NH patterns Autumn 2018 - Forget the analogues ...

[SMU]

Evening All -

Its been a long long time since I opened a thread - So I will try to make it interesting...

The first dip of the toe into Autumn is for many of us the change in mindset away from summer heat & into the ever shortening days & colder weather...

Traditionally as we head through September & especially October the vortex & westerly jet increases to a point where the probability of southerly warmth is significantly reduced in probability- 

Notable dates in the diary for this is around the 10th of October onwards where the winter time Stratospheric vortex is ~ half of its winter peak speed @ ~ 16-20 M/S Westerly.

Shapes of high pressure through 40- 50N should be flat & the mode of the AO / NAO historically reads as a positive...

There is one other important Teleconnection that I never hear anyone ever mention but Ive kept revisiting it each winter for about the last 5 / 6 years is the POL ( the polar eurasia pattern )

The loading pattern for POSTIVE PHASE is measured across Northern Russia down to about Mongolia & is a similar measure to the NAO -

The more POSITIVE the phase the lower the geopotential heights are over Norther Russia supporting a westerly circulation

So + AO + NAO + POL all indicate a traditional zonal flow.

To emphasise this the 90s was where the jet was roaring & the AO & POL certainly in autumn months peaked heavily positive

So all said & done taking into consideration natural variation between occasional stronger & weaker years & of course ENSO phases we generally see a uniform process to our weather through Autumn which decends into 'westerlyness' - & this years Autumn forecast would seemingly be very straight forward if you wanted to pluck out things like matches from ENSO state & QBO phase  & of course they 'could' still play their part however ENSO will be solid Neutral for SON & QBO will be dwindling Easterly -

Anyway- What changes do we see potentially impacting our weather & the imposed 'Westerlyness' ...

Pattern Induced Climate change is probably a phrase thats not bantered about to much but it certainly will be in the coming years-

The globe is warming however the poles are warming much faster than the average annual rate - this is creating a NEW ( circa 2007 onwards ) feedback loop over the polar cell & * SOME * of the mid lattitudes -

It is causing autumn tropospheric decoupling from the stratospheric vortex & it  occurs in the low sea ice areas ( or more specifically the areas with the biggest negative anomaly to the norm )

What we have seen since 2007 is not only the decadal average of sea ice decline ( especially August / Sept & Oct ) but also focal points of significant negative anomalies in areas close to where the POL teleconnection is measured.

The Barents / kara & laptev seas have all been in the 'ice news' for the wrong reasons & the graphs below show how this summers ice coverage has taken a real beating -

The 3 above are in Anticlockwise order from Scandi Eastwards - Notes being

* Barents melting out early like the decadal Trend

* The next in line Laptev taking a further hit this year - being probably the worst on record 

* Kara as well - under the decadal ave & close on record lows -

- Its also worth noting how far away they are from the 70s / 80s are - imagine how far they would be from the 50s & 60s !

The net fallout from this is the amount of residual latent heat in these areas through Autumn & *Possibly* now Early Winter & what the net fall out is - the creation of a new feedback loop of Positive heights In Northern Russia.

This is also probably the net reason 'globally' why there is a reduction in the overall jet speed & depth of negative geopotential heights because of the reduced Thermal Gradient..

This illustrates well if you chunk up Sept & Oct 500 height anomalies charts for

1948 -1990 The base period 

1990 - 2006 a fairly significant 16 year phase of ice loss

2007 -2017 the last 10 years in ice loss creating this new feedback loop & pattern change.

We see a CLEAR Modal change in the height field over the pole - especially concentrated over the 3 weak ice areas.

Lets reintroduce the POL teleconnction to include the last decade

The mode has swing to a very sharp -POL especially in Autumn but not exclusive.

The data indicates 

ftp://ftp.cpc.ncep.noaa.gov/wd52dg/data/indices/poleur_index.tim

That 2007-2017 Sep / Oct / Nov 20/30 months have been negative with 9/9 on the last 3 Autumns !!! 100%

Its also about the 'negativity' of the mode as well - going off the scale more recently..

