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Old December 17th 13, 12:53 PM posted to uk.sci.weather
Dave Cornwell[_4_] Dave Cornwell[_4_] is offline
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First recorded activity by Weather-Banter: Nov 2010
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Default Winter Index (Snow Survey for Wanstead / Greater London and southEssex)

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.

---------------------------------
Hi Norman - indeed I have been helping Scott with this and have
suggested Fahrenheit or adding a constant to the means to get a more
proportional index and I think Scott will do that when time permits.
Most interesting though and a good approach I think as it takes away
some of those more subjective memories.
Dave