weatherjunkie
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Excellent introduction
It will be interesting to see how the strong Nino matches up with the +QBO. I'd place bets that the strong Nino with wave breaking events in the N. Pacific and perhaps N. Atlantic that will eventually win out but I think it will be rather difficult. As you've stated, the chances of a SSW are heightened with a Nino. Should be a fun battle.
Cheers from across the pond on another insightful thread. There is much to be learned about the troposphere-stratosphere dynamic.
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Was looking optimistic over the last few days but less so today.
Can't complain though since the E US has been quite cold and snowy. We wouldn't need a full SSW to keep it that way the rest of the winter. The PV has been entrenched into Canada for a while and another lower stratosphere split at some point in the next two weeks would most likely keep things cold. I like the wavebreaking we're seeing in the N. Atlantic. GFS showing warming events coming from that region and hopefully it'll be enough to knock the PV down some more. I've already convinced myself not to pay attention to the 6z forecasts...too much hope that gets dashed away in subsequent runs.
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To expand slightly about one of the points recretos makes is the +MT torque event projected by day 10. Even if this doesn't work out too well this go-round, there are indications (outside of dynamical model forecasts) that the MJO will fire into phases 6-7-8 by the third week of January and these phases increase the likelihood of a +EAMT event. So we could be seeing several round of warming coming from there this month.
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I remember saying that I will post some animations when things get interesting. Well, now I present 2 3D animations from the latest 12z GFS. Both present 3 layers. 10mb, 30mb and 100mb. The animation goes from 204h to 384h on a 12h interval.
The main goal will be to spot the interaction on different levels and possible propagations. In this case I only have one parameter. Both the topography and the colour present geopotential height. I will do topography+temp animations when/if the whole "SSW" process intensifies in the coming days.
First is a side view animation. To explain the perspective: It is like looking from Europe (man that sounds weird
). It is like looking Netweather.tv or meteociel stratosphere maps in 3D.The interesting thing about it, is the fact that the early shift of "power" from left to right (from Siberia to Canada) is pretty much instant in all layers throughout the strat. while the later height rises are mostly evident on 10mb level and slightly on 30mb, while 100mb seems mainly unaffected.
The animation repeats 2 times.
Second is the front view animation. This is the same perspective as on instantweathermaps.com
So just imagine that you are looking those gph maps in 3D. The interesting thing here, is the intensity by which the vortex gets beaten up at 10mb. You can see fast height raises and around the end, the two waves almost connect over USA. If the animation would go on for a few days, the vortex would be pretty much a goner.
I can only imagine how brutal the animations would look for the upper strat. I have to apologise for not making one, because I still haven't found the master grib files for the full GFS output, which has the whole strat included on the complete timescale. I can only find files for individual times, but that would takes ages to process. I guess I will have to wait for the event to go by, and then plot it from reanalysis.
Personally I really like these animations, because it allows me to quickly asses the dynamics and spot some aspects that would otherwise be harder to notice on the classical 2D maps, since you cant see multiple layers at once.
Nevertheless, here are 384h 3D layers of the upper strat. The layers from top to bottom are 1mb-3mb-5mb-10mb-30mb.
The thing that stands out the most, is the wave intesity. In the upper strat, the Atlantic wave is the dominant one, but lower we go, the more dominant the Pacific wave gets, with the Atlantic wave hardly there at 30mb. This is pretty much the answer to the dynamics that Snowking was pointing out earlier, how the vortex gets tiled back with height on a horizontal axis.This pretty much explains it by showing how the stronger Pacific wave acts pretty much as a blocking ridge that prevents the vortex to tilt in general and prevents displacements towards that region. In the upper strat the Atlantic wave is stronger and is pushing the vortex toward west where the Pacific wave is not strong enough to hold in the "pat" position that we were used to see in the past days/weeks.
First aspect is from the Europe side again, while the rest 3 are from the classical "USA in front" perspective, demonstrating the wave intensity with height and the impressive vortex tilt that corresponds with the changing wave intensity with height.
I was thinking of pasting some ensemble output, but I dont want to be a partybreaker.
The ensemble output has no dynamics, except for the classical two waves in the pat position. It seems that it just cant grab onto the dynamics, which is mainly the consequence of the low model top. I am counting on the improved ECMWF EPS to do the ensemble job here. Does someone remember the CFSv2 outputs I presented in November?
