Stratosphere Temperature Watch 2014/2015

[feb1991blizzard]

Was this warming forecast??? Are we looking at a pleasant surprise here? So hopefully the ramifications of this will feed into the trop quickly and the heart of winter will reep the benefits for us in the uk.

 

It has been forecast on the GFS for a few days now but I have refrained from commenting on it too much as there have been times when warmings have been forecast at this range and then the charts change after a few runs, this run though shows a much more aggressive warming, i have been thinking for a few days now that there might be more comment on it and was going to leave it to the experts to decipher what will happen troposherically but to me the fact that it downwells pretty quickly into the mid  strat without too much variation wrt vortex location, it doesn't take a genius to work out that if it does verify and downwells into the trop, we would be looking some potent cold spells in a few weeks time.

[WINTRY WALES]

Thanks for the reply feb

It does seem that the usual experts comments and analysis has wained of late. Of course everyone has other things going on in their own lives....just a bit surprised that this thread is not a tad livelier with what is going on regarding the strat at the moment.

[snowking]

Thanks for the reply feb

It does seem that the usual experts comments and analysis has wained of late. Of course everyone has other things going on in their own lives....just a bit surprised that this thread is not a tad livelier with what is going on regarding the strat at the moment.

I think the thing is at this stage, given a fairly mundane winter tropospherically up until this point, people are now only really interested in the end game of any stratospheric activity - i.e. What is the downwelling time and what is the specific effect likely to be on the longwave pattern in the troposphere.

To that extent, I personally (and I know this is not restricted just to me, this includes the likes of Nick, Ed, Tony, Andrej et al - too many other wonderful posters in this thread) will only post something when I think it will be of interest to the wider community.

At the moment we are in the very early stages of a projected warming - if this was December 1st and we had an entire winter left to see how that plays out I think this thread may be a little more active. Unfortunately there is definitely a growing sense of impatience this season, and to that extent I think nobody wants to 'poke the bear' and start making wild estimations which do not bear fruit (and at this stage that is all we could offer, essentially a guesstimate)

There are a couple of things we need to wait for therefore

1. The warming/geopotential activity shown to come down towards days 5-7 with some consistency across suites

2. The downwelling (if at all) to start showing within a reliable timeframe

Until we see these two, whilst we can speculate, ultimately interest in this potential event and how it unfolds via NWP will largely be limited to the sad few of us who find the stratospheric story a fascinating one irregardless of its ultimate tropospheric effect for NW Europe - every such event is still very much a learning curve for all of us, even the most seasoned of experts on the matter such as Ed, Tony, and I would imagine even full time pro's such as Matt (I'm sure he won't mind me saying this because this is true of everyone studying wintertime stratospheric conditions - even all the way to the top of the Met Office who were a couple of years slower to use stratospheric warming forecasting - publicly at least - than this thread!) and so the more activity we get to see and monitor the effects of, no matter where those effects are hemispherically, is more to help us refine our technique.

Of course with impending snow events potentially this week too eyes are also drawn elsewhere - one of the many quirks of this community that you get to see over the years

I hope that's a clear enough explanation and any questions feel free to ask away

Regards,

SK

Edited January 18, 2015 by snowking

[WINTRY WALES]

Excellent reasoning snowking. Whilst the timing of this isn't at the start of winter as you pointed out the running analysis from the gents who you mentioned is of great help for us all to learn from...even if we don't see any impact in our part of the world from any downwelling that occurs. Hopefully the thread sparks in to life from these chaps in upcoming days as this will be a good sign of what might occur in the non too distant future.

[Snowman.]

2nd run coming.

 

[hammy]

Sorry to go off topic, but I was just wondering if anyone could point in the right direction.. I have always been interested in the goings on with the stratosphere and how it effects our weather, could anyone give me any direction to where I could read about it please?

 

Again sorry to go off topic but I wasn't sure where else to put this! 

 

Cheers

Hammy

[chionomaniac]

Sorry to go off topic, but I was just wondering if anyone could point in the right direction.. I have always been interested in the goings on with the stratosphere and how it effects our weather, could anyone give me any direction to where I could read about it please?

 

Again sorry to go off topic but I wasn't sure where else to put this! 

 

Cheers

Hammy

Have you read the first post - this is set up as a basic tutorial. From there on google is great and the teleconnective paper thread.

[hammy]

Have you read the first post - this is set up as a basic tutorial. From there on google is great and the teleconnective paper thread.

 

Didn't even cross my mind to look haha! 

 

Cheers! 

Edited January 18, 2015 by hammy

[Snowman.]

3rd

 

[snowking]

^^^

 

Yep, without wanting to over-analyse each individual op run at such distance (awaiting control and ensemble mean guidance too) the 12z det. warming is stronger and remains stronger for longer - we are likely to see some tooing and froing (as ever) over the coming days with this forecast warming, but that temperature wave peaks at 0-4c and is with us from +324 right through to the end of the run.

 

The other thing to note is the warming actually begins at +264, so come Tuesday we should be able to see in the outer reaches of the ECMWF whether we have any such support for such a scenario. 

 

SK

[MPG]

Near to a technical SSW.

 

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2015011800&var=HGT&lev=10mb&hour=384

 

 

Out at 384 hours? Garden path again?