So Bringing that back to this Autumn & NW Europe the net effect is that the eastward propergation of the atlantic is expected to be weaker & weaker - so for Western Russia we could be promoting an earlier signal for Colder weather developing -

This signal fades as we come SW towards Norther & Central Europe, however the extent of the high promotes higher probability of early warmth from the south but again later into Autumn could also promote Colder air filtering through -

The UK sits as ever at the end of the blocking - & whilst its immediate impacts may be slightly tempered its still expected to impact us ... but how?

I would consider the following in terms of probabilities !!! NOT forecasts...

* Higher probability of warmer phases in Sept Oct in particular from the south & East 

* Higher probability that the atlantic jet will be displaced further NW towards Greenland ( although occasional split jets towards Spain & portugal as well )

* Rainfall - Probability should be that its drier however we could up in the unique scenario where the westerly jet runs out of puff over the UK & its very wet ( the weather becomes stationary ) - this would be very unlucky. Also short periods of very high rainfall could occur 

* Whilst the probability remains high that it will be warmer than usual - the locality of that blocking high means that as we transition through Oct & Nov the chances of early season chill & cold could also be higher- We could see drastic swings in the weather from extreme Mild & warmth to Cold as the jet flow will be buckled...

- Also there could well be some overlap into December in these conditions - Highlghted below--

The transition from Autumn & Winter this year will see the usual array of teleconnections to measure up-

Currently 

- ENSO appears to be Neutral out to December, possible low end El Nino, critically here the lower we stay the weaker the impact will be

- QBO - decending Westerly at the moment, whilst this isnt great in the long run the effects of the 'westerly' are unlikely to impact until the late part of winter perhaps reducing the prospects of a SSW ( other factors like MJO activity may support either  way )

- Sunspot activity continues to be at a low point in the cycle which is a huge positive-

- The troposheric disconnect that may well run through sept > Oct could Extend to Nov > Dec for 2 reasons

* The feedback from the ice anomalies is so significant that if on average the signal in the last decade is muted out mid Oct - then how long will the new record low take to mute out ?? Another 4 weeks ?? Plus the wildcard this winter may be that theres support for the feedback from greenland in the form of more warmth due to record low ice here as well

Plus the stratosphere is being modelled to be weak-

The mean of the all the CFS runs should be taken with a pinch of salt - however its modelling significant weakness as we head through Oct & Nov -

Further delaying the onset of the westerlies...

So there we go as I see it -

Autumn - Blocking to the East supports weaker westerlyness - although the UK could sit on the periphery where the jet holds stationary - ( worst case scenario )

Best case scenario >> Jet up to iceland & warmth 

Winter - Everything is in place to positively support a blocked winter - however the last peice being the strat will only become clearer in another 8-10 weeks ...

Best

S

 

 

[bobbydog]

funnily enough, i was just thinking today that trying to work from analogues of previous winter teleconnections- doesn't work. there are too many variables, many of which are major players in influencing weather. however, some do need to be in place for western europe to be in with a favourable chance. one of which is the "POL" you mention. though i've never before seen it given a title, the persistent 'siberian high' which is often referenced, seems to be what you are referring to. the tabloids often say "icy blast all the way from siberia" - and that stubborn high (when it happens) is the source. that high is a product of the extent of the eurasian snow cover which we all watch intently through october. we've got to be due a proper epic winter soon...

[Snowyowl9]

Most interesting post I`m read all year.

2007 was the big new change to something much different.

[SMU]

Cheers

This  would be the approximate 500MB anomaly for sept into Oct 18

Note the wind flow south - SE poss more so continental

[BLAST FROM THE PAST]

Very interesting read.  I have touted anticipation of ‘Indian Summer conditions with a lovely warm September likely to extend into Oct with HP domination.  I also anticipate an early winter visit..... 