2-month lead time forecast. How about this for a verification? A few days faster than GFS, but still impressive with the general idea in my view, considering it was a mid-November run. (I cant believe I published such low quality processed graphics at that time, but It was as good as I was capable back then).Currently, CFSv2 is quite on terms with GFS, but as usually warmer on the waves and in the vortex core.
I have noticed that compared to 12/13, we have somehow forgot about the ozone this season.
There was some talk about it in the early parts of the season only. So much for now. Bring on the rock'n'roll.
Kind regards.
Maps are absolutely amazing. Keep up the good work!
Looks like the long range is promising. All eyes on the downwelling possibilities but also to the strength of the warming. It may take another round of warming in late January-February to completely topple this strong PV. Going to be looking at the last week of January for another +MT event out of Asia to knock this off for a while. We'll see how it goes.
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Well, I was about 60% done (or around there somewhere), when I had some other priorities, thinking I can just go back to it when I will have time. Turned out that my methodology was just as complicated as it was efficient, so I totally forgot the system I was using in just two weeks (yes it was that complicated
but very efficient, as I said). Later I got a new computer, delaying it even more, so I gave it a shot two weeks ago but I just couldn't figure it out (changed excel versions in between too). I will just try to salvage the finished data, and complete the rest when I create a new methodology for the efficient data extraction from the dataset. Talking about GWO composites of course. MJO is also in plan. I'm glad to hear that you haven't abandoned ship with it. I'm sure quite a few of us appreciate the effort that you put into this kind of work and it would be of amazing value to the weather community. I look forward to seeing what you come up with.
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The QBO is solidly west between say 20mb and 70mb. Judging by its pace over the past several months, I'd say any flip to the east based side will occur well after winter. However, there should be weakening of the westerlies starting at the top of the stratosphere and working there way down, so perhaps this affects the PV later on down the road for late winter. I'm on board with those that think long term the PV remains pretty strong. However, the latest forecasts charts hold promise for the more immediate time period regarding some blocking with a brief PV split/elongation. We'll see how it goes...
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Very interesting. I will definitely consider this one as more legitimate. But there are probably differences in the testing modes. Some used averaging of the runs, some just individual runs, etc... Too bad the full article that I mentioned is not free, so I could see what was their method and compare it to the results from Long. That pdf does give some basic info, but the methodology is not really described.
Speaking of the 2009 event, I actually plotted some 3D visualisations (never before seen
) for it as a test. I extracted the data from the NCEP DOE Reanalysis 2 dataset, on 6-hourly intervals. The time period is from 12/01/09 to 05/02/09. The 3D surface is the geopotential height, and the colours are the temperature at that layer. Layers from top down: 10mb, 20mb, 50mb, 100mb, 250mb, 500mb and surface temperature.
https://dl.dropboxusercontent.com/u/16376055/09.mov
This is is from the pacific viewpoint:
https://dl.dropboxusercontent.com/u/16376055/09_pac.mov
This is just some preliminary testing. I am just trying to figure out the system, so in the future I will be able to plot basically any SSW event. Will try to figure out how to plot additional parameters too.
Best regards.
EDIT: As a bonus, here is another animation for the same period as above. There are only 2 layers. The layer above is the 3D 10mb geopotential height, and the second layer is the 10mb 3D temperature topography. The temperature topography is lower so both can be nicely seen, and the temp. topo kinda looks like a better indicator of the dynamics.
https://dl.dropboxusercontent.com/u/16376055/09_up.mov
This is some great, great stuff. Can't wait to see what comes of this.
On a side note, how has your MJO reanalysis/composite project gone? That one looked quite interesting as well.
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Well, I think that is what we are going to find out, once we put the composites into practical use.
I am already doing the ENSO filtering, and February is now 100% completed, and ready for coding the data files for upload.
And here is the finished Phase 8 (0.5) for February, in ENSO neutral phase, and with AMP>1
P.s.: The MEI dataset goes till December 2012, so that is why I also decided to use the dataset for GWO Jan 1970-Dec 2012. So no 2013 dates included.
EDIT:
Just for fun, I did the same thing as yesterday. Taking the Phase 8 (0.5) which is now corrected with Neutral ENSO and AMP>1, and I plotted 10mb anomaly, with a 12-day negative lag applied. So before the onset of the phase. And I added the anomaly of this year for a similar period, around 12 days before the onset of the phase 8. Of course the anomaly of this year is much greater in the reanalysis, because it contains much less days than the GWO phase composite. Now I am not really trying to make a specific point here. Only trying to say that it should be quite interesting to experiment with all this data.
