Stratosphere and Polar Vortex Watch

[feb1991blizzard]

Just now, Don said:

Not great news, then?  However, plenty more twists and turns to come yet?

Can't really tell yet as run to run deviation is less the higher we go and we are talking high up the atmosphere - we really want that split to suddenly appear again in the late 300's,

[Dennis]

nice ideas at the forecast but need to focus of what it shows soon when it will start around end of January

Displacement later it shows now first

[phil nw.]

I do wonder how much credence we can give to the later frames of the GFS strat modeling. 

We have seen so many false dawns from this model wrt to zonal wind forecasts this Winter. 

I think I will get interested when I see the ECM suite coming on board within 10 days. 

Seaonal slowing down of zonal winds will start to show up anyway as we go into February so there will be more chance of ridging further north. 

Edited January 26, 2020 by phil nw.

[knocker]

PSC's have been observed in Norway and Finland and but for cloud could have been at Lerwick. The coldest part of the vortex is now moving NE via Finland

 

Edited January 26, 2020 by knocker

[knocker]

The EP flux seems to cropped up a fair bit of late. For those like myself not particularly au fait with this

Eliassen-Palm (EP) Flux Diagram

Meridional fluxes of westerly momentum and sensible heat can be easily calculated from constant pressure charts at various levels in the atmosphere. As per the Eliassen-Palm theory, these parameters give fluxes of geopotential wave energy in the meridional-vertical (y, p) plane. Streamlines can then be drawn in (y, p) plane, giving the direction and intensity of flow of energy in this plane.  Figure 4.17 is a schematic diagram representing the flux of wave energy in (y, p) plane. The curves of 1/f = constant streamlines for the flux of wave energy. It may be noted that the flux of wave energy in a channel between two adjacent streamlines is not a constant, but varies along the channel in proportion to U as indicated by the length of the arrows in the diagram. Thus when energy flows toward increasing value of U, the wave energy flux increases in the direction of the streamline, carrying energy from the basic zonal flow. The opposite phenomenon occurs in the direction of decreasing U. In any way, wave energy cannot cross the singular line U = 0.

Source: Stratosphere Troposphere Interactions, K. Mohanakumar

[knocker]

These charts pretty much self-explanatory

 

[Spah1]

 

[Mike Poole]

1 hour ago, Spah1 said:

 

Looks like the same charts as posted by knocker above, but I don't think this is inconsistent with a colder output later after a potential SSW, the timeframe for the mild outlook is well before any such SSW and I don't think it is different from what the op models are showing for the next couple of weeks, or am I missing something?

[Mike Poole]

So here's the take on the 0z runs as per the stratobserve charts, fair few ensemble members now going for the reversal

GEFS and GEM ensembles at T384:

If you look at those runs which show a reversal or near reversal, a split of some sort does seem to feature. It is far too early to call this as a SSW, but if it does firm up in future runs and go on to happen, then winter may have a sting in the tale, will certainly be worth watching how this unfolds.

[Don]

2 hours ago, Spah1 said:

 

In other words, b*gger*ll change for us then!  I give up!

Edited January 26, 2020 by Don

[Nick F]

21 minutes ago, Don said:

In other words, b*gger*ll change for us then!  I give up!

I wouldn't worry too much for now, there's no knowing how the SPV will 'react' to the forecast warming, it may be elongated as per charts in the tweet but the GFS eventually displaces an intact SPV towards Russia/NE Europe on 06z. And we won't know how the trop will be affected by this possible shakeup in the stratosphere 

Edited January 26, 2020 by Nick F

[DavidS]

18z GFS isn’t going for the split, but still a significant warming and a potential secondary warming at the end of the run.

 

[Griff]

Marco Petanga "that's a heck of a warming... #ssw" 

His words not mine... 

[Paul_1978]

57 minutes ago, Griff said:

Marco Petanga "that's a heck of a warming... #ssw" 

His words not mine... 

I’m still concerned that he also said a couple of days ago that the effect on the UK would be “enhanced westerlies”. Just our luck. 

[knocker]

The morning update The alignment of the tpv shows some connection to the lower strat and the regression of the Atlantic trough and subsequent movement of the subtropical high will hopefully portend a more prolonged settled spell for most

[Interitus]

 

14 minutes ago, Paul_1978 said:

I’m still concerned that he also said a couple of days ago that the effect on the UK would be “enhanced westerlies”. Just our luck. 

 

You might be more concerned whether a SSW is going to happen at all!

[Dennis]

This morning seen - its not bad to have a start of weakening the Core PV

 

  

[Paul_1978]

4 hours ago, Interitus said:

 

 

You might be more concerned whether a SSW is going to happen at all!

That goes without saying. 

[bluearmy]

i'm not really sure what marco is referencing in his tweet anyway …. he posts a ten day op chart for the upper strat and a six day ens mean for the following six day period …… not particularly joined up thinking ??  a+ b isn't necessarily c and he is potentially mixing apples and oranges 

Edited January 27, 2020 by bluearmy

[Nick F]

6 hours ago, Paul_1978 said:

I’m still concerned that he also said a couple of days ago that the effect on the UK would be “enhanced westerlies”. Just our luck. 

It does concern me that some hang on every word of meteorologists, like they know for sure how the troposphere will be affected by potential changes in the stratosphere beyond 7 days, no-one can know with confidence what will happen, given each model is spewing out different outcomes from elongation, splits or displacements. And his tweet the other day said to 'take with a huge pinch of salt' anyway.

[knocker]

!50kts towards the edge of the vortex at 16mb at Keflavik,Iceland, at midday

Edited January 27, 2020 by knocker

[Interitus]

Well the GFS has backed down from a SSW quite a bit, here are the 1mb zonal winds on the runs since the last negative values on yesterday's 06z -

The x-axis represents the 3 hourly forecast intervals and the minimum on today's 06z of 17.5 ms at T219 - day 9 - fairly accurate at that range. It's not unlikely that it could flip back beyond this, though at the moment it is looking increasingly like perhaps a first bite of the cherry. The GEOS out to T240 (one run per day) still has the 1mb wind down to 8.9 ms at the last timeslice, will be interesting to see its direction on the 28/01 00z.

 

[Paul_1978]

3 hours ago, Nick F said:

It does concern me that some hang on every word of meteorologists, like they know for sure how the troposphere will be affected by potential changes in the stratosphere beyond 7 days, no-one can know with confidence what will happen, given each model is spewing out different outcomes from elongation, splits or displacements. And his tweet the other day said to 'take with a huge pinch of salt' anyway.

I am not “hanging on the word” of any meteorologist (unfair statement if aimed at me) given the fluidity of the science of weather, I was simply observing a stated possible outcome. 

Edited January 27, 2020 by Paul_1978
Clarity

[winterof79]

What a thoroughly well explained article

 

*Stratospheric warming UPDATE* The warming phase is about to start this week. It will compress the Polar Vortex, reduce the core power and disconnect it from the troposphere! » Severe Weather Europe

WWW.SEVERE-WEATHER.EU

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-spread the word- The new stratospheric warming phase is set to start this week. It will greatly reduce the strength of the...

 

[summer blizzard]

No SSW on the mean today however 5 ensembles do produce a SSW by the 10th.