Stratosphere Temperature Watch 2015/2016

[Recretos]

GFS evolution of the zonal mean zonal wind at 60N, by height. It is like looking at the FU Berlin zonal wind plots, but you would cut out the 60N vertical line from 1000mb up to 1mb and run it in the GFS forecast for 16 days. 

 

 

 

[MJO]

58 minutes ago, mezzacyclone said:

I wouldnt be so sure according to the atmospheric & enviro research centre mjo?

"The polar cap geopotential height anomaly plot continues to show a strong stratospheric polar vortex into the foreseeable future"

Yet further into their latest report it becomes ambiguous?

"the models predict a fairly robust pulse of vertical wave activity flux (WAFz) or vertical energy transfer next week that is predicted to perturb the stratospheric polar vortex and cause it to begin weakening" 

Just a bit 'chicken & the egg' syndrome to me?

yes you are right.

i mean the PV will be less stronger.. AO will peak strongly positive early next week before drifting back towards neutral.

 

however in AER, they say : " if our expectations of more upward pulses of WAFz is correct, this should be sufficient to force a sudden stratospheric warming (SSW) sometime in January"

i think SSW makes the PV very weak which mean AO negative ... am i right ?

Edited December 16, 2015 by MJO

[Cloud 10]

Nice little tease right at the end of the 18z gfs.

 

[Singularity]

13 hours ago, Cloud 10 said:

Nice little tease right at the end of the 18z gfs.

 

That bears a lot of resemblance to the warming in 6 days time:

The 06z goes on to drop a similar hint to the 18z right at the end but not as well advanced. There does look to be a lot of figuring out to be done with respect to how quickly the process progresses - and given the issues with the handling tropical forcing at the moment it may not be possible to pay  much attention to trends either, as the output even at the strat. level may be prone to significant changes as early as 10 days from now.

I'll be watching this next chart for any further increase in the 'Faux MJO' signal tomorrow, taking it beyond what GEFS and ECMF are foreseeing.

[sebastiaan1973]

http://iopscience.iop.org/article/10.1088/1748-9326/10/10/104007/pdf Some research.

There has been a great deal of recent interest in producing weather forecasts on the 2–6 week sub-seasonal timescale, which bridges the gap between medium-range (0–10 day) and seasonal (3–6 month) forecasts. While much of this interest is focused on the potential applications of skilful forecasts on the sub-seasonal range, understanding the potential sources of sub-seasonal forecast skill is a challenging and interesting problem, particularly because of the likely state-dependence of this skill (Hudson et al 2011). One such potential source of state-dependent skill for the Northern Hemisphere in winter is the occurrence of stratospheric sudden warming (SSW) events (Sigmond et al 2013). Here we show, by analysing a set of sub-seasonal hindcasts, that there is enhanced predictability of surface circulation not only when the stratospheric vortex is anomalously weak following SSWs but also when the vortex is extremely strong. Sub-seasonal forecasts initialized during strong vortex events are able to successfully capture the associated surface temperature and circulation anomalies. This results in an enhancement of Northern annular mode forecast skill compared to forecasts initialized during the cases when the stratospheric state is close to climatology. We demonstrate that the enhancement of skill for forecasts initialized during periods of strong vortex conditions is comparable to that achieved for forecasts initialized during weak events. This result indicates that additional confidence can be placed in sub-seasonal forecasts when the stratospheric polar vortex is significantly disturbed from its normal state.

[feb1991blizzard]

Renewed warming at top in FI on GFS - decent wave 1 and elongated vortex further down, that's probably the best GPH 1mb chart ive seen this winter.

[Cheshire Freeze]

Just now, feb1991blizzard said:

Renewed warming at top in FI on GFS - decent wave 1 and elongated vortex further down, that's probably the best GPH 1mb chart ive seen this winter.

Every time I see the strat charts I envisage someone half concious bobbing in the middle of the ocean with a number of sharks circling. So far any warming seems to be circling the main vortex but you get the impression that it is in fact a dead man walking in reality as it's only a matter of time before the sharks (warming) strikes meaningfully.

[karyo]

10 minutes ago, CreweCold said:

Every time I see the strat charts I envisage someone half concious bobbing in the middle of the ocean with a number of sharks circling. So far any warming seems to be circling the main vortex but you get the impression that it is in fact a dead man walking in reality as it's only a matter of time before the sharks (warming) strikes meaningfully.

Sadly, there is nothing dead about this vortex!

I think it will take a long time for it to weaken sufficiently.

[knocker]

Don't know if this has already been posted.

New paper on polar vortex and blocking. Open view http://www.tellusa.net/index.php/tellusa/article/view/29184 …

[Dorsetbred]

47 minutes ago, knocker said:

Don't know if this has already been posted.

