Winter 2022-23 early thoughts - general chat

[SqueakheartLW]

Maybe we should take note of this chart today and how 3 of the 4 CFS runs are going for a reversal of the 10hpa zonal winds. 2 of these in December and the other one in January.

[Penrith Snow]

A lot of talk about climate change preventing a cold winter but really?

Is the Earth really that much warmer in October 2022 than it was in October 2009 or 2010?

Just saying.....

Andy

[Don]

13 minutes ago, Penrith Snow said:

A lot of talk about climate change preventing a cold winter but really?

Is the Earth really that much warmer in October 2022 than it was in October 2009 or 2010?

Just saying.....

Andy

That's an interesting question, perhaps 0.2-0.5 degrees higher?

28 minutes ago, SqueakheartLW said:

Maybe we should take note of this chart today and how 3 of the 4 CFS runs are going for a reversal of the 10hpa zonal winds. 2 of these in December and the other one in January.

Are they the non biased runs?

[Beanz]

1 hour ago, Penrith Snow said:

A lot of talk about climate change preventing a cold winter but really?

Is the Earth really that much warmer in October 2022 than it was in October 2009 or 2010?

Just saying.....

Andy

Is it not more likely that global warming is more likely to be affecting global weather patterns.  The type of winter we experience is indirectly a consequence of global warming…. 
 

 

[Frost HoIIow]

2 hours ago, Penrith Snow said:

A lot of talk about climate change preventing a cold winter but really?

Is the Earth really that much warmer in October 2022 than it was in October 2009 or 2010?

Just saying.....

Andy

It just shows with the BFTE in 2018 that extreme cold still can occur in these times. IIRC it was the coldest upper air temps to engulf the UK since at least Feb 1991. If only it happened a month earlier in late Jan rather than late Feb can you imagine wow. Would've given Jan 1987 a run for its money.

[Eagle Eye]

32 minutes ago, Penrith Snow said:

A lot of talk about climate change preventing a cold winter but really?

Is the Earth really that much warmer in October 2022 than it was in October 2009 or 2010?

Just saying.....

Andy

 

3 minutes ago, Beanz said:

Is it not more likely that global warming is more likely to be affecting global weather patterns.  The type of winter we experience is indirectly a consequence of global warming…. 
 

 

That is an interesting topic that could be discussed for a long time, in fact it just so happens to tie in with the document my friend Olivia picked out, a quote from the model thread so you kind of understand that last bit.

"
I'm getting my friend Olivia to pick between a choice of 3 documents every week for the next 3 years and I will summarise each document by the end of each week, so by the end of the 3 years when including holidays I should have read nearly 150 documents on Meteorology by the time I'm hopefully starting university."

Now, away from humans and onto some less complicated stuff 

How can climate change affect SSW's?

62 page master's thesis summarised:

Firstly, note that the SSW is primarily driven due to tropospheric-stratospheric coupling and Rossby waves vertically propagating from the troposphere into the stratosphere and as they carry an easterly effect onto where they propagate, the westerly jet is slowed down in the stratosphere. The reversal of the zonal winds being the way to identify a SSW. Therefore it makes sense that they occur in times of enhanced vertical Rossby wave propagation completely reversing the vortex and warm air rushes over the Arctic through dynamical processes that I don't have time to go over here because I'm starting writing this quite late.

The coupling of the troposphere and the stratosphere is at it's strongest between Winter and early Spring because the polar-night jet oscillation (something I went over last week in the model thread but isn't needed to understand everything here) is the most variable at that time.

One thing that has been overlooked a lot is that the Arctic Ocean can have effects on the SSW as the ocean-atmospheric dynamics would likely play a role because SSW's sort of begin in the troposphere as previously discussed. With climate change warming the Arctic, it's less likely that the Arctic sea ice extent can recover every year (although that could be debated but I think you'd be suffering from a recency bias as I'm pretty sure I remember people talking about decent sea ice extent in recent years but in the grand scheme of things this thesis is probably right on this topic). Although this document does go on to say, "Previous research indicates that the influence of the declining Arctic sea ice trends on the frequency of SSW events remains unclear". 

 Now we introduce the, "Coupled Model Intercomparison Project (CMIP)", which is used as a foundation for ocean-atmospheric coupling research and simulations. 

