21st October 2018
Established 1872. Online since 1996.

April was milder and duller than normal with near average rainfall

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Across the Northern Isles, like the rest of the UK, the first week of April was unsettled. After this, as high pressure wandered slowly around the British Isles until mid-month, there was a period of relatively settled weather. This left the second half of the month again cyclonic and unsettled over northern Scotland.

Mean temperatures for Scotland were about 1°C above the 1971-2000 normal. For the UK as a whole April was mainly dry and fine, with most parts recording less than 50 per cent of average rainfall. In Scotland, although it was drier in areas close to the east coast – with less than 50 per cent of average recorded in the Borders – rainfall was closer to average.

It was a sunny month, particularly over England and Wales, where provisionally it was the fourth-sunniest April in a series from 1929. Sunshine totals were generally some 20 per cent above average, the exception being parts of the Western and Northern Isles, where it was somewhat duller than normal.

With a low to the north of Shetland, moderate or fresh west to north-westerly winds brought a scattering of showers on the 1st. These died out and winds eased moderate southerly during the 2nd, as the filling low moved away east and pressure built across the area.

After a cold, bright start, freshening south-east to east-south-easterly winds brought rain later on the 3rd as a depression, tracking east over southern Britain, pushed fronts north-west over the Northern Isles.

The rain turned showery overnight, with the 4th ending up mostly dry and bright with light westerly winds, as the low moved away and pressure built over northern Scotland. After an early frost, the night turned milder as cloud thickened and southerly winds freshened.

With a complex area of low pressure to the west of Scotland and a frontal system moving slowly east, the 5th was a dull, misty day with periods of rain and fresh or strong south-easterly winds. As low pressure tracked north towards Iceland, the front remained slow-moving over the Northern Isles, bringing rain and strong south or south-easterly winds for much of the 6th.

With the front clearing east overnight, the 7th was a dry day with plenty of sunshine and lighter westerly winds. As an anticyclone, moving in over southern Britain, ridged northwards, the 8th was a bright day, with sunny spells and fresh west-south-westerly winds bringing a scattering of showers.

Mostly dry and settled conditions were maintained across northern Scotland through the next few days, with light westerly winds slowly backing south-easterly and later freshening, as the high drifted north-east over the North Sea into southern Scandinavia. Mist and sea fog affected the Northern Isles on the 11th.

On the 12th the anticyclone moved from Scandinavia to a position between Scotland and Iceland. Mild southerly winds veered to a cooler northerly later in the day as a front moved down from the Norwegian Sea, bringing dull, misty conditions with a little patchy drizzle.

Pressure then built across northern Scotland to give a dry, sunny day on the 13th, although it did feel rather cool in a fresh north to north-easterly wind. The ridge then declined south and, with pressure remaining high to the west, moderate or fresh north-westerly winds brought a few showers on the 14th and 15th.

As the high slipped further south, a small low – moving east from Iceland – trailed a warm front across Shetland, bringing cloudy conditions with patchy rain or drizzle and strong west-south-westerly winds on the 16th.

Fresh westerly winds and showers followed on the 17th, as the low moved east into Scandinavia. It also turned colder and – as fresh to strong winds turned north-west or northerly in direction – wintry showers were frequent by the 18th, with some of the heavier ones leaving temporary deposits of melting snow and ice on the ground.

Snow showers died out overnight, with a weak ridge bringing a frosty start to the 19th. A depression, tracking south-east from Iceland, brought rain, sleet and hill snow later as south-westerly winds freshened.

The low – a relatively small but vigorous feature – slipped through the Fair Isle Channel overnight, and the 20th saw a return to colder weather with wintry showers and strong north-westerly winds. By evening some places again had a thin covering of snow.

As the low moved away and pressure gradually built across Shetland, the 21st, 22nd and 23rd were steadily improving days. Wintry showers became more scattered and eventually died out, as cold, strong and gusty north-westerly winds slowly eased and backed westerly.

After a frosty start, mild southp-easterly winds freshened on the 24th as the ridge declined, with some patchy rain following overnight as Atlantic fronts moved east.

During the next five days – with a complex area of low pressure over the Northeast Atlantic – mild, moist south-westerly winds brought rather cloudy, misty conditions with hill fog and outbreaks of occasionally heavy rain or drizzle to Shetland.

Later on the 29th, as low pressure moved into southern Scandinavia, a cold front swung south over Shetland, introducing colder and showery conditions for the 30th as winds veered fresh north-west to northerly.