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Hi everyone,

 

The gradual, step-wise diminution continues as September's global temperature anomaly on UAH is now down to +0.14c. As I've been noting in a couple of my posts hitherto, this drop isn't a surprise, mostly due to the significant cooling that the southern hemisphere has undergone over recent months. Conversely, the NHEM is still running quite warm. 

 

Nonetheless, I believe this will begin to countermand some of the erroneous ideas postulated by some during the 2016 super Nino: namely, "this will establish a new base/plateau, from which we will warm further." I formerly partook in climate change discussions elsewhere awhile back, and the general consensus on that forum was that the 2016 Nino would establish a new plateau. I disagreed then, and I still disagree. Current global temperature anomalies have returned to that which we experienced pre-super Nino, throughout much of the 2002-2015 period, around +0.1c to +0.3c.

 

Aside:

 

Just a cursory note regarding the QBO -- taken in a vacuum, it should not be a cause for concern in and of itself. There are case examples of -QBO / strong vortex winters and +QBO / weak vortex winters. For instance, 1963-64, 1969-70, and 1977-78 all featured weakly positive QBOs, but were quite blocky winters. The modality itself is only one factor. As most already know here, it's not only the modality, but also the trend, magnitude, interaction w/ other variables, background forcing, ENSO state, among others.

 

 

 

xglbgm.jpg

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10 hours ago, Snowy Hibbo said:

What level? From the chart above, looks like just above -10, which is a bit of a progression from last time I checked a week or so ago. Reality is that it will be in positives by winter, although QBO forecasting is fraught with danger I might add.

 

 

Which is the proper Qbo index that I should be referencing? The ESRL Qbo index value was at -20.41 for August, if this isn't the correct Qbo index to be referencing, what is its importance.

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7 hours ago, mbaer1970 said:

I have read that Qbo stalls, neutral trends, and around transitional periods are clues to watch for storm signals, as well as when the Qbo is between -10.0 & +10.0. Has anyone else seen any verification for this? I have always thought that a negative Qbo was an important driver for negative NAO setups, but am learning that is not the end all be all where negative NAO drivers are concerned. I am actually beginning to believe that the PDO may be a bigger influence on the NAO, than the Qbo.

 

Hi mbaer1970. I can't recall reading anything about "storm signals" during QBO transition, so if you've got some info I'd be interested in having a look.

 

Trying to predict the NAO state for the coming winter is complex and even the best models currently available have only limited success. The drivers (teleconnections) behind the NAO are multiple with complex interactions between each other, as @Isotherm has touched upon above. The QBO is just one of these drivers. A good read is this 2017 paper A robust empirical seasonal prediction of winter NAO and surface climate that provides a good insight into these (drivers) and the forecasting complexities. Here's some extracts:

 

The slowly varying factors influencing seasonal-to-interannual variability in the winter NAO primarily include Sea Surface Temps, Sea Ice Concentration, El Niño/Southern Oscillation (ENSO), and the quasi-biennial oscillation (QBO). The Atlantic SST has classically been recognized as a useful predictor for the winter NAO. Summer and fall SST anomalies from the extra-tropical and the equatorial Atlantic are found to correlate strongly with subsequent winter NAO anomalies. Moreover, summertime (May through September) Arctic sea ice concentration and extent have gained attention in recent years for their close connections with the winter AO/NAO. However, Atlantic SST or Arctic sea ice alone are not sufficient to provide skilful statistical prediction of the winter NAO. The winter NAO/AO has also been linked to stratospheric polar vortex variability, through downward coupling in zonal mean circulation or planetary waves. Efforts to combine some of these predictors have exhibited slightly higher, yet still limited, skill than individual predictors.

 

Although numerous efforts have been made to improve forecast skill of NAO, it has remained largely unpredictable over seasonal and longer time scales. It is an open question what level of predictability can be reached beyond the limited skill currently achieved for both dynamical and statistical approaches. For dynamical models, state-of-the-art forecast skill (as measured by the anomaly correlation coefficient, ACC) of DJF-mean NAO has just recently increased to a significant level of 0.62 for 1993–2012 by the United Kingdom Meteorological Office(UKMO) Global Seasonal forecast System 5 (GloSea5).

