Stratosphere watch 2022-23

sryanbruen

https://www.boards.ie/discussion/comment/120193185#Comment_120193185

Whilst I usually say CFS is Can't Forecast System or Complete Failure System, I can't say I disagree with what you describe here for what it shows. Although we got a cold, blocked April and a cold, wet May in 2021, we have not had a genuine cold early spring since 2018 (March 2020 was a bit chilly for some). We've had a good run of Marches as far as fine March weather is concerned, especially last year. I hope I am very wrong with my feeling - not scientific at all of course - that we'll get a cold spring unless it guarantees a stunning summer to follow like 2013.

sryanbruen

This evening's EC46 has brought forward the deceleration but again no reversal indicated by the ensemble mean. Interesting how much it keeps significantly under the average for a prolonged period of time though. More time and more runs needed. Talking like 2 weeks away after all for any shot of this. Health warnings and all that.

nacho libre

It will be interesting to see if there are any changes to the UKMO long range for the end of February to Early March within the next week. If we see a change stating that colder conditions are more likely, then we will know Glosea forsees something interesting happening in the strat with a good result for us.

sryanbruen

The saga continues on the GFS today, no backtracking this morning. Reversal starts on 13th and still goes on to the end on the 19th.

A significant cluster of the GEFS 0z reversing again.

sryanbruen

No changes, looks like a major displacement will occur next week. This evening's EC46 a big "upgrade" on the reversal.

Keithchap

https://www.severe-weather.eu/global-weather/sudden-stratospheric-warming-polar-vortex-collapse-effect-forecast-february-march-united-states-europe-fa/

This popped up in my news feed today, I thought it might be worth sharing as it explains it quite well for people not that familiar with the topic, like me.

Larbre34

UK Met have a good SSW explainer on their SM. Makes clear that an incident of one doesn't always influence NW Europe weather and that at the moment, a neutral temperature profile is indicated, ie close to seasonal norms.

thejuggler

The independent seems to think Beast from the East 2 is imminent.

‘Beast from the East 2’ a possibility later this month as Sudden Stratospheric Warming event looms

https://www.independent.ie/weather/beast-from-the-east-2-a-possibility-later-this-month-as-sudden-stratospheric-warming-event-looms-42335708.html

sryanbruen

https://www.boards.ie/discussion/comment/120222816#Comment_120222816

Don't be posting this nonsense on the thread please.

pauldry

Nonsense indeed.

Not really sure what SSW is but it is happening.

Is it a split in the Polar Vortex displacing the cold South. I told my wife its something like this but the cold can get displaced to any country.

Looking at Models a lot of the cold gets shifted to Greenland and North America while we stay average.

So initially this SSW event seems to bring cold to Greenland Canada and the Northern States. Then later in February or March our weather may get cold but this strong high pressure near or over us could just bring frost.

What I have observed is the JAXA in the Arctic has begun to decrease but this may be the strong Southerlies over the Barents more than anything else.

Packrat

Is there then no chance at all that there's any truth in the Indo article and it's totally made up bs?

(For those of us who aren't meteorologists and don't understand all the lingo)

Sorry if non-boffins aren't allowed post in this thread, I came to the forum to see if there was any better analysis of what they're saying might happen.

sryanbruen

https://www.boards.ie/discussion/comment/120223712#Comment_120223712

Please refer to the FI charts thread. The "Beast from the East" part of it is totally made up bs and goes without saying.

Wait for the major SSW event to happen first of all, it's to begin Wednesday next week according to the latest GFS model run. Any effects from that directly wouldn't be 'til at least 2-4 weeks away when we reach the start of March.

Larbre34

https://www.boards.ie/discussion/comment/120223712#Comment_120223712

Its a possible outcome, but a low one. Maybe 10%.

Most SSWs either don't affect or only marginally effect the dominant weather pattern in this part of the World.

Put it this way, how many Emma/Beast situations can you recall in your lifetime?

Exactly.

They are called 1 in 100 year events for a reason.

Kermit.de.frog

There will almost certainly be an ejection of seriously cold air from the pole but where is the question.

Gonzo

https://www.boards.ie/discussion/comment/120227393#Comment_120227393

Hopefully not down into Greece yet again! We've been 5 years waiting for winter to happen, time we had a bit of luck.

nacho libre

P16 please Bob.

sryanbruen

Okay so here's the latest on what's happening.

The stratospheric polar vortex right now is weaker than average, the U-60N today was 13.2 m/s according to the GFS. It's only going to go down further in the next few days as warming of the stratosphere continues reversing to easterly (negative U-60N) by Wednesday afternoon which would likely peak by this time next week. The most recent GFS run shows a prolonged reversal where the U-60N continues to hover between 0 and -10 m/s up to day 13 then a secondary warming occurs bringing yet another descent in the U-60N back down into the double digits with a big ridge over the Arctic. If that were to occur, there is very little remnants of the stratospheric polar vortex to be seen anywhere. It is still a wave-1 major displacement as it's all one big ridge but the troughs are set up in a conducive position to bringing the North Atlantic Oscillation into negative territory and therefore, a heightened risk of Greenland or Iceland blocking high pressure. This is not your run of the mill displacement event if the GFS is correct. Generally speaking, it is said that the deeper the reversal and more prolonged it takes place, the higher the likelihood a shake up in the weather patterns occurs. Of course then comes the million questions as to where Ireland would find itself on which side of the jet stream to determine our weather.

