It is to be regretted that observations from Elphin, Sutherland and Glen Livet, Banffshire, are no longer available. On the other hand, data have been received from the Paps of Jura (2571 ft.) for the 1949–50 season and from Ben Cruachan (3689 ft.), Argyllshire; Ben More (3169 ft.), Isle of Mull and the Harris Hills (Clisham, 2622 ft.), Outer Hebrides as from 1 December, 1949.
Although snowfall in the south was not remarkable for its frequency, the duration of snow cover on mountains above 2000 ft., particularly in Scotland, was this season the longest since the abnormally heavy snow season of 1946–47.
Taking the same five representative mountains (two in Scotland, two in Wales and one in England), the average duration of snow cover at 2500 ft. was as follows: 1946–47, 91 days; 1947–48, 57; 1948–49, 41; and 1949–50, 64. The duration of snow cover was longest in December, February and April throughout the country. No snow was reported as lying at any level from any station during September, the first snow cover being observed from Glen Lyon on October 19th, when the snow line was down to about 3300 ft.; on the 21st the snow line was down to 2000 ft. on the Cuillins and to 2500 ft. in Glen Lyon and on Ben More, Isle of Mull.
Diagrams showing the distribution of snow cover relative to height for ten stations are given on pages 523 and 524 on the basis set out on p. 131 of the 1946–47 Report (Vol. 1, No. 3, 1948).
On the Harris Hills the snow line came down to sea-level on 8 days during the period December to May; and in April the summits above 2000 ft. were snow-covered for a total of 20 days. From Glen Brittle, in the Cuillins, snow cover was reported in every month from October to May, with
a maximum of 29 days at 3000 ft. in December and April. In February at and above this level the snow cover lasted throughout the month. The snow line fell to sea-level on two days in December and April respectively.
In Glen Lyon the snow line was down to 1500 ft. in every month of the season except September and March; and in February the snow cover lasted for 26 days down to the 2000 ft. level. On Ben Cruachan the snow line was down to 2000 ft. in every month of the season except September and March, and at 3000 ft. the peak was covered during the whole of February.
Ben More, Mull, received no snow cover in September, March or May; but the duration reached or exceeded 14 days at 2500 ft. in December, February and April. In the Isle of Jura, the Paps had some snow cover on the summits in each month except September and March, with a maximum duration of 13 days at 2000 ft. in April.
In the Lake District, from High Close, snow cover was reported at 2500 ft. on at least one day in each month of the season except September, March and May, with a maximum of 13 days in April. The Caernarvonshire mountains, as observed from Capel Curig, were covered down to
2500 ft. during the whole period except in September and May; and in February the cover exceeded 10 days down to 2000 ft. The summits above 3000 ft. had 13 days’ cover in April. The distribution of snow cover on the peaks around Llanfrothen was very similar to that in Caernarvon-shire, with a maximum of 11 days at 2500 ft. in February. The Brecon Beacons had a slightly more prolonged cover at all levels, with a maximum of 17 days at 2500 ft. in February.
Curves showing the total duration at all levels throughout the season at six representative stations are given in Fig. 1 (p. 525). It will be noted that for the Scottish stations the durations were of similar length to those of the 1946–47 season.
Fig. 1
The duration in Glen Lyon exceeded that of other stations at all levels, reaching a maximum of 128 days on the summits. A duration of 100 days was exceeded in the Cuillins at 2500 ft. and on Ben Cruachan and the Glen Lyon peaks above the 3000 ft. level. Apart from the extreme summits in Caernarvonshire, no snow cover exceeded 50 days’ duration at any level south of the Scottish border.
