Early run up to Winter 2021/2022 discussion

[jules216]

Also week 5 ECMWF starting to look a lot like 1998 analog for November,at least heading that way.

[jules216]

Also here for comparison EPS days 6-10 vs Oct 1998. To me its best pattern match then Other La Ninas which are considered as good analogs for this winter(2007,2011,2016,2017 etc.)which had most strong UK/Scandi blocking present and SE Europe trough. That is not happening this Oct for sure

 

 

 

[Don]

As others have said, 1998/99 had a few cold snaps but was pretty grim overall and certainly not one to excite a snow lover!

[jules216]

4 minutes ago, Don said:

As others have said, 1998/99 had a few cold snaps but was pretty grim overall and certainly not one to excite a snow lover!

What can I say for winter 1998/1999 in Slovakia? this image is self explanatory. I was in secondary school that year and we had snow holidays for about a week which is not like usual for our standards, snowiest winter on par with 2004/05, 2012/13 and 1995/96 

[Don]

6 minutes ago, jules216 said:

What can I say for winter 1998/1999 in Slovakia? this image is self explanatory. I was in secondary school that year and we had snow holidays for about a week which is not like usual for our standards, snowiest winter on par with 2004/05, 2012/13 and 1995/96 

Slovakia could be the place to be this winter then!

[Cheshire Freeze]

Wasn’t ‘98 during a time of generally high solar activity?

You have to tweak the analogues for this, as we found out during the summer just gone.

How close were we to cold set ups during 98/99 synoptically? No two analogue years are the same so it actually could benefit us.

Edited September 27, 2021 by CreweCold

[jules216]

1 hour ago, CreweCold said:

Wasn’t ‘98 during a time of generally high solar activity?

You have to tweak the analogues for this, as we found out during the summer just gone.

How close were we to cold set ups during 98/99 synoptically? No two analogue years are the same so it actually could benefit us.

 I like solar analog of 1998 too, it was  generaly rising from minimum too. And flux around 90-100 can be achieved too.

[Sunny76]

6 hours ago, jules216 said:

What can I say for winter 1998/1999 in Slovakia? this image is self explanatory. I was in secondary school that year and we had snow holidays for about a week which is not like usual for our standards, snowiest winter on par with 2004/05, 2012/13 and 1995/96 

1998/99 was the winter I flew out to the Toronto for a weeks holiday. I was there in February 1999, which unknown to me at the time, was just a month after one of their worst snowstorms for many years. 
 

January 1999 was one of their snowiest spells, and the army even had to be called out. 
 

I remember flying back into England, and noticing the West Country was covered in snow, during the second week of February.

It was a mild winter, but a colder one compared to the previous very mild winter of 97/98.

[SqueakheartLW]

Another thing to say about winter 1998/99 is that it had 2 SSW events too

[SqueakheartLW]

Who wants an October snow event. This P18 from today's GFS Extended run for 12th October

12/10/2021     850hpa temp -10.3     2m temp min -0.8C     max 4.0C

[jules216]

13 minutes ago, SqueakheartLW said:

Another thing to say about winter 1998/99 is that it had 2 SSW events too

Not unlike this year with some weakening of zonal winds in mid October and if we believe Glosea then also down the line in November

[damianslaw]

Mmm can't say I would like to see another winter akin to 98/99. Was generally wet and mild, but as said there were a handful of northerly outbreaks, most notably second week of Feb which delivered some snow. Too much of the winter was very wet and mild though. Could live with a Nov 98 and start to Dec 98, but then something else please.

[sebastiaan1973]

https://www.metswift.com/late-2021-risk-of-disruptive-cold-weather-eastern-usa-europe/

Welcome to the ‘light’ version of MetSwift’s look ahead to the risk of disruptive cold weather hitting the Eastern USA and/or Europe in Nov-Dec 2021. For a more in-depth read, please see the full article here.

The Northern Hemisphere’s autumn is barely a third done, yet already, the thoughts of some are turning to the cold season ahead. This is because it pays to size up severe winter weather risk and plan accordingly.

This year, more than most: I’m writing this blog in the wake of sharp rises in wholesale power and gas prices. This has put some energy companies at risk of collapse, including Bulb, the 6th largest in the UK.