This is incredible and I'm sure many will thank you for taking the time to do this.
Keep us updated
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Just wondering if someone could help me out please, most gratefull if they could, i understand what a 2 wave pattern is at 500mb level and what that brings but i am confused slightly as to this stratospheric chart, i am confused as to the 3d meaning of it.
I understand the chart posted below as the mean wind speed at various levels.
however, not sure exactly what the 3rd dimension of the first chart represents.
The first chart simply measures the intensity of wave amplitude at various levels of the atmosphere and at certain longitudes. Basically what we see today from the ECM between hour 0 and hour 240 of its forecast period is much stronger wave 1 activity at the top of the stratosphere centered around 70N.
The biggest question we have right now is not if we see a SSW but when and how do the subsequent displacement and fragmentation lead to colder/stormier pattern. It looks to be case of various levels of the stratosphere doing different things as the GFS/ECM show variations in what happens to the polar vortex as you make your way from 1mb to 100mb, which is to be expected when the PV becomes significantly weakened.
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I'd like to introduce myself, my name is chris, I'm from across the pond in Langhorne, Pa which is about 30 mins north of Philadelphia. I have 3 questions I would like to ask:
1. what affects will the warming of the stratoshere have on my area?
2. will the warming have any affect on the mjo, i've noticed the european model has it going into phases 4 and 5 (which does not look good for cold in the east coast)
3. will the warming affect the ao and the nao?
I've enjoyed reading your posts
thank you
Chris
I would like to take a stab at some of these questions if you don't mind. I'm also from the Philly metro area...small world I guess
.1. The affects of the warming are highly dependent on what happens to the polar vortex as a result of the warming. Most of the charts we see on the GFS show a split vortex by the end of the long range. This split will have to be monitored since one piece may setup over Canada/Greenland and will create quite a problem if we wish to see a -NAO. We would prefer to see the split where one piece heads to Siberia and the other to Europe which would allow HP over Greenland and a -NAO. For now we understand a warming is coming but the exact details of what happens to the PV remain a mystery and won't be really understood until middle January.
2. The MJO is a tropical atmosphere model which is dependent on deep tropical convection. The general principle is that the MJO affects large scale patterns in both the tropical and subtropical latitudes but is not as influential when it comes to high latitude patterns, although to say it has no affect would be erroneous. In fact, there have been numerous instances where the MJO was in an unfavorable phase and directly opposed to cold in the E US but the warming affects were dampened due to the more favorable Atlantic/NAO blocking. This is certainly a possibility if we can get blocking established prior to the MJO reaching phases 3-4 but at the moment this doesn't appear so and I do think we will warm up a bit come mid-january. It's the old battle of Atlantic vs Pacific and which one is more important for the E US in the winter.
3. Pretty much the same answer as 1 except the AO will almost certainly drop strongly negative as high pressure pushes away the PV from the North Pole. The fragmentation of the polar vortex is still uknown and details are hard to come by at this range. Right now if we were to take the GFS at face value in the 2+ week range we would likely see an east based -NAO which is better than positive NAO but would favor above average snow into the Great Lakes instead of I-95.
Hopefully this clarified a few things.
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What a pleasure it is to find such a thread every winter. Monitoring this kind of stuff if incredibly quite interesting and those who have posted in here have done a marvelous job in both explaining model outputs and potential impacts on sensible weather.
To add some food for thought, it has been proposed that in order to help propagate the warming down from the top of the stratosphere to the troposphere, EP flux vectors must point to the poles in the troposphere. EP (Eliasssan-Palmer) flux is used to help describe eddy forcing of zonal wind anomalies. When EP vectors are pointed to the poles, wave propagation is enhanced and the polar jet is decelerated. These poleward propagating EP-fluxes are generated by tropospheric planetary waves which lead to our SSW events.
Essentially when pointed polewards in the troposphere the zonal mean wind state is weakened allowing for some warming to make its way down. Of course, we also have to get the warming down from 10 mb where the 0z GFS shows 60+C temp change at the north pole. So far seeing displacement from 30mb to 100mb from strong wave 1 and weaker PV but the intensity of the warming is dampened as you go down which won't give it a final blow unless we see more events. But then again, the degree of displacement should be sufficient unless you're out for blood against the PV, which in that case we will need more for the kill.
