blizzardof96
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Posts posted by blizzardof96
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With tropospheric driven wave 2 activity, it will take some to get a SSW. I know that there is a lot of chatter tonight on twitter regarding some fantastic ensemble strat means from day 10 that are showing a split. Brilliant news, because if they verify it is very likely that we will see a great block develop to our northwest along the line of the split, and, from what I have seen the -ve NAO would not be west based like tonights ECM op.
In January 2009 we saw a large strat warming that led to a split SSW - but that event was a downwelling split powered from the top of the strat.
What we much prefer to see are the upwelling wave 2 split that tend to occur following a previous ( normally wave 1 attack) warming of the vortex, and (without being able to see the restricted charts) that appears to be what is being forecast here. This type of scenario occurred with the weakened vortices of early winter 2009/10 and 2010/2011 and these wave 2 splits are without doubt the better for more guaranteable cold. If these forecasts of the wave 2 splits verify, then we could once again be on the cusp of some special winter synoptics.
Hey Guys,
Quick question... what are the differences in tropospheric forcing during downwelling v.s upwelling events. Polar wave breaking/standing ridges v.s EAMT surges?
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Heres the latest sunspot number trends from the BOM Australia site. Notice the recent spike in the september number after a first max back in Feb/March of this year.
2014 82.0 102.8 92.2 84.7 75.2 71.0 72.5 74.7 87.6
Although sunspots have been slowly decreasing since early October, if we do see another spike I found some interesting trends. In the 4 years with an ONI between 0.3 and 1.1 in the DJF trimonthly period, a -30mb QBO and a Jan monthly SSN at or above 100 we get this result at 500mb.
Notice the -NAO/AO
March was particularly cold in both the S UK and North America
30mb Stratospheric Temperatures
Also found it interesting how 3/4 of these years had a CW in November:
1958-59 had a CW in Nov/Dec with a FW in March.
1968-69 had a CW in November.
1969-70 had a SSW in January.
1979-80 had a CW in November and a FW in March.
This increase in sunspots is a possibility but a low one at this point. I'll add some of the other analogs I'm watching and see what we get at 500mb. The main focus of my years was -QBO,monthly SSN between 40-90, weak el nino or warm neutral conditions while considering other factors like the PDO, Walker Cell, AMO, KOE,ONI trends etc(with some obvious exceptions within some of the analogs). There were some really interesting results for the UK especially in Dec-Jan.
Dec:
Jan is strongly -WPO,-NAO/AO,-PNA,-Ve over the UK:
Feb:
March:
Strat was very warm overall with strong wave one.
GPH
30mb Air Temperature
Cheers from Canada and hopefully we can share some of the snow this winter,
Blizzardof96
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Great post Ed! Hoping to join in on the discussion this fall/winter.
Cheers from Toronto, On.
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Since correlations seem to be a point of interest at the present time, I also decide to have a go at them.
Awesome work Recretos! Based on some of my research regarding QBO phase correlation's with upper strat temps, ENSO, PDO and solar activity are very important factors to consider when relating the QBO to the strength of the NAM state. This is how I look at it, going from most to least favourable conditions for a major SSW event or intensification of the BDC. Obviously never a linear correlation, as other factors can make major differences in these years(strength of EAMT events, RWT setup's, East Pac ridging, and ozone from previous ENSO events).
1. -QBO, Smin, any ENSO/PDO conditions(see a major SSW event almost 100% of the time in the DJF period)
2. -QBO, Smax, la nina or neutral ENSO
3. -QBO, Smax, el nino/+PDO
4. +QBO, Smax, +PDO, el nino
5. +QBO, Smax, -PDO, la nina/neutral ENSO
6. +QBO, Smin, +PDO
7. +QBO, Smin, -PDO/la nina
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This would tie in with the suggestion of heights to the NE receding away eastwards in response probably to a reenergised polar vortex moving towards Greenland. For medium term prospects i.e. as we move through the second half of January this isn't a good situation for UK snow and cold prospects, however, I'm encouraged by the prospects of wave breaking and strat warming perhaps helping to develop stronger heights to the west of the Greenland and in the vicinity of Canada and I highly doubt the polar vortex can develop the strength it has in recent weeks - February thus could see a scandi trough scenario and a negative west based NAO pattern with a much weaker diffuse Jetstream.
Can anyone shed light on why the polar vortex has been so cold and strong so far this winter... a number of people were calling for a very dry December, how wrong? Can't help but think the aluetian heights during November helped to lock and intensify the PV in situ over Canada - and this was all in response to the PDO and ENSO state. Anyone help with an explanation?
In +QBO and Smax years(when jan SSN is above 95) the PV tends to stay stronger then normal for the first half of winter before the HT effect begins to turn that around from mid january onwards. Cohen's SAI also backed up a strong early season vortex as the Oct snow cover had little to no advance which helps keep the north siberian high anomalously weak. It also helps keep Eddy heat flux at or below normal from Oct through Dec. Notice how that is beginning to turn around, with a recent spike in EP heat flux.