New paper on polar vortex and blocking. Open view http://www.tellusa.net/index.php/tellusa/article/view/29184 …

Interesting reading material.

[bobbydog]

looks to me like the strat is due to take a pounding....

 

[Ruben Amsterdam]

Slap in the face yes, knock-out blow no. 

All forecasts seem to let this wave subside at the +240-300 timeframe. At the outer reaches of FI the wave may revive but its strength is as yet unknown. If no renewed and stronger activity is in the forecast at new year, I fear we have to surrender to this almighty vortex..

I still feel EC is a bit more progressive at the upper strat but that remains to be seen. I'm not very optimistic at this point.

Edited December 18, 2015 by Ruben Amsterdam

[Recretos]

Best looking strat forecasts so far, are coming from the bias-corrected GEFS members 19 and 20. 19 has the best heights forecast, and the 20 has the best temp. forecast. 

 

  

 

Also it can be seen on the GEFS zonal mean zonal wind graph comparison, how much the 19 member deviated.  Notice the general reduction of zonal winds at 10mb 60N following the WAFz, and then restrengthening as the WAF reduces. #Cycling

 

Edited December 18, 2015 by Recretos
Wrong image link

[Weather-history]

2 hours ago, Ruben Amsterdam said:

Slap in the face yes, knock-out blow no. 

More like the first part than the second part of this?

 

[Recretos]

Remember where you have seen it first, and who showed you it!  This is the new GFS experiment by NCEP, and let me proudly be the first to present you its stratospheric output. And this run looks very potent to say the least. Its in a pre-parallel stage (as noted by Ryan Maue), so it will probably get a tweak or two down the line.

 

 

 

 

 

 

As cool as it looks, it could be either a failed run, or just the way the model is currently configured, aka a bias, or it might hold some merit. We will see. To me the vortex looks just simply a bit too much under attack.

 

 

 

Edited December 18, 2015 by Recretos

[Ruben Amsterdam]

2 hours ago, Weather-history said:

More like the first part than the second part of this?

 

 

Haha, looks like GFS12z has found a slightly bigger fish to hit with. Mostly trop. driven, though. Looking similar to the excellent exp. charts posted above by Recretos. 

Edited December 18, 2015 by Ruben Amsterdam

[Nouska]

I'm not sure if this is what Recretos is mentioning above but the new parallel GFS is now on Meteociel.

The 06Z loaded to 384 - a comparison between old and new.

      new.   

[Frank_Wx]

It seems GFS OP is really trying to weaken / displace the PV by 300+ hours. Here was the 18z run at 10hPa. 

 

 

 

[Ruben Amsterdam]

Tendency towards a split in the lower vortex on the Berlin charts (+240 at 50hPa shown) this morning. Ofc. following yesterdays impressive tropospheric developments, but maybe there to stay in the next runs? 

[Singularity]

I greatly admired the combination of an extensive poleward ridge from the Baltic region an a deep Aleutian trough on the ECM 00z det. run days 8-10.

I notice that the MJO plots suggest the tropical convection has propagated a bit faster than the models were predicting over the past few days. It may be that the models think the're working with an MJO pulse and this is why they're not moving it fast enough; the kelvin wave that's actually in place should move considerably more quickly as far as I know.

I have a theory that a positive amplification bias in the ECM model from around +168 is actually enabling it to better show the probable consequence of the tropical forcing propagating across the Pacific more quickly and with decent amplitude, despite the ECMF not depicting that as such as of yesterday (though it could be that they've changed today). GFS/GEFS, on the other hand, are if anything prone to being too flat, or at least that was the case before they were upgraded this year. I've had mixed impressions from GFS since then, while for GEFS it's too early for me to tell really.

 

May the forcing be with us.

[Frank_Wx]

I noticed increased geopotential heights around Scandinavia beginning next week and beyond. Does this enhance energy transfer from the Troposphere to Stratosphere at all?

 

[feb1991blizzard]

The Berlin wave 1 height chart is going to make pretty viewing tomorrow morning but how much faith can we have in it baring in mind the 'Over Amplifier' 's record over the lat few winters. In reply to the post above, this should be a good example of how a wave can break from the Troposphere in to the Stratosphere.

[Weather-history]

Never noticed that before, ECM does 150hpa charts.

 

[Frank_Wx]

So....

 

[Ruben Amsterdam]

1 hour ago, Frank_Wx said:

So....

 

So? Trop. driven split in the lower stratosphere, as expected given current tropospheric model output. The upper and middle strat. thusfar do not show a similar pattern. Yet.