Note that a lot of this is theoretical but if the Ocean and the troposphere are truly coupled then the rest of it is very useful for understanding the impact of climate change on 'some' Winters and this difficulty in understanding coupling between the ocean and the atmosphere is why Winters are much more difficult than summer's to forecast using climate models.

SSW's occur roughly every 2 year's but with varying strength's, for example, minor SSW's can occur when the descending weakened jet cannot make it into the troposphere because it does not have enough downwards movement. The most severe events and the most in general happen in January (my and Olivia's birth month lol) but some years they have been seen as late as March. Later events are considered to be "stratospheric final warmings".

During the Winter, to make it easier to read zonal wind graph's in case anybody reading this is confused, to put it basically:

When the zonal winds are negative - Easterly jet (hence why you see the cold lovers go crazy when they see 1 little bit of negative, just kidding I feel like that'll be me this Winter though I tend to get overexcited)

When the zonal winds are positive - Westerly jet

This is typically more stable during the summer but during the Winter those pesky(or helpful) Rossby waves begin affecting the zonal winds and so it's more unstable during the Winter. It can be thought of that, there is westward momentum in the troposphere which is transported upwards mainly in the Winter and disrupts the stratospheric movement. However, this westerly angular momentum is changed and refracted. I didn't know lot about that last part and so searched up about that but could only find it about electromagnetic waves and so my best guess its that a large thermal gradient as these waves propagate into the stratosphere causes a change of speed and of direction sort of how light bends in water which makes sense because the atmosphere is best thought of as a fluid made of gas and these waves act similarly to light waves. This large thermal gradient caused by the Rossby wave vertical propagation, I did note in the PJO discussion although I don't remember going over this. A large upward flux of westerly energy is therefore not necessarily a bad thing in the context of a SSW if there is a large thermal gradient in the stratosphere as far as I can understand because that'll likely get reversed into an easterly angular momentum. This specifically is the dynamics of how the vortex decelerates.

SSW's can be of significant impact to the Northern Hemisphere over Winter and so we have to consider the area that it takes place over. Sea ice is important for balancing the energy processes because it regulates the fluctuations of heat at the surface. Unfortunately, due to climate change, the Arctic has lost a lot of it's sea ice volume and so it's unable to recover and refreeze as well as it used to be able to.  There is therefore, a heightened sensitivity in the Arctic with thermal gradients and increased forcing products. It is believed that increased warming in the Arctic especially compared to most of the rest of the world (or just the Northern Hemisphere specifically) could lead to a more amplified jet although that is theoretical.  Although the suggestions for this are difficult to tell, there is some supporting evidence such as the moisture, cloud cover, air temperature and heat flux all increasing in recent years (up to 2017 for this paper).

Using the previously mentioned Ocean-atmospheric model, there is shown to be a weak change in the amplification of the planetary waves but enough to be statistically significant suggesting westward jet amplification and also westerly angular momentum amplification in the troposphere should be possible if the surface and troposphere couple as the model shows.

The model also shows the AO more predominantly in the neutral phase with less and less Arctic sea ice which favours a SSW because the closer the AO is to negative, the more the zonal winds slow down  and the polar vortex is affected a lot easier when this happens.

However, the lower-tropospheric thermal gradient is predicted to decrease by the climate modelling and the upper-tropospheres will increase and so it's unclear the response in the circulation of the jet would be here.

Then it goes on to how it got that data and a conclusion which if you want to read, I have attached the whole document below, note that I missed out a few paragraphs in the sections when typing this up because I've already spent 2 hours doing it and I need to rest sometime as my brain is getting confused.

https://scholarworks.sjsu.edu/cgi/viewcontent.cgi?article=8344&context=etd_theses

[Chesil View]

7 hours ago, Penrith Snow said:

A lot of talk about climate change preventing a cold winter but really?

Is the Earth really that much warmer in October 2022 than it was in October 2009 or 2010?

Just saying.....

Andy

It may well be very slightly. But the real question is do the polar regions and Siberia still get very cold during winter and the answer to that is an emphatic yes. Consequently any extended period/season with sustained winds from air sourced in those regions is very likely to be well below normal temperature wise with an increased threat of snow.