The north pac low is expected to strengthen over the next 15 days which will only help weaken the already wave 2 ravaged vortex. We may see enough warming/heat flux by D7-9 to displace the vortex completely or this could take until the last few days of Jan into early feb as the bering sea low return's. Either way, we are likely looking at a significant SSW event occurring, which should have major sfc implications starting anywhere between Feb 2nd-20th IMO. Interesting regime change on the way...
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With regard to any significant SSW occurring this winter, its looking very slim in DEC/JAN given the indices on the table this year. For +QBO, -PDO, N/- ENSO and years with the JAN SSN below 95 no significant warming's have even occurred since 1950 in DEC/JAN. In february their are a few exceptions, one begin 08-09 which had a strong East Pac ridge, definitely aiding in the wave 2 response. 00-01 is another example of this, although the PDO was neutral/positive and the QBO was transitioning from positive to negative. The common denominator in these two years is a strong Kamchatka PV lobe and bering sea/GOA ridging. Unless we see an uptick in the PDO/ENSO domains, or a quick downturn in the QBO by feb a major warming in the DJF period is going to be tough to come by. EP heat flux anoms are already starting off winter well below normal ever since the wave 1 response in late october. Our best shot will probably be a wave 2 warming in Feb if we can keep the EPO ridge consistent which becomes more likely given the +QBO/N ENSO and -EPO persistence. If this doesn't work out then their is always the FW question in March/April that should arise with a mean state similar to our current one. This SSW timing is much more favoured given the current setup and could have impacts on spring, especially with the warming ENSO region expected and a transitioning QBO index(favourable for high heights across the NAO/EPO region's).
Feb 2001
Feb 2009
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Asian pattern looking very interesting in the medium range wrt potentially adding additional HF anoms towards the upper strat. We are seeing an overall pattern shift from a +VE anomaly north of India to a major lowering in SLP across Siberia and areas to the West of the Tibetan Plateau according to the ECMWF and its ensemble suite.
Notice the northeastward momentum flux across northern and western europe. This is helping setup equatorward propagation of -AAM and a -EAMT response.
OLR, 850mb stream function and wave flux:
SLP response across asia is unsupportive of significant heat flux transport
Big changes going on by D9. This pattern will help amplify the current positive temp anoms showing up at 10mb in a poleward fashion. Significant warming took place at 10mb as a result of the last EAMT spike in the Nov 6-14th period but these warm anoms are stationary at the moment. The usual EAMT-->HF feedback response should show up in the 6-10 which will help enhance the Wave 2 setup the euro is showing by day 15.
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If we take a look at +QBO years where we saw no major SSW's events from Dec-March at 30mb we get this pattern at 500mb. Notice the suppressed heights over the tropics which is probably indicative of above normal stratospheric temps across this area. Their is also a fairly neutral NAO signal with a strong bering sea ridge. When we see a strong bering sea ridge coupled with a neutral or positive NAO it really goes against any WAVE 1 or 2 warming's. This is why any major warming of the strat looks unlikely until we can get out of this current pattern.
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Blizzardof96 surely you are not suggesting that we will see a FW (final warming) before years
end as this is would be imposible. Also when using abbrivations it is helpful to show what they
mean in brackets for those not familiar with stratospheric events etc, such EAMT which I take
it is east Asian mountain torque.Cheers.
The synoptic charts certainly do look as if they mean business in trying to pump heights
into the Arctic from the Pacific side. A good mountain torque brought about by a strong
MJO event (Madden-Julian Oscillation) or Asian mountain torque could very well see the
dame break. Hopefully this is more a case of when rather than if but once this happens
it could very well be game on.
No i am not suggesting that at all... but a late season warming is something you look for in low solar/+QBO years whether its a FW or just a late winter SSW. I will try to add brackets to abbreviations when possible in the future and yes EAMT does stand for east asian mountain torque. Cheers.
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Some interesting trends developing with regards to the stratosphere....
The vortex has began to strengthen again and upper stratospheric temps are beginning to return to near or below normal levels. Been looking more into stratospheric analogs for the upcoming few months, based on a -PDO, neutral ONI and +QBO state. Best years include 78-79, 01-02, 90-91, 61-62 and 66-67. In these analogs we saw a tendency to see early winter CW's with December 78 and 66 showing this response.
Dec 1978 warming at 10hpa:
Tropospheric response shows a very anomalous alaskan block with CPF evident from siberia to NA. There was also a very strong -VE anomaly across western europe/ east asia with a gradient pattern look for the UK and what appears to be a very active storm track.
In Dec 1966 the CW response was greater across the mid and lower level of the stratosphere with a similar 500mb setup afterwords. Notice how the western siberian block becomes dominant with mean troughiness across the mid latitudes.
Besides these two years in the data set I found that 61-62 had no Major SSW events. 90-91 had a Major late winter warming. In the 01-02 season, despite several significant disruptions to the upper vortex, it was tough for these warm anoms to down well, which made minimal impact on the surface pattern until spring.
What may end up occurring this year is we either see a significant warming early on in the winter or we see no major warming's at all until Late feb into April. The stratosphere looks increasingly vulnerable to some sort of early winter response, especially if we see the MJO moving into phases 4-7 by DEC. This would help force an EAMT surge with bering sea troughiness and a wave 1 response.
