Stratosphere Temperature Watch 2012/2013

[BLAST FROM THE PAST]

So a test period coming

1. Forecast warming, how good will the forecast be in coming to fruition [seems to be forever, t240 but that may be just misjudged perception

2. Similar warming to 1962? Well if it continues lets see what result it brings. If continues similar then theoretically we should see similar scale blocking and widescale lengthy cold outbreak ?

BFTP

[Weather-history]

So a test period coming

1. Forecast warming, how good will the forecast be in coming to fruition [seems to be forever, t240 but that may be just misjudged perception

BFTP

Well here's 0 hour

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20121219;time=00;ext=00;file=npst10;sess=846b6de43e84ea8b5756f810961f94de;

And here's 120 hour

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20121219;time=00;ext=120;file=npst10;sess=846b6de43e84ea8b5756f810961f94de;

And here's 180hrs

http://nwstatic.co.uk/viewimage.pbx?type=gfs;date=20121219;time=00;ext=180;file=npst10;sess=846b6de43e84ea8b5756f810961f94de;

You can clearly see the warming even at 120hrs.

So it is definitely getting closer and not always on the edge of the horizon.

Edited December 19, 2012 by Weather-history

[Duane S.]

The EP vectors from ECM are looking a touch insane this morning at 10 hpa - not seen that before.

http://wekuw.met.fu-...mwf1/fluxes.gif

That is pretty mad, I noticed it on yesterday's forecast but that's even more extreme. I wonder though, could this work against us as the warming hits? Knowing our luck, probably!

[chionomaniac]

The EP vectors from ECM are looking a touch insane this morning at 10 hpa - not seen that before.

http://wekuw.met.fu-...mwf1/fluxes.gif

The EP vectors tend to become dramatically increased as pressure is put on the vortex.

Here is a link to a post back in 2009 that shows how this occurred in that year prior to the record SSW.

http://forum.netweat...00#entry1509486

And last years fluxes for comparison

[LomondSnowstorm]

That is pretty mad, I noticed it on yesterday's forecast but that's even more extreme. I wonder though, could this work against us as the warming hits? Knowing our luck, probably!

It certainly would do, no one really wants to see an equatorward EP flux wit any strength going forward. I believe that was partly responsible for the sub optimal positioning of blocking last winter too.

Cheers for the explanation above chiono, I wasn't aware of that pattern. Quite an encouraging sign at this stage then.

Edited December 19, 2012 by LomondSnowstorm

[lorenzo]

Excellent Ed interesting to see a match on the 2009 chart prior to the SSW that somewhat mirrors the last few days on 2012 plots. Good job those threads are still around.

[chionomaniac]

Here are the last 3 frames from the 00Z GFS run at 10 hPA (courtesy of NW extra)

What we see here is the vortex beginning to move away from Siberia very quickly. Having spent years looking at these type of events now, and having watched most SSW's on the sudden stratospheric warming website when it was still available, I recognise this as the initial movement of the vortex prior to its collapse. It is akin to letting go of a blown up balloon that is yet to be tied. So, if this run was to continue for five more days then we would see a SSW with complete disintergration. Around the 10th January.

[chionomaniac]

Excellent Ed interesting to see a match on the 2009 chart prior to the SSW that somewhat mirrors the last few days on 2012 plots. Good job those threads are still around.

Remember, Feb 2009 was a split SSW as was 62/63 I believe.

[mcweather]

Here are the last 3 frames from the 00Z GFS run at 10 hPA (courtesy of NW extra)

What we see here is the vortex beginning to move away from Siberia very quickly. Having spent years looking at these type of events now, and having watched most SSW's on the sudden stratospheric warming website when it was still available, I recognise this as the initial movement of the vortex prior to its collapse. It is akin to letting go of a blown up balloon that is yet to be tied. So, if this run was to continue for five more days then we would see a SSW with complete disintergration. Around the 10th January.

Very interesting post Chiono .Pretty much in line with GP'S post in the model discussion a day or so back about things getting interesting from the around the 10th January.

[lorenzo]

Was just running through Dec 2008 then Jan / Feb 2009 on Meteo NH archive, what a monster North Pacific ridge develops mid Jan and this slices the established vortex. 62-63 shows as split event central date at the end of January

Found a couple of tables I ripped from one of the papers on my old PC, excuse the annotations cannot recall what they referred to right now.

http://www.agu.org/p...9GL038776.shtml

Edited December 19, 2012 by lorenzo

[CloudyFrost]

What are your thoughts Chiono on how PV may split? For example where would the split lobes most likely locate given the current 10 hPA charts? And if the 10th Jan is a date to look for splitting to occur, how/when would it start to show in the daily H500 charts?

Sorry for all the questions, enjoy this thread and it's reasoned approach!

[Vertical Limit]

Very interesting developments re increasing probablity of a SSW. Having read Cohens paper and the analogue years for a displaced and spilt vortex, it seems that our chances of a prolonged cold spell are much better if the vortex splits.

Can vortex disintergration be defined as a split?

[chionomaniac]

What are your thoughts Chiono on how PV may split? For example where would the split lobes most likely locate given the current 10 hPA charts? And if the 10th Jan is a date to look for splitting to occur, how/when would it start to show in the daily H500 charts?

