Today is the anniversary of the end of the December 2017 cold spell and of course, it's only appropriate that we do a post on the spell as well as the memorable slider low snow event on 10th December.
As Storm Caroline pushed eastwards across Scotland on December 7th 2017, the winds became a northwesterly and then a northerly on the western flank of the low. It was a relatively mild day for most as the cold air was sinking southwards from the north with a lot of cloud around at first and some rain. This cleared to sunny spells later with showers turning wintry over Scotland.
These northwesterly to northerly winds became ever more evident on the 8th with widespread wintry showers occurring over the UK and Ireland, most notably over Northern Ireland and the north of Scotland where they were very frequent and as a result, there were accumulations. Nowhere reached 10c with the maximum temperature out of both countries being 9.0c at Mullagh_Carrowlagan, Co. Clare. Over high ground in Scotland and northern England, temperatures failed to get above freezing all day including an observation of -2.0c at South Stainmore, Cumbria. Gale force winds made it feel much colder at times than what the actual temperature suggested. Otherwise, it was a nice bright day with plenty of sunshine.
The northerly flow got cut off on the 9th as the low pressure pushed further eastwards into Scandinavia. As a result, a more flat westerly airstream reached Ireland and the south of the UK which made it a milder day overall though the north was still cold with further wintry showers and icy conditions including a maximum of -0.9c at Malham Tarn, North Yorkshire and an air minimum of -7.3c at Bewcastle, Cumbria in the morning whilst Mullingar, Co. Westmeath had an air minimum of -2.6c. It was another dry, sunny day for the most part but much of Ireland and the southwest of England clouded over during the afternoon. This was as a result of an approaching slider low from the Atlantic which would bring rain at first to the west of Ireland and the southwest of England through the evening.
As the low slid further down Ireland and the UK into the 10th and pushed a bit northeastwards, the rain turned to snow in the cold air. The snow became heavy with significant accumulations recorded over the Midlands of England and some parts of Ireland including an observation of 30cm at Sennybridge, Brecknockshire. Close to coasts, this was mainly cold rain. Scotland recorded further wintry showers and Dalwhinnie in the Highlands had an air minimum of -12.4c early on the 10th, the lowest December temperature in the UK since 2010. Keep in mind, December minimum temperatures haven't been low for a good number of years as the Decembers have tended to be very mild since 2010 for the most part - some have been rather average like 2012 and 2014. Mullingar recorded an air minimum of -3.9c meanwhile. Another ice day over parts of Scotland. More snow occurred over the Midlands of England during the evening.
The slider low cleared on the 11th leaving a bright but cold day across the UK and Ireland although there was some rain in the southeast of England which had pushed up from France during the morning. This would have brought some snow accumulations over the hills. Some wintry showers to the north once again. Dalwhinnie recorded an air minimum of -13.0c whilst Horseleap, Co. Offaly and Casement Aerodrome, Co. Dublin recorded an air minimum of -6.6c. Sennybridge's snow depth was still 31cm at 9am on the 11th. Another very cold morning on the 12th with an air minimum of -13.0c at Shawbury, Shropshire and -3.7c at Horseleap but this cold spell ended there as low pressure approached from the west during the morning.
Here's some pictures:
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