 

The Research Portal link is: https://www.33andrain.com/topic/1397-a-robust-empirical-seasonal-prediction-of-winter-nao-and-surface-climate/

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On 10/5/2018 at 1:21 AM, Isotherm said:

Hi everyone,

 

The gradual, step-wise diminution continues as September's global temperature anomaly on UAH is now down to +0.14c. As I've been noting in a couple of my posts hitherto, this drop isn't a surprise, mostly due to the significant cooling that the southern hemisphere has undergone over recent months. Conversely, the NHEM is still running quite warm. 

 

Nonetheless, I believe this will begin to countermand some of the erroneous ideas postulated by some during the 2016 super Nino: namely, "this will establish a new base/plateau, from which we will warm further." I formerly partook in climate change discussions elsewhere awhile back, and the general consensus on that forum was that the 2016 Nino would establish a new plateau. I disagreed then, and I still disagree. Current global temperature anomalies have returned to that which we experienced pre-super Nino, throughout much of the 2002-2015 period, around +0.1c to +0.3c.

 

Aside:

 

Just a cursory note regarding the QBO -- taken in a vacuum, it should not be a cause for concern in and of itself. There are case examples of -QBO / strong vortex winters and +QBO / weak vortex winters. For instance, 1963-64, 1969-70, and 1977-78 all featured weakly positive QBOs, but were quite blocky winters. The modality itself is only one factor. As most already know here, it's not only the modality, but also the trend, magnitude, interaction w/ other variables, background forcing, ENSO state, among others.

 

xglbgm.jpg

 

LONGER TERM SEA SURFACE TEMPERATURE CHANGES

 

Hi Tom @Isotherm I'm really interested with what you show above and entirely agree with your comments. Here we can move away from the short to medium term atmosphere/ocean coupling influences (AAM, GWO, Kelvin waves, MJO and ENSO) and examine the longer term changes and trends. Of course ENSO phases can still produce long lasting influences and very powerful shorter term events can have a legacy lasting over a few years (more below). We need to look down at the deeper ocean currents and also up at solar activity as two primary drivers of longer term SST changes and our understanding of both of these, although seeing major advances, still has a long way to go. 

 

s2.PNG.ff02ae4c2b260c6d21a81fd6dc5d9a11.

Accepting that there will always be slight inconsistency over measures, means, time periods etc and not to mention all the very short term fluctuations, we are looking for trends. The last 3 months has been pretty flat roughly  between + 0.1c and + 0.3c and well within the range shown on Tom's chart above for all of 2018. So, where do we go from here?

 

s1.PNG.1fa7b93055c4e8b8404139c709027be4.

Tom, you mentioned that the NHEM was still "running quite warm" which it is but let's consider this. The "average" conditions are strongly influenced by several very warm areas. We know that the Arctic is running at huge +ve anomalies and that's partly a legacy of the 2015/16 super El Nino with a powerful PV and the relentless south west/north east Atlantic jet stream pumping  warm waters right up to the edge of Arctic ice sheet. Unfortunately, it may take several years of more favourable patterns in the Arctic until we see those anomalies fall back significantly. Then, this summer we've had a string of powerful typhoons which have pumped up some very warm waters into the far NPAC. That anomalous warm pool in the western Atlantic has started to contract. The central and west Mediterranean still has well above average SSTs as part of the legacy of the widespread mid-latitude NHEM hot summer but other mid lat SSTs have eased back to some extent. 

 

sst4.PNG

This chart confirms the extremely +ve SST anomalies "locked" into the Arctic. The dark browns are over +4c and those olive patches (such as west of Svalbard) are over +8c anomalies.