[snowking]

Out at 384 hours? Garden path again?

Always a possibility at that range, but some interesting discussions going on over at Twitter at the moment...

First of all to say that the 12z GEFS suite continues strong support for the warming scenario created by an East Asian mountain torquing event

We also seem to have confirmation though that this is now supported by the ECM EPS suite too - always a good sign.

As ever no guarantees of anything at this range - even if this comes off we need to see how the potential downwelling effects look - but this provides much more optimism as we head in to February. Especially if we can see some of the bias corrected MJO projections from today coming to fruition

SK

[chionomaniac]

Out at 384 hours? Garden path again?

Is this the garden path that led to a fairly substantial warming 10 days ago, with some subsequent downwelling and that would have been a SSW if it wasn't for the fact that the strat pv had already split? I'll take it thanks.

[feb1991blizzard]

Out at 384 hours? Garden path again?

 

A warming has been showing for a few days now and I was waiting to see how it pans out and let others decipher, however, that strength of warming warranted at least a mention seen how it actually starts a lot earlier than 384, also it has now been backed up on 2 subsequent runs and their ensemble suites, each slightly upgrading the warming from the previous run.

 

 

EDIT : Perhaps this will be the other half of the SSW chiono!

Edited January 18, 2015 by feb1991blizzard

[Jonan92]

And again

 

 

[feb1991blizzard]

GEFS 18z bias corrected mean is even more aggressive than the GEFS mean. I wonder if its because its reacting to the signal to kick the MJO back out of the COD into phase 6.

 

Edited January 19, 2015 by feb1991blizzard

[MPG]

Is this the garden path that led to a fairly substantial warming 10 days ago, with some subsequent downwelling and that would have been a SSW if it wasn't for the fact that the strat pv had already split? I'll take it thanks.

And what effect did it have on the UK? Never mind the UK, I suppose we are still waiting for the 'blocking' to appear over higher latitudes (maybe Greeland) from that event? Or because the vortex was split, blocking won't happen?

 

Or are we expecting 'blocking' to occur once this event verifies?

 

This cooler period surely has no relation to the previous 'half SSW'?

Edited January 19, 2015 by MPG

[bluearmy]

Don't really know the answer to that MPG. Need some careful re analysis of the trop/strat charts over the past fortnight.

Ed is right though - we were very unlucky to miss a proper SSW two weeks or so back. That would definitely have had consequnces for nw Europe .

And so we move on.

As I have said before this winter - I don't believe the strat will force changes in the trop pattern without a sustained reversal of upper zonal flow.

That doesn't mean I am right and that the early jan warming hasn't forced the weaker trop vortex we currently see.

[Catacol]

And what effect did it have on the UK? Never mind the UK, I suppose we are still waiting for the 'blocking' to appear over higher latitudes (maybe Greeland) from that event? Or because the vortex was split, blocking won't happen?

 

Or are we expecting 'blocking' to occur once this event verifies?

 

This cooler period surely has no relation to the previous 'half SSW'?

 

Ummm  - warming was 10 days ago. Anyone who understands even a bit about the strat knows it takes a bit of time for effects to downwell. We are about to have an interesting week with the atlantic depowered and high pressure more evident than it has been so far this winter. You do the calculation. 

 

SK - for my part I do believe that the weaker trop vortex and profile over the atlantic sector is directly related to the previous split above. Stop pumping the handle, and that old spinning top will begin to slow down...

Edited January 19, 2015 by Catacol_Highlander

[Recretos]

If you are using GEFS for strat guidance, let me recommend the bias corrected version. That is pretty much the only GEFS version I ever use.

[MPG]

Hows the 6z looking? A weaker signal?

[Crocodile23]

Hows the 6z looking? A weaker signal?

 

Much weaker.

[Lacking Geopotential]

If you are using GEFS for strat guidance, let me recommend the bias corrected version. That is pretty much the only GEFS version I ever use.

 

That sounds sensible.  Out of interest, what bias is being corrected?

[Duane S.]

Can you give the link that contains the WMO definition?

Thanks.

Hi, sorry just remembered I didn't get back ref this...

This is copied and pasted from the wiki SSW page which cites the WMO as source...

"Minor warmings are similar to major warmings however they are less dramatic, the westerly winds are slowed, however do not reverse. Therefore a breakdown of the vortex is never observed. Mclnturff states: a stratospheric warming is called minor if a significant temperature increase is observed (that is, at least 25 degrees in a period of week or less) at any stratospheric level in any area of winter time hemisphere. The polar vortex is not broken down and the wind reversal from westerly to easterly is less extensive."

Which to my mind backs up my earlier comments that we did have an SSW but of the 'minor' variety. I think confusion comes from some (rightly or wrongly) only calling it an SSW if it is of the 'major' variety which specifically requires a U wind reversal at 10hpa / 60N, which although close, was not achieved earlier in the month.

[Duane S.]

That sounds sensible.  Out of interest, what bias is being corrected?

As I understand it, past forecasts and their verifications are looked at along with the input/start data of the current run. Adjusting previous inaccuracies often improves the midrange (and I suppose subsequently longer range) forecasts as opposed to short range which wouldn't be that affected.