On balance I'd say maybe a step away from colder uppers in the mid term to long term - most likely outcome being still chilly and largely settled but without being cold enough for snow most of the time. 

The positive if you're after cold is *if* the pattern does persist, the chances of a cold pool heading our way increase, even if the charts don't initially show that but the size of the *if* is relevant and it's usually rather large. 

So glass half full, likely to be a spell of below average weather, feeling cold/raw for many with a lower possibility of something cold enough to be more interesting if the pattern persists and things fall our way.

Anyway - my point is that it's a continuing trend now in the models....

If you are hinting at an SSW, there is very little indication of that happening in the current model output:

https://charts.ecmwf.int/products/extended-zonal-mean-zonal-wind?area=nh&base_time=202501310000 

Yes I did see that but what we are seeing in the shorter GFS range is that there is consistent signs of an SSW appearing each run.

10hPa zonal wind reversal at 60°N. Got a link?

Yep, being talked about on SM a lot

https://x.com/thesnowdreamer/status/1885409177939374566?s=46 

Think there is a slight confusion in his terms! SSW to him doesn’t mean reversal as far as I can see

I have checked and there is little evidence to support a SSW irrespective of where the polar vortex is located. The animation shows the ECM 10hPa temperatures, tying in with the disruption of the polar vortex, the 10hPa wind flow at 60°N doesn’t come anywhere near reversal, as is shown in the link I posted.

An SSW has a specific technical definition and there is no clear sign that one is likely. It does not mean that one will not occur but it is not being shown in the model output except in the smallest minority of the ensemble data. 

Yes, you’re absolutely right. An SSW is not the same as a displacement in the polar vortex nor is it simply an increase the temperature in one part of the stratosphere (although that of course plays part of the overall picture). Having said all that, even if a major SSW does occur it doesn’t inevitably lead to a wintry outbreak here anyway.

There’s clearly some warming in the model output but it falls far short of the definition of ‘Sudden Stratospheric Warming’, which is generally used to describe a very sharp increase in temperature of up to typically around 50c over a couple of days.  It’s that sudden ‘jolt’ that is associated with a wind reversal and then sometimes propagates down into the troposphere.   What we’re seeing now is just the run-of-the-mill slight warming over Asia that happens every winter.

But there is some evidence in the GFS run of the PV being split.  

Well recent runs show temps at 10hpa over N Pole go from -75c to -20c which is an increase of +55c and it splits the PV. So it's showing an SSW.

I’m not going to labour the point but (a) it doesn’t show that much warming and (b) it’s not within 48 hours.

Indeed, and it is also not preceded by a reversal in zonal winds at 10 hPa.

There is a very low chance that if the high orientates in such a way that a more easterly (rather than southerly/southeasterly) flow develops, a spell of much colder conditions could develop across the UK.

Updated: 14:00 (UTC) on Sat 1 Feb 2025

Yes the fact it's on the table is a positive

That’s interesting because I had assumed that the SSW was the catalyst for the wind reversal, not the other way round.  Simplistically I likened it to the SSW creating something akin to a high pressure cell, with the wind rotating clockwise.

Which is presumably why yesterday you were labelling it a ‘Scandal High’….  This inkling seems very sudden?

The dynamics, from what I have read, seem quite complicated but it appears the zonal winds decrease begins prior to the warning. I’m not totally sure that the reversal necessarily completes before the warming becomes evident. There are quite a few academic papers that discuss the events and this one  has some detailed consideration, although the teleconnections thing has never been my strong point!

It's confusing because the SSW we had in 2018 occurred between 8th and 13th February which is 5 days not 48hrs but was still considered an SSW. So Gandalf...what would this be considered as if this was to come off as 06z  suggests? Because the PV does split. So what is it? Just a SW? Minor warming?

It may reach the threshold for a minor warming.

There is not yet any great consensus on a major cold outbreak , but the building blocks are there …and the possibility has creeped into the UKMO forecasts …just as the cold slowly begins to creep westwards across the continent .