Talk:1987 United Kingdom and Ireland cold wave

Thickness below 500dam
'''Three extreme instances of 1000–500mbar thicknesses of 500dam or lower have been recorded in the UK during the last 60 years: in a northerly airflow at Stornoway, Outer Hebrides, where exactly 500dam was measured by radiosonde at 1200 utc on 7 February 1969; at Hemsby, Norfolk, where 497dam was reported at 1200 utc on 1 February 1956 and, again at 1200 utc, on 12 January 1987. For our purposes, we shall define these rare cold pools of 500dam or lower over the UK in winter as extreme.'''