[Sceptical]

Apparently Svalbard is the fastest warming place on earth. Temperatures have increased by 4c in the last 50 years.

2030 could be the next WTF moment for UK winters.

Svalbard: The race to save the fastest-warming place on Earth

WWW.BBC.CO.UK

---

Svalbard, a Norwegian archipelago, is thought to be heating at six times the global average.

 

 

Edited October 27, 2022 by Sceptical

[johncam]

5 hours ago, Chesil View said:

It may well be very slightly. But the real question is do the polar regions and Siberia still get very cold during winter and the answer to that is an emphatic yes. Consequently any extended period/season with sustained winds from air sourced in those regions is very likely to be well below normal temperature wise with an increased threat of snow.

Think we are now struggling to get  really cold from the north as the sea is a lot warmer and sea ice in the European sector of the Arctic is a lot less than it has been in the past 

[Alexis]

Didn't the Arctic see an extremely cold winter last year? Not the first time as the cold keeps being bottled up and failing to descend to lower altitudes as often.

Obviously still seeing extreme warming in summer which lowers overall sea ice.

[northwestsnow]

Subtle hints of change  in the outer reaches of 00z NWP..

Along the lines of recent EC 46 runs..

Hoping EC 46 continues in its drying out/cooling down suggestion...

[Uncertainty]

CFS continues with the blocking N of the U.K. for December

I think in this case the precipitation anomaly is even more informative than the heights! 
 

Here they are for reference 

 

It’s an unusually consistent signal. 

 

[Sunny76]

18 hours ago, Atleastitwillbemild said:

I was kidding about the relocate. I don't think Svalbard has that many cut price bedsits for a minimum wage dog like me. I couldn't even move up the road right now. But I tell you what if they needed a pot washer or waiter in the restaurant of some of those tacky Lapland Christmas cringe fests I'm ready to move and slap on the marigolds. 

Lol.

[phil nw.]

What won't change is the occurrence and length of the Polar night so cold pooling will continue in Winter at high latitudes.

The problem for us and other mid latitude regions is the increasing warming of the oceans nearby causing more modification of any cold heading south.

Add this to the Arctic source of cold being compromised by climate change then it does become increasingly difficult to see notable cold spells in the UK I am afraid.

Our best chance is Russian/Siberian sourced cold as land masses will hold and build cold pooling much easier under the right conditions.

Let's hope for one of those increasingly rare North easterly/easterly patterns from northern blocking.

[damianslaw]

Late Feb 18 does prove extreme cold can make it to the UK still in the right circumstances.. yes that was strat induced.. had such synoptics occured a month earlier we could have seen record breaking cold. Alas 1 March did bring date records.

Feb 21 produced a low of -22 or -23 in Highlands in less than cold synoptic.

Extreme Cold will happen when the synoptics allow. Its not gone away, it just getting the synoptics.

[Sceptical]

1 hour ago, damianslaw said:

Late Feb 18 does prove extreme cold can make it to the UK still in the right circumstances.. yes that was strat induced.. had such synoptics occured a month earlier we could have seen record breaking cold. Alas 1 March did bring date records.

Feb 21 produced a low of -22 or -23 in Highlands in less than cold synoptic.

Extreme Cold will happen when the synoptics allow. Its not gone away, it just getting the synoptics.

January 21 was also a bit snowy in NE Scotland.

Edited October 27, 2022 by Sceptical

[Sunny76]

1 hour ago, damianslaw said:

Late Feb 18 does prove extreme cold can make it to the UK still in the right circumstances.. yes that was strat induced.. had such synoptics occured a month earlier we could have seen record breaking cold. Alas 1 March did bring date records.

Feb 21 produced a low of -22 or -23 in Highlands in less than cold synoptic.

Extreme Cold will happen when the synoptics allow. Its not gone away, it just getting the synoptics.

Yes, and I feel we need to be careful what we wish for this coming winter.

1 week of below 0c with snow, will possibly tip the country into a desperate situation. 

[northwestsnow]

Exeter sticking with colder and drier mid month with bits of rain in the south.

That's- NAO so clearly the signal is maintained ..

Going to be strange watching the world cup with Fog and frost outside the window !!

[Cheshire Freeze]

3 hours ago, Uncertainy said:

CFS continues with the blocking N of the U.K. for December

I think in this case the precipitation anomaly is even more informative than the heights! 
 

