A mild (+0.7°C) month with rainfall slightly below
(97.6%) and sunshine a little above (106.5%) average.
With a ridge extending across Shetland
from high pressure over Scandinavia the month began mostly dry, mild and sunny
– although light southeasterly winds brought fog on the 2nd.
A large Atlantic depression, moving
slowly north, brought mild and moist southwesterly winds by the 5th
with fronts crossing the British Isles during the next few days bringing periods
of rain and drizzle. A weak ridge
of high pressure gave a dry and sunny day on the 7th before the next
front - associated with a deep depression tracking across Iceland -
brought strong southwesterly winds and rain to the area.
A vigorous wave low, forming on the front over the Atlantic early on the
11th, ran rapidly northeast across Shetland on the 10th -
increasing the southwest wind to gale force.
As the low moved away into Scandinavia the wind veered northerly and
eased, giving a fine sunny day on the 11th.
The next low, tracking east across the
north of Scotland, brought a spell of strong southeast to easterly winds with
rain and drizzle on the 12th.
As this low became almost stationary over Scandinavia for the next few
days a period of strong northerly winds and snow showers followed.
The low eventually drifted away northwestwards, backing the wind into the
northwest bringing showery and a little milder conditions.
A ridge of high pressure extending south across Iceland on the 18th
returned the wind to a northerly direction and gave a cool but mainly dry
weekend.
A very deep Atlantic low, tracking
towards the UK on the 20th, saw the wind backing into the southeast
and increasing to gale force as frontal systems pushed north over Scotland on
the 21st. During the
following days as the low gradually filled and drifted northwards to the west of
the British Isles the southeasterly winds eased moderate to fresh with rain or
drizzle and persistent low cloud or fog affecting the Northern Isles.
The weather then became dry and sunny as high pressure built across Shetland from Scandinavia on the 25th, with a small anticyclone developing across northwest Scotland on the 26th. The high then drifted south during the next couple of days with a developing low running quickly east across Faeroe on the 29th bringing near gale force westerly winds and rain followed by strong, cool and showery northwesterly winds to bring the month to a close..
 | Daily Data |
| Weather Diary |
|
1999 |
Day |
1974-98 |
1999 |
Day |
1974-98 |
|||
|
Mean Maximum Temperature |
8.0 |
7.3 |
Highest Max temp |
10.8 |
9 |
12.2 |
||
|
Mean Minimum Temperature |
4.7 |
4.0 |
Lowest Min temp |
-1.0 |
14 |
-4.0 |
||
|
Mean Sea Temperature |
8.1 |
7.5 |
Lowest grass minimum |
-3.1 |
14 |
-8.9 |
||
|
30 cm Earth temperature |
7.0 |
6.0 |
Days with ground frost |
6 |
7.2 |
|||
|
100cm Earth temperature |
6.6 |
5.8 |
Days with air frost |
4 |
2.0 |
|||
|
Total Rainfall (mm) |
48.8 |
50.0 |
Days with snow/sleet |
8 |
6.4 |
|||
|
Wettest Day (mm) |
14.6 |
20 |
11.0 |
Days with snow cover at 09hr |
0 |
0.6 |
||
|
Rain Days (> 0.1mm) |
19 |
17.3 |
Days with hail |
9 |
7.3 |
|||
|
Wet Days (> 0.9mm) |
14 |
11.8 |
Days with fog during 24hrs |
13 |
6.1 |
|||
|
Total sunshine, hrs |
158.4 |
148.7 |
Days with fog at 09hrs |
7 |
1.7 |
|||
|
Sunniest day, hrs |
12.5 |
17 |
12.7 |
Days with NIL sun |
5 |
4.6 |
||
|
Mean wind speed, kts |
13.8 |
14.8 |
Days with gale |
2 |
2.3 |
|||
|
Maximum gust, kts |
64 |
21 |
55.7 |
Days with thunder |
0 |
0.2 |
||
|
Mean Sea Level pressure |
1010.3 |
1013.3 |
Days with aurora |
1 |
2.4 |
|||
|
Wind Direction (%) North |
6.7 |
14.6 |
Wind Direction (%) S. West |
20.0 |
11.5 |
|||
|
at 09 hr N. East |
10.0 |
9.4 |
at 09 hr West |
10.0 |
14.4 |
|||
|
East |
23.3 |
12.6 |
N. West |
16.7 |
10.7 |
|||
|
S. East |
10.0 |
13.5 |
||||||
|
South |
3.3 |
12.2 |
CALM |
0.0 |
1.0 |
