[Stratosphere temperature watch - 2016/17]

This mornings ensemble looks very promising with about 50% of the members opting for a reversal at 10hpa @65N. Only one member shows an "increase" of zonal wind speeds but mind you, that is only just above todays zonal winds which are unseasonably low. 

[Stratosphere temperature watch - 2016/17]

I can't help but thinking that GFS outer FI is showing the onset of a proper SSW now. Ofcourse, very far away still, but not entirely unlikely given the persistent troposferic pattern. 

 

Edit: the GFS12z operational turned the warming signal slightly down, but it is still there. Meanwhile, we see the dipole pattern rotate somewhat, with main height anomalies over Canada and the cortex core over Northern Russia. I suspect we are very close to reversal at this point. The pattern is also present lower down (30hPa) and, if you would litteraly translate this down to the troposphere, one would expect the lowest gph to move slowly eastward over Scandinavia towards Russia while heights are rising over Greenland again. Do any of the more knowledgeable on the subject have any thoughts about this?

[Stratosphere temperature watch - 2016/17]

First proper Canadian Warming modelled? 

 

[Stratosphere temperature watch - 2016/17]

Quote

u profiles from GEFS have relaxed from the vaunted Canadian Warming angle/ reversal - this I know is a trend as have got excited about this prior to vortex intensification in previous years, for Ed to reign me in! you can see the shift in projection and tightening of the ensembles as we exit the disruption of the anomalous heat flux. 

Speaking of which is shown on the first plot a considerable incursion to the vortex and interesting to see it stick around the upper levels of the vortex, juxtaposed is the u response and note the disruption (blue) and the forecast acceleration in vortex activity from here. 

Some less pretty modelling I suspect for those inclined to enjoy the NH blocking anomalies as we enter the climatalogical vortex development phase.

I tend to disagree with the above re. recovery of the vortex and tightening of the ensemble members. Even in the "tightened" ensemble the strongest u mean winds do not even match the wind speeds from early October. Besides, I believe GFS's ultimate FI is tending towards a more displaced vortex in contrast to runs from a few days ago and, on top of that, todays ensemble shows that there are still options for a double dip-scenario (of course considering the limitations, 65NB only, of these graphs). 

. 

 

[Stratosphere temperature watch - 2016/17]

6 hours ago, feb1991blizzard said:

Does anyone think that split will be sustainable for long enough to enable Tropospheric high latitude blocking to occur during December?

I guess in case of a split much depends on the actual positioning of the strongest part of the vortex (in the lower stratosphere). We should hope for the minor part to set up shop over Greenland with the bulk of all "blue and purple" concentrated over the Asian and Alaskan sector. If this works out well for us, I think we may have a good shot at it. 

[Stratosphere temperature watch - 2016/17]

On 22 Oct 2016 at 10:16, davster11 said:

A complete novice but the learning curve is steep following you guys.

I have a simple question, I won´t try backing it up with my personal arguments, I'll simply ask the question:
Has science ruled out the possibility that SSWs can contribute to significant cooling?

Bearing the rules of thermodynamics in mind, spreading a concentrated cooled down area to a large warmer area and having 
that area being cooled down again seems like it would....cool things down?

 

I have been thinking about this again and I think it is a nice thought experiment to add the Southern hemisphere into the equation. The SH is completely different to our half of the globe as it lacks large landmasses and mountain ranges at middle latitudes. This results in far less wave breaking, and subsequently SSWs are very rare. I think this is one of the reasons that Antartica is not warming as fast as the Arctic: the tight vortex makes the continent actually more isolated to warmth from lower latitudes.

[Stratosphere temperature watch - 2016/17]

11 hours ago, davster11 said:

A complete novice but the learning curve is steep following you guys.

I have a simple question, I won´t try backing it up with my personal arguments, I'll simply ask the question:
Has science ruled out the possibility that SSWs can contribute to significant cooling?

Bearing the rules of thermodynamics in mind, spreading a concentrated cooled down area to a large warmer area and having 
that area being cooled down again seems like it would....cool things down?

 

Hei and welcome from neighbouring Norway

I don't think science rules anything out per se, but a quick glance at the literature does not really yield any papers that directly address your question. I assume you mean cooling at the surface by the way? As far as I know IPCC assumes the stratosphere in general to cool down as a result of climate change. 

What comes to my mind is that, yes, stratospheric events can cause colder than average temperatures at lower latitudes but at the same time these events are usually accompanied by strong WAA that causes warmer than average conditions in other places, usually at high latitudes. For example, the average temperature yesterday in Longyearbyen, Spitsbergen, was +7.4°C in stead of the normal -6.5°C (winter has not arrived there at all so far, very concerning). Also, stratospheric events occur irregularly and are temporary in nature.

I think that global warming/Arctic Amplification (snow, ice, and vegetation albedo feedbacks) is causing the arctic to warm so rapidly and to such extend that it far outweighs any possible effects of temporary stratospheric events. 