 

BFTP

[SMU]

These patterns woukd support both

[BLAST FROM THE PAST]

Steve

Interesting to note that Greenland ice sheet mass is well above The Norm. The theory I’m working on is we will see cooling of landmass to the norm first, earlier snow and more freak ‘in a rut’ weather hot or cold.  Growing seasons to be greatly / negatively impacted.....sea temps to lag but fall over next 10-15 years.....bingo.  We are seeing impacts of rut Weather patterns, late/reduced growing seasons or negative impacts on..... we are in step down 1 on my understanding.....and next few winters should....’should’ reflect this on my understanding.    Then we have wildcard.........major global impacting volcanic eruption....anticipated as we approach ‘Deep minima’.  So your research is very very interesting indeed.....

 

BFTP

[BornFromTheVoid]

11 hours ago, BLAST FROM THE PAST said:

Steve

Interesting to note that Greenland ice sheet mass is well above The Norm. The theory I’m working on is we will see cooling of landmass to the norm first, earlier snow and more freak ‘in a rut’ weather hot or cold.  Growing seasons to be greatly / negatively impacted.....sea temps to lag but fall over next 10-15 years.....bingo.  We are seeing impacts of rut Weather patterns, late/reduced growing seasons or negative impacts on..... we are in step down 1 on my understanding.....and next few winters should....’should’ reflect this on my understanding.    Then we have wildcard.........major global impacting volcanic eruption....anticipated as we approach ‘Deep minima’.  So your research is very very interesting indeed.....

 

BFTP

Just a quick note, it's the "surface mass balance" (SMB) that's above average for Greenland. That's basically the balance of surface snowfall vs surface snow/ice melt, which is almost always a positive balance. 
The mass of the ice sheet as a whole for the last year isn't known yet. But there are lots more going on around the ice sheet edge that can take mass away, such as iceberg calving or melting from the nearby oceans/seas where they're in direct contact with the ice (for example). These edge effects are very important, which is why despite a positive SMB each year, the overall mass of Greenland in on a long term decline

[Methuselah]

11 hours ago, BLAST FROM THE PAST said:

Steve

Interesting to note that Greenland ice sheet mass is well above The Norm. The theory I’m working on is we will see cooling of landmass to the norm first, earlier snow and more freak ‘in a rut’ weather hot or cold.  Growing seasons to be greatly / negatively impacted.....sea temps to lag but fall over next 10-15 years.....bingo.  We are seeing impacts of rut Weather patterns, late/reduced growing seasons or negative impacts on..... we are in step down 1 on my understanding.....and next few winters should....’should’ reflect this on my understanding.    Then we have wildcard.........major global impacting volcanic eruption....anticipated as we approach ‘Deep minima’.  So your research is very very interesting indeed.....

 

BFTP

Any known mechanism going to cause that, Fred?

[BLAST FROM THE PAST]

1 hour ago, BornFromTheVoid said:

Just a quick note, it's the "surface mass balance" (SMB) that's above average for Greenland. That's basically the balance of surface snowfall vs surface snow/ice melt, which is almost always a positive balance. 
The mass of the ice sheet as a whole for the last year isn't known yet. But there are lots more going on around the ice sheet edge that can take mass away, such as iceberg calving or melting from the nearby oceans/seas where they're in direct contact with the ice (for example). These edge effects are very important, which is why despite a positive SMB each year, the overall mass of Greenland in on a long term decline

Thanks for input BFTV.

 

BFTP

[BLAST FROM THE PAST]

1 hour ago, Ed Stone said:

Any known mechanism going to cause that, Fred?

Hi Pete

statistcally it is documented that major eruptions occur during deep minimas.  Coincidence or not?  I think it can be said a ‘strong coincidence’ at this point.....and I think we are headed towards a true deep minima.

 

BFTP  

[SMU]

On 27/08/2018 at 12:00, Steve Murr said:

Cheers

This  would be the approximate 500MB anomaly for sept into Oct 18

Note the wind flow south - SE poss more so continental

Opener to September height anomaly showing almost a perfect mirror match to the forecast-

[BLAST FROM THE PAST]

Looking forward of interest here.....my method / research nothing linked to Steve reads and has done for a while.....HP ‘domination’ and Indian Summer conditions.....this could well extend ‘generally’ into October.  A bang then comes for early winter.....I’ll firm detail up soon but December for me is COLD

 

 BFTP

[jonboy]

On ‎29‎/‎08‎/‎2018 at 09:47, Ed Stone said:

Any known mechanism going to cause that, Fred?

