Stratosphere and Polar Vortex Watch 2020

[fromey]

41 minutes ago, Battleground Snow said:

Would this support the GFS with its continuation of more northern blocking and a less flat profile?

Shame we can’t quote that in the model thread

[Battleground Snow]

6 minutes ago, fromey said:

Shame we can’t quote that in the model thread

I was going to, but thought it may get moved, hopefully someone will read this soon haha. I'm a novice, but I think it can only be positive that the zonal winds are slowing faster than predicted

Edited January 3, 2021 by Battleground Snow

[Windysun1]

9 minutes ago, Battleground Snow said:

I was going to, but thought it may get moved, hopefully someone will read this soon haha. I'm a novice, but I think it can only be positive that the zonal winds are slowing faster than predicted

So if say the SSW kicks in tomorrow or tuesday. Will its effect be a week to 10 days from then?

[Battleground Snow]

Just now, Windysun1 said:

So if say the SSW kicks in tomorrow or tuesday. Will its effect be a week to 10 days from then?

I think maybe a little faster than 10 days, but in relation to the zonal winds, if 06z is correct it may back the whole pattern a little west in the 120-144 period compared the Ukmo/ECM. 

[Windysun1]

17 minutes ago, Battleground Snow said:

I think maybe a little faster than 10 days, but in relation to the zonal winds, if 06z is correct it may back the whole pattern a little west in the 120-144 period compared the Ukmo/ECM. 

Cheers BGS

[Snowjokes92]

48 minutes ago, Battleground Snow said:

I was going to, but thought it may get moved, hopefully someone will read this soon haha. I'm a novice, but I think it can only be positive that the zonal winds are slowing faster than predicted

Probably the cause of the big swings at such short range across the models. All the data that is probably flooding into these models  from such short range is bound to have a massive impact on how they perform. I can only believe this is why the output in 3 to 4 days is very much all over the place. If this SSW is becoming major from tomorrow, then keep expecting big swings to come, as none of the models havent a solid clue on what to do. 

Edited January 3, 2021 by Snowjokes92

[minus 9]

Quick question. When you get a strat reversal does that mean the polar vortex starts spinning east to west instead of the usual west to east motion. Sorry if that sound like  stupid question. 

[ghoneym]

5 minutes ago, minus 9 said:

Quick question. When you get a strat reversal does that mean the polar vortex starts spinning east to west instead of the usual west to east motion. Sorry if that sound like  stupid question. 

Watch this video minus 9, very helpful

 

[danm]

 

[Nick F]

37 minutes ago, minus 9 said:

Quick question. When you get a strat reversal does that mean the polar vortex starts spinning east to west instead of the usual west to east motion. Sorry if that sound like  stupid question. 

No, the polar vortex still rotates counter-clockwise in the NH, just it doesn't do it over the pole where it normally sits, instead it's displaced equatorward or split into two vortices that head equatorward. A vortex will always spins counter-clockwise in the NH, whether at the surface or strat. The strat reversal is over the polar region - where a stratospheric high develops with a clockwise circulation.

[minus 9]

57 minutes ago, ghoneym said:

Watch this video minus 9, very helpful

 

Thanks for reply

[minus 9]

21 minutes ago, Nick F said:

No, the polar vortex still rotates counter-clockwise in the NH, just it doesn't do it over the pole where it normally sits, instead it's displaced equatorward or split into two vortices that head equatorward. A vortex will always spins counter-clockwise in the NH, whether at the surface or strat. The strat reversal is over the polar region - where a stratospheric high develops with a clockwise circulation.

Thanks for replying 

[sebastiaan1973]

