Temperatures perhaps reaching 22-23C across NE Scotland today, thanks to the Foehn Effect.
Rather warm conditions for late September are likely across NE Scotland today, especially towards the coast, thanks to a phenomenon known as the 'Foehn Effect'
This is when warm moist air blowing in on a strong breeze is forced to rise on the windward side of a mountain range, the air cooling and condensing into clouds producing rain on the windward slopes. So by the time the air reaches the leeward side of the mountain range, it has lost most if its moisture. As this drier air descends down the leeward slopes, it warms and as drier air warms more quickly than moist air, it reaches a higher temperature towards the bottom of the leeward slope than when it began its ascent on the windward slope.
This often happens across NE Scotland, when, like today, a strong warm and moist westerly or southwesterly flow off the Atlantic sheds its moisture over the Cairngorms and Grampian mountains then descends and warms as it reached the east coast of Scotland. This can lead to temperatures across Aberdeenshire and Morayshire being 5 to 10 degrees higher than across the west coast of Scotland.
In other parts of the World, such as the leeward side of the Rockies in North America or the Alps, the foehn wind can raise temperatures more dramatically, as much as 30C in a matter of hours.
Today we could see temperatures reach 22 or 23C across Aberdeenshire and coastal areas around the Moray Firth, especailly where we see any brightness, while across western Scotland temperatures are likely to be around 15-16C under cloud and light rain or drizzle.
