Scottish weather discussion - Spring 2023/24

[Hairy Celt]

Maximum here of 13C, very gusty (probably some gale-force blasts), dry apart from a few mins light rain early afternoon.

Chris Faulks on the radio talking about the Foehn effect being partly responsible for the high temps.... Is that actually the case when the wind is so strong? My poor understanding suggests that with very strong and gusty winds, there'll be so much mixing that air warmed would be diluted by cooler... But I suppose the answer is, well, what else is causing these elevated temps, and I have no answer.

[ANYWEATHER]

21 minutes ago, Hairy Celt said:

Maximum here of 13C, very gusty (probably some gale-force blasts), dry apart from a few mins light rain early afternoon.

Chris Faulks on the radio talking about the Foehn effect being partly responsible for the high temps.... Is that actually the case when the wind is so strong? My poor understanding suggests that with very strong and gusty winds, there'll be so much mixing that air warmed would be diluted by cooler... But I suppose the answer is, well, what else is causing these elevated temps, and I have no answer.

Compressed air running down the lee side of hills and mountains warms up dramatically,  for example,  when using a pump to blow up your bike tyres ,the valve gets hot as the air is compressed,  similar situation with the Fohn effect....

[Hairy Celt]

  @ANYWEATHER  I think the temperature goes up in the air in the valve because the pressure is being increased but the volume is constrained. Can that be analogous to an air mass?

 

[drm]

  @Hairy Celt not sure the Foehn effect was in action here the flow of the wind seems to have been nearly all over sea. Just a very warm air mass transported direct from Northern Africa by the looks of the Earth map

[Hairy Celt]

  @drm If you draw a line due south from Kinlochewe, the line does cross lots of mountainous ground. The air has possibly been over mountains as far south as Goat Fell!

It will certainly be a lot colder in the west Highland places tomorrow! 4C so possible ground frost at dawn.

Edited January 28 by Hairy Celt

[drm]

  @Hairy Celt 12c colder tomorrow will feel nippy for them

[dryfie]

I seem to remember reading the Met conclusion after the Achfary UK Dec record a few years ago.  It wasn’t a true foehn as we know it; The air wasn’t lifted from sea level over the mountains as it approached, it was already very warm at height.  Once it reached the mountains it was mixed down by turbulence from the strong winds.  Only saying what I read, not knowledge based!

[mardatha]

Chemikal my dad's side were from Cellardyke, on the fishing boats. Lovely wee place but not been for ages.

Got suddenly windy late afternoon here.

[Snowandrocks]

The mountainous track of the air to Kinlochewe must have something to do with it, whether a true Foehn or just mixing, because I messaged a friend on Skye to ask if he was sunbathing (maybe 30 or 40 miles away) and he replied saying that it was 8 degrees and blowing a gale! 

[Hairy Celt]

  @Snowandrocks Was your friend north or south of the mountains?

[Snowandrocks]

  @Hairy Celt near Dunvegan so neither I suppose! 

[ANYWEATHER]

2 hours ago, drm said:

not sure the Foehn effect was in action here the flow of the wind seems to have been nearly all over sea. Just a very warm air mass transported direct from Northern Africa by the looks of the Earth map

Such a high temperature that far north  at this time of year ,would have to be the effects of the Foehn .........

[Hairy Celt]

  @ANYWEATHER Of course, that's the only thing that affects air temperature?

[Coopsy]

Geeky Foehn alert. 

I remember turning up in Canada during their first winter freezing at minus 20 when suddenly the wind picked up,  strange clouds formed and within a few hours it was well above freezing. Then woke up to minus 20 again. 

Ive since found out these warm chinook winds (as the Canadians call them) happen very regularly and are a god send in the depths of winter. Except for the wind speed. Which regularly reach 60mph.

In Alberta winter, west winds = chinook and nice warmth whilst East winds = upsloping and feet of snow. 

Apparently, the adiabatic warming rate is approx 10oC per 1000m on the leeward side as the dry wind drops down.

So if its 9oC nearby then itll be approx 19oC under the affects of the foehn/chinook if the mountain height to location is approx that.

I'll try and did out some of the weird clouds I've photographed under the chinooks winds. Some are truly amazing from clouds cascading over mountains like a waterfall to multicoloured arches where the winds collide. 

Also just wanted to say a belated thanks for all the snow pics. I was watching daily. Love the variations of weather in Scotland and the lifestyle. No matter where you are in the world,  the weather never fails to interest. 

Here's to a snowy February for everyone (planning on visiting mid Feb so if you can have a word with the Scottish snow gods for me I'd appreciate it )

Edited January 29 by Coopsy

[Blessed Weather]

I don't know whether this helps the 'foehn' discussion:

Weather record for warmest January set in Scottish Highlands

A new UK record high temperature has been set in the Scottish Highlands, according to provisional figures from the Met Office. It recorded a peak of 19.6C (67.3F) at Kinlochewe on Sunday, making it hotter than Rome and the Cote d'Azur.

BBC Scotland forecaster and meteorologist Calum MacColl said the balmy weather was due in part to something known as the Foehn effect. He explained: "The Foehn effect is where, within a stable atmospheric environment, air is forced to rise up and over the hills and mountains, before descending back towards the surface on the leeward or downwind side of the mountains.

Full article: https://www.bbc.co.uk/news/uk-scotland-highlands-islands-68119951

[Hairy Celt]

An average January day today, which is a bit of a novelty for this January. Little wind, started bright but now overcast, and the temp struggling to reach 5C.

I like the little wind part, strong winds are pretty destructive or at least disruptive. 

[Northernlights]

2c start almost calm{ very nice}  and sunny intervals  all morning. Shifted sheep and have got into garden this afternoon. Cows going ba in neep field picking any they missed  .First time since October they have done this  as its usually been too wet or windy they just fill up on clean ones and then head straight back to gate to come inside again

[SW Saltire]

Shockingly awful. Light/moderate rain all day (11mm so far), currently 4c. Grim

[Jo Farrow]

Some observation stations don't automatically send in the data, they are checked at 09Z (NCM data)

A manual reading at Achfary has come in with a provisional 19.9C so exceeding Kinlochewe's 19.6C, both on Sunday 28th 

[Hawesy]

I’m not normally one to rush and criticise the Met Office but I do wish they would update their text forecasts when the forecast goes wrong. Today is a good example. Rain set up further north than expected and it’s been raining here since 2pm. Forecast is dry all day and the hourly app has 90% chance of rain. Not ideal! 

[dryfie]

With all these extremes going on up north I do wonder if anybody has been monkeying with the instruments?

[Hairy Celt]

The temp here has just dropped below 0C for the 1st time in er several days.

<sarcasm alert>

@dryfie Yay let's have some conspiracy theorizing! Go on, it's all a plan to make out the atmosphere is just as stable as ever and we'll be fine burning oil and gas as fast as possible so the big oil companies can keep on getting wealthier for their already stupidly rich shareholders.

[Norrance]

  @Hawesy

Just up the road we have just about been dry so the rain must have barely reached the Tay. It has been cloudy all day though and quite cool with a max of 5.4C.

[johncam]

  @dryfie jeezo 

[Ravelin]

Chilly out, didn't think I'd be saying that after last week. Got below freezing around 5:30pm and currently -1.4C. Had to scrape the car windscreen this morning with a min of 2C, expect I'll be doing the same tomorrow.