 

Now if we remove the extremes, we could easily say that the NHEM would be running below average! This is not an anti climate change use of statistics but helps us to look for the "main" underlying trends. If we do see an El Nino developing later this fall and into the winter, a weak event should not have such a widespread extended influence on SSTs beyond the tropics. 

s3.PNG.5c842b1024064a0f3ea739bed1e3968d.

We've seen that anomalous cold pool in the north west Atlantic for several years now and there have been a number of papers written about that. That was, however, confined to a small patch around and to the south of the southern tip of Greenland and slightly westwards and south westwards from there. Earlier this summer, we saw that cold pool start to expand.  This seemed to be in a response to the NHEM patterns - while the middle latitudes saw all that warmth, further north it was colder than usual (Iceland saw one of their coldest summers for many years).  As the warmth further south eased and the NHEM patterns changed, North Atlantic SSTs did very briefly recover to nearer neutral but they have fallen back again to some extent.  Not only that but the cold pool has now greatly expanded in all directions and stretches across the whole of the North Atlantic from roughly 50N to 70N (as shown in the map above).

 

Obviously short term influences can distort the trend in either direction but overall it does look like the NHEM "may" join the SHEM with global  SST anomalies "perhaps" turning -ve.  Time will tell but we now need to examine the primary causes, the deep ocean currents and solar influences.  In particular we should focus on the natural variability in the longer term oscillations such as:

 

  • The AMO - the Atlantic Multidecadal Oscillation (also known as the AMV - Atlantic Multidecadal variability)
  • The PDO - the Pacific Decadal Oscillation (the PMO - Pacific Multidecadal Oscillation and the IPO - Interdecadal Pacific Oscillation)
  • The PCO - the Pacific Centennial Oscillation

 

We already have a few excellent papers on these in the Research Portal and these (and others) can be reviewed on here.  We have discussed longer term SSTs in bits and pieces over the last few months on the Teleconnections thread, in ENSO posts, Malcolm @Blessed Weather and I on several hurricane thread posts (the AMO in particular) and Tom on the Countdown thread (as well as in a number of PM exchanges).  I would like us (all those who are interested) to get our SST analyses, views and comments coordinated on this Teleconnections thread.  Just as we did with the ENSO debate, we can develop this in the coming days, weeks and months. We can examine the facts in a balanced way without all the hype at either end of the climate change debate. 

 

David  :) 

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2 hours ago, Blessed Weather said:

 

Hi mbaer1970. I can't recall reading anything about "storm signals" during QBO transition, so if you've got some info I'd be interested in having a look.

 

Trying to predict the NAO state for the coming winter is complex and even the best models currently available have only limited success. The drivers (teleconnections) behind the NAO are multiple with complex interactions between each other, as @Isotherm has touched upon above. The QBO is just one of these drivers. A good read is this 2017 paper A robust empirical seasonal prediction of winter NAO and surface climate that provides a good insight into these (drivers) and the forecasting complexities. Here's some extracts:

 

The slowly varying factors influencing seasonal-to-interannual variability in the winter NAO primarily include Sea Surface Temps, Sea Ice Concentration, El Niño/Southern Oscillation (ENSO), and the quasi-biennial oscillation (QBO). The Atlantic SST has classically been recognized as a useful predictor for the winter NAO. Summer and fall SST anomalies from the extra-tropical and the equatorial Atlantic are found to correlate strongly with subsequent winter NAO anomalies. Moreover, summertime (May through September) Arctic sea ice concentration and extent have gained attention in recent years for their close connections with the winter AO/NAO. However, Atlantic SST or Arctic sea ice alone are not sufficient to provide skilful statistical prediction of the winter NAO. The winter NAO/AO has also been linked to stratospheric polar vortex variability, through downward coupling in zonal mean circulation or planetary waves. Efforts to combine some of these predictors have exhibited slightly higher, yet still limited, skill than individual predictors.

