Cold Winter Night

Thanks. If anything shows the effect of the SSW, it is this. Not the amplified pattern, the Greenland High, or an Easterly from Russia to Canada. The models are losing their grip on the situation. We are only just getting started with the effects of the SSW. The current amplified pattern that is shown in the output is not necessarily the result of the SSW, even if it is consistent with it. So if there is a High Latitude Block (HLB) in the output, there is no way anyone can say with certainty that it was the result of the SSW. Nature doesn't do labelling for the convenience of scientists. We have not seen, as it sometimes happens, a sudden switch from a tight zonal pattern to an amplified pattern that was obviously the result of the SSW. This season we already were in an amplified pattern beforehand. Any further amplified/blocked patterns we get to see in the output (or perhaps the lack thereof) can only be ascribed to the SSW with terms like: 'possibly', 'likely', 'consistent with' etc. So everyone be careful with those oneliners accompanied by charts, "SSW clearly shows its hand"/"Rubbish SSW, did not work in our favour". We barely passed the 10 day mark after the SSW, the effects are going to be trickling in slowly, in a waxing and waning manner, over the next few weeks, or even months. The article that @sebastiaan1973 shared in this thread several times claims that an SSW of the European blocking type has its strongest influence after about 35 days, so that would take us to the middle of February. Now that does not say anything about cold in our part of the world, but it does say something about the reliability of, for example, ensemble means in deep FI. They might very well be the last ones to pick it up if something changes. The real setup of patterns might very well sit outside the current spread.

Wasn't the story when the SSW happened that a quick tropical response would take us to the 20th as landing date, but that it's usually a slower process, like 3-6 weeks? If we say: "Don't look beyond +144h", that means even the quickest QTR would only just be visible in the reliable timeframe today, let alone the slower response. I'm not saying that we will see Narnia on the charts tomorrow, but maybe we should wait just a little longer with conclusions about the SSW.

If the UKMO model itself doesn't decipher the way ahead from there (except that hidden 168h), then why should you? There is a reason why UKMO only runs up to 168h (up to 144 visible for us) and EC High res Op only to 240. This afternoon the runs so far don't show any unexpected changes. Take a breath and take the advice of many experienced members on here and stop looking further ahead for a while. Unless you consider it as what it is: Just for fun, grown up people watching bright colours moving around every 6 hours

ECM had something similar at 240h two days ago. In that massive, deep low all sorts of smaller features pop up and together they can create a High. With a little more CAA the formation of a proper Scandi High is not unheard of. I think that is what makes this setup still fascinating. There is the large scale setup, which most of us hope will put Greenland Highs and Arctic Highs in the best location for cold coming our way, but on the smaller scale there can be interesting developments too, that might have large repercussions for us.

Comparing today's EC 12Z with yesterday's 12Z, it's fairly similar up to today's 120h, but from that point on seemingly small differences lead to considerable differences at 240h. So 144h is FI already. The Arctic and Russia, the Atlantic and North America, all very different. No changes in the big picture though. I doubt if the ensembles will be much of a help at the later timeframes in this situation. They will probably pick up the correct solution even later than the high res operational. For example, I was just looking at the De Bilt plume that came out January 9. I saved it for future reference, because it was the coldest yet. See below. Just five days later the whole thing is different, compare the two for next Wednesday, the 20th. On Saturday, almost all members stayed below 5C, this morning's ensemble is almost entirely above 5C. Not even one member was as warm as what is now the mean for that day. Ensembles flip. They really do. So do not despair coldies, that deep cold that is not in any ensemble, might become reality once day 14 arrives. Or not!

Curious about this, I ran it through NOAA's HYSPLIT model for a central UK location (using the available GFS 6Z output) and found this: On Thursday the 21st: - Air at 10m agl would come from Taimyr Russia, through Greenland and Iceland. - Air at 500m agl would come from the central Atlantic looping through the Norwegian Sea. - Air at 1500m agl would come from Labrador, doing that same looping. On Friday the 22nd: - Air at 10m agl would come from Taimyr Russia, through the Barents Sea. - Air at 500m agl would come all the way from the Bering Street, doing a tour along the Russian Arctic coastline and the Barents Sea. - Air at 1500m agl would come from Ireland, moving through Greenland and back.

