Fair Isle Weather - February 1999

A cold (-0.9°C), wet (163.0%) and windy month with sunshine (102.3%) close to normal. The 13 days with snow cover at 0900 UTC equalled the highest February (1979) total, but fell somewhat short of the 1981 December value of 18 days with snow lying.

The month began with high pressure centred close to the southwest of the British Isles with a mild but showery SW airflow across Shetland. A deep depression, tracking northeast across Iceland on the 2nd, moved on into the Norwegian Sea on the 3rd bringing spells of heavy rain and very mild gale force SW to W’ly winds, with the month’s highest temperature occuring late in the evening. Winds increased to storm force on the 4th, with gusts to 85 kt

Low pressure then became established across Scandinavia veering the gale force winds across Shetland from W’ly to NNW’ly. The strong to gale force winds persisted for the next week, bringing cold Arctic air with heavy snow showers and drifting of the lying snow.

High pressure, developing to the south of Iceland on the 8th, maintained the cold N’ly winds for the next couple of days. As the high drifted south on the 10th, the winds backed W’ly cutting off the supply of cold arctic air. The high then slipped away towards Portugal with mild SW’lies becoming established across the north – bringing a rapid thaw of the lying snow on the 11th. The thaw continued during the next few days as strong SW’ly winds brought further periods of rain and drizzle.

A deep depression, tracking quickly east across Iceland into the Norwegian Sea on the 15th, brought cooler W’ly winds to the north. As the low moved on into Scandinavia the strong to gale force winds veered NNW’ly on the 16th bringing colder air and heavy snow showers south across Shetland. Low pressure over Scandinavia maintained a strong to gale force N’ly airflow with snow showers for the next few days. A developing Atlantic low, tracking north towards Iceland on the 18th, drove its associated fronts east across Scotland bringing strong to gale force SW’ly winds with rain and drizzle and a rapid thaw of the lying snow. This low then drifted southeast over the weekend, maintaining a strong W to NW’ly airflow across the area with frequent and occasionally heavy and thundery wintry showers.

Low pressure, moving east into the Baltic, brought fresh to strong N’ly winds and further wintry showers by the 22nd. High pressure then built across Shetland to give a brief settled spell. The high quickly declined on the 24th, as a developing low near Iceland pushed fronts east across Fair Isle on the 25th with strong SW’ly winds and spells of heavy rain and drizzle.

The low became slow-moving in the Norwegian Sea, leaving Shetland in a bright and showery SW to W’ly airflow to the end of the month.

Daily Data
Weather Diary

 

1999

Day

1974-98

1999

Day

1974-98

Mean Maximum Temperature

5.0

5.6

Highest Max temp

10.2

3

10.5

Mean Minimum Temperature

1.8

2.9

Lowest Min temp

-3.8

16

-5.6

Mean Sea Temperature

7.5

6.7

Lowest grass minimum

-4.8

9

-12.3

30 cm Earth temperature

4.3

4.3

Days with ground frost

14

9.8

100cm Earth temperature

5.1

5.1

Days with air frost

7

3.8

Total Rainfall (mm)

115.6

70.9

Days with snow/sleet

19

11.4

Wettest Day (mm)

11.6

20

11.8

Days with snow cover at 09hr

13

3.5

Rain Days (> 0.1mm)

27

20.7

Days with hail

18

12.0

Wet Days (> 0.9mm)

24

15.2

Days with fog during 24hrs

12

3.8

Total sunshine, hrs

59.1

57.7

Days with fog at 09hrs

1

0.4

Sunniest day, hrs

5.9

27

6.9

Days with NIL sun

6

8.2

Mean wind speed, kts

21.2

19.2

Days with gale

8

7.5

Maximum gust, kts

85

4

66.9

Days with thunder

3

0.6

Mean Sea Level pressure

1004.4

1009.5

Days with aurora

1

3.4

Wind Direction (%) North

14.3

9.5

Wind Direction (%) S. West

17.9

16.7

at 09 hr N. East

0.0

4.2

at 09 hr West

25.0

16.2

East

0.0

8.2

N. West

17.9

8.2

S. East

0.0

13.5

South

21.4

22.9

CALM

3.6

1.3

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Last edited on 07 March, 1999   Dave Wheeler weatherman@zetnet.co.uk
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