 

Although numerous efforts have been made to improve forecast skill of NAO, it has remained largely unpredictable over seasonal and longer time scales. It is an open question what level of predictability can be reached beyond the limited skill currently achieved for both dynamical and statistical approaches. For dynamical models, state-of-the-art forecast skill (as measured by the anomaly correlation coefficient, ACC) of DJF-mean NAO has just recently increased to a significant level of 0.62 for 1993–2012 by the United Kingdom Meteorological Office(UKMO) Global Seasonal forecast System 5 (GloSea5).

 

The Research Portal link is: https://www.33andrain.com/topic/1397-a-robust-empirical-seasonal-prediction-of-winter-nao-and-surface-climate/

I appreciate the quick reply and for steering me in the right direction. Being on 33 is like taking a college course.

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13 hours ago, mbaer1970 said:

Which is the proper Qbo index that I should be referencing? The ESRL Qbo index value was at -20.41 for August, if this isn't the correct Qbo index to be referencing, what is its importance.

The most common one is the 30mb, and the one above probably is the same. It's fairly standard, but I just wanted to check :) 

 

However it gives the false impression that the QBO is this one number index, which isn't what it really is. It really is an Oscillation that goes from 5-10mb all the way down to 90-100mb within the equatorial region in the stratosphere, bounded by more anomalies associated with ground conditions and the Hadley cells below, and the Semi Annual Oscillation (SAO) above it. This means when the QBO is positive and descending at 30mb, it may for example be negative zonal wind anomalies below 50mb to 100mb. This shows that the effects of the QBO are not strictly linear, because of this inconsistency within the same Oscillation, creating different effects depending on the height and phase of the descending QBO. As indicated by @Isotherm, there is also the strength of the QBO to contend with, and whether the trend is for a normal QBO phase progression, or a sudden change in progression. These are all factors which play into the QBO's effect polewardly towards the Stratospheric Polar Vortex, therefore on it's tropospheric counterpart and then the general hemispheric circulation. And of course, there are other factors that play upon these phases and stages, including snow cover and ice cover, volcanoes, torques, MJO and equatorial waves, SSTs, ENSO, etc. These all make the QBO hard to understand and certainly make it's effects less discernible, but still important.

 

Given the recent speed of the +QBO trend, it is certainly predictable, but not absolute, that the majority of the QBO range will be in positive values for this winter, and will be showing the downstream effects attributable to that phase, however not in a linear fashion, as demonstrated above. But to further put this into context, it is required that we have more information on factors that directly impact upon the stratosphere, like Siberian Snow Cover, and stratospheric momentum transports. We also need more information on ENSO, given this delightful paper I have found and added to the Research Portal. It demonstrates a relationship between ENSO and the QBO, that can be tracked. I won't dig into the paper, but ENSO, and observations throughout the Pacific basin are important to this discussion, given the feedback loop. There may be also not currently indexable relationships between the QBO and other major oceanic or atmospheric factors, but with noted relationships between the AO, NAO, SPV, ENSO, etc, we certain have a lot to work with.

 

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And a cheeky peek at what the AAM models are getting up to, CMC and EC ensembles.

IMG_5305.JPG

IMG_5306.JPG

-AAM in the forecast, stronger on GEPS than EPS. And half of Twitter is on about how we are already in an atmospheric Niño? Plenty of action before that process.

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Perhaps a question for the more experienced members, but how much confidence is there for a -NAO this winter? The NAO has been impressively positive the last couple of months. Low solar, basin-wide weak Niño conditions would argue for a -NAO. QBO value was -9.91 for September and heading to the positive direction. QBO values that go from from east to west (- to +) would be more conductive to +NAO conditions. Some conflicting signals.

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5 hours ago, Ace said:

Perhaps a question for the more experienced members, but how much confidence is there for a -NAO this winter? The NAO has been impressively positive the last couple of months. Low solar, basin-wide weak Niño conditions would argue for a -NAO. QBO value was -9.91 for September and heading to the positive direction. QBO values that go from from east to west (- to +) would be more conductive to +NAO conditions. Some conflicting signals.

