As early as midday on the 21^st forecasts were warning of the possibility of damaging winds over Central, Western and Northern Scotland. At this time the depression that would bring the stormy conditions was still well away in the Western Atlantic and, with a central pressure of 1022 mb, still an apparently insignificant feature! By midday on the 22^nd the depression was in mid-Atlantic, with a central pressure of 1008 mb - and tracking north-east at some 75kt! As it was still expected to cross Northern Scotland - somewhere south of the Pentland Firth - it seemed that here on Fair Isle we would miss the strongest winds. I must admit to a feeling of relief - January 1992 and January 1993 had given us enough stormy weather for one decade - but there was just a bit of disappointment. You have to be an extreme weather enthusiast to know the feeling!

The 22^nd on Fair Isle had been an interesting day. West-south-west winds touched storm force during the morning, with gusts to 76 kt in frequent squally showers of rain, rain and snow, soft hail, ice pellets, snow and hail (hailstones up to 12 mm diameter). There had also been several thunderstorms, with the visibility falling to 800 m in heavy snow and hail! In the afternoon the wind moderated to gale F8 and, by early evening, had become west-south-west F7. During the course of the evening - as the wind eased and backed further to SSW F4 - there was a further thunderstorm with heavy snow and 600 m visibility.

Up to this point all seemed to be going as forecast. However, by 2130 UTC, the wind had begun to increase - S'W F8 by 2250 UTC - and the pressure was falling very rapidly. At the midnight observation, the pressure had fallen 11.3 mb in the past three hours. Still expecting the depression to track to the south of, or possibly pass directly over, Fair Isle I went to bed - a decision that I have regreted ever since! I slept through everything!

The S'W wind continued to increased reaching storm force F10 by 0100 UTC. At 0223 UTC - the wind having veered SW'S - the island’s wind generator shut down and, as the power failed, the recorder reverted to full range and the direction trace was lost. By 0300 UTC the wind had increased to hurricane F12.

Between 0300-0025 UTC there were 8 gusts that took the speed trace off the chart - i.e. greater than 95 kt. The highest 10 minute mean, between 0310-0320 UTC, was 69 kt. The wind then began to ease - falling to gale F8 by 0515 UTC. By 0547 UTC, when I switched on the inverter and power was reinstated, the direction was NW'W.

During this ‘hurricane’ variation in pressure was quite extreme. Between 0000 UTC (991.2 mb) and 0300 UTC (970.0 mb) on the 23^rd the pressure fell 21.2 mb. At 0300 UTC the pressure then began to rise extremely rapidly - 12.0 mb in the hour to 0400 UTC, and 18.8 mb in the 3 hours to 0600 UTC. The barograph trace was quite impressive!

The gale force W'N winds continued all day, with gusts often above 60 kt in the frequent and squally showers of small hail and snow. Visibility, though generally 10 km to 20 km, was often poor in the showers - on occasions falling to 400 m in heavy snow. By 1800 UTC there was 1 cm of lying snow.

Since the anemograph was installed in 1982 gusts of 100 kt or more have been recorded on only two occasions on Fair Isle. A gust of 100 kt occurred on 13^th February 1989 (during this storm a gust of 123 kt was recorded at Fraserburgh on the NE coast of Scotland). On 17^th January 1990 a gust of 109 kt - the highest to date - was recorded. On both occasions the strongest gusts were associated with a veer in the wind direction from S'W-SW to W'N to NW.

Considering the number of roofs with missing tiles - far more widespread than either of the two earlier storms - it is likely that on this occasion the strongest winds were again from the gustier W to NW direction. Though it is impossible to estimate what the highest gust may have been, it was probably well in excess of 100 kt. The hurricane force winds - gusting to 104 kt at Sumburgh Airport - caused widespread damage throughout Shetland.

For the period 1982-1988 the average annual maximum gust was 71 kt. For the period 1989-1994 it was 95 kt.

Dave Wheeler

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Last edited on 09 January, 1999   Dave Wheeler weatherman@zetnet.co.uk
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