Not much change in the output this morning. I stick to my reasoning that the roots of a good Greenland High should 'grow' in a location nearer to North/Northwestern Europe first. We have seen the crazy swings that were expected as a result of the SSW and I can imagine that going on for a while, especially since the changes higher up are still an ongoing event. Is there still hope for coldies? I would say yes. - The NH troposphere is still in a meridional state, models don't have it nailed yet. - The Arctic High is traditionally poorly modelled and observed, note that the models are struggling with it. Significant changes in its shape and location can still result in significant changes in our weather. - The SSW effects are still a wildcard. - As noted above, the MJO isn't helping now, but later on? So all in all, temperatures are average or just below average, and I estimate the chances of that continuing higher than the chances of us staring down the barrel of endless mild SWlies. And then there are those two EPS members that surely got it right in De Bilt

EC doesn't want to play with the other models. Same issue as yesterday and this morning. The low over Newfoundland is more reluctant to move East, therefore WAA happens too far West, setting up the High too far West. UKMO and GFS were just far enough East.

Perhaps a small cluster that closely follows the Op, but there's a whole bunch of them that have the High more East than earlier today, so I'would say this is definitely in line with these 12Z upgrades. The models must have eaten some good data today. Hopefully the ECM and its EPS shared that meal.

The changes that led to this did not happen post day 10 though. At +120h already you see how the low over Newfoundland undercuts the Atlantic heights, forcing WAA to occur more to the East. UKMO did something kind of similar, although the undercut is stronger there. And about downgrades: I'd rather have a 1947 spell modelled at 240h that gets watered down to a 2021 version, than a 2021 version at 240h downgraded to a 2020 version...

Not a single perturbation on the GEFS at that timeframe was as good as this one. Pleasantly surprised about both GFS and UKMO.

Much better. This is something we can work with. High sets up more to the East, closer to the Arctic High as well.

UKMO interesting. Changes all around. Different angle to the High, that is getting undercut from the West.

That same page also shows the wind directions. The control is indeed mostly SW (225 degr), as is the majority of members. Just a handful that goes NE (45 degr), those must be the same ones that still show a minor grouping of ice days in De Bilt later on.

The interesting thing about the output the last few days is that the short term has not been worked out properly yet. Models are underestimating the heights to our East in the earlier timeframe (48-96h), which could still throw up surprising developments. I think that is what @carinthian has been hinting at too. Keeping an eye on that, what seems to happen to our West in the 120-240h timeframe has changed compared to two days ago. Most have now woken up to this particular Greenland High scenario probably not working in our favour. The High, as in the output today (and tbf yesterday) simply does not develop in the right place for us, whether it's an official West based -NAO or not. Not all Greenland Highs are a guarantee for a winterfest. The EC at +120h below illustrates what I mean. WAA (Warm Air Advection) comes out of Newfoundland, directed at West Greenland. In my opinion, we need WAA for a proper Greenland High (that does deliver the goods) to be more or less East of the black line. I have looked at the development of many decent or legendary cold spells, and so far I haven't seen any that started with WAA in the Newfoundland area. Some were reinforced from there later on, yes, but it was not the starting point. If anyone knows of historic cold episodes that did start this way, please let me know. In the second picture, I have drawn where, as I see it, the High pressure should ideally originate (and where not). 1. A UK/East Atlantic/Western European High. Retrogresses towards Greenland. Classic example: Nov 2010 2. A Scandi High, retrogressing to Greenland. Developed in situ, or split off of a Eastern European or Russian High. Classic examples: Jan 1947, Dec 1962 3. An Arctic High extending Soutwest, retrogressing through Scandinavia towards Greenland. Usually assisting no's 1 and 2. I can see this one, combined with no.2, happening in late January and into February. Look at that area in the output the coming days and weeks. Perhaps delayed SSW influences and MJO effects could help us here. As of now, the extended output shows this to some extent, but not convincingly yet. 4. A West Greenland High, as we see in this morning's output. Too far West for us, tendency to retrogress to Ellesmere Island, seeking to connect to Pacific Highs.

Glad to see that GFS 18Z showed improvements right in the areas of concern. GEFS P7 at 240h shows why some of us are cautious about the location of the Greenland High. More Westerlies at 240, and a small ridge in Eastern Europe thrown up, blocking Russian cold. GFS Op at 240h has the far better solution, with better heights to the East of Greenland and immediately you see a better flow of cold through Scandinavia and more fuel for the Greenland High to become a sustained feature afterwards.

Haha, and I would absolutely love to see February 86 or 56 repeated one day! I love snow and photography of white landscapes, but I also love that bone chilling cold and skating on 'singing' deep black ice. Right now the output has the promise of at least some snow for many, so that's good, and for now you won't have to worry about Feb 86 weather just yet! (But who knows in February... ). This is exactly why everyone should keep in mind that there are a lot of people on here, spread out over many places, with a lot of personal preferences. What is a dream chart to one, is a sub par to another. And next week it'll all be reversed.