You also want the MJO at Phase 6 (+ 10 days lag). Can't say I'm that confident about that, given the convection forecasts and SST forcing. Snow & ice cover over Greenland has been well above average over summer, but of course there has been limited growth elsewhere. That would give way to Greenland blocking. Warm SSTAs around Greenland would keep ice from developing, which isn't great, but if the last 7 days is anything to go by, they are staying warm, so that would help a high also. Wouldn't want the whole North Atlantic to warm up though. Other snow & ice feedbacks like Barents-Kara Sea and Siberian Snow Cover haven't come in either. 

 

At the moment, I'd say the chance of a -NAO this winter is slightly above average. That might change once I see some more forecast come in though. But that said, you'd want a -EPO more for the Eastern CONUS.

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sst.daily.anom.gif

Well then. In the week that I've been away on holiday, the surface warmth has suddenly made some pretty good progress all things considered. I must admit I didn't expect to be seeing so much warming to the east of the area affected by the wide WWB that recently took place between 180 and 100W. 

 

Meanwhile, the South Pacific looks to have seen some areas of warming, and the N. Atlantic has the least widespread or strong negative anomalies that I can remember seeing it in a while. The eastern tropical Atlantic seems to have undergone quite the transformation from cool to warm, too. Is this a wobble or a more significant trend, I wonder?

 

Part of this trend in anomalies may be related to changes in the overall rate of cooling during the autumn season; autumns of decades past cooled at least a little faster as lower total atmospheric moisture and GHGs allowed the heat input April-September to escape at least a little more quickly. Or so the theory goes (which I currently see little reason to disagree with - but I am sure to keep my mind open to alternative explanations).

 

The difference to global mean SSTs mapping may tell a different story for the past week; I'll leave that to others who are more familiar with using that approach.

 

Hope you're all having good weekends, today was impressively warm here in S. UK, in fact record-setting for mid-October :).

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The Impact of the Quasi-Biennial Oscillation (QBO) on the Northern Hemisphere Winter

 

It’s the time of year for winter forecasts so it's appropriate to look at an important teleconnection that will influence how this coming winter plays out. But of enormous importance - and the biggest challenge with long range forecasting - is that it is rarely one teleconnection in isolation that will provide the most accurate forecast, rather it is about taking into account a number of different teleconnections and how they interact with each other. Therefore, although this post is centred around the QBO, it looks at the relationships and interactions with other teleconnections.

 

Overview and main impacts

 

The QBO is a function of the speed and direction of the zonal winds in the stratosphere over the equator, extending from a height of  ~5mb down to ~80mb. The two common measures of QBO activity are taken at 30mb and 50mb and NOAA publish these indices. When the winds are in the positive phase (westerly) this supports a stronger polar vortex (PV) and stronger mid-latitude jet streams. The negative (easterly) phase usually sees a weaker PV with increased possibility of a meandering (meridional) jet stream and blocking weather patterns; the PV is also more prone to sudden stratospheric warmings (SSWs). Therefore an eQBO increases the chance of cold air incursions into northern hemisphere mid-latitudes including the US and Europe.

 

The paper Surface impacts of the Quasi Biennial Oscillation identifies three possible routes for QBO influence at the Earth’s surface, as summarized in their Fig. 1.

 

QBO influence at surface.jpg

 

Extracts from the paper:

 

“In summary, there are multiple possible influence and feedback routes (teleconnections) between the QBO and the surface. While a data study alone is unable to establish cause and effect, nor isolate these individual routes of influence and feedbacks, it can nevertheless point to the primary QBO impacts at the surface and the potential contributors.

A stronger, undisturbed polar vortex was found to be associated with westerly QBO wind anomalies in the mid–lower stratosphere, in good agreement with previous studies.

A previously reported mean surface level pressure (mslp) response in January, with a pattern that resembles the positive phase of the North Atlantic Oscillation under QBO westerly conditions, is confirmed and found to be primarily associated with a QBO modulation of the stratospheric polar vortex. This mid-winter response is relatively insensitive to the exact height of the maximum QBO westerlies and a maximum positive response occurs with westerlies over a relatively deep range between 10 and 70 hPa."

