Stratosphere Temperature Watch 2015/2016

[Frank_Wx]

If Tropospheric ridges drive splits in the lower Strat, what is there to drive splits further upstream? 

[KyleHenry]

15 hours ago, Frank_Wx said:

If Tropospheric ridges drive splits in the lower Strat, what is there to drive splits further upstream? 

One factor is where Brewer Dobson concentration forms and for it to locate in the correct Geo planetary position (which it currently is) can assist the EAMT events.

As it heats Stratosphere via UV rad it can form a bridge or a target for Trop wave to advance towards in altitude. May not be enough during this wave phase but you just feel it will by the next if all continues as is. 

 

Edited December 21, 2015 by KyleHenry

[Singularity]

 

Hang on... GEFS is taking the convective signal through to phase 7 now, that's a good sign 

Based on verification over the past 5 days (by eye on my part), an outcome that's about 2/3 GFS and 1/3 UKMO could be a good bet. If that's achieved then we ought to have the launchpad in place for boosting AAM and attacking the vortex via those amplified waves.

Which reminds me...

So much for the AAM going negative! GFS has completely changed its tune over the past week.

[KyleHenry]

The signal is faint but in the outer reaches of GFS at 384z on 7th January 2016 could be the beginning of the elusive SSW. More runs needed. 

[Paul123]

5 minutes ago, KyleHenry said:

The signal is faint but in the outer reaches of GFS at 384z on 7th January 2016 could be the beginning of the elusive SSW. More runs needed. 

This is consistent with yesterday's Cohen blog. 

'We have been discussing the polar vortex model developed here at AER that predicts the strength of the polar vortex one month in advance.  As we discussed in the blog for the past month, the model was predicting the polar vortex to become disturbed the third week of December, which is predicted by the weather models to occur this week.  The polar vortex model also predicts a similar perturbing of the stratospheric polar vortex in the first week of January, which again is now being predicted by the weather models.  And as we have been discussing, the polar vortex model predicts an even bigger event the second week of January.  As we discussed above the predicted atmospheric circulation is nearly optimal for the vertical transfer of energy from the troposphere to the stratosphere that results in weakening of the polar vortex.  Therefore, based on the polar vortex model and the upcoming atmospheric circulation pattern, we are anticipating more upward pulses of WAFz. If the predicted atmospheric circulation pattern is correct and our expectations of more upward pulses of WAFz is correct, this should be sufficient to force a sudden stratospheric warming (SSW) sometime in January. And if our expectations of a weakened polar vortex verify, this will likely favor an increased likelihood of severe winter weather across the continents of the Northern Hemisphere.  One ongoing inhibiting background factor is the westerly phase of the quasi-biennial oscillation (QBO) that favors a strong vortex over a weak vortex. If this prevails and our expectations of an active period of WAFz is incorrect, then the polar vortex will strengthen and likely the AO will remain positive and the weather pattern mild for the Eastern United States, Northern and Western Europe and East Asia.  However we are becoming increasingly confident in the first solution of a weakening polar vortex and an increasing bias towards a negative AO.'

http://www.aer.com/science-research/climate-weather/arctic-oscillation

The upward pulses of WAFz are being triggered by the building of a high over Western Russia, which is showing ever more often on the prog charts.

 

[KyleHenry]

Latest GFS at 384z has lost the warming but placed the wave and position of the core cold Siberia bound, we know from previous years that the GFS is reliable at picking up signal but can be out by 7-14 days.

We are at the interesting point of the year and I see us looking at Strat charts on Christmas Day. 

[IDO]

2 hours ago, KyleHenry said:

Latest GFS at 384z has lost the warming but placed the wave and position of the core cold Siberia bound, we know from previous years that the GFS is reliable at picking up signal but can be out by 7-14 days.

We are at the interesting point of the year and I see us looking at Strat charts on Christmas Day. 

ECM forecast from Twitter:

 

[Paul_1978]

So many conflicting messages. I'm sure I'm not the only one to be confused. 

[Singularity]

ECM's not been keen on taking the convective signal through phase 7/8 lately so that may be having a negative impact on the wave breaking it's predicting?

Hopefully GEFS/UKMO as of yesterday's runs are in the right ballpark and ECM's having another one of those moments where it sends the signal to the COD too soon. I've seen it do that a number of times in the past couple of years.

[Recretos]

parallel GFS going into serious mode. Which i think is a bit too much of a disturbance. We will see. 

 

  

 

GEFS sees an upcoming period of intensification, and an unknown terrain afterwards.

 

[karyo]

1 minute ago, Recretos said:

parallel GFS going into serious mode. Which i think is a bit too much of a disturbance. We will see. 

 

  

 

GEFS sees an upcoming period of intensification, and an unknown terrain afterwards.

 

What do you mean? That it is forecasting an even stronger polar vortex?

