Stratosphere Temperature Watch 2012/2013

[AWD]

Can anyone post a link to the 10hpa stratosphere temperature forecasts from GFS that keep getting posted here?

http://www.cpc.ncep.noaa.gov/products/stratosphere/strat_a_f/

[Recretos]

Can anyone post a link to the 10hpa stratosphere temperature forecasts from GFS that keep getting posted here?

http://www.meteociel.fr/modeles/gfse_cartes.php?ech=6&code=code&mode=10&mode3h=&runpara=0&carte=1

http://www.instantweathermaps.com/GFS-php/showmap-strat.php?run=2012121512&var=TMP&lev=10mb&hour=384

[chionomaniac]

I would like to point out that according to Cohen there is a temporary height rise to our SW days -28 to-21.

if any can paste the chart from his paper I would be grateful. Thanks.

[Recretos]

I would like to point out that according to Cohen there is a temporary height rise to our SW days -28 to-21.

if any can paste the chart from his paper I would be grateful. Thanks.

In high resolution. Presented in color are sea level pressure anomalies, and mean values with lines.

a,b,c - prior to vortex displacement,

d,e,f - prior to vortex split

500mb pattern and MSLP forecast, for comparison.

Regardless of the latest GFS runs slightly reducing the warming intensity, I still think that the runs are great, because of the continuing trend of the weakening cold core.

Edited December 15, 2012 by Recretos

[Buriedundersnow]

I would like to point out that according to Cohen there is a temporary height rise to our SW days -28 to-21.

if any can paste the chart from his paper I would be grateful. Thanks.

so is it roughly a week till we start to see anything from the russian high moving west then if the patterns are correct and it all works out like stated in the cohen paper

[Buriedundersnow]

we are getting hieght rises to the southwest which is what it says in cohen as u can see in the ecm at +144 but when u roll on to +168 u see there is a part of the russian high split off and sat around scandanavia would that tie in well with that cohen paper with the high sat there ready to move in from the west.

http://meteociel.com/modeles/ecmwf.php?ech=144&mode=1&map=1&archive=0

sorry about the questions but still trying to learn.

[Mark Bayley]

Just got round to reading the Cohen paper "Tropospheric Precursors and Stratospheric Warmings" and "Eurasian Snow Cover Variability and Links with Stratosphere-Troposphere Coupling and Their Potential Use in Seasonal to Decadal Climate Predictions"

Very interesting reads, also downloaded a few other papers, although annoyingly even with university access there's still some i can't get on to! This is how i read the following papers, so please correct me if i have made any misconceptions.

To summarise vortex displacement events are associated with above average heights over Siberia, which in turn is associated with above average October snow cover (with cold dense air promoting higher pressure) while splits are associated with the core of the heights centred closer to Scandinavia (how in interpreted text and the figures).

Prier to vortex displacements we see an increase in wave one activity, i.e. large scale planetary waves (Rosby waves) propagating up into the stratosphere, while during splits there is a greater increase in wave two activity, which i interpreted from the following. "Previous studies have shown that snow cover anomalies and SLP anomalies associated with the Siberian high prior to stratospheric warmings and winter AO events have more of a wave-one characteristic (Cohen et al. 2001, 2002), which are more closely associated with vortex displacements (Martius et al. 2009)" "Prior to vortex splits (Panel 1c), both of these features are present, but are weaker instead the most statistically significant feature is anomalous high pressure stretched across the mid-latitudes of the North Pacific. The anomaly features resemble a wave train emanating from the North Pacific and propagating over the Pole or an asymmetric shift in the main storm tracks, with a northward shift in the North Pacific and a southward shift in the North Atlantic. Together these anomaly centers more closely resemble a wave-two anomaly pattern" Cohen and Jones, (2011).

After a warming event, wave activity decrease and a -AO ensues. I also read that displacements may be more ideal for the UK, with blocking more likely in the atlantic basins, while splits are often associated with blocking in the pacific basins. Although im aware that the placement of the vortex fragments will vary with each warming event and other controlling factors.

Based upon the current position of the Siberian high, and the forecast increase in wave one activity, would it seem reasonable to suggest that a displacement of the PV, although quite a large one based on the strength of the warming, would seem likely, with height rises in the north Atlantic and Greenland soon after the warming downwells into the troposphere?

Edited December 15, 2012 by Mark Bayley

[kold weather]

Impressive looking second burst of warming between 360-384hrs, this personally something I want to see, looking at the 2008-2009 animation, it took several bursts of warmth to finally deliver that SSW.

