Stratosphere watch 2020-21

nacho libre · 25-12-2020 2:33pm

Gonzo wrote: »

The split seems to be gone for now, the GFS backtracked on a big split few days ago. It still looks a decent warming, a displacement and stretch rather than a split. Perhaps in January we will see further warming and perhaps a split.

Yes the GFS seems to have backtracked, and the ECM has now taken up the mantle. Hopefully the GFS goes back to what it was showing previously, but considering it led the way, it could well be that it turns out to have things right. We really don't want to see a lobe of the Vortex ending up in the Atlantic.

Gonzo · 26-12-2020 3:12pm

the most recent charts for the SSW does not produce a split, however as the PV shows signs of reorganizing itself by the 11th of January, we have another possibly significant warming developing, if this intensifies further into mid January we could end up with a split if all goes right.

gfsnh-10-384.png?6

It appears that the PV will be put under alot of pressure for possibly most of January.

sryanbruen · 26-12-2020 3:29pm

GFS operational has been confusing of late ever since the ECM started to show the major SSW event. The GFS parallel has been going completely the other way to that of the operational with quite vast differences as soon as t180 when it shows more impact from the secondary warming that develops in the North Atlantic. Have not looked at the parallel well enough to know how good its verification record is however but with similarities outlined below with the ECM, it's not entirely alone.

The ECM 12z yesterday (0z charts at University of Berlin have not appeared as of now) at t240 was similar to that of the GFS parallel at t180 with what looks to be a major wave-1 displacement and an attempt at splitting the vortex, there is a reversal. Wave-1 amplitude looks high and wave-2 continues to look modest in nature.

My thoughts remain the same as per Christmas Eve post. As for thinking of impacts for the surface and developing blocking, that's besides the point at the moment. All the eyes are on seeing this SSW develop and see how dynamical/spectacular it will be. It's like seeing when a cold spell is going to end before it has even started.

bazlers · 26-12-2020 8:09pm

Sryanbruen, great informative posts.
Hopefully an SSW will deliver Narnia.

nacho libre · 27-12-2020 1:53pm

sryanbruen wrote: »

GFS operational has been confusing of late ever since the ECM started to show the major SSW event. The GFS parallel has been going completely the other way to that of the operational with quite vast differences as soon as t180 when it shows more impact from the secondary warming that develops in the North Atlantic. Have not looked at the parallel well enough to know how good its verification record is however but with similarities outlined below with the ECM, it's not entirely alone.

The ECM 12z yesterday (0z charts at University of Berlin have not appeared as of now) at t240 was similar to that of the GFS parallel at t180 with what looks to be a major wave-1 displacement and an attempt at splitting the vortex, there is a reversal. Wave-1 amplitude looks high and wave-2 continues to look modest in nature.

My thoughts remain the same as per Christmas Eve post. As for thinking of impacts for the surface and developing blocking, that's besides the point at the moment. All the eyes are on seeing this SSW develop and see how dynamical/spectacular it will be. It's like seeing when a cold spell is going to end before it has even started.

Too much time on netweather will do that! Some people are of the view a displacement could work in our favour. I would have thought a lobe of vortex in the Atlantic would be bad news.

It's interesting how the gfs is now consistent about a second warming that could split the Polar Vortex, if that does happen, i hope we won't start to hear that its too late in the year. With the profile of the northern hemisphere you'd like to think any down welling might have a more immediate impact this time, assuming we don't end up with something more zonal from the displacement. It's good you are not swayed away from your previous thoughts anyway.

Artane2002 · 27-12-2020 1:53pm

the GFS 6z is now finally showing a split but around January 10th/11th, later than the other models and also quite a big reversal. this is still deep FI, this SSW business is starting to give me a headache so hopefully everything is resolved soon!

Gonzo · 27-12-2020 3:24pm

latest chart at the end of the GFS looks very good, the first SSW causes a displacement but just as the PV begins to start strengthening another fairly significant warming in the first week of January causes a split by the 11th/12th of January. Fingers crossed the split works out in our favour this time.

gfsnh-10-384.png?6

sryanbruen · 28-12-2020 4:29pm

I wouldn't worry about or get hung up on individual runs, the trend is what's important. Don't forget my headaches I mentioned from February 2018's major SSW event, that wasn't very smooth sailing either!

