I thought that I would take a retrospective look back (excuse the tautology) at the last two cold snaps that we’ve had, and some of the snow depths that were reported by various AWS around the country. The graphs show accumulated and fresh snow depths that I’ve gleaned from SYNOP reports which in the UK helpfully include hourly snow depths (NWS please take note). The blue bar chart in the graph represents fresh snow, that is the difference in snow depth between each hour, red bars indicate snow melt, and the light blue bar series is the hourly snow depth. Bars that span more than an hour are because I’m missing those observations.
From the recent cold spell that started last weekend (17th March) I’ve included the chart for Dunkeswell in Devon (fig 1) and High Wycombe in Buckinghamshire (fig 2).
As you can see the snow on the higher ground of Devon (Dunkeswell 252 m amsl) will do well to survive much longer than four days, all though the deeper drifts on the moors will last longer. You can see why the heavy snow on the morning of the 18th at High Wycombe caught the Met Office out, with the bulk of the 27 cm falling in just two hours (fig 2).
Here are three charts from the much longer and severe cold spell that started at the end of February 2018:
The snow came quite late to St Athan in south Wales (fig 3), but when it did come overnight on the 1st and 2nd of March, it did it in style and put down 56 cm before it had finished. That amount of snow took a whole week before it thawed away completely.
The snow at Wittering in Cambrigeshire started on the evening of the 26th and came in a couple of batches, with a maximum depth of 37 cm by the 3rd of March (fig 4).
Scotland also had a lot of snow, as these next two graphs testify. The first is from Bishopton in Glasgow, where a maximum depth of 46 cm was reached on the morning of the 2nd of March (fig 5).
Finally here’s the snow graph for Drumalbin a weather station on a low hill in south Lanarkshire, where 55 cm or more of snow had accumulated by the 1st of March (fig 6).
I’m sure these laser measured snow depths are very accurate, but in both snow events the wind was strong and there was a lot of severe drifting going on, so how representative these depths are is open to question.