As Cassley in Sutherland reached 16.8°C overnight and as this was being reported and discussed in several other places I thought a dedicated thread for this and other related issues would be a good idea.

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As Cassley in Sutherland reached 16.8°C overnight and as this was being reported and discussed in several other places I thought a dedicated thread for this and other related issues would be a good idea.

 

The fact this happened at 3am makes it all the more remarkable.  The next 4 or 5 days could see more records go some crazy 850s predicted. 

 

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The fact this happened at 3am makes it all the more remarkable.  The next 4 or 5 days could see more records go some crazy 850s predicted. 

 

I am not sure that day or night time makes as much of a difference as it would at other times of the year. The Föhn effect and lack of insolation at this time of the year are more important. Although it will remain (mostly) mild in the next week or so, the factors in place today, and resulting temperatures, are less likely to be repeated I think.

I do wonder however if it could also reach 16°C later on today along the Moray Firth.

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Can someone explain in simple terms to a simpleton like me the Fohn effect?

Does daytime sun have no effect?

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Can someone explain in simple terms to a simpleton like me the Fohn effect?

Does daytime sun have no effect?

https://en.wikipedia.org/wiki/Foehn_wind

 

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Can someone explain in simple terms to a simpleton like me the Fohn effect?

Does daytime sun have no effect?

Believe it or not in isolation the sun will not have any significant effect on the temperatures at this stage of the season in this situation. That is of course very different to other situations. The perfect conditions with sunshine would probably give a slightly higher value even at this time of the year but that would be a small consideration. The upper air, moisture and wind would by themselves outweigh any effect of sunshine. 

There is a nice description of the Foehn/Föhn effect here https://www.bbc.co.uk/news/uk-scotland-31767933 

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Thanks guys

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Good thread. 

I find the NE Scotland fohn effect fascinating.

They are the very reason for micro-climates all over the place, even over modest elevations of 100 metres or so.

 

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interesting that it doesn't match the 18.3dc maximum seen in the 1940's....

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As Cassley in Sutherland reached 16.8°C overnight and as this was being reported and discussed in several other places I thought a dedicated thread for this and other related issues would be a good idea.

 I know Glen Cassley quite well and am not sure where the recording station is but it certainly has it,s own microclimate which i have experienced on several occasions.

The final figure for Cassley was actually 16.9c

Because it was recorded in the early morning of the 29th, it counts, under MetO rules, as being on the 28th ..... And is thus a new date record for the 28th, rather than the 29th. Also highest temperature officially recorded anywhere in the UK during the last 10 days of December.

However, unofficially, there was a reliable reading of 18.4c in Inchnadamph .... !

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The final figure for Cassley was actually 16.9c

Because it was recorded in the early morning of the 29th, it counts, under MetO rules, as being on the 28th ..... And is thus a new date record for the 28th, rather than the 29th. Also highest temperature officially recorded anywhere in the UK during the last 10 days of December.

However, unofficially, there was a reliable reading of 18.4c in Inchnadamph .... !

Similar to the 1948 record on the 3rd.
The time of day is practically irrelevant even if the sun was not cloud covered or behind a hill it has barely any effect in December.

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 I know Glen Cassley quite well and am not sure where the recording station is but it certainly has it,s own microclimate which i have experienced on several occasions.

Based on the co-ordinates on the Met Office site I believe it's actually one valley over from Glen Cassley. Looks like it is at the Cassley power station near the head of Loch Shin. You can see the white Stevenson screen here I think, just south of the buildings: https://www.google.com/maps/@58.1678939,-4.7311292,519m/data=!3m1!1e3

 

 

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Except that warmth is no longer unseasonal these days. Something has definitely flipped in our climate, with decent UK winters becoming something of the past. Look at the tatters of the MO thread - nothing to get excited about even in deepest FI, as yet another relentlessly mild January comes into view. Hey ho!

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The final figure for Cassley was actually 16.9c

Because it was recorded in the early morning of the 29th, it counts, under MetO rules, as being on the 28th ..... And is thus a new date record for the 28th, rather than the 29th. Also highest temperature officially recorded anywhere in the UK during the last 10 days of December.

However, unofficially, there was a reliable reading of 18.4c in Inchnadamph .... !

The record for the 28th was already 16.8C dating from 1974 so this last 0.1C will be important if this reading hopes to beat the previous record and not just equal it

 

 

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I thought of this thread as I was washing thick frost off my car this morning.

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I thought of this thread as I was washing thick frost off my car this morning.

And I thought of it as I came in from the garden just now, bathed in the gentle warmth of the midwinter sun. The only reason I was wearing a coat was because I was hacking away at brambles; if it had just been regular weeding I'd not have needed it. It's like a sparkling March day out there!

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And I thought of it as I came in from the garden just now, bathed in the gentle warmth of the midwinter sun. The only reason I was wearing a coat was because I was hacking away at brambles; if it had just been regular weeding I'd not have needed it. It's like a sparkling March day out there!

Certainly is. Wasn't cold here at dawn. 6'c with broken cloud

Except that warmth is no longer unseasonal these days. Something has definitely flipped in our climate, with decent UK winters becoming something of the past. Look at the tatters of the MO thread - nothing to get excited about even in deepest FI, as yet another relentlessly mild January comes into view. Hey ho!

Sorry to bang on about this but we keep hearing that and yet the past decade or so has certainly been the snowiest in my lifetime since at least the 1980s (and I suspect that locally here in Hampshire it beats the 1980s hands down).

We've had decent (10cm+) snow events in 2008, 2009, 2010, 2013, 2018 and 2019 as well as smaller snow events in 2015 and 2016. Not to mention the first subzero CET month December since Victorian times! To say that decent UK winters are a thing of the past seems very odd. If you'd told me that in the late 1990s or early 2000s I might have believed you.

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Sorry to bang on about this but we keep hearing that and yet

You'll keep hearing it too, at least until we get our regular(*) midwinter easterlies back. Something changed in 1997 and whatever it was it means we've had an unprecedented-in-the-last-110-years lack of easterlies.

You won't notice if you're far inland like you are, but if you're on the coast and rely on deep cold from the east to generate your snow you can't help but notice it.

2018 was a lovely reminder of what can be, but it was very short (just 3 days of noteworthy cold) and of course it was at the arse-end of winter, much like the last genuine easterly spell we had (late Feb 2005, which gave 14 days of falling snow here.)

* - by which I mean at least a couple of midwinter easterlies per decade, or more, as was the norm up to and including the 90s.

first subzero CET month since Victorian times!

I hadn't realised she was still on the throne in 1986!

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