The stratospheric polar vortex will be in an absolute mess, split or not. The tropospheric polar vortex is not much better. Wave-1 wreaking havoc at the moment with record breaking amplitude. Won't take much from wave-2 to put the SPV in its grave..

nacho libre · 28-12-2020 4:34pm

sryanbruen wrote: »

The stratospheric polar vortex will be in an absolute mess, split or not. The tropospheric polar vortex is not much better. Wave-1 wreaking havoc at the moment with record breaking amplitude. Won't take much from wave-2 to put the SPV in its grave..

Do you think given the state of the troposphere vortex already that the impacts of a SSW could be felt quicker in the Troposphere than they normally might be?

sryanbruen · 28-12-2020 9:26pm

Happy New Year from the stratosphere :cool:

sryanbruen · 30-12-2020 3:24pm

https://twitter.com/judah47/status/1344285150767706112?s=20

nacho libre · 30-12-2020 4:31pm

If the GFS is correct, then any warm up will hopefully be temporary. It certainly look like a good split. It would be great if we could see if Glosea5 and the GFS are on the same page, or whether it agrees with the ECM

Artane2002 · 30-12-2020 5:33pm

nacho libre wrote: »

If the GFS is correct, then any warm up will hopefully be temporary. It certainly look like a good split. It would be great if we could see if Glosea5 and the GFS are on the same page, or whether it agrees with the ECM

we really need this to fall correctly more so than usual, how ironic would it be if after all those years of waiting for a good trop-led pattern the SSW comes and ruins everything!

Artane2002 · 30-12-2020 6:10pm

nacho libre wrote: »

If the GFS is correct, then any warm up will hopefully be temporary. It certainly look like a good split. It would be great if we could see if Glosea5 and the GFS are on the same page, or whether it agrees with the ECM

the Glosea shows zonal winds (65N though not 60N) not really recovering for the rest of the month. you'd think we'd be incredibly unlucky to miss out on some decent cold/snow but that's our luck! I saw it on netweather but I wouldn't want to post it just in case the chart is supposed to be behind paywall or something.

nacho libre · 31-12-2020 12:22pm

Some indications that a lobe of vortex could end up being displaced into the Atlantic, I would have thought it's bad news if that happens, but some netweather posters are saying that the the piece of vortex would be so weak that it would not flip us into a bad setup.

lapua20grain · 01-01-2021 10:02pm

https://twitter.com/METclimate/status/1345109847432433665?s=19

sryanbruen · 01-01-2021 10:10pm

lapua20grain wrote: »

https://twitter.com/METclimate/status/1345109847432433665?s=19

Busy at the moment thus the lack of posts but very quick one to note on this: If the latest GEFS verifies, looks like Tuesday or Wednesday (5/6 January) will be the point this becomes a major SSW event with the zonal mean zonal winds at 60N reversing.

bazlers · 01-01-2021 11:21pm

sryanbruen wrote: »

Busy at the moment thus the lack of posts but very quick one to note on this: If the latest GEFS verifies, looks like Tuesday or Wednesday (5/6 January) will be the point this becomes a major SSW event with the zonal mean zonal winds at 60N reversing.

Hi Sryanbruen, hopfully the PV ends up falling favourably for us .

Gaoth Laidir · 02-01-2021 4:52pm

I made this chart to show how good the ECMWF model is at resolving the full depth of the atmosphere, right up to 80 km. It has 137 vertical levels, compared to the new GFS' 128 (recently upgraded from the very paltry 64 before last year).

The spacing between the levels on an altitude scale is due to the logarithmic falloff of pressure with height. Actual model levels are defined at pressure levels, not actual altitude, but I've shown them on a linear altitude scale to get a proper idea.

