.