Stratosphere Temperature Watch 2015/2016

[chionomaniac]

42 minutes ago, Greenland1080 said:

Hi chiono...genuine question...

When was last time a normal trop event caused cold weather and a strat event increased the trop event so that we got a protracted cold spell....is that coupling?

I don't believe that there is such a thing as 'normal' - everything happens for a reason. But I have never seen an instance of HLB's during a period of strat Vortex Intensification. However, early winters 2009 and 2010 were times when trop based splits into the strat prolonged any cold spells because the strat vortex was disrupted significantly. But these were upward internal strat splits, which are completely different to downwards propagating warming events of a more mature vortex.

The more we get to know about SSW's we realise that they are set off by 'trigger' blocking events that deflect the waves sufficiently into the strat that can trigger the SSW which can then come back and lead to a more prolonged NH cold spell at mid latitude level. I have linked to these precursor triggers in recent posts.

 

[bluearmy]

The gfs warming at the very top comes into T240 on current output.  Wonder if Berlin will show this tomorrow?

[chionomaniac]

1 hour ago, bluearmy said:

The gfs warming at the very top comes into T240 on current output.  Wonder if Berlin will show this tomorrow?

Yep - definitely there at day 10 on 18Z - and through a Scandi based block which is my climo favourite for EN. So that wave 1 stationary wave will hopefully become established in the last third of the month. Question remains is that will this lead to the eventual big one. Feel tentatively that at this point the winter forecast is still on course.....

[Singularity]

I like the increase in mid-strat. (30 hpa) wave activity in the 9-12 day range on that 18z GFS det. run; the first significant improvement for a while at that level that hasn't been a whole two weeks away. Ties in with the 1 hpa warming reaching +240.

 

...but only two runs ago there was hardly any trouble at 30 hpa at all so this amount of downward propagation during the festive run-up is by no means given.

[bluearmy]

9 hours ago, bluearmy said:

The gfs warming at the very top comes into T240 on current output.  Wonder if Berlin will show this tomorrow?

And it is 

I'm sure someone will post the wave 1 temp chart at the same time which. Also some wave 1  gepot showing at the end of the run high up. 

Too early to get over excited in this . However, it does fit in with what's expected in the NW winter forecast. 

 

[feb1991blizzard]

3 minutes ago, bluearmy said:

And it is 

I'm sure someone will post the wave 1 temp chart at the same time which. Also some wave 1  gepot showing at the end of the run high up. 

Too early to get over excited in this . However, it does fit in with what's expected in the NW winter forecast. 

 

The reduction in 60N zonal wind speeds not as steep as forecasted the other day though.

 

 

 

[Interitus]

11 hours ago, chionomaniac said:

I don't believe that there is such a thing as 'normal' - everything happens for a reason. But I have never seen an instance of HLB's during a period of strat Vortex Intensification. However, early winters 2009 and 2010 were times when trop based splits into the strat prolonged any cold spells because the strat vortex was disrupted significantly. But these were upward internal strat splits, which are completely different to downwards propagating warming events of a more mature vortex.

The more we get to know about SSW's we realise that they are set off by 'trigger' blocking events that deflect the waves sufficiently into the strat that can trigger the SSW which can then come back and lead to a more prolonged NH cold spell at mid latitude level. I have linked to these precursor triggers in recent posts.

 

Well closer examination of winter 2009/10 shows that there was copious high level blocking through December and January while the MERRA 10mb wind strengthened from 19.77m/s on 08/12/09 to 55.23m/s by 10/01/10 accompanied with vortex cooling as expected with VI.

[Ruben Amsterdam]

Latest GFS06z seems a bit more progressive with the continuation of wave-1 activity than previous runs. It appears to start somewhere around the +168hrs mark but remains rather insignificant for considerable time. At the end of the run wave activity intensifies. Let's hope for an even more amplified signal in runs to come.

 

 

Edit: the 12z seems pretty consistent with max and min heights a little higher than in the 06z at the +384hr mark. 