One of the theory's is that during a deep and prolonged minimum the earth has less protection from the sun's magnetic field which allows amongst other things greater cosmic ray activity to reach earth and it is as part of the process of decay etc that particles such as muons then penetrate the earths mantle and in decaying transfer energy into the earth's core thus slightly increasing its temperature and thus volume which in turn leads to greater volcanic and earthquake activity at times of deep prolonged minimum.

Very over simplified but hope you get the gist

[Man With Beard]

Brilliant post Steve. 

But if a Scandi High holds in situ for several weeks with lower heights over Europe, surely the warmth could drain a lot quicker? You can already see Eastern Europe cooling down significantly even on deterministic runs for mid September. 

[SMU]

Yes MWB -eventually that cooler upper air with fill Northern Europe, however there could be oscillations where the lows filtering cool air south into Scandi could be replaced by warmer atlantic air again-

Lets see how week 3-4 of September pan out especially as the atlantic springs into life--

[jules216]

Hi Steve, Many thanks for highlighting the clear connection between the sea ice loss and Polar/Euroasian pattern with further feedback on the atmospheric pressure patterns. One think I can confirm to you is that in the recent decade the month of October has been the least warming out of all months in central Europe. In recent years there is a very early winter blast in October with snow down to moderate altitudes. Unfortunately the trend doesn't keep up and we end up with mild Decembers appart from 2009,2010,2012, the atlantic jet is too strong for the anticyclone to fight it of  at the back of strong zonal wind anomalies in stratosphere, suma sumarum, autumn with northern blocking for sure being replaced by strong zonal flow in december, that has been the pattern in central Europe last decade or so  

[Leo97t]

59 minutes ago, jules216 said:

Hi Steve, Many thanks for highlighting the clear connection between the sea ice loss and Polar/Euroasian pattern with further feedback on the atmospheric pressure patterns. One think I can confirm to you is that in the recent decade the month of October has been the least warming out of all months in central Europe. In recent years there is a very early winter blast in October with snow down to moderate altitudes. Unfortunately the trend doesn't keep up and we end up with mild Decembers appart from 2009,2010,2012, the atlantic jet is too strong for the anticyclone to fight it of  at the back of strong zonal wind anomalies in stratosphere, suma sumarum, autumn with northern blocking for sure being replaced by strong zonal flow in december, that has been the pattern in central Europe last decade or so  

The reason December is such a westerly mess I because we are paying our debts back to the weather gods for their generous gift of December 2010

[SMU]

* Rainfall - Probability should be that its drier however we could up in the unique scenario where the westerly jet runs out of puff over the UK & its very wet ( the weather becomes stationary ) - this would be very unlucky. Also short periods of very high rainfall could occur 

The above extract for the Autumn review is really coming into pay this week with a low pressure becoming almost stationary over the UK bringing long periods of rain ! 

Possibly snow over the tops in Scotland...

[bluearmy]

interesting read steve ......

 note the latest DJF seasonal updates from cvsv2 and ec re height anomolys - guess which is which ?

  

 

[Don]

1 hour ago, bluearmy said:

interesting read steve ......

 note the latest DJF seasonal updates from cvsv2 and ec re height anomolys - guess which is which ?

  

 

EC top

CFS v2 bottom

Could they be much more different?!

[John Cox]

Steve, thanks for a great topic and detailed opening post.

I posted the following comment on an Irish Facebook forum in July.

"From what i can see, the same synoptics in general have prevailed since the historic snow storm back at the end of February. In winter this gives snow, in summer sunny and hot. I cannot remember any such prolonged synoptic similarities (easterlies) in all the 40 years i have been weather watching. Is this linked to the slowdown in the North Atlantic drift? This being caused by the speed up in the melting of the Artic ice and Greenland Ice? Could the NAD slowdown be speeding up? We know what this would eventually cause. Perhaps I am being over dramatic. We shall see."