Sorry for all the questions, enjoy this thread and it's reasoned approach!

Thanks CF and welcome to NW.

I don't think that we are likely to see a vortex splitting event here ( so far as we can tell). We are more likely to see a displaced vortex which can completely disintergrate in a strong event, rather than return to the pole.

The exact effect that this can on the troposphere is unknown at this point. However, it is akin to turning the stratospheric hoover off and watching where the tropospheric dust settles over the NH high latitudes. There will be areas where vortex remnents will remain and areas where blocking will be prevalent. My only guess at this point is that blocking is likely over Eurasia as it has been such a feature this winter. The paper by Cohen suggests that blocking is likely over Greenland but in truth we don't know.

VL has a point about perhaps splitting being more favourable to the UK. Certainly, after the 2009 event the Se UK was directly in the firing line when a split remnant of vortex directed a pulse of energy eastwards. After the stratospheric hoover is turned off, I do believe that tropospheric underlying teleconnections become critical for blocking (for the UK) in the post 45 day period and these should be monitored closely.

[feb1991blizzard]

Warming goes off the scale on the 6z GFS at the 30mb level!!

[chionomaniac]

Warming goes off the scale on the 6z GFS at the 30mb level!!

Yes, another good run.

Up until now we have been seeing a strong warming forecast with no end result, as the warming has been caught in the vortex without penetrating. We are seeing a new trend over the last few runs with penetration forecast - even though a SSW has not yet been forecast - my guess is that it would be a fait accompli if the runs verified up to that point. So lets hope they do!

[feb1991blizzard]

Yes, another good run.

Up until now we have been seeing a strong warming forecast with no end result, as the warming has been caught in the vortex without penetrating. We are seeing a new trend over the last few runs with penetration forecast - even though a SSW has not yet been forecast - my guess is that it would be a fait accompli if the runs verified up to that point. So lets hope they do!

As a novice on this subject and my first year of actually trying to understand the charts rather than just you or GP to tell us if its good news, to my untrained eye, it looks like the models in FI are far more consistent from run to run with stratospheric forecasts than 500mb and surface pressure forecasts.

[Glacier Point]

and the GFS and ECM runs at day 10 are almost identical which gives confidence that at that point, the modelling is fairly robust.

The issue is around days 12-15 - how fast and what overall shape the vortex takes in its final days ?

GEFS days 6 through 10 look like further adding to the tropospheric preconditioning for a vortex destruction with ridges over E. Europe and troughing over the Aleutians. Mountain torque activity should be high at this stage, so more killer blows if we need it around mid month.

[lorenzo]

From the displacement list above, analogs for H5 beginning on the central date listed, broken down into 2 rows.

The first row shows the first 15 period, 2nd 15 day period then 3rd 15 day period, followed by the 30 day and 45 day anomalies.

Took me a while building these so will spend some time now looking through them to see what we can learn from them. Will also be a useful reference come January 2013.

1962

1970

1987

2002

2004

[bluearmy]

stewart, re the recent gfs fi strat forecasts - is the vortex now taking on the shape and placement you expected pre the issue of the winter forecast. (extended on siberia/canada axis?)

[Glacier Point]

... was definately along the lines of a Canadian / Alaskan ridge and displaced vortex towards Russia.

The key think for me looking at Lorenzo's plots is that troposhperic pressure falls in the North Pacific. If that occurs, I think we stand a well above average chance of latching onto a piece of the vortex.

This is what I like about our current projected pattern. It screams El Nino type pattern across the NH rather than the 2002 La Nina type variant.

Edited December 19, 2012 by Glacier Point

[bluearmy]

'latching onto a piece of the vortex'......................................... as ever, a high risk for us that it may not be where we need it to be to deliver the results so many crave. at least it means we may be in the raffle though !!

[Glacier Point]

however, not entirely for this thread... we are not soley relying on the stratosphere going into mid January. Nino region 4 is about to show a not insignifcant jump in temperatures in response to Kelvin Wave and another westerly wind burst (the most easterly since 2009) is beginning which should add fuel to the tropospheric signal converging on a net increase in angular momentum / MJO phase 7/8 type pattern for mid January onwards which should really gun for a -NAO/-AO pattern. Moreso than any other month, the strength of the AO should force the NAO negative which in most cases should deliver the goods.

Edited December 19, 2012 by Glacier Point

[chionomaniac]

however, not entirely for this thread... we are not soley relying on the stratosphere going into mid January. Nino region 4 is about to show a not insignifcant jump in temperatures in response to Kelvin Wave and another westerly wind burst (the most easterly since 2009) is beginning which should add fuel to the tropospheric signal converging on a net increase in angular momentum / MJO phase 7/8 type pattern for mid January onwards which should really gun for a -NAO/-AO pattern. Moreso than any other month, the strength of the AO should force the NAO negative which in most cases should deliver the goods.

This was the point I was trying to make earlier, GP - but less well than you. The Strat could possibly deliver the stage, but without these tropospheric actors in position, we will be left with no performance.

Edited December 19, 2012 by chionomaniac

[Glacier Point]

Actor at the theatre entrance ?

[AWD]

This is different I think;

Is that not two separate warming's now? With the vortex stuck inbetween & about to pop? Cross polar flow?

Edited December 19, 2012 by AWD