 

Link to paper in the Research Portal: https://www.33andrain.com/topic/1442-surface-impacts-of-the-quasi-biennial-oscillation/

 

The QBO zonal westerly winds are currently continuing their descent down through the stratosphere and the measure at 30mb is forecast to switch from easterly (negative) to westerly (positive) later this October. The following ECMWF zonal wind charts for Oct 3rd (actual) and Oct 17th (forecast) shows this descent with 30hPa above the equator circled in red. As an aside, the Polar Vortex zonal winds, measured at 10hPa 60 N, can be seen ramping up.

 

QBO 03Oct and 17Oct forecast.jpg

 

But as well as the actual phase of the QBO being important, there is evidence that the trend in the index is equally as important for US winter weather. The following analysis is from Frontier Weather and Weather Ops (both organisations owned by Weather Decision Technologies of Oklahoma). When reading this, bear in mind that the QBO has been negative but is now turning positive (and trending to stronger westerly) - not a good trend for cold in the US.

 

A Quick Guide to Important Drivers of US Winter Weather Patterns
“…..trends in the QBO are often more important than the actual value. On average, eastern US winter temperature anomalies are more likely to be cold when the QBO falls during winter, and more likely to be warm when it is rising.”

 

QBO and US Winter Temps.jpg

 

And this blog from Weather Ops:

 

QBO and Winter Temperature Trends

“The following plot shows four different QBO regimes. “A” denotes winter seasons when the QBO is both negative and trending more negative. “B” denotes winter seasons when the QBO is negative but trending in a positive direction. “C” denotes winter seasons when the QBO is positive, but trending negative. “D” denotes winters when the QBO is positive and trending more strongly positive. Winter seasons tend to be coldest when the QBO is in regime “A” and warmest when in regime “D”. Also, when the QBO is trending in a negative direction the western US tends to be warmer than the eastern US, and when the QBO is trending in a positive direction, the eastern US tends to be warmer than the western US.”

 

QBO and US Winter Temps Trend.jpg

 

Note that Weather Ops rightly point out that “The QBO is just one of many factors that influence winter temperatures, the combination of which is more important than any individual factor.”

 

Link to Weather Ops blog: https://blog.weatherops.com/will-the-negative-qbo-increase-the-odds-for-a-colder-winter-this-year

 

Winter storm tracks

 

Focussing in on how the QBO impacts both North Pacific and North Atlantic winter storm tracks, a March 2018 research paper titled Interannual Modulation of Northern Hemisphere Winter Storm Tracks by the QBO found an alternating pattern, depending on whether the QBO was easterly or westerly. NOAA summarised the research as follows:

 

To improve seasonal storm track forecasts, look to the tropical stratosphere

"Winter storms tend to form and travel within narrow 'atmospheric conveyor belts', called storm tracks, which can change location over a period of years.

After analyzing 38 years of model data, the research team found that an alternating pattern of winds high up in the tropical stratosphere, called the QBO, affects significant year-to-year changes in both the North Pacific and North Atlantic storm tracks."

 

Link to NOAA write-up: https://research.noaa.gov/article/ArtMID/587/ArticleID/2330/To-improve-seasonal-storm-track-forecasts-look-to-the-tropical-stratosphere

 

And these extracts from the paper itself:

 

“As shown in this study, Northern Hemisphere winter storm tracks are significantly modulated by the tropical stratosphere through the quasi‐biennial oscillation (QBO). The North Pacific storm track shifts poleward during the easterly QBO winters associated with a dipole change in the eddy refraction and baroclinicity. The North Atlantic storm track varies vertically with a downward shrinking (upward expansion) in easterly (westerly) QBO winters associated with the change of the tropopause height.”

 

Unfortunately this paper is currently behind a paywall. Please pm me if you have access to a free-to-view copy as it would be great to update this post with more detail of implications for this coming winter.