If their is no DEC warming, we could see a FW with a heightened HT effect coming into play this year. This would become more likely if solar activity drops off and we can get help from tropical forcing as KW's upwell warmth over the western tropical pacific. The ENSO modelling is honing in on this type of situation, although the -PDO forcing will try to resist any FW attempt. Many factors coming into play here but the two period's to watch closest this winter look to be Dec and late winter.
Cheers,
Ethan
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Thanks chionomaniac,
On the topic of the GWO, the next month is going to be key to see where we are headed for the start of winter. Last year from Nov 1st to Dec 15th we had a strong -AAM anomaly propagating equatorward with +AAM in the subtropics below 30N. This caused a broader hadley cell to form with troughs favoured further south and ridging dominating over the mid latitude belt from 40 to 60N. Notice the tendency for anticyclonic wave breaking across the NE pac.
The -NAO pattern in the means really saved the UK from having a very warm period as ridging was favoured over almost all other locations with the same latitude. By mid and late winter, we saw a -AAM anomaly propagating polewards with -surface torque/FT anoms dominating the 40 to 55N belt.
Positive ST anoms were favoured north of the arctic circle which really helped strengthen blocking highs. This sudden shift in the pattern could have been driven from a major SOI dip which coincided with the SSW event last year. This event was definitely aided by strong KW propagation over the west pacific which released latent heat and favoured +EAMT spikes. Here was the late winter H5 setup, note the stronger blocking with more troughiness favoured over the mid latitudes:
So whats going on this year in the GWO department? Looks like we have -ST/FT anoms set up in a much more favourable position although total AAM is still not in the type of setup you would like to see. Hopefully we can rally in november and see a northward AAM transport. The long range GEFS forecast looks optimistic with easterlies dominating the subtropics and +AAM favoured to the north.
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Hey Guys,
I am from Toronto, Canada and am new to netweather forums. I run the torontowxcenter blog if anyone is familar with it. A friend of mine recommended I take a look at the strat page on this forum. Just wanted to point out that the info here is really incredible(and at a much higher quality then most canadian/american forums).
Anyways, the current state of the atmosphere is such that we saw a pretty robust MJO wave over the west pacific. This, combined with building pressure over asia, has helped produce a burst of west pacific typhoons over the last two weeks. This has triggered a positive feedback loop as these typhoons have distributed latent heat and negative potential vorticity anomalies downstream. This has helped pump the west pacific ridge and contributed to a strong bering sea trough( -EPO/WPO pattern). So why does this have any significance in relation to the strat? Stagnant bering sea troughiness and a very potent EAMT event(trigerred by tropical forcing over the W Pac) has really helped trigger a wave 1 response over NE siberia. Mean H5 pattern in the last 7 days shows the -WPO/-EPO setup.
As others have mentioned, the stratosphere is in a strengthening state which it should be at this time of year. As the heat source(EAMT + W PAC typhoons) for this warming fades, the vortex should rebuild stronger then it was before. -AAM anoms propagating equatorward will also help rebuild the vortex, with a potentially long period of a +AO coming up. In any case, it is a good sign to see such a strong fight against the vortex in a west QBO year. I suspect this won't be your typical +QBO year as we are in a westerly shear phase which promotes more pertubations to the vortex. In addition, we have a more poleward the normal 0 u line, with a greater then normal build up of ozone over the north pacific. These factors should make a major warming easier this winter.
The analog years I have been using for the stratosphere are 85-86, 01-02, 80-81, 90-91 and 08-09 which all have a neutral ENSO state(with the exception of 08-09), a +QBO shear phase and low solar activity. All these wintera had some form of a SSW event with the exception of perhaps 85-86 which didn't make as much of an impact at the surface. I'll give 2001 and 2009 as examples, with a 2-3 wk lag for the peak H5 response.
2009:
H5 Reflection:Notice how the cold signal is muted across NA while their is a very strong -VE anomaly across western europe.
2001 had the opposite pattern with warmth in W europe and cold anoms across NA:
If we look at all +QBO shear years, without isolating for solar or ENSO we get the following H5 setup. The important feature to note is the strong East PAC ridging and bering sea trough which would help promote a mid/late winter wave 1 response as well. The euro monthlies have also been hinting at strong GOA ridging, which combined with aforementioned factors make a good case for a SSW this winter.
So the point being made here is that you can see significant SSW's in downwelling +QBO years, especially when other factors are favourable for development. Although significant SSW's can occur, placement of the coldest anomalies at 500mb will only favour some locations across the N Hem, whether its europe, asia or NA.
Cheers from canada,
Ethan
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Stratosphere Temperature Watch 2014/2015
in Spring Weather Discussion
Posted · Edited by blizzardof96
Thanks so much Ed. That explanation makes a lot of sense. Because internal upwelling typically occurs after an initial wave break can penetrate the surf zone of the PV, would that type of progression be more common following wave 2 events? The 0z run of the euro ensembles are really aggressive with a transition to strong wave 2 or even wave 3 warming after day 10. This predominantly comes from the Greenland/AK blocks but the E euro high begins to become more active near D13 and this is quite a strong signal for an ensemble mean at that range.