Customers, faced with higher prices or being ‘left in limbo’ as their suppliers fold, will hope for a kind end to the year; one that demands less artificial heating than usual (i.e. has low heating degree days; HDD).

Are November and Dec going to ‘play nice’, or make matters worse? Let’s see what we can learn from history.

A NATURAL LEADER: THE NORTH ATLANTIC OSCILLATION (NAO)

Analysis here focuses on a major North Atlantic circulation pattern known as the NAO. It varies between positive and negative states, which in northern Europe and the eastern USA are broadly associated with an increased frequency of mild and cold spells of weather, respectively.

Britannica provides a good illustration of it here. At MetSwift, we take it to the next level, by sub-dividing it into ‘East’ (ENAO) and ‘West’ (WNAO) variants. Associated weather tendencies are illustrated below.

 

A negative ENAO state is mainly distinguished from a negative WNAO state by the fact that it brings unusually warm, not cold, weather to the eastern USA. It also doesn’t have to be as strongly negative to bring widespread cold weather to Europe.

FREQUENCY DISTRIBUTIONS

To obtain guidance on how the NAO is likely to behave, I have filtered daily NAO observations to ones on which three key driving forces of weather patterns (teleconnections) were behaving in the same way as they’re expected to be during the upcoming months.

Those teleconnections are:

The El Niño Southern Oscillation (ENSO): Variations in sea surface temperatures (SSTs) across the tropical Pacific from the Dateline eastward. Once every 1-3 years, these become strong and coherent enough to be classified as La Niña (low SSTs) or El Niño events (high SSTs).

Pacific Decadal Oscillation (PDO): Another SST cycle, but occurring in the northern Pacific Ocean, with predominantly positive and negative stages that usually last a decade or two.

Quasi-Biennial Oscillation (QBO): A cycle of westerly and easterly winds occurring in the stratosphere above the tropics.

All three are expected to be in negative phases (but the QBO specifically in the lower to mid-stratosphere).

That filtered data has then been compared with unfiltered data, using frequency distributions. This shows us what historically suggests the WNAO and ENAO are most and least likely to be doing.

NOVEMBER WNAO: PROBABLY NOT UP TO MUCH

The distribution of the filtered Novembers suggests the number of snowfall events could be a little above average, with mild and wet winter weather less prevalent than usual, especially in north-eastern USA.

NOVEMBER ENAO: PROBABLY WEAK ONE WAY OR THE OTHER

For the ENAO frequencies, we again see an indication that November will be dominated by ‘average’ conditions, especially in Europe. However, there is certainly some scope for notably mild or cold spells of weather (just not in a big way).

DEC WNAO: POSITIVELY INCLINED…?

The filtered distribution here has a strong positive skew. This points toward a wetter, windier than usual month for the north-eastern USA. However, a very negative WNAO also has a raised frequency compared to average. There could be a few more unusually cold, snowy days than usual in the eastern USA, perhaps Europe too.

DEC ENAO: UNUSUALLY PRONE TO BEING VERY NEGATIVE

Last but far from least, we come to December’s ENAO filtered frequency distribution. Cold, potentially snowy weather is suggested to be much more common than usual in Europe. This corresponds to more unusually mild days than usual in the eastern USA.

It’s possible that this signal is connected to something called a ‘sudden stratospheric warming’ (SSW).

SSWS TRIGGER SEVERE COLD SPELLS… AND ONE MAY OCCUR BY DEC

Within a 1-3 weeks of one of these events, weather patterns change drastically. Cold air, usually ‘bottled up’ over the Arctic regions, spills south across one or more regions. Weather systems become slow-moving, prolonging the impact of the cold weather where it occurs. Meanwhile, adjacent regions can experience unusually high temperatures, sometimes rainfall too.

Broadly, these can be sub-classed as ‘major’ and ‘minor’ SSW events. As you may imagine, the major ones tend to affect the largest combined area and have the longest-lasting impacts.

Recently, numerous long-range weather forecasting computer models have been predicting a SSW, or something close to it, to occur by Dec. Most notably, that of ECMWF, which has one of the best track records.

To gauge how seriously we should take these predictions, I’ve studied the frequency distribution for filtered historical years, as was done for the NAO earlier. A minor SSW is suggested to be likely (73% risk) in November, less so (33%) in Dec.

