wrote:

On Sunday, 10 December 2017 11:07:17 UTC, Graham P Davis wrote:
High Wycombe has been reporting this nonsense for hours. Sigh!

--
Graham P Davis, Bracknell, Berks. Web-site:
http://www.scarlet-jade.com/ "Nobody can get the truth out of me
because even I don't know what it is. I keep myself in a constant
state of utter confusion." [Col. Flagg] OS: Linux [openSUSE
Tumbleweed]

You're quite right, as an ex-observer heavy snow would mean a
visibility of a 1000 metres or less.

In Tideswell, I find that moderate snow often reduces visibility to
300-500m. Heavy snow would almost always have a vis of less than 300m.

Heavy snow is defined as snow accumulating at a rate of more than 4
cm/hr. That doesn't often happen here.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
https://peakdistrictweather.org
Twitter: @TideswellWeathr