Link to paper abstract in Research Portal: https://www.33andrain.com/topic/1443-interannual-modulation-of-northern-hemisphere-winter-storm-tracks-by-the-qbo/

 

Solar Cycle

 

As well as the dominant annual cycle in solar variability impacting surface weather, there is also an 11 year solar cycle with longer underlying modes of variability. Research has found that the strength of the Arctic polar vortex, a key component of stratosphere – troposphere coupling, could be influenced by the solar forcing but the response is modulated by the phase of the QBO.

 

This from the paper Life cycle of the QBO-modulated 11-year solar cycle signals in the Northern Hemispheric winter:

 

“More recent studies have found that SSWs are more prevalent in low solar years during the eQBO phase and in high solar years during the wQBO phase, suggesting that the Holton Tan relationship is reversed during high solar years.”

Link to paper in the Research Portal: https://www.33andrain.com/topic/1444-life-cycle-of-the-qbo-modulated-11-year-solar-cycle-signals-in-the-northern-hemispheric-winter/

 

This effect is confirmed in a study Sunspots, the QBO, and the Stratosphere in the Northern Polar Region that finds there is “a clear tendency for SSWs in the westerly phase of the QBO to occur during solar maximum (solar flux above 150 units) and out of 11 cases 10 took place in solar max and none in solar minimum.”

Link to paper in the Research Portal: https://www.33andrain.com/topic/1445-sunspots-the-qbo-and-the-stratosphere-in-the-north-polar-region-–-20-years-later/

 

MJO

 

Finally a look at the impact of the stratospheric-tropospheric coupling between QBO and the MJO. Here’s some extracts from the paper Stratospheric Control of the Madden–Julian Oscillation:

 

“It is shown that the boreal winter MJO amplitude is closely linked with the QBO rather than with ENSO. The MJO activity around the Maritime Continent becomes stronger and more organized during the easterly QBO winters. The QBO-related MJO change explains up to 40% of interannual variation of the boreal winter MJO amplitude. This result suggests that variability of the MJO and the related tropical–extratropical teleconnections can be better understood and predicted by taking not only the tropospheric circulation but also the stratospheric mean state into account.

 

It should be noted that this research does not necessarily indicate that ENSO has no impacts on MJO amplitude. In fact, recent studies reported a significant ENSO–MJO link during boreal winter. Such a relationship, however, is nonlinear and highly dependent on the characteristics of ENSO itself. For example, it is shown that the MJO becomes stronger than normal during the central Pacific El Niño winters whereas it becomes weaker during the eastern Pacific El Niño winters.”

 

Link to paper in the Research Portal: https://www.33andrain.com/topic/1446-stratospheric-control-of-the-madden–julian-oscillation/

 

Conclusions and Implications for Winter

 

Based on the teleconnections discussed in this post, indications are for a winter period with a decreased likelihood of lengthy spells of extreme cold for the US and Europe. To summarise the factors behind this:

 

·       A westerly QBO (with unfavourable trend from negative to positive)

·       A likely organised and strong PV

·       A likely stronger mid-latitude jet stream

·       Decreased chance of a SSW

·       Increased likelihood of +AO pressure pattern

·       Increased likelihood of +NOA pressure pattern

·       Decreased likelihood of high amplitude MJO events

 

This does not rule out short-lived severe cold outbreaks, but rather - taking the winter as a whole - teleconnections point to an increased chance of temperatures being 'average' or 'above average'.

 

With many seasonal forecasts now being produced by various models, of interest is a report Why the Quasi-Biennial Oscillation matters published by ECMWF in 2015 that states that many of the models used for numerical weather prediction (NWP) and climate modelling are either unable to produce a QBO, or they produce a QBO which looks very different from observations. For example, back in 2015 there were only 4 of more than 30 models used in climate forecasts that had any sort of QBO. ECMWF seasonal models include QBO. Link: https://www.ecmwf.int/en/about/media-centre/news/2015/why-quasi-biennial-oscillation-matters

 

I will end with these thoughts. The dramatic warming of the Arctic and the reduction in ice cover is having notable impact including reduced temperature gradient between Polar regions and mid-latitudes, a weaker jet stream prone to more frequent meridional flow and increased blocking ('stuck') patterns. Extreme weather is increasing and records are tumbling. We appear to be entering uncharted waters and working from a different base state. This begs the question - how reliable are studies and analogues that are based on the past? I for one will be following winter developments with keen interest.