A CHILLING PROSPECT

In conclusion, there’s a heightened risk (not guarantee) of a substantial spell of cold, snowy weather affecting Europe sometime Nov-Dec. Considering the NAO analysis performed earlier, the risk for the eastern USA is close to the long-term average.

If a minor SSW occurs, probable duration of highly anomalous weather patterns is 3-6 weeks. One small comfort is that we’re not talking about a major SSW here – although I can’t rule that one out, sadly!

Regardless of duration, such an event would see soaring demand place strained energy companies under even more pressure. Certainly, one worth making contingency plans for, just in case.

 

James Peacock MSc
Head Meteorologist at MetSwift

Edited September 28, 2021 by sebastiaan1973

[SqueakheartLW]

Time for my 6th winter update based on the CFS 00z 9 monthly run dated 30/09/2021

This time I haven't gone through all of the charts and posted what happens but the run should still be there on meteociel until at least the middle of tomorrow if you wish to look at it

I have instead displayed a table of all 6 updates figures below. Also discovered a few errors with the formulas in the spreadsheet for the December figures and had to correct those. The now correct December figures are below. All the January to March figures were already correct. The overall figures for all Decembers as well as the winter as a whole have changed in some cases.

                   December 2021                     January 2022           February 2022        March 2022           OVERALL Dec 21 to Mar 22

91_20       4.97C                        Anom      4.66C       Anom        4.89C      Anom      6.74C      Anom      5.32C                      Anom

Update 1  4.73C (Correct)      -0.24C      1.95C     -2.71C         3.50C     -1.39C       4.26C     -2.48C      3.61C (Correct)       -1.71C

Update 2  3.40C (Correct)      -1.57C      3.42C     -1.24C         1.43C     -3.46C       3.92C     -2.82C      3.04C (Correct)       -2.28C

Update 3  4.39C (Was 5.44)   -0.58C      3.95C     -0.71C         3.34C     -1.55C       3.89C     -2.85C      3.89C (Was 4.15C)  -1.43C

Update 4  2.55C (Was 5.44)   -2.42C      2.40C     -2.26C         4.21C     -0.68C       6.21C     -0.53C      3.84C (Was 4.57C)  -1.48C

Update 5  6.81C (Was 5.45)   +1.84C     4.47C     -0.19C         1.07C     -3.82C       4.98C     -1.76C      4.33C (Was 3.99C)  -0.99C

Update 6  4.16C (LATEST)      -0.81C      4.76C     +0.10C        2.73C     -2.16C       4.90C     -1.84C       4.14C (Latest)         -1.18C

OVERALL 4.34C                       -0.63C     3.49C     -1.17C         2.71C     -2.18C       4.69C     -2.05C      3.81C                         -1.51C

 

SUMMARY

CFS is still maintaining its overall colder than average outlook and the good news I discovered was with the errors for December 2020 that this overall pulled December down into the colder than average category too after trending slightly above average overall before I discovered that the formulas were linking to the wrong December data for updates 3, 4 and 5

December 2021

With the corrections CFS is now going for a colder than average December overall with an average running mean of 4.34C which is -0.63C below the 1991-2020 mean. A bit of variation in the runs however ranging from the mildest update 5 of 6.81C (+1.84C above 1991-2020 mean) to the coldest update 4 at 2.55C (-2.42C below the 1991-2020 mean). You could say with this that December is still very much up for grabs and could go either way if the CFS uncertainty persists but the overall trend is more likely colder with the running mean showing this.

January 2022

January 2022's figures were already correct anyhow so no need to elaborate on this. The overall running mean after update 6 for January 2022 is standing at 3.49C which is -1.17C below the 1991-2020 mean. January 2022 looks a better bet for a colder outcome as the mildest latest update 6 stands at 4.76C (+0.10C above the 1991-2020 mean) to the coldest update 1 standing at 1.95C (-2.71C below the 1991-2020 mean). Since the only update that gets above average is update 6 with an anomaly of only +0.10C then very much an average or colder than average month is being predicted so far.

