"Martin Rowley" wrote in
:

The latest GFS run (12Z as I write this) out to T+180 has a large area
sub-512 dam across Wales, most of Scotland and large area of north &
central England. This would appear to be nudging the lower boundary of
those figures for November ... and the series would have included the
cold spells during November 1985 which, in some respects, is an
approximate analogue to the current set-up, though note that in that
month the *whole* month was cold, not just the latter third.

Martin

I've gone back to my thickness study I stuck on here last month - top 10
lowest thicknesses I could find from the NCEP reanalysis (which I realise
will have its errors, and I've only looked from 1960-2000) is - and these
are daily mean thickness for a gridpoint in west/central England:

Date TT500
22/11/1965 517.2
19/11/1971 519.2
19/11/1962 519.4
21/11/1993 519.4
29/11/1969 519.7
23/11/1993 520.7
28/11/1985 520.8
22/11/1993 520.8
28/11/1980 521.2
25/11/1978 521.3

Richard