Data from here.

bazlers · 02-01-2021 6:54pm

GL, if a SSW occurs say tue/wed does this not change the whole dynamics of what the models foresee. So As unreliable a forecast is 5 days in advance surely then they become even worse? or are they intelligent enough to take this into account aswell?
( Be gentle with your response i know it may have no effect ; ) )

Gaoth Laidir · 02-01-2021 7:08pm

bazlers wrote: »

GL, if a SSW occurs say tue/wed does this not change the whole dynamics of what the models foresee. So As unreliable a forecast is 5 days in advance surely then they become even worse? or are they intelligent enough to take this into account aswell?
( Be gentle with your response i know it may have no effect ; ) )

It's actually fairly good at handling the dynamics of the middle atmosphere (stratosphere and above), but there is a lack of conventional balloon observations the higher up you go. Compare today's observations at 10 hPa compared to 70 hPa (many balloons will have burst before reaching 10 hPa). Things move more slowly in the stratosphere, so a high density of observations is less important, and of course there is great coverage from polar-orbiting satellites.

bazlers · 02-01-2021 7:25pm

Gaoth Laidir wrote: »

It's actually fairly good at handling the dynamics of the middle atmosphere (stratosphere and above), but there is a lack of conventional balloon observations the higher up you go. Compare today's observations at 10 hPa compared to 70 hPa (many balloons will have burst before reaching 10 hPa). Things move more slowly in the stratosphere, so a high density of observations is less important, and of course there is great coverage from polar-orbiting satellites.

Oh very good. Didnt realise. Thank you.

Donegal Ken · 04-01-2021 1:48pm

A great article and update from Met Éireann this morning on the sudden stratospheric warming event. https://www.met.ie/forecasts/meteorologists-commentary

nacho libre · 04-01-2021 11:02pm

Some less than favourable developments today it has to be said. The main worry is the GFS was the first to pick out a displaced vortex rather than a split, so it could well be right about a quick recovery of the upper Vortex. Also there is a real danger we end up with a displaced section of the vortex in the wrong place, which might mean cold and wet for us rather than cold and white.
The GFS does suggest a further warming, which maybe enough to kill off the vortex or lead to a proper split, but that extends the waiting time. Could it be another 2013 event? Back to back SSW'S not delivering would be very bad luck. Hopefully there are positive changes to come!

lostweekend3 · 04-01-2021 11:53pm

nacho libre wrote: »

Some less than favourable developments today it has to be said. The main worry is the GFS was the first to pick out a displaced vortex rather than a split, so it could well be right about a quick recovery of the upper Vortex. Also there is a real danger we end up with a displaced section of the vortex in the wrong place, which might mean cold and wet for us rather than cold and white.
The GFS does suggest a further warming, which maybe enough to kill off the vortex or lead to a proper split, but that extends the waiting time. Could it be another 2013 event? Back to back SSW'S not delivering would be very bad luck. Hopefully there are positive changes to come!

Yet some meteorologists on social media would have you believe that it’s all going to work out in our favour, it’s all looking good for UK etc. This could easily go wrong for us just like 2019. Time will tell!

Gaoth Laidir · 05-01-2021 12:20am

lostweekend3 wrote: »

Yet some meteorologists on social media would have you believe that it’s all going to work out in our favour, it’s all looking good for UK etc. This could easily go wrong for us just like 2019. Time will tell!

It gets them retweets. That's all it's about. You should ask some on this forum

Billcarson · 05-01-2021 12:36am

nacho libre wrote: »

Some less than favourable developments today it has to be said. The main worry is the GFS was the first to pick out a displaced vortex rather than a split, so it could well be right about a quick recovery of the upper Vortex. Also there is a real danger we end up with a displaced section of the vortex in the wrong place, which might mean cold and wet for us rather than cold and white.
The GFS does suggest a further warming, which maybe enough to kill off the vortex or lead to a proper split, but that extends the waiting time. Could it be another 2013 event? Back to back SSW'S not delivering would be very bad luck. Hopefully there are positive changes to come!

It would be no surprise to me if things didn't gi in our favour, initially at least. Remember we haven't had a proper cold spell in the second half of Jan in yrs.
If there is a delay in a potential cold spell I hope it's in Feb and we dont get another march 2013.......

nacho libre · 05-01-2021 4:26pm

I see a lot of GFS members are going for a third warming after the Vortex tries to recover. Some twitter commentators are definitely after the clicks, but some just post what they see. It's a pity we never got the split, as that could increase our chances of a favourable outcome.

lapua20grain · 05-01-2021 5:48pm

https://twitter.com/afreedma/status/1346491970588467202?s=19

Gaoth Laidir · 05-01-2021 6:06pm

lapua20grain wrote: »

https://twitter.com/afreedma/status/1346491970588467202?s=19

See, this is the type of hype I'm on about. It's "poised to bring...", as if it's set in stone. Pure clickbait.

Stratosphere watch 2020-21

Comments