On 19/12/2016 18:15, John Hall wrote:
In message , Col
writes
But isn't the single snowflake definition essentially that of a 'snow
day' which
is a standard meteorological obsevation? The only other way to do it
would be a day with snow lying, which would seem rather unfair if a
major blizzard set in at 10am.

I don't know see that as especially unfair. After all, with the single
snowflake definition, if it truly was just one (or even a handful) of
snowflakes, the observer might very well miss it. (I doubt that there's
any automated equipment capable of spotting a single snowflake.) Or you
could get a snow shower occurring a mile away from the met. station but
not at the station itself (or vice versa). The phrase "white Christmas"
makes much more sense if it refers to lying snow, and it's certainly how
I have always thought of it.

Unfair in the sense that it would miss the official definition of a
'snow lying day' if there was lying snow after the 9am observation time.

--
Col

Bolton, Lancashire
160m asl
Snow videos:
http://www.youtube.com/channel/UC3QvmL4UWBmHFMKWiwYm_gg