Stratosphere Watch 2025-2026

bazlers

As the Stratosphere is in the toaster at such an early phase of winter/autumn (which is quiet unique) i think it dserves its own thread. Another personal opinión but the teleconnections overall are some of the best I have ever seen. Infact Carbsberg could not do better. Wheather this actually projects at ground level is another thing and it all could dissipate like a fart in the night.

bazlers

Sorry, just another thing to note and this is also quiet rare is the weakening is from the very top right to the very bottom of the sPV.

Sryanbreun I am sure will comment soon although we have all been bitten way too many times so may leave it awhile.

I for one unfortunately have jumped on the rollercoaster and am all in! May come to nothing but there is alot of cold building out north east if we do strike it lucky.

Kaybaykwah

The stratosphere hates it when sumbdy misspells it.

bazlers

Well we better not upset it or it may not respond as we wish!

mcriot29

no chance it effects us due to high solar output overpowering the trade winds and the Atlantics mild power

ClimateObserver

Interesting…

www.twitter.com/BenNollWeather/status/1991136881837478343?s=20

https://www.boards.ie/discussion/comment/124000944#Comment_124000944

Cue everyone saying cold air into North America will fire up the jetstream 😅

Gonzo

https://www.boards.ie/discussion/comment/124001347#Comment_124001347

that's the bit that worries me, same every year! It would be just our luck to have every ingredient in the right place at the right time and still we could end up with mild Atlantic muck or sitting pretty in no man's land! Let's see what happens, at least we have some interesting model watching for the start of winter.

esposito

https://www.boards.ie/discussion/comment/124001347#Comment_124001347

It’s about darn time that we got the rub of the green and not the U.S.

Does anyone know if a major sudden stratospheric warming could lead to a split of the polar vortex rather than a displacement? Because as we know, splits are much better for cold prospects i.e Feb 2018

bazlers

Okay, so a little bit of a punch to below the waiste line. Slight down grade to the forecast of longevity of zonal winds. A blocked pattern is still form horse heading into December but do not want this trend to continue. ( as he thinks he should have never started this fuc#en thread in the first place) See what tomorrow brings!

esposito

Wise words ⬇️ It’s about the trend. And the trend is good for the SSW.

Besides, we don’t need a SSW to bring us cold weather. There are many other drivers in the troposphere that can deliver this as some posters have spoken about.

Ros4Sam24

Not great signs for longevity but a weakening of the SPV for the next few weeks should give us a decent chance from about week 2 of December. With the MJO going into favourable phases it’s game on but with current NWP modelling it could be a slog..

bazlers

https://www.boards.ie/discussion/comment/124004739#Comment_124004739

I will give it another few days but I think I saw this movie many times before...

sryanbruen

Important to remain calm and sensible whether it's getting hyped/excited for potential cold or alternatively throwing toys out of the pram. I've been waiting a couple of days to comment to get more of a clearer idea on what is likely to happen. This is my best judgement based on the modelling of recent days:

1 ) A sudden stratospheric warming (SSW) event will be occurring in the final few days of November. This will be driven by equal record wave-1 patterns for the time of year to give the possibility of a very rare November major SSW (when the zonal mean zonal winds at 60N 10hPa reverse from westerly to easterly) which would be the first of its kind since 1968. It will be close and temporary if it does occur as zonal mean zonal winds will swiftly recover thereafter. This is quite normal to do so but it's looking like the recovery will be quite dramatic due to wave reflection whereby the same waves that caused the SSW will "flush down" the strong SPV waves is the simplest way I can explain it.

This event will likely displace the stratospheric polar vortex (SPV) to Greenland and Canada with a build of pressure to the east. What this means for our weather in Ireland is we could possibly see a very mild start to December with exceptional mild air wafting up from the southwest. Whether it would be a cyclonic or anticyclonic kind of mild is unknown as there's no way of telling how close low pressure systems would end up to Ireland. Of course we are no stranger to very mild winter weather in Ireland.

2 ) The same pattern that follows on from the initial late November 2025 SSW, aided by tropical drivers, has the possibility of driving further stratospheric warming events in early to mid-December as more blocking gets going around the Urals. This in theory could give the chance to splitting the polar vortex down the line. The latest GFS 06z shows a split of the tropospheric polar vortex towards the end of its run with one lobe of the vortex over Canada and the other towards the Urals with blocking high pressure trying to develop inbetween. If you're seeking cold and snowy weather, ideally you'd see the anticyclonic blocking inflate to fend off the Canadian vortex which would be developing low pressure systems and feeding in on the North Atlantic jet stream but it could be worse. This seems too quick for an evolution like this but as the model shows it, it's a theoretical possibility.

If you're expecting cold weather any time soon after today, I'd hold back and keep watch on the hemispheric charts. The Nov SSW is more likely than not to be a negative for cold weather due to wave reflection as described and would be relying on a secondary warming in December or other drivers to help bring high pressure blocking to northern Europe which would in turn increase the risk of cold conditions.

Video from the Met Office on how it might play out, well worth a watch

https://www.youtube.com/watch?v=KweNLXCdaqI