I think the 18z GFS is good with regards to the warming of the stratosphere, decent warming already showing up now at 180hrs, though the more interesting warming doesn't really get going till 276-300hrs.

[Glacier Point]

Again, another fascinating GFS forecast.

Something we may be underplaying here is a strong warming trend in the middle and lower stratosphere, particularly over the Canadian Arctic. This is modelled at day 10 onwards with a strong ridge centred over Alaska and Canada. This would lead to a marked rise in temperatures modelled at day 10, especially so at 70 hPa.

Note also the displaced vortex at 30 hPa undergoes another split.

30 hPa

70 hPa

Around the end of the month we see a surge of warmer air at 10 hPa and 5hPa into the core of the vortex consistent with a surf zone intrusion and strong ridge over Alaska.

So are we looking at a split vortex event or Canadian warming hybrid in the lower and middle stratosphere preceeding the major warming at 10hPa ? Tropospheric feedbacks will be interesting to monitor given these potential timing complexities.

30 hPa jump of temperatures by around 15C 25th December > blocking signature 3 weeks later on > 14th Jan, possibly sooner given lower stratospher being equally if not more agressive warming.

10 hPa jump forecast at 31st December > initial fast propogating wave response 3-8th January, then second response 20th January, more sustained end January onwards.

The cumulative net impact of these warmings throughout the different layers is the conundrum. Will this bring forward the wave responses through faster downwelling -ve zonal wind anomalies ? If so, January looks like a lot of fun if you like a strongly negative AO.

Edited December 16, 2012 by Glacier Point

[sundog]

Sorry if this is a silly question but are the forecast models for the strat much more reliable at greater timescales then say those of the troposphere? In other words is fi much further out in the modeling of the strat then that of the troposphere. How serious would one take the forecast for the strat say past 144 hrs? Great thread btw.

Edited December 16, 2012 by sundog

[Skyraker]

I get the strat & SSW events etc, but it's a relatiely new discipline.

Should we imply that all model discussion pre-strat monitoring should be disregarded?

Simply playing devils advocate , nothing more.

Des.

Edited December 16, 2012 by Skyraker

[Recretos]

@Sundog: Well, actually they are. The troposphere is much more complex. You have terrain interaction, not to mention the water, then a very complex Rossby wave global system, different forcing from the tropics, different factors on the meso-gamma and meso-delta scale that affect the overall picture, etc,... Basically a ton of variables that affect the weather and which must be taken into the calculations of a model.

While the stratosphere is in a certain way much less complex, basically on a "flat surface" (so to speak) with less intense activity, and the features being on an overall large scale (synoptic-global), while troposphere has features all the way down to the storm scale.

Of course I simply have to mention the troposphere-stratosphere interaction. Basically the activity in the troposphere, reflects in the stratosphere in a certain way or through succession. (it can also be the other way around, which is basically the primary reason why this thread is up and running ).

So looking from the model perspective, it is easier to forecast stratosphere activity, than the troposphere activity.

This is the "skill" (Anomaly Correlation) of the global models on day 6, for the last month, with ECMWF in the lead (as always).

For the mid and upper stratosphere, I would say the day 10 skill score would be around 0.94 and around 0.88 from day 11 to 13 in average, and around 0.82 from day 13-15. Just my assumption. Nothing official.

This is a summary from a report from Shin and Cai. http://www.esrl.noaa...ic_modeling.pdf

"The NCEP operational GFS still has a remarkable prediction skill of (stratospheric) polar vortex oscillation (PVO) index at the lead time of day 16, despite a very poor skill in forecasting tropospheric circulation anomalies beyond day 7.

The largest gain of prediction skill w.r.t. the persistence is over the stratospheric polar region. The remarkable skill comes from the signal of systematic poleward propagation of thermal anomalies from the equator to the pole in the stratosphere associated with the global mass circulation variability (intensity/time scale)"

So to simplify: GFS stratosphere gph and temp. forecasts in the 300h-384h period, are as "reliable" as the 500mb forecasts on day 6-7.

Maybe some of the pros in here can add a thing or two on this subject

Best regards.

Edited December 16, 2012 by Recretos

[sundog]

Thank you recretos for your reply and the best of luck to you and Chino and others on your future work on this very interesting subject.

Edited December 16, 2012 by sundog

[Ian Brown]

Again, another fascinating GFS forecast.

Something we may be underplaying here is a strong warming trend in the middle and lower stratosphere, particularly over the Canadian Arctic. This is modelled at day 10 onwards with a strong ridge centred over Alaska and Canada. This would lead to a marked rise in temperatures modelled at day 10, especially so at 70 hPa.