 

Edit 2: just as you think there's a consistent signal, GFS reduces the pressure on the vortex. 

Edited December 10, 2015 by Ruben Amsterdam

[aginob]

Hi to all

Gino ... Switzerland ... remember ?

interested ?

Stratosphere Frcst at 10 mb ... New charts available

09.12.2015 => two UK Weather outlook

+0 h - +384 h 

http://www.theweatheroutlook.com

http://www.theweatheroutlook.com/twodata/datmdlout.aspx

have fun

 

[sebastiaan1973]

The AO is currently positive and is predicted to trend negative but still remain near neutral.

The negative AO trend is reflective of the model forecast of initial low pressure/geopotential heights over the North Atlantic side of the Arctic transitioning to more high pressure/geopotential heights.  Though the models are not predicting necessarily cold weather it should result in damping of the large positive temperature anomalies for Europe, western Asia and the Eastern United States.

However the models predict low pressure/geopotential heights to continue on the North Pacific side of the Arctic.  This will likely result in any cold weather being focused in Western North America for much of the remainder of December.

Models are predicting an increase in energy transfer from the troposphere to the stratosphere starting the third week of December.  This will likely lead to perturbation of the polar vortex during the latter half of December.  The more the vortex is perturbed, the higher our confidence in a cold second half of winter.

Longer-term high latitude boundary conditions favor a negative bias to the AO including extensive Eurasian snow cover and low sea ice extent in the Barents-Kara seas.  The key will be how strong the energy transfer from the troposphere to the stratosphere is in late December and how much the polar vortex is perturbed. If the energy transfer does not significantly weaken the polar vortex, the AO will likely remain mostly positive and mild temperatures will dominate the mid-latitudes.

The duration and amplitude of the atmospheric energy transfer or WAFz is likely to be critical for the weather during the middle and later parts of winter.  We continue to anticipate the active transfer of energy from the troposphere to the stratosphere and a weakening of the polar vortex starting in December and continuing into January.  Following the weakened polar vortex we would further expect a negative AO and cold temperatures across the Northern Hemisphere continents.  However if the active WAFz does not persist and/or strengthen in amplitude then the polar vortex will recover and remain strong, and it becomes increasingly likely that the stratosphere and troposphere will couple in a way that favors a positive AO with mild to even very mild temperatures across the Northern Hemisphere mid-latitude continents.

 

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

[Snowy L]

Decent warming on the 12z warming the North Pole by around 10-15c and by the end of the run there are 3 distinct warming events. That first warming is making its way to the High Res too which is encouraging.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015121012/gfsnh-10-384.png?12

 

 

Edited December 10, 2015 by Snowy L

[chionomaniac]

48 minutes ago, Snowy L said:

Decent warming on the 12z warming the North Pole by around 10-15c and by the end of the run there are 3 distinct warming events. That first warming is making it's way to the High Res too which is encouraging.

 

http://modeles.meteociel.fr/modeles/gfs/runs/2015121012/gfsnh-10-384.png?12

 

 

Check out the trop led split...

[Ruben Amsterdam]

7 minutes ago, chionomaniac said:

Check out the trop led split...

Yes, indeed. But trop. led and thus likely to vanish next run?

 

 

[chionomaniac]

11 minutes ago, Ruben Amsterdam said:

Yes, indeed. But trop. led and thus likely to vanish next run?

 

 

Exactly, but interesting nonetheless.

[bobbydog]

12 hours ago, Ruben Amsterdam said:

Yes, indeed. But trop. led and thus likely to vanish next run?

 

 

 

or not.......?

 

 

Edited December 11, 2015 by bobbydog

[lorenzo]

Indeed, it's still around on the 00z and yes always wary of troposphere led splits, the dynamics are knife edge.

Couple of charts from this morning 7hPa beginning to move into the 25-30 day look for precursor pattern to stratosphere event.

Also from NASA the heat flux plot along side this morning's wave 1 heat flux from Berlin.

From matthewman paper on the left image analog Nino vortex breakdown and on the right 97 by comparison, hopefully gives some insight into how the higher vortex is under attack.

