Graham Easterling wrote:



Have found a Met Office pdf showing a map of Cornwall with average days of
lying snow for the period 1971-2000. It look like at least 50% of the
county has 3 days or less. Interestingly, one of the snowiest parts is the
Lands End Peninsula with up to 10 days over the high ground to the west of
Penzance.


http://www.metoffice.gov.uk/media/pd...st_England.pdf


Dick Lovett

Sorry, those maps gaive a great impression of detail & accuracy, shame they
are totally wrong. I suspect they are some sort of projection based on
altitude and reports from up the County (Camborne etc.)

I can see the tops of the moors from just behind Penzance, and the only
winter in the last 20 years where there has been 5 days with snow cover,
even on the highest tors, was 2010 with 12 (give or take 1) Several recent
winters have seen no days with snow cover, even at the highest levels.

In Penzance, since 1992,
2010 had 9 days snow cover
next comes 2009 with 2 days
All the others have 1 (4 years) or 0 (15 years!)

I've also kept note of snow cover both on the Penwith Moors, and the Lizard,
visible across the bay.

The Penwith moors have surprisingly little snow. Whilst the notable snowfalls
are easterly blizards (now a long time since the last 1 in '87) almost all
the snow here comes from a northerly. The 'snow' normally actually falls as
rain & sleet (if you see what I mean!) until it crosses the tops of the
moors, the highest points are only 1 mile from the north coast and about 200m
or so. The snowiest parts are just above places like Madron, a couple of
miles behind Penzance on the SE facing slopes.

From my observations I would give the average snow cover days per annum on
the snowiest parts of the Penwith moors to be around 2 days (3 days at an
absolute push - but I seriously doubt that).

The Lizard plateau is significantly snowier. The average on the snowiest
parts could well be around 5 days (MCC Stithians?) I have noted many days in
a showery northerly when the Lizard peninsula is almost entirely snow
covered, when the showers are falling as rain/sleet/hail even at the highest
levels behind Penzance. The Helston to Redruth area being the snowiest. I've
had discussions with Martin R. about this. I think there are 2 main factors

1. Distance from the onshore north coast in a snowy northerly.
2. The Land's End peninsula is virtually an island, and turbulence created in
the northerly airstream caused by it seems to mix in warmer air from the sea
surface. In a northerly Penzance is often warmer than Scilly. (Not so in an
easterly!)

Sorry it's all a bit long, but these accurate looking but inaccurate maps
irritate me. I still recall the time when Scilly double recorded rainfall for
10 months, and despite me reporting it (and the fault acknowledged to me
through the 'back door' - together with an account of why) the monthly
rainfall anomaly maps for the western half of Cornwall were something to
behold. THe computer obviously having problems in reconciling the conflicting
Camborne & Scilly data! Poor old Penzance in the middle was shown having
rainfall wildy out.

Graham
Penzance

Don't forget, Graham, the great God Computer is infallible and it tells nothing
but the truth!!!!! Sorry if I sound cynical but these days I often find that
another crank of the computer handle is presented as factual data, in
preference to measured data.

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