Note also the displaced vortex at 30 hPa undergoes another split.

30 hPa

70 hPa

Around the end of the month we see a surge of warmer air at 10 hPa and 5hPa into the core of the vortex consistent with a surf zone intrusion and strong ridge over Alaska.

So are we looking at a split vortex event or Canadian warming hybrid in the lower and middle stratosphere preceeding the major warming at 10hPa ? Tropospheric feedbacks will be interesting to monitor given these potential timing complexities.

30 hPa jump of temperatures by around 15C 25th December > blocking signature 3 weeks later on > 14th Jan, possibly sooner given lower stratospher being equally if not more agressive warming.

10 hPa jump forecast at 31st December > initial fast propogating wave response 3-8th January, then second response 20th January, more sustained end January onwards.

The cumulative net impact of these warmings throughout the different layers is the conundrum. Will this bring forward the wave responses through faster downwelling -ve zonal wind anomalies ? If so, January looks like a lot of fun if you like a strongly negative AO.

But shouldn't we already be in a -ve NAO/AO from events previous ? And we are not. We are heading towards a strongly +NAO as heights rise from the South in response to the mid-latitude (flat) jet.

Already twice this winter, the NWP has picked up on Atlantic activity at the T120/144 stage that apparently flew in the face of what was 'supposed' to happen, but both times it has been correct.

[Weather-history]

But shouldn't we already be in a -ve NAO/AO from events previous ? And we are not. We are heading towards a strongly +NAO as heights rise from the South in response to the mid-latitude (flat) jet.

If you look here it doesn't look strongly positive NAO on the predictions. Around neutral even more slightly towards negative at the end.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.sprd2.gif

And the AO is -ve and rises towards +ve

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.sprd2.gif

Edited December 16, 2012 by Weather-history

[Weather-history]

The analogue of 1968-69 has been mentioned as being similar to this winter. If you look at that winter, it should be noted that January 1969 was actually pretty mild, it was even a touch milder than last January for the CET, which shows that even when conditions are favourable it is still not a guarantee for cold weather in the UK.

[Duane S.]

Mid strat temp increase now showing on the radar on the ECM

and higher up, looking a bit toasty!

Wave 1 intensity continues to grow out at D10

And wave 2 making a reappearance???

I think its safe to say January could get interesting!

[Recretos]

But shouldn't we already be in a -ve NAO/AO from events previous ? And we are not. We are heading towards a strongly +NAO as heights rise from the South in response to the mid-latitude (flat) jet.

About that:

CFS is propagating the Novaya Zemlya blocking west and into Scandinavia, weakening it along the way and forming a new one just W/SW of Greenland. Basically quite the idea that ECM is also promoting.

About 1968/69.

This was the December pattern.

This is December so far, and the ECM ensemble forecast.

And the strat+AO comparison between 68/69 and this year.

Best regards

Edited December 16, 2012 by Recretos

[Cloud 10]

So my early guess would be for a northerly around the festive period - let's see how it plays out.

c

This is looking like a good call.

Also i note a new oscillation has arrived,the Polar Vortex Oscillation!

[chionomaniac]

This is looking like a good call.

Thanks, but I realise that it is at odds with the climatology suggested by Cohen. Perhaps we can have a northerly followed by easterly!

Stonking warming forecast today - upto 10.7ºC at 10hPa

Some great posts from Recretos above.

[kold weather]

Yep, the great thing about that chart though Chino is there already has been some wamr air injected into the PV core, but that is a huge second warming and even if the first one doesn't quite finish the job, that 2nd warming will almost certainly smash the PV out of the park.

[snowking]

In high resolution. Presented in color are sea level pressure anomalies, and mean values with lines.

a,b,c - prior to vortex displacement,

d,e,f - prior to vortex split

GFS 6z @ 120:

A pretty good anomaly match for both A and B

SK

Edited December 16, 2012 by snowking

[bluearmy]

The 06z fi strat profile a tad diffent to recent runs. Less warmth drives into the canadian sector and the shape of the vortex remains more rounded.

[-uksnow-]

Complete novice here, but seeing as there are no other posts for me to drool over, is the warming becoming slightly more watered down?

and not as well integrated?

Edited December 16, 2012 by -eded-

[feb1991blizzard]

Complete novice here, but seeing as there are no other posts for me to drool over, is the warming becoming slightly more watered down?

and not as well integrated?

Just posted the same thing but accidently deleted it!!!, Not sure if the 30hpa level is good news or bad news, the warming seems further into Greenland but seems less pronounced than on the 12z.