All quiet on the weather front

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After being assaulted by rain, hail, snow, thunder, lightning and wind so far this winter, the weather has finally quietened down.

This respite in our weather is all due to a very welcome and huge area of “high pressure” which has anchored itself near Ireland over the past week or so - and looks like remaining there for several days yet (at least at the time of writing).

With a central pressure of perhaps as high as 1047hPa (millbars) last Sunday, it is one of highest ‘highs’ of the past ten years or so, although its intensity or large size are unlikely to have broken any records.

High pressure areas are huge blobs of mostly warm, stable and sinking air covering hundreds (sometimes thousands) of miles.

The upward motions of air necessary for thick clouds and steady rain are largely absent from these weather systems, hence they are usually associated with fine and settled weather.

Low-level cloud, fog or ‘smirs’ of drizzle are still possible across windward slopes and coasts including the Isles during high pressure, however, because enough moisture is still continuously evaporated from the surface of our 24/7 warm seas.

If winds turn offshore, however, glorious sunny skies are the norm.

And as we head into mid-February, being on the cusp of spring, the days are certainly growing longer as the Sun grows stronger.

February, on average, has almost twice as much bright sunshine as either December or January (despite February having a shorter length of only 28/29 days), and chance of rainfall decreases markedly with 30% less rain falling in the average February than during January.

Strong winds can still occur however, as can night frosts, and sudden blasts of wind from the north can turn the brief semblance of a spring morn quickly back into the depths of winter within a few hours - but for the moment it seems like we can enjoy the mild and settled weather for a few days yet.

January 2015 statistics

Average daily high: +6.5°C (Highest: 10.6C on 9th and 25th)

Average daily low: +1.3°C (Lowest: -2.2°C on 20th)

Deviation of temperature from long-term average: -0.2°C

Precipitation Total: 250.7mm (9.87 in), or 192% of the long-term average for the Stornoway area, making it the wettest January since 2007.

Wettest day: 29.6mm (1.16in) during 24hrs to 08h00 on 9th

Days with Thunder: 3

Days with Hail: 20

Days with Snow Falling: 19

Days with Snow Lying: 10 (greatest since December 2010)

Strongest wind gust: 113mph during the ‘Hurricane’ on 9th.

By Eddie Graham


Weather Blog:

Photos by Eddie Graham: Snow and sparking skies in the Lews Castle grounds on February 2nd.