Norman wrote:

Scott W wrote:

Of interest to contributors in the Home Counties I have published a snow
survey / winter index on my blog for my area in east London. It is inspired
by the old Snow Survey of Great Britain which ceased publication after the
1991/92 season.

Further to Dave Cornwell's comment a few weeks back that people mostly
remember a winter through the amount of days with snow lying I decided to
use the data I produced for my winter forecast and try to find out what snow
cover has been like in my area going back to 1946/47 - the first year of the
original snow survey. I then divided the snow lying days by the winter mean
to give the index. I realise there is the work of Bonacina to consider but
as this is national I wanted to look more indepth

Not surprisingly the 62/63 season came out a long way ahead of the rest -
mostly through the sheer sustained depth of the cold. There's also one or
two surprises - strange how the memory can fool you.

It is a work in progress and I would welcome any input.

http://wp.me/p2VSmb-8M

Using the mean temp in deg C gives a highly non-linear index as the temp
approaches 0 deg C. For example, for the same snow depth the index calculated
with a mean temp of +0.1 is double the index calculated with a mean temp of
+0.2 deg C, which is certainly not the sort of result you are looking for. A
mean temp of 0 deg C would give an index of infinity then as mean temps
dropped below 0 deg C the index would be a decreasing negative value. Using a
mean temp in deg K would be a much more valid approach.

Sorry, I meant "for the same number of snow-lying days" not the "same snow
depth".

To illustrate the non-validity of using temps in deg C, if you carry out an
identical exercise using temps in deg F instead, the relative severity of the
individual winters changes markedly. Neither method is valid. The only valid
way is to use deg K.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.