Until the first spike (assuming the GFS is correct with forecasting a second spike in warming) occurs by later next week, I don't think there is much use in looking at if downward propagation takes place from the strat to the trop. Models will be playing lots of solutions. For the sake of it as I know some will not resist it, here's the latest GFS North Annular Mode (NAM) forecast anyway. The orange colours are indicative of a negative NAM (also known as a negative Arctic Oscillation (AO) which refers to blocking over the north pole and is associated with the major sudden stratospheric warming. The left side of the chart is the various layers of the atmosphere, if there's downward propagation visible you'll see those orange colours descending towards 1000hPa. At the moment, the GFS does not show this but note the model only takes us to final few days of February and if we are to see effects directly from this warming event, it'll likely be in the early days of March at earliest. Any earlier is probably down to other drivers such as the MJO.

After being inactive all season, University of Berlin have finally updated their ECM stratosphere charts though the latest run available is yesterday's 12z (10 February). The EC sees the U-60N reverse later Wednesday into Thursday, in line with the GFS. However, the warming is less dramatic on this model and does not reverse the U-60N quite as much. Details like that to be revealed though closer the time. It's variations on a theme.

In summary... A major SSW is happening, the U-60N will reverse mid-week next week and it waits to be seen whether there will be tropospheric impacts from this. Ignore the talks of beast from the east, it's usual media drivel. Let's wait for the event to happen first before thinking of the effects of our weather, shall we?

cudsy1

Any update guys? Great thread, thanks for the information

nacho libre

Zonal Winds should be reversing today or tomorrow so it will officially be a SSW at that stage. If we are to see any impacts that lead to cold weather, that can take two to four weeks with a pv displacement.

sryanbruen

GFS starting to show signs of downward propagation for the start of March.

Latest run analysis suggest we should see the reversal occur around midnight tonight.

highdef

North Pole temperature at 10 hPa rising very sharply at the moment

highdef

Massive jump in temperature from yesterday

sryanbruen

Both EC and GFS analysis show the U-60N just barely did not reverse at midnight but it should be now and will be confirmed in the 12z analysis so we can finally say the major SSW has happened.

sryanbruen

There we go.

The zonal mean zonal wind at 10 hPa 60N is today (GFS analysis): -3.9 m/s

Weakest zonal wind at 10 hPa 60N in ERA5 record for todays date is: -17.4 m/s 2018

Strongest zonal wind at 10 hPa 60N in ERA5 record for todays date is: 62.4 m/s 1988

almostthere12

https://www.boards.ie/discussion/comment/120248445#Comment_120248445

Can we expect is to get a lot weaker sryanbruen? I think I saw that there is a potential second warming as well in the next week or so.

sryanbruen

https://www.boards.ie/discussion/comment/120249552#Comment_120249552

Absolutely, this is only the start of it. Provided the GFS is accurate (I know I know 😂), the U-60N should bottom out ~14 m/s on Saturday before a recovery to weak westerly this time next week. As you say there's the potential for a second dip a few days after that recovery back down to similar values to the current warming.

The latest EC46 suggests this is not the final warming of the season with a swift recovery forecast through March. The earliest final warming on record is 5th March 2016 whilst the average date is 15th April. I do not see this record being broken at this time. Typically winters with major SSW events see later than normal final warming events whilst winters with no major SSW events see earlier final warming events though this does not always work out this way.

If we are to see any effect from the warming, the GFS outer range extends out this far and now that it's happened, I'd say it's an okay time to start speculating now on what could happen whilst giving the usual caveats that it's all a long way off etc. Don't start shouting beast from the east from the rooftops though like the mainstream media and radios have!

nacho libre

If the UKMO long range is anything to go by it may be the second week of March before we see anything interesting. Even if this isn't the final warming and there is a swift recovery, there will be a lag effect before things go back to normal in the trop. So we could be cold for a few weeks after this recovery.

sryanbruen

https://www.boards.ie/discussion/comment/120250705#Comment_120250705

Oh I wasn't trying to suggest any tropospheric effects from a recovery. If a blocking pattern gets hold, it will likely remain blocked for a prolonged period regardless of what's happening aloft due to the time of year where climatologically U-60N is declining anyway.

But from a stratospheric point of view, this major SSW is highly unlikely to be the final warming for this season assuming the EC46 is correct.

Based on current modelling, there looks to be high pressure yet again continuing into the first week of March and a small toppler (likely MJO induced) possible next week. It's what happens after though of what this major SSW event could bring impacts for. Will that ridge start to amplify northward?

nacho libre

It looks like that it will be the 2nd week of March at the earliest that we see any high latitude block, if one is to occur. By Mid March we need to hit the jackpot for snow to stay on the ground. It happened in the UK back in 2018 and up North back in 2013. It would be the one time I would prefer cloud cover all day. Of course there would still be some melt no matter how cold or cloudy it is.

Elmer Blooker

Apologies if I come across as being sarcastic but we need to hit the jackpot for snow to stay on the ground in January and February let alone March!

No appreciable snow in January for 13 years is a shocking statistic, can’t remember the last time I saw snow during the first three of February, 2009 I think?