ResearchGate - Temporarily Unavailable

WWW.RESEARCHGATE.NET

 The tropospheric response to mid-winter sudden stratospheric warmings (SSWs) is examined using an idealised model. SSW events are triggered by imposing high-latitude stratospheric heating perturbations of varying magnitude for only a few days, spun-off from a free-running control integration (CTRL). The evolution of the thermally-triggered SSWs are then compared with naturally-occurring SSWs identified in CTRL. By applying a heating perturbation, with no modification to the momentum budget, it is possible to isolate the tropospheric response directly attributable to a change in the stratospheric polar vortex, independent of any planetary-wave momentum torques involved in the initiation of a SSW. Zonal-wind anomalies associated with the thermally-triggered SSWs first propagate downward to the high-latitude troposphere after ∼ 2 weeks, before migrating equatorward and stalling at midlatitudes, where they straddle the near-surface jet. After ∼ 3 weeks, the circulation and eddy fluxes associated with thermally-triggered SSWs evolve very similarly to SSWs in CTRL, despite the lack of initial planetary-wave driving. This suggests that at longer lags, the tropospheric response to SSWs is generic and it is found to be linearly governed by the strength of the lower-stratospheric warming, whereas at shorter lags, the initial formation of the SSW potentially plays a large role in the downward coupling. In agreement with previous studies, synoptic waves are found to play a key role in the persistent tropospheric jet shift at long lags. Synoptic waves appear to respond to the enhanced midlatitude baroclinicity associated with the tropospheric jet shift, and preferentially propagate poleward in an apparent positive feedback with changes in the high-latitude refractive index.

[sebastiaan1973]

https://www.wcrp-climate.org/images/WCRP_conferences/S2S_S2D_2018/pdf/Programme/orals/presentations/A8-03_Alexey_Karpechko_MAC.pdf

Might be intresting to some of you.

[bluearmy]

Ec op strat remains on the same page as the gfs op 

[sebastiaan1973]

Sudden stratospheric warmings (SSWs) are significant source of enhanced subseasonal predictability, but whether this source is untapped in operational models remains an open question. Here we report on the prediction of the SSW on 12 February 2018, its dynamical precursors, and surface climate impacts by an ensemble of dynamical forecast models. The ensemble forecast from 1 February predicted 3 times increased odds of an SSW compared to climatology, although the lead time for SSW prediction varied among individual models. Errors in the forecast location of a Ural high and underestimated magnitude of upward wave activity flux reduced SSW forecast skill. Although the SSW's downward influence was not well forecasted, the observed northern Eurasia cold anomaly following SSW was predicted, albeit with a weaker magnitude, due to persistent tropospheric anomalies. The ensemble forecast from 8 February predicted the SSW, its subsequent downward influence, and a long-lasting cold anomaly at the surface.

ResearchGate - Temporarily Unavailable

WWW.RESEARCHGATE.NET

 

[Anthony Burden]

Major information feeding through Marco Patanga Twitter regarding SSW reversal and recent charts.

[Anthony Burden]

Just to add winds go east 10 hpa later tomorrow.

[sundog]

The cold spell that hit parts of North America in late jan 2019,was that due to the ssw earlier that month?

[Catacol]

Probably 15 days and a bit more to go yet.... 

[ALL ABOARD]

5 minutes ago, Catacol said:

Probably 15 days and a bit more to go yet.... 

Hi mate, 

 

Top of your head what's the longest reversal we've ever had in terms of days? 

Obviously excluding final warnings? 

[Catacol]

36 minutes ago, ALL ABOARD said:

Hi mate, 

 

Top of your head what's the longest reversal we've ever had in terms of days? 

Obviously excluding final warnings? 

That's quite a tough question to answer - the data is not easy to find. I'll do a bit of digging over the next few days and see what comes up. I know 2013 was pretty long, but it was also an event like 2019 where a reflective setup meant that impacts did not downwell as efficiently as they might have. There is a lot to grasp with regards to SSWs, not just duration. However obviously the longer the event, the longer the impacts can run. 

[Allseasons-Si]

1 hour ago, Catacol said:

Probably 15 days and a bit more to go yet.... 

Hi @Catacol,what is your name anyway?

anyway,do you have the 60 N and is there a site for viewing these or are they behind paywall?

[snowy weather]

Is it possible for us to be on the wrong side of a SSW? 

For example can it happen that instead of the UK, it is the US that gets all the cold due to the SSW?

 

[Allseasons-Si]

2 minutes ago, snowy weather said:

Is it possible for us to be on the wrong side of a SSW? 

For example can it happen that instead of the UK, it is the US that gets all the cold due to the SSW?

 

Yes this is possible as we would not know yet where the pv segments would end up in the lower latitudes but a greater chance than without an SSW.