A note on the period of extended rainfall deficit beginning November 2004
	One of the regular features of the media coverage of Britain's weather during 2005 was a recurring story concerning grave water
	shortages which never quite seemed to materialise.  The year 2005 was certainly dry over England and Wales, and exceptionally
	so in some southern counties of England, but those national agencies with some expertise in the area have indulged in a curious
	exercise which appears to exaggerate the statistical severity of the rainfall shortfall, by cherry-picking facts and figures. One can
	only speculate about the reasons why this should be so.
	Here are some un-spun statistics which summarise the long dry spell, averaged over England and Wales:
	Rainfall starting in November 2004
	(NB:  the 'return period' and 'driest since' columns refer only to equivalent periods starting in Nov)
	Period	Length	Rainfall	Percentage	ReturnPeriod	Driest Since
		(months)	(mm)		(years)
	Nov	1	52.8	56	9	1988
	Nov-Dec	2	116.6	60	17	2001
	Nov-Jan	3	171.1	59	25	1988-89
	Nov-Feb	4	215.3	60	25	1962-63
	Nov-Mar	5	271.3	63	15	1975-76
	Nov-Apr	6	349.4	70	13	1975-76
	Nov-May	7	394.4	71	13	1975-76
	Nov-Jun	8	449.7	72	12	1975-76
	Nov-Jul	9	524.9	77	16	1975-76
	Nov-Aug	10	586.4	78	16	1975-76
	Nov-Sep	11	654.8	78	12	1988-89
	Nov-Oct	12	780.7	84	9	1994-95
	Nov-Nov	13	868.6	85	12	1988-89
	Nov-Dec	14	942.5	84	16	1995-96
	Nov-Jan06	15	973.4	80	22	1995-97
	Nov-Feb06	16
	Year 2005	12	825.9	89	6	2003
	Water Year
	Oct'04-Sep'05	12	809.7	87	6	1995-96
	Driest periods of differing lengths during the 2004-06 dry episode
	(NB: the 'return period' and 'driest since' columns on the left-hand side of the page refer only to the equivalent
	period starting in the same month, but those on the right-hand side of the page refer to any sequence of months)
	Length	Period	Rainfall	Percentage	ReturnPeriod	Driest Since			ReturnPeriod	Driest Since
	(months)		(mm)		(years)				(months)
	1	Jan 06	30.9	33	33	1997			12	Aug 2003
	2	Jan-Feb 06	86.5	54	12	1964			12	Aug-Sep 03
	3	Jan-Mar 05	154.7	66	12	1997			8	Aug-Oct 03
	4	Nov-Feb 05	215.3	60	25	1962-63			9	Jul-Oct 03
	5	Nov-Mar 05	271.3	63	15	1975-76			11	Jun-Oct 03
	6	Jan-Jun 05	333.1	78	8	1996			11	Apr-Sep 03
	7	Nov-May 05	394.4	71	13	1975-76			13	Apr-Oct 03
	8	Nov-Jun 05	449.7	72	12	1975-76			17	Mar-Oct 03
	9	Nov-Jul 05	524.9	77	16	1975-76			24	Feb-Oct 03
	10	Nov-Aug 05	586.4	78	16	1975-76			30	Feb-Nov 03
	11	Nov-Sep 05	654.8	78	12	1988-89			30	Jun96-Apr97
	12	Nov-Oct 05	780.7	84	9	1994-95			8	Jan-Dec 03
	13	Jan-Jan 06	856.8	84	12	1988-89			7	Mar03-Mar04
	14	Jan-Feb 06	912.4	81	20	1995-96			7	Feb03-Mar04
	15	Nov-Jan06	973.4	80	22	1995-97			12	Mar96-May97
	16	Nov-Feb06	1029.0	80	30	1932-34			15	Apr96-Jul97
	It should be reiterated that several places in southern England, notably in a narrow band from south Wiltshire to west
	Kent, together with south Cornwall, received 15-20 per cent less than the national figure throughout the dry episode. In these
	areas the drought was more intense, and the return periods more noteworthy. Locally here, 2005 was the driest year since
	1996 or 1973, or in one exceptional case since 1921.
										©  Philip Eden