Couldn't have said it better. We should not expect too much from the initial Greenland High, but the later stage EC-Op and the ensembles show developments to our Northeast that have way more 'potential' (hate that word though). I still think a serious cold spell is possible late January into February.

Well, that's the thing, I don't think that the pattern as shown now is very good. It pleases the eyes, with yellows in Greenland, but the location and size is not good for us. It takes more than a few tweaks to get it right. The cold is sent Southwest too far to the West. Not just in this ECM run, but actually all models and ensembles support this. ATM I don't expect it to be corrected much to the East. (I hope so I'm wrong about that!) Don't get me wrong, this pattern will result in below average temperatures and falling snow, but will that snow last during the day? Will this spell be longer than a few days? With this setup I doubt it, and I just think that's such a pity with a troposhere messed up like it is now.

ECM Conclusion: Pattern too far West. I fully agree with @sebastiaan1973 and @Mike Poole. I see some calling boom on +168, but the 850hPa Temp chart (below) shows where the cold is going: spilling out towards Iceland. So Iceland is where you need to be, or a ship on the North Atlantic. Southern half of the UK is probably not going to be happy with this setup. The real interest at the moment IMO, apart from the next few days, is the movement of the Arctic High, moving towards Russia, extending towards Nova Zembla and possibly Scandinavia, visible at +240h.

We're not looking at a true Easterly though. Not often an air mass this cold moves from the Barents Sea along the Norwegian coast towards the UK. Norwegian Sea and North Sea will always be relatively warm, due to the Warm Gulf Stream. Only after a longer cold period will the North Sea truly cool down, the Norwegian Sea will barely respond to seasonal influences at all. A classic Easterly takes air over the Ural, Baltic Area, Poland or Scandinavia (mostly over land) towards the UK. It might move over the Baltic Sea, which is cooler anyway, and it has a shorter trip across the North Sea.

The very cold upper air on the move over the relatively warm waters of the Norwegian sea generates lows. I think @Singularity mentioned this too, earlier today, only about lows in the Atlantic.

GFS +192h takes the Greenland High and therefore the cold West, mainly to the Atlantic, as per previous concerns. The development of the Arctic High, near Svalbard is encouraging though. Fits in with some clusters on EPS, bringer deeper cold, but later.

From a coldie's perspective there is much reason to remain cautious today, but just as much reason for hope in the longer term. The negative IMO is still what I feared yesterday, a Greenland High that sits too far North and West for most of us to profit optimally. Others have mentioned this too this morning. In these situations we probably should do well to check an excited poster's location first, because it may well come down to a North vs South split. Although more movement of the West Greenland High towards Ellesmere Island could even make the North miss out on the deepest cold. The problem is that the best Greenland Highs have their origins in a High either over the UK (Jan 1947 style) or over Scandinavia (Nov 2010 style). Retrogression then moves the core of the heights towards Iceland and Greenland. This succession pulls in the deep cold from Russia, across the Baltic or Poland towards the Low Countries and ultimately the UK. The GH we see in the output around +200 now originates in the Labrador/West Atlantic area. The High goes up towards Greenland, but the following retrogression moves it towards Baffin/Ellesmere Island in the Canadian Arctic, leaving room for the jet to move back North, towards us, where we don't want it. Also, the early Scandi High option I mentioned yesterday does not seem to develop further, so I'm ready to dismiss that after the 12Z's. The positives are still there though. Models are still jumping around like crazy so nothing is set in stone at all. Some GEFS members have the Greenland High extending a bit more East, the GFS Op too, so I'd like to see more of that. The EC surprised me at +240h with more cold moving through the Baltic, couresy of a surface high over Nova Zembla, see the circled area in the image. EPS also shows clusters post +240h that extend the Arctic High into the Eastern Hemisphere. In these circumstances, a surface High can develop and become a stronger feature later on. Those are options that might come on the table once the cold pool moves our way, even if the Greenland High is too far NW for direct impact, so that is a big positive for me, definitely something to watch out for in the coming days.

Indeed, it does. In Yorkshire, where you live. I live in Holland, in the 0-4C zone. Now, let me be clear, I am so winter starved that I'd rather take puddles of melting snow at 4C than get stuck in the 12C of last January. But the 30 yr average for January 21st here is about 5C at that time of the day, so having 0-4C in the heart of the Arctic attack is worthy of a sad face IMO. Continental Europe is at or above average in that chart. Good cold spells (2009, 2010, 2012, 2013, 2017, 2018 the most recent ones) bring ice days here, so that's my standard: No ice days = No cold spell. Anyway, soon a new round of model runs will come out, changing everything again, so who knows what improvements we will still see. Even this week is getting better (possibly even that ice day, says EPS!), so all hope is far from lost!