It's a watch and see how it evolves still, however that monster Aleutian low could give things a decent shot in the arm.

[Interitus]

To put a dampener on the optimism, from today's MERRA 60-90°N average 10mb temperature of 199.63K for example, the earliest an SSW has been achieved from a similar level is 13 days in the case of 6/1/2013....but the second earliest is 45 days for 5/2/1995.

[Singularity]

To me that highlights how strong the wave action needs to be to take down the strong vortex any time soon. I'm not sure if trop-led splits follow quite the same rules though - that's a real wildcard being suggested by some output, if only we could depend on it!

[Cheshire Freeze]

Does any of the more learned on here know how any warming is likely to manifest i.e would we be looking at a fairly rapid trop response or are we going to be waiting around? I only ask because I don't fancy using up the best (first half) part of January waiting for any effects to be felt. February cold is never the same in my opinion.

[Ruben Amsterdam]

12 minutes ago, CreweCold said:

Does any of the more learned on here know how any warming is likely to manifest i.e would we be looking at a fairly rapid trop response or are we going to be waiting around? I only ask because I don't fancy using up the best (first half) part of January waiting for any effects to be felt. February cold is never the same in my opinion.

Don't you think we have to wait before warming actually happens, before making statements on the possible effects of such a warming? Warming may or may not have implications (positive or negative) for Western-European weather. For all we know downwelling may not even occur. Count your chickens after they hatch, not before (in Dutch we say "don't sell the hide before you shoot the bear"). 

Edited December 11, 2015 by Ruben Amsterdam

[Cheshire Freeze]

4 minutes ago, Ruben Amsterdam said:

Don't you think we have to wait before warming actually happens, before making statements on the possible effects of such a warming? Warming may or may not have implications (positive or negative) for Western-European weather. For all we know downwelling may not even occur. Count your chickens after they hatch, not before (in Dutch we say "don't sell the hide before you shoot the bear"). 

Exactly why I said 'any warming' instead of THE warming or words to that effect. No chicken counting, just a hypothetical question in all honesty.

[Ruben Amsterdam]

9 minutes ago, CreweCold said:

Exactly why I said 'any warming' instead of THE warming or words to that effect. No chicken counting, just a hypothetical question in all honesty.

Personally I think any predictions more accurate than "higher change of northern latitude blocking" are speculation, especially since warming has not occurred and the specific type of event is not yet known (apart maybe that a wave-1 event is more likely). 

But maybe one of the semi-pro's has some interesting thoughts, yes. I am all ears. 

Edited December 11, 2015 by Ruben Amsterdam

[Cheshire Freeze]

1 minute ago, Ruben Amsterdam said:

Personally I think any predictions more accurate than "higher change of northern latitude blocking" are speculation, especially because warming has not occurred and the type of event is not yet known (apart maybe that a wave-1 event is more likely). 

But maybe one of the semi-pro's has some interesting thoughts, yes. I am all ears. 

Thanks

[Singularity]

-35*C+ appears on the GFS 12z det. run at 216 hours and is maintained throughout the rest of the run with little sign of abating. There's a very persistent Aleutian trough on this run with plenty of vigorous storms in the vicinity.

 

That's a long way improved from the 06z det. which once again was the least encouraging run in lower-res. That's the 3rd or 4th day in a row which has followed that pattern, for whatever reason.

Today's 12z det. is the best I can recall seeing so far at the 30 hpa level. Meanwhile at 1 hpa:

 

Very nice to look at, but heavily laden with the usual caveats.

Edited December 11, 2015 by Singularity

[Singularity]

Just look at that deep trough right over the Aleutians from the ECM det. tonight, and coming about a week after that ex-tropical monster expected in  a few days time.

Having said that, I'm not sure what the ideal trough position is - is it slap bang overhead or more to the side (east or west) and how far poleward, for that matter? I'm sure this can be interpreted from a paper somewhere but a simplified summary would be most appreciated, thanks.