Here's a study which brushes over the EP flux. http://center.stelab...mazaki_koji.pdf
Some more background on the EP http://www.rsmas.mia...Palm Theory.pdf
Source of EP flux forecast that I could get my hands on http://ds.data.jma.g...x.html#monit_nh
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Looks like a rather sizeable +MT event coming out of NA. Height rises penetrating to near the Pole from 30-100hPa and troposphere. Another punch for sure to the PV. We already know that the lower strat PV is beat up, so anything from here on out is pretty much overkill. Still not seeing a technical SSW, but we're good to go for high latitude blocking whenever the troposphere decides that it is time.
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Quick synopsis of the latest data:
GFS/ECMWF showing PV propagation to the pole at almost all levels, with the GFS being quite aggressive in indicating PV recovery while ECMWF still tries to retain some form of a split at the mid-levels and a weakened upper strat PV state. Both do however exhibit signs of a wave two type pattern. Zonal charts from the ECM indicate strong rebound of westerlies from 5-30 hPa between 60 and 80N. Momentum/heat fluxes weaken significantly by day 10 according to the Euro from planetary waves 1 and 2.
Temp anomaly obs indicates downwelling of the +anomalies that were a product of previous warmings. This should help to drop AO in the short term. Most lower strat charts and tropospheric models indicate transient -NAO signals, so we again wait for chance of sustained cold. But hey, EP fluxes are neutral toward the end of the forecast period instead of equatorward, so that's some good news.
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GFS showing some nice warming over Greenland/N. Atlantic in the lower stratosphere with what I'm assuming is local wavebreaking action. As noted by a few, the top of the stratosphere is showing an significantly weakened PV. The problem is getting this to occur at lower levels and it appears the GFS wants to restrengthen the mid-stratosphere vortex a bit. More warming over Siberia is expected but EP fluxes remain unfavorable.
ECMWF actually is showing a wave 3 signal in the lower stratosphere plots.
It'll be an interesting few weeks...
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I don't think that it is doom and gloom in this thread. I know my emotions don't get swayed up and down by every run.
All I have suggested today is that I have concerns about the propagation of the warmings that have occurred so far and that have been forecast up to T+240. There is still the largest warming at that timeframe that we do not know how any propagation might occur.
There is still a lot of promise, but one should be cautious as well.
Why is it that EP fluxes must be poleward? I understand that this aids in propagation of momentum and heat from the planetary waves to the poles (and deceleration of westerlies). How this transfers to the lower levels of the stratosphere and then troposphere is a concept I still struggle with. The only thing I can think of is tropospheric/lower stratosphere poleward EP flux to help decelerate westerlies and allow for the upper stratosphere warming to filter down.
Speaking of decelerating westerlies. Looking at the ECMWF zonal mean forecast charts we see that by 240 the high latitude upper level westerlies are completely removed. Something else to keep an eye on.
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In terms of a disintegrated PV, ECMWF isentropic charts show low potential vorticity in what would appear to be the heart of PV in the upper levels. Certainly another good sign. We will also have strong heat flux between both waves 1 and 2 from 60 to 90 N. It appears wave 2 will be the primary contributor of momentum flux in the next week or so as we see great increases in amplitude and perhaps that is why we are seeing some signs of wave 2 on the 10 hPa charts by 240.
All in all you can't complain about the latest forecast outputs.
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At 360 hrs... Does Joe B. actually know the value of these charts?
I believe what he was trying to get across was that the ECMWF was indicating a warming of 50C, not that the actual temperature reaches 50C.
JB along with quite a few meteorologists in the US are having a rough time with their winter forecasts. JB in particular is having one of his worst seasons that I can recall. He has made forecasts and then has came out with new forecasts only to rescind them week or so later. He generally does decent in the long range (1 month +) but he's a bit off his game as of late.
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Wave 1 is expected to increase height amplitude and temperature amplitude congruent with the expected warming. Very nice heat flux from wave 1 between 5 and 10 hPa and even wave 2 by 240 indicating it wants to get going a bit. Pretty solid momentum flux as well by day 10 from wave 1 but this occurs at the top of the stratosphere. Very strong momentum flux from wave 2 by 240 in the Euro but again it as at the top of the stratosphere.
Looking at some forecasts, I expect to see IO convection increase at a pretty good amount around the 25th of January, perhaps setting off another Asian MT event to cap the month off and give the PV one more blow heading into February. This is the hope that I have for February in giving us the high latitude blocking that we all seek. As of now the warming will help but I'm sure most can't shake the feeling that we'll need 1 more warm push to set us free.