[Stratosphere temperature watch - 2016/17]

It's getting hard to hide excitement with the 06z ramping things up even further. I do not recall seeing charts like this so early in the season, 2010 was more modest, wasn't it?

[Stratosphere temperature watch - 2016/17]

There is no direct answer to that question, although we would all like to know the answer, of course. For now all we can conclude is that the vortex may not develop uninhibited through early winter like last year, but could be displaced. 

Not all years with early or Canadian Warmings, or even SSWs, yield fierce winters. Some did ('62), others did not. A weaker vortex should theoretically allow more meridional flow and more blocking, but blocks need to be in the right place - and they very well may not be - to deliver cold to where we live (which is just a "pixel" if you look at the world wide scale of things). 

 

[Stratosphere temperature watch - 2016/17]

I was just about to post the same graphs, haha. Very interesting indeed, especially because runs are getting more progressive. 

Great to see the thread reopened this year and thanks to all who contribute!

[Model Output Discussions 12z 01/09/2016]

Crewcold, I would not call it a split (yet). However, the blue "tail" does show the vortex is not happy as could be

Quote

GFS suggestive of a possible eventual split at the end of the run into November, certainly a lot of pressure being put on the fledgling vortex.

As others have said, very interesting.

 

[Model Output Discussions 12z 01/09/2016]

14 minutes ago, Sperrin said:

Hi guys, could you explain what Ruben's chart is indicating for the novices here? Cheers. 

To me it shows that, in contrast to last year and I would say "normal" circumstances, the stratospheric vortex is not in a state of uninhibited intensification, centered over the north pole. On the contrary, we see heights rising over the Eastern Russian/Canadian sector and as a result the vortex is displaced. This might (!!) cause mean zonal mean winds at 60NB to come close to reversal. I strongly believe it is this that could support blocking at high latitudes. 

That being said, I should probably add that the vortex is not yet being "ripped apart" as would often be the case with mid-winter Sudden Stratospheric Warmings. It is displaced, but the core does not warm all that significantly and heights continue to drop. This - as far as I know - is in agreement with what we call Canadian Warmings (an early winter stratospheric event) but I am no expert in these definitions. 

[Model Output Discussions 12z 01/09/2016]

GFS inching closer to a reversal in zonal mean winds at 10hPa? Most interesting chart of the suite I would say. 

[Stratosphere Temperature Watch 2015/2016]

1 minute ago, Gael_Force said:

A couple of the GFS ensemble members going for it at 65N.

http://www.atmos.albany.edu/student/hattard/realtime.php

Not the curve usually associated with the start of November.

 

Thanks a bunch and the most important conclusion I think is that none (!!) of the members go for increasing mean zonal wind speeds! 

[Stratosphere Temperature Watch 2015/2016]

Maps like these this early on in the season: one eye open for me! 

 

Anyone info on zonal mean wind predictions (GFS ENS)?

[Stratosphere Temperature Watch 2015/2016]

Split yes, but SSW...?

[Stratosphere Temperature Watch 2015/2016]

06z close to a technical? 

[Stratosphere Temperature Watch 2015/2016]

9 minutes ago, Katrine Estella said:

I have just seen this on Twitter today: SSW being shown on the GFS map.

 

 

If this is the map shown along with it, it does not show a technical SSW  

[Stratosphere Temperature Watch 2015/2016]

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.

[Model output discussion - 1st December onwards]

44 minutes ago, blizzard81 said:

Looking at 00z ECM Debilt ensembles, and there are more colder members in the mid to long term when compared to yesterday's 12z set.

This mornings run (note that this is for the eastern part of the Netherlands, close to the German border, De Bilt is in central the Netherlands and is a bit warmer, usually) shows some colder members indeed. Mostly inversion weather in a slow continental flow, would be my guess. I also included an ensemble with wind directions which shows a tendency towards more south/easterly winds instead of south westerly wind, but this is not all convincing yet.

From top to bottom: T2m, dew point, precip., wind 10m, wind 10m gusts, cloud cover.

[Stratosphere Temperature Watch 2015/2016]

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? 

[Stratosphere Temperature Watch 2015/2016]

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. 

[Stratosphere Temperature Watch 2015/2016]

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.

[Model output discussion - 1st December onwards]

12 minutes ago, Fozfoster said:

Sorry Ed but things have been much colder too!! But I don't buy that balancing out thing either. Not in one season or for that matter year. 

It's funny how some interpret the fact that averages result from high and low values as an almost supernatural "power of compensation". 

[Thursday 17th December 2015 - General Weather Chat.]

2 hours ago, carinthian said:

Hi Ruben, Whats the latest. See 16C now reached in parts of Benelux.

 C

15.3 is the max. at the official station De Bilt so far. I do not expect it to rise any further given the cooling trend in the last hour. Some other parts of the country reached temperatures of >16ºC.

Highest max. temp recorded at an amateur station (stations that meet national standards, but are not official stations of the Dutch met. service) is 18.9ºC in the south-east of the country. That's mad!

So, not a new Tmax record, but ex equo score. We can still break some all-time winter daily average and minimum temperature records though.