[Recretos]

GEFS is normally forecasting a period of stronger zonal mean winds at 60N at 10mb, as the WAFz reduces. 

[karyo]

56 minutes ago, Paul_1978 said:

So many conflicting messages. I'm sure I'm not the only one to be confused. 

You are certainly not the only one!

 

[phil nw.]

The way i see it at the moment is there is currently some warming at the very top levels 1 and 5mb from the present wavebreaking but is not forecasted to downwell to any extent.Thus the bulk of the vortex remains very cold and well organised across the Pole.

We need further wavebreaking and that is why the focus is again across the tropics and in particular the MJO forecasts.

Edited December 22, 2015 by phil nw.
Spelling-again

[karyo]

19 minutes ago, Recretos said:

GEFS is normally forecasting a period of stronger zonal mean winds at 60N at 10mb, as the WAFz reduces. 

Thank you. So things are getting even less condusive to northern blocking as we move into January.

[The PIT]

Out of interest how well these forecasts verify ans is there a link to the actual performance ratings?

[phil nw.]

2 minutes ago, The PIT said:

Out of interest how well these forecasts verify ans is there a link to the actual performance ratings?

iHi Pit,if you mean the MJO data they are not infallable like any other forecast and often vary between the different agencies.

A link here all about it.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml#clivar

hope that helps.

.

[Snowy L]

1 hour ago, Recretos said:

 

 

GEFS sees an upcoming period of intensification, and an unknown terrain afterwards.

 

 

Looks like a respite  in energy at the 7-10 day range. We've had the pulse of energy in the 3rd week of December which has currently had a small effect, though most of it has been deflected by the monster vortex. Then we are forecast another pulse in the day 10+ range if the NW Eurasian high hopefully verifies.

Edited December 22, 2015 by Snowy L

[Hocus Pocus]

26 minutes ago, karyo said:

Thank you. So things are getting even less condusive to northern blocking as we move into January.

I think that's looking a distinct possibility with the MetO having low confidence of any prolonged cold up until the 20th January. Still things can and do change at short notice so all is not lost seen as we are still in the first month of winter.

[Bristawl Si]

Genuine question.

How reliable are the strat charts? Are they any more reliable than the charts we see in the Mod Disc thread?

Just wondering

[snowking]

37 minutes ago, Bristle boy said:

Genuine question.

How reliable are the strat charts? Are they any more reliable than the charts we see in the Mod Disc thread?

Just wondering

In theory yes, it's mostly down to the number of variables to calculate. At the surface, you have to deal with all of the various elements of physics that make up 'the weather' and then add to it the thermal differences in oceans/landmasses, inland water, hills & mountains etc etc. In the stratosphere you're looking at a relatively flat 'landscape' so as to speak.

But of course sometimes stratospheric events are reliant on things such as upwelling wave activity and perhaps even mountain torquing events (can be linked to one another) and so if we are saying things are more chaotic at the surface, and the stratospheric conditions are then reliant upon the outcome of these chaotic conditions at the surface, all of a sudden you probably have merit to question the stratospheric forecasts.

So in theory - yes. In practice, not always.

 

SK

[Recretos]

To add to the general "flatness" of the stratosphere that Snowking mentioned, two main causes that add to better skill scores for the strat, are mainly the reduced wave frequency, and general higher wave amplitude.

[Singularity]

ECM's coming around to the idea of propagation through phases 7 and 8 and GEFS is now indicating decent amplitude in 7. 

Signs are the responding amplification could unfold as a major ridge from Siberia toward Greenland, with the 12z GFS the best det. effort of the past few days in that respect.

This also allows the Atlantic trough to extend SE through the UK and into Europe, which matches recent long-range indications of a regime featuring more in the way of polar maritime air.

First hints around day 12 with a weak attempt, followed by a stronger effort from day 14 onward that leads to a very disturbed looking trop. vortex by the end of the run.

Not sure what to make of ECM given it's disagreement with all the other 'big' models as early as +120 hours with respect to how well the disturbances phase to generate a deep Atlantic trough. It certainly sets things back by allowing LP to drive all the way through to Siberia by +240 hours, in place of the blocking high that GFS goes for.

As for the GEM 12z... I'll have what it's having 

Edited December 22, 2015 by Singularity
taming

[joggs]

Lol singularity.Going to come back to this thread in between Xmas and new year and hopefully momentum will gather pace.

[damianslaw]

Reading posts from the start of the winter, we are now entering the critical period so to speak when changes to the stratosphere need to start appearing to help engender a possible change in the northern hemisphere in time to produce a much colder spell of weather - but we have time on our hands still, as we are just at the start of that period.

 

Conflicting signals it seems, MJO moving into Phase 7 could help, tropical convection being the end result, also heights building out of NW Russia which is what a number of forecasts were going for to help probe and weaken the PV - displacing it somewhat. We have signals for both this things occurring in the days ahead. We shall see..