I hope today has once and for all dispelled the misbelief that cold air can be ‘hard to shift’. I’ve even read that models somehow find it ‘difficult’ to account for entrenched cold air. That might of been true in the 80s but not now.
The outlook continues to be one where the new a la mode of significant heights across Iberia and points east will prevent Arctic incursions, or at least any lasting ones. We might sneak a day or two out of the next few weeks, but it’s generally a set up with a flow between SW and NW until the end of the year - as it stands.

Originally Posted by: nsrobins 

1) I hope today has once and for all dispelled the misbelief that cold air can be ‘hard to shift’. I’ve even read that models somehow find it ‘difficult’ to account for entrenched cold air. That might of been true in the 80s but not now.

2) The outlook continues to be one where the new a la mode of significant heights across Iberia and points east will prevent Arctic incursions, or at least any lasting ones. We might sneak a day or two out of the next few weeks, but it’s generally a set up with a flow between SW and NW until the end of the year - as it stands.

Originally Posted by: nsrobins 

1) Completely agree. It's one of many annoying things which get passed off as fact on weather forums by people who just regurgitate what they have previously read

2) Don't really agree with this. There seems to be a reasonable signal for cold/ish conditions in much of the UK (including the south) between Xmas and the New Year, but it could be from a mid latitude high pressure rather than cold uppers

Originally Posted by: Brian Gaze 

Most would take the 06z control run for Christmas! 

Originally Posted by: squish 

I hope today has once and for all dispelled the misbelief that cold air can be ‘hard to shift’. I’ve even read that models somehow find it ‘difficult’ to account for entrenched cold air. That might of been true in the 80s but not now.
The outlook continues to be one where the new a la mode of significant heights across Iberia and points east will prevent Arctic incursions, or at least any lasting ones. We might sneak a day or two out of the next few weeks, but it’s generally a set up with a flow between SW and NW until the end of the year - as it stands.

Originally Posted by: nsrobins 

I don’t think that’s entirely fair.  It has always depended on the ‘angle of attack’: a strong surge of mild air from between south and north-west has always been capable of displacing ‘entrenched cold’. But there are occasions when the push has less momentum and it is in those situations that the mild air can override the cold at the surface.  This never looked like one of those occasions: it was always modelled as a ‘snow to rain’ event, with the tunes being played around the mix/balance between the two.

Originally Posted by: Gandalf The White 

I can't paste the image from the GEFS data tables but the link for London is below.

https://www.theweatheroutlook.com/premium/gefs-tables.aspx?run=00&fv=tmp2max&loc=london&lat=51.5&lon=0&p=&cty= 

The GEFS 00z suggests max temps of between 1C and 5C on the London grid point as the most likely outcome from 26/12 to 30/12. On 27/12 74% go for this and on 28/12 71%.

Originally Posted by: Brian Gaze 

Most would take the 06z control run for Christmas! 

Originally Posted by: squish 

The one with the 11 C and 55 mph SW gusts on the day itself for my neck of the woods? I must be not in the "most" category.  🤣

Originally Posted by: idj20 

Somewhat connected to this discussion, if you have a bit of time the Met Office have a really good fact sheet (36 pages with graphics and explanations) on different air masses and weather fronts. Well worth a read: https://www.metoffice.gov.uk/binaries/content/assets/metofficegovuk/pdf/research/library-and-archive/library/publications/factsheets/factsheet_10-air-masses-and-weather-fronts.pdf 

Originally Posted by: doctormog 

FWIW, the ECM EPS show a cold picture too from the 27th-30th:

https://charts.ecmwf.int/products/opencharts_meteogram?base_time=202212180000&epsgram=classical_15d&lat=51.5084&lon=-0.125533&station_name=London 

As for the "cold air is hard to shift" trope, it is true to a limited extent. Today, for example, it's still only 2.1C here (with cold drizzle), despite several hours' worth of Atlantic onslaught. The reason is that ahead of the front the cold drains from the Continent; it was well below zero all morning in northern France and the dregs of that air get dragged across the Channel. It's only a shallow cold layer, but if it was one of those all-too-rare cases of a low approaching, then being deflected, it'd have been enough to maintain the cold.

It'll only be later this evening that the mild stuff really arrives in earnest. It's already there aloft, of course (hence the rain), but the cold wedge of air near the surface does indeed take some shifting... at least in the SE!


 

Originally Posted by: Retron 

That's the op. The control is much more pleasant! 😊

https://www.meteociel.fr/modeles/gefs_cartes.php?code=0&ech=174&mode=0&carte=0&ext=0 

Originally Posted by: Retron 

 ...

As for the "cold air is hard to shift" trope, it is true to a limited extent. Today, for example, it's still only 2.1C here (with cold drizzle), despite several hours' worth of Atlantic onslaught. The reason is that ahead of the front the cold drains from the Continent; it was well below zero all morning in northern France and the dregs of that air get dragged across the Channel. It's only a shallow cold layer, but if it was one of those all-too-rare cases of a low approaching, then being deflected, it'd have been enough to maintain the cold.

It'll only be later this evening that the mild stuff really arrives in earnest. It's already there aloft, of course (hence the rain), but the cold wedge of air near the surface does indeed take some shifting... at least in the SE!


 

Originally Posted by: Retron 

Hopefully the euro high is being modelled to be too dominant which is possible and the op run can change the mood today.

Originally Posted by: ballamar