 

As always, comments welcomed.

 

 

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For the record, I am in the camp of people who are concerned about QBO implications, especially as we move into the second half of the winter. This is a very underrated indicator and I do agree that the rapid transition to positive will have an impact later this winter. I think many are erroneously believing February will be the coldest and snowiest month. Think we have one shot at a pattern changing snow event early in February, but then we’re basically done after mid-month. I do believe the -EPO and active STJ will propel us to at least normal snow in December and January.  

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last year the QBO was similar to 1963...by January 64 it was a plus 3.94...the last QBO number was -9.91...up from -20.41...the following table are plus QBO winters that followed a minus QBO winter...reds are el nino years...looking at this chart a weak positive QBO would be very good...1957-58, 1963-64 and 1977-78 were all great winters...

1957-58....+5.25

1963-64....+3.94

1966-67....+11.03

1971-72....+8.20

1975-76....+9.22

1977-78....+3.21

1980-81....+8.51

1982-83....+10.85

1987-88....+7.81

1992-93....+9.63

1994-95....+8.32

2001-02....+4.64

2008-09....+10.71

2010-11....+9.18

2015-16....+9.34

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2 hours ago, 33andrain said:

For the record, I am in the camp of people who are concerned about QBO implications, especially as we move into the second half of the winter. This is a very underrated indicator and I do agree that the rapid transition to positive will have an impact later this winter. I think many are erroneously believing February will be the coldest and snowiest month. Think we have one shot at a pattern changing snow event early in February, but then we’re basically done after mid-month. I do believe the -EPO and active STJ will propel us to at least normal snow in December and January.  

 

This is WAR. 

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2 hours ago, 33andrain said:

For the record, I am in the camp of people who are concerned about QBO implications, especially as we move into the second half of the winter. This is a very underrated indicator and I do agree that the rapid transition to positive will have an impact later this winter. I think many are erroneously believing February will be the coldest and snowiest month. Think we have one shot at a pattern changing snow event early in February, but then we’re basically done after mid-month. I do believe the -EPO and active STJ will propel us to at least normal snow in December and January.  

 

I think you are leaning one indicator here for a 5 month lead. 

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17 hours ago, Blessed Weather said:

The Impact of the Quasi-Biennial Oscillation (QBO) on the Northern Hemisphere Winter

 

A Quick Guide to Important Drivers of US Winter Weather Patterns
“…..trends in the QBO are often more important than the actual value. On average, eastern US winter temperature anomalies are more likely to be cold when the QBO falls during winter, and more likely to be warm when it is rising.”

 

QBO and US Winter Temps.jpg

 

 

IMO, the QBO has to be used in concert with at least one other variable, i.e. QBO/ENSO, QBO/Solar, etc. 

 

Looking at the QBO data back to 1953 on the Berlin chart (and Singapore stratosphere data), there are 4 winters in which the QBO was negative at 50mb in Dec and rising thru winter during an El Nino (should be the same this winter).  Those winters are:  68-69 (cold across the U.S. with massive -AO / -NAO like 09-10), 72-73 (warm in eastern U.S., but was a high end strong Nino), 77-78 (cold in eastern U.S.), 94-95 (warm in eastern U.S. but tainted by era of cold stratosphere).

 

So, mixed results, but certainly not a slam dunk warm lean for the El Nino cases....sample size is small. 

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1 hour ago, PB GFI said:

 

I think you are leaning one indicator here for a 5 month lead. 

Well, I'm also concerned about the ENSO state. Not convinced the current region 1+2 cooling is long term. The next 2-3 weeks are critical, as always. You don't need to worry about me putting all my eggs in one indicator basket.

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