Here they are for reference 

 

It’s an unusually consistent signal. 

 

Shift that anomaly N and we’re in business. Looking at how it is, it seems to be suggestive of a UK inversion high.

[cheeky_monkey]

10 hours ago, Sceptical said:

Apparently Svalbard is the fastest warming place on earth. Temperatures have increased by 4c in the last 50 years.

2030 could be the next WTF moment for UK winters.

Svalbard: The race to save the fastest-warming place on Earth

WWW.BBC.CO.UK

---

Svalbard, a Norwegian archipelago, is thought to be heating at six times the global average.

 

 

its warming faster than average simply because ..

It’s only possible because of the deceptive use of the word “average.” The average referred to is the average temperature of the entire planet. The story is not that any country is warming twice as fast as the average of every other country. Rather, it is that the country in the story is warming faster than the average temperature of the entire planet. But the entire planet is not just the land countries are on, it is the land and the oceans. And, as we all learned in school, the Earth’s surface is only 30% land and 70% ocean.

According to NASA, (the US National Aeronautics and Space Administration) from 1881 to the present the ocean surface has warmed about 0.6 C but the land surface has warmed about 1.8 C.  The large ocean surface warms much more slowly than the smaller land surface.

Using the 30/70 distribution of the Earth surface, that implies combined warming of 0.3 x 1.8 + 0.7 x 0.6 = 1.0 C.

Thus, if every country warmed at exactly the same rate, every country would be warming at 1.8 times the global average. But they don’t all warm at quite the same rate. The tropics warm less quickly than the higher latitude regions: NASA Latitude Bands. With that adjustment for latitude, any country outside the tropics will warm approximately twice as fast or more as the (land and ocean) average of the entire planet.

[damianslaw]

1 hour ago, CreweCold said:

Shift that anomaly at howN and we’re in business. Looking at how it is, it seems to be suggestive of a UK inversion high.

 

[Skullzrulerz]

I really hope that we do get a cold and snowy winter, it's been quite a few that I have experienced a decent snowfall here in the far south west.

Sadly, thanks to climate change snow is going to become a increasing rarity here, of course they will be extreme events that would produce snowfall.

Hopefully fingers crossed we might get some snowfall no matters the odds.

[BLAST FROM THE PAST]

22 hours ago, Don said:

I agree that whilst you shouldn't by any means write off the following season a month before it starts, given the year we've had so far with every month above average, a hot summer with 40C breached all the way up to the north Midlands and an exceptionally warm autumn so far, bar the second half of September, you cannot blame folk for getting a little twitchy about cold prospects for this upcoming winter season.

I’m not convinced of this 40c breach, uhi and positioning of weather stations have compromised it eg in uhi hot spots.  For sure it was hot, but for example Charlwood in Surrey wasn’t the 1st 40c….it was 37.5c…that ‘disappeared’.   The summer overall was of similar ilk to past greats.

1984 had ridiculously mild and wet October and VERY mild November

 

BFTP

[Premiere Neige]

9 minutes ago, BLAST FROM THE PAST said:

I’m not convinced of this 40c breach, uhi and positioning of weather stations have compromised it eg in uhi hot spots.  For sure it was hot, but for example Charlwood in Surrey wasn’t the 1st 40c….it was 37.5c…that ‘disappeared’.   The summer overall was of similar ilk to past greats.

1984 had ridiculously mild and wet October and VERY mild November

 

BFTP

But we were in the cold phase of the AMO at that point. Am I correct in thinking that there were a lot of cold shots from the North West during that winter which would have been aided by the colder Atlantic? Or have I got that wrong? I know it was one of the early to mid 80's winters.

[Methuselah]

41 minutes ago, BLAST FROM THE PAST said:

I’m not convinced of this 40c breach, uhi and positioning of weather stations have compromised it eg in uhi hot spots.  For sure it was hot, but for example Charlwood in Surrey wasn’t the 1st 40c….it was 37.5c…that ‘disappeared’.   The summer overall was of similar ilk to past greats.

1984 had ridiculously mild and wet October and VERY mild November

 

BFTP

Just how much of a UHI effect can there be -- in Lincolnshire, Fred?