26th May 2018
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Little or no sun for half of February, and otherwise it was mild, damp and windy

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Over the UK as a whole, a “westerly” weather type prevailed for most of the month, bringing plenty of cloud and bands of rain or showers at times.

Between the 1st and the 5th a sequence of deep depressions tracked north-east between Shet­land and Iceland, bringing some very strong winds to the north of Scotland. From the 6th to the 11th conditions remained cyclonic, but depressions tended to be shallower and followed a track close to – or over – the British Isles.

Between the 12th and 24th, with an anticyclone slow-moving over Scandinavia and complex low pressure over the near-Atlantic, a sequence of fronts were held close to the Northern Isles in a per­sistently strong south-easterly airflow. As the high moved away eastwards, a mobile south-west to westerly airflow returned for the end of the month.

In Shetland, as with much of the UK, February was milder than average by 1°C – due in large part to cloudy nights and elevated overnight minima. A wetter and also duller than normal month for Shetland went counter to the data from the rest of northern Scotland. But for a reasonably sunny start and end, February would have been an exceedingly dull month in Shetland.

Temperatures were generally near or above normal throughout and there were few frosts. Similar conditions prevailed across Scot­land. Here mean temperatures were between 1.0°C and 1.5°C above the 1971-2000 average. Rainfall ranged from close to normal across much of northern Scotland to well above normal south of a line from Aberdeen to Glasgow. Sun­shine totals were somewhat above normal in the north-west but it was duller than usual across the south-east.

On the 1st, as one deep depres­sion over Iceland moved away into the Norwegian Sea, another took its place. Strong to gale force south-west to westerly winds brought sunny spells and wintry showers. Winds backed southerly as fronts moved east from the Atlantic, bringing overnight rain to Shetland. Fronts cleared east early on the 2nd, and a mainly dry day followed with fresh to strong south to south-westerly winds.

With a deep depression north of Iceland, strong to gale force westerly winds brought heavy wintry showers early on the 3rd. Winds backed south or south-eastrly and strengthened further, as another small but vigorous low – developing in mid-Atlantic – ran rapidly north-east.

This, the most intense winter storm of the season, brought wide­spread severe west-south-westerly gales, with heavy wintry showers or more prolonged periods of pre­cipitation later in the day. Lightning was reported from Fair Isle during the evening, and winds of storm force gusted to 93mph at Lerwick overnight. Waves of up to 15.9m (52ft) were recorded west of Shetland at 3am GMT by the Met Office buoy K7.

Winds eased strong westerly on the 4th, becoming light south-westerly by evening as the low continued across Faroe and its front cleared the Northern Isles. However, westerly winds increased strong to gale force again over­night, bringing rain, sleet and then wintry showers, giving some lying wet snow as a front cleared north from Shetland early on the 5th, and leaving a cool, bright day with scattered wintry showers and a fresh south-westerly wind. The 6th was a similar day.

A small depression, tracking north-east across Scotland on the 7th, gave a cloudy day with lighter winds and some rain at times. As the low moved away, a freshening north-westerly wind brought cool­er, brighter and showery conditions. Winds fell light on the 8th as a ridge crossed from the west. Clear­ing skies resulted in a widespread frost.

After a cold, bright start, fronts – driven east by a very deep depression near south-east Green­land – resulted in a cloudy day with rain and strong south-easterly winds on the 9th. Winds eased to a lighter westerly later in the day as fronts cleared Shetland. Fresh westerly winds with some rain or showers followed overnight, as a small low developed to the north of Shetland. This then moved into southern Scandinavia, bringing a mainly dry day with fresh north-westerly winds on the 10th.

The 11th was a dry, cool and mainly dry day. As a small anti­cyclone developed over the Nor­wegian Sea, winds veered fresh north-easterly overnight, and then south-easterly through the day, as the high transferred into Scandinavia.

With a very deep depression (933hPa) off south-east Greenland and intensifying high pressure across Scandinavia and the Nor­wegian Sea, south-easterly winds increased strong on the 12th: a cloudy day with outbreaks of rain or drizzle. As the depression begin to fill, its fronts – coming up against the high pressure to the east – remained slow-moving over Shetland in a strong south-easterly airflow, bringing a very wet 24 hours on the 13th.

For nearly a fortnight, the synoptic pattern remained almost unchanged. A complex pattern of low pressure over the near-Atlantic continued to feed fronts eastwards. However, blocked by the strong anticyclone to the east, they came to a halt and weakened near Shetland. Strong, occasionally gale force south-eastery winds blew day after day. Skies were mostly overcast, with outbreaks of rain, drizzle and occasionally sleet, the 16th being a particularly cold, raw day. The 12th to the 24th was an extremely dull period, with only the 15th having any sunshine.

On the 24th, another cloudy day with patchy rain, high pressure moved away into Russia and the centre of low pressure moved north-westwards. As fronts cleared, milder Atlantic air pushed east on the 25th. Early rain and drizzle was followed by brighter conditions, as strong to gale force south to south-easterly winds finally veered fresh south-westerly. The 26th was mostly dry with moderate south-westerly winds and plenty of most welcome sunshine.

Early on the 27th, a cold front moving east brought a mostly dry, cooler and bright day with moderate north-westerly winds, as high pressure to the southwest of the UK ridged towards Iceland. After a frosty start to the 28th, the day was dry and sunny. Light westerly winds backed fresh southerly later, as a ridge of high pressure over the Northern Isles moved down into mainland Scotland.

Dave Wheeler