February 2022

February 2022 has consistently come out as the best shot at a colder than average month on the CFS with an overall mean of 2.71C which is -2.18C below the 1991-2020 mean. With all updates coming back with a colder than average anomaly ranging from the least cold update 4 standing at 4.21C (-0.68C below the 1991-2020 mean) to the coldest update 5 at 1.07C (-3.82C below the 1991-2020 mean) then this puts February 2022 in with a good shot of a cold month overall. Even update 2 was nearly as cold as the decent update 5 too and was also another in the -3's for the anomaly too.

March 2022

March 2022 has almost been as good as February 2022 for colder than average updates too but with an overall mean of 4.69C which is -2.05C below the 1991-2020 mean then not bad for a March average so far. We range from the least cold update 4 standing at 6.21C (-0.53C below the 1991-2020 mean) to the coldest update 3 standing at 3.89C (-2.85C below the 1991-2020 mean) so very much a consistent colder than average update and even update 2 was a very close 2nd with a mean of 3.92C (-2.82C below the 1991-2020 mean).

OVERALL DECEMBER 2021 TO MARCH 2022

Overall a very promising 6 updates so far if you are looking for a colder than average winter. The CFS pattern so far is general a back loaded winter with the core of any cold most likely in February and with a good chance of persisting into March too. With the colder January anomaly it is also possible that the CFS is seeing the cold getting underway during January, peaking in February before gradually going away during March.

December 2021 is however still up for grabs with the wide variety of updates from cold through to mild. If we can get a colder month here then we could be setting up a rather cold winter overall. Even if we get the mildest outcome then colder months in 2022 could still pull the mean down to a colder than average outcome overall.

Edited September 30, 2021 by SqueakheartLW

[SqueakheartLW]

Wonder if this is a teaser chart for the possible winter pattern on the latest GFS 12z

That big area of high pressure to our NW. I wonder

Although this has little support when looking at the mean of the members of the GFS on this run

Edited September 30, 2021 by SqueakheartLW

[Thundery wintry showers]

I remember the winter of 1998/99 had quite a few northerly outbreaks, resulting in parts of northern Scotland and some eastern coastal counties of England having near-average snow despite it being a generally mild winter.  Early December 1998 and the second week of February 1999 were generally the coldest spells, and a more sluggish northerly in the second week of January 1999 was followed by quite a widespread frontal snow event on the 12th.  However, for many regions away from North Sea coasts there were just a few dustings that didn't last for long. 

One issue with a repeat of the 1998/99 winter would be that with the marked warming of the Norwegian and Russian Arctic, northerlies often aren't as potent these days as they were back then.  I remember several occasions last winter when northerly and north-easterly winds brought sleety rather than snowy weather to counties bordering the North Sea, including one on Christmas Eve which, had temperatures been a degree or so colder, could have given a fair number of eastern areas a white Christmas.  On the other hand, as we saw repeatedly in early April 2021, we're not yet close to the stage where it's not possible to get widespread snow off a northerly.

It's worth noting though that the 1998/99 La Nina was unusually strong.  2021/22 isn't forecast to have such a strong La Nina, and generally a weaker La Nina increases the chance of cold snowy spells.

Edited September 30, 2021 by Thundery wintry showers

[virtualsphere]

On 28/09/2021 at 01:40, jules216 said:

 I like solar analog of 1998 too, it was  generaly rising from minimum too. And flux around 90-100 can be achieved too.

Simplifying things a bit, 1998 is close to a series of ascending solar cycle colder winters for the UK that includes 1956, late 70s*, 1987, Dec 2010:  

*1979 is nearer solar max due to the fast ascending phase: Jan '77 and Feb '78 may fit in this particular cycle. 

Often we see a cluster of at least two colder winter spells together, the first close to minimum (e.g. 1977, 1985-6, 2009-10) and the second shortly after (1979, 1987, 2010).   In that particular cycle we had 1995-96 and 1996-97, ending with the warm Feb '97, so not far off.  

Worth mentioning that significant colder weather still can still show up close to solar max (e.g. 1947, 1979 and 2013).  On this basis I think we could see a colder winter or two coming up in the next few years depending on the other factors in play.

[Summer8906]

I hope we are not heading for an October like 1998, that's for sure.

As for the winter, Dec and Jan were grotfests, that's for sure. Feb was mild and changeable