I am not there most techical member here and I just have observed the weather for the last 50 years and studied the charts for as long.... and things, i believe,  have changed big time since early in the year. I did predict to family members and friends after the Late February and 18th March cold spell that if the weather synoptics continued as they were at that time we would be in for a scorcher of a Summer. The synoptics generally stayed the same and lo and behold the hottest, sunniest and longest Summer came to Ireland this year.

Stephen, my technical reasons for the change above may be quite simplistic.

I think perhaps, what you have stated in detail may be actually what is taking place. This winter could be facinitating and indeed one to watch, based on your thoughts.

 

[BLAST FROM THE PAST]

John

For different reasons, but on your lines I think if the set up continues we’ll see a switch to a very cold early winter.  This whole year is fascinating and this minima is looking a fair bit deeper than the last...and thus mouthwatering times for me over coming few years

 

 

BFTP

 

[Interitus]

Strong sense of deja vu here as the POL was brought up in the discussion on the OPI back in 2014. At almost the same time the concept of the Taymyr Circulation Anomaly came to the fore in the paper October circulation precursors of the wintertime Arctic Oscillation (Kryjov 2014). This highlighted the correlation between Taymyr October geopotential anomalies and the following winter AO, but it seems the paper is still paywalled. At the time an arbitrary point was used to investigate this correlation (74.5°N 104°E) using 500hPa geopotential.

However, the author co-wrote a follow-up paper Predictability of the wintertime Arctic Oscillation based on autumn circulation (Kryjov & Min 2016) which gives an insight to the earlier work and its application to forecasting (they use 700hPa geop. anom averaged and area weighted over 80-70°N 100-120°E). This paper is available - https://www.researchgate.net/profile/Vladimir_Kryjov/publication/292075140_Predictability_of_the_wintertime_Arctic_Oscillation_based_on_autumn_circulation/links/56c3f03708ae8a6fab5a3396/Predictability-of-the-wintertime-Arctic-Oscillation-based-on-autumn-circulation.pdf

As illustrated in 2014, the homebrew Taymyr index proved superior to the POL in correlations with the AO, below are the correlations from 1950 up to last winter -

		Winter AO	Dec AO	Jan AO	Feb AO
Taymyr index	0.390		0.265	0.342	0.258
POL index	0.182		0.090	0.145	0.167

In particular it supports the link between October circulation and winter AO suggested by Kryjov. This doesn't tell the whole story however as shown in this chart of running 20-year correlations between the indices and winter AO. Also included are a Mongolian z500 anomaly (50°N 120°E) which has been used to create an estimated POL -

The first few years are poor for all, this may be due to issues with data quality in the early reanalysis - the authors above use from 1958 onwards.

After this though, the Taymyr index is better than the POL except for the 3 year period 2005-2007 (interestingly the artificial POL also beat the Taymyr), but more than this it proves to be relatively stable providing consistently good correlations over time. The same can't be said of the POL however which is poor in the early years even anticorrelated to winter AO and this is more strongly the case for the Mongolian anomaly - it would suggest that the value of the POL is given by the node in the area of the Taymyr circulation and it is dragged down by its dipole in Mongolia.

In the second half of the period the Mongolian anomaly correlation improves which leads to better performance from the POL and there is also quite a marked sudden improvement for all including the Taymyr index. Couple of possibilities spring to mind - the timescales of Mongolian and POL correlations with winter AO are similar to the AMO. The 30 year correlation between the Mongolian anomaly and October AMO exceeds -0.7 when AMO leads by 29 years - but is >0.8 when AMO lags by 9 years (with over 0.95 for 10 year averaged AMO) - because of the timescales involved more data would be required to investigate this link further. The apparent sudden improvement in all indices may coincide with improved reanalysis with satellite data maybe.

Finally with regards to changes since 2007, it is worth noting that all the correlations have fallen since the 2007-12 period.

 

[jules216]

This anomaly by CFS from most recent output would certainly confirm the theory discussed in this topic, shortly we will find out what October brings.