"Mike Tullett" wrote in message
...
On Fri, 23 Jan 2004 14:01:59 -0000, Col wrote in


2 pages in the Mail today, quoting lows of -8 in Scotland..


The local news has just quoted -10 to -12C for this region next
week. Quite possible but it would be a pretty unusual spell of
weather to give those kinds of values.

So much will depend on whether there is a snow cover or not. Those
figures
would be most unlikely over bare ground, but given the insulating effect
of
a layer of snow are entirely possible.

There was an article in 'Weather' in the mid-80s (I think) on the
factors required to produce very low minima in the UK
by Roach and Brownscombe. One of their conclusions was
that widespread lows below minus 10 almost always require
a snow-cover, preferably fresh and reasonably deep. It was
a rather patronising article, I remember thinking, and I trawled
the MWR and DWR for every occasion since 1945 when
a temperature of -10 or below was recorded with a less than
50% snow cover; I drafted a sarcastic Letter to the Editor, but
(probably wisely) never sent it. I think I found about 20 examples
in 40 years, but only 3 or 4 of these could reasonably have been
described as "widespread", and many of the others were
isolated observations at well-known frost-prone sites.

Philip Eden