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Looks like another solid MT event. Frictional torque and AAM tendency still on the rise, so perhaps some more umph in this event.
Latest 10 hPa temp anomalies indicate significant warming in E. Asia/ N. Pacific relative to where our Ozone increase/wave breaking has occured. Looking at the forecasts for the upper stratosphere I still don't see much from the PV aside from movement toward Siberia.
It seems like this will be a long struggle.
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I suspect the low level wind reversal on the ECMWF is a function of the MJO pushing into phase 6 and given the composites I've seen the high latitude HP is allowed to build and amplify. Certainly phase 6 suggests -NAO given the W Pac tropical forcing.
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Yes.
I think it is far too early to tell due to the centres of potential vorticity that change throughout the levels of the stratosphere. Also if we get a SSW then tropospheric factors could have a large deterministic effect of where blocking is most likely.
That is what I had suspected. As always, your input is greatly appreciated.
I may well be completely wrong here but if you consider where the warming
has started and where it is most intense at the 1 and 5 hpa level I would
guess blocking in the north Atlantic (- NAO) becoming east based (block
transfering to Iceland, Scandanavian area. The reason I say this is that
over the last couple of winters the warming has initiated much further east
with the block being more -NAO west based.
Of course the warming my not propagate ( although it is showing signs of
doing so) and any effects to the troposphere will be at least 2 weeks down
the line (Jan 7 onwards).
As I say I could be completely wrong though.
Yes, I see what you are saying. It looks like we'll just have to wait and see. At the very least it gives us something to monitor other than lack of cold and snow.
Wave breaking potential also on the increase given the wave 1 amplitude (and forecast strengthening). Also seeing signs from forecasts of wave 2 strengthening.
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GFS shows 12z shows 2 warmings, second bigger than the first
http://176.31.229.22...nh-10-96.png?12
http://176.31.229.22...h-10-336.png?12
Is that looking good?
The location of these warmings doesn't appear to bode well for the N. Atlantic. Again, I know the propagation of the warming doesn't translate directly from level to level, but this still doesn't appear to be good for a -NAO, am I right?
is an MMW the same as an SSW?
MMW = major midwinter warming, but I'm unsure if the criteria is the same
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wave 1 and wave 2 picking up in intensity...might get some extra help for the stratosphere
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Someone give the berlin site server a kick! Must be a massive warming that has caused it to fail!
Matt- I can understand the thoughts regarding possible two minds regarding this winter - I was relying on the possiblility of a SSW to throw the strong PV out of kilter to allow Northern Blocking later in winter. I still feel that that is likely to happen, more so looking at GP's composites in the model thread yesterday evening. I don't believe that cold zonality will last into the new year and from now on I am on a watch for a potential SSW. I don't think that cold zonality ever delivers for the southern third of the country, so on a personal note whereas I love the current synotic set up and dramatic weather further north I would still want a piece of the action myself.
weather junkie - I think it is very difficult to predict any wave breaking events - most waves don't break into the stratosphere and those that do often get absorbed quickly. Certainly if the strong Siberian blocking occurs then we may get some wave disruption either locally into the centre of the vortex itself or perhaps more remotely from an Asian MT event and this would be over the top - circling the edge of the vortex before entering at the top and propagating downwards.
Yeah, I remember quite a few cases where there was a significant Asian MT/Siberian blocking event followed by -AO/-NAO. Thank you for the response.
). It is like looking Netweather.tv or meteociel stratosphere maps in 3D.
The ensemble output has no dynamics, except for the classical two waves in the pat position. It seems that it just cant grab onto the dynamics, which is mainly the consequence of the low model top. I am counting on the improved ECMWF EPS to do the ensemble job here. 
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Stratosphere Temperature Watch 2015/2016
in Spring Weather Discussion
Posted
We've seen fantasy range SSW forecasts before, only to become less aggressive as it approaches. It looks promising, and while the stratosphere is generally easier to predict than the troposphere, it is far from over. I do like the model agreement. We are still in that day 10+ area so the only thing we can do is wait and see.
There is also another factor to consider and was perhaps mentioned in this thread but I'm too lazy to look
. A recent article (2012) showed a correlation between MJO phases and a SSW. When in phases 7-8 during winter there is an increased probability of an SSW during days 1-12 following the MJO orbit. This is where we currently are according to WH phase plots.
Now if this does happen we would have to see how it propagates downward, which is highly dependent on the willingness of lower levels to cooperate...best case scenario is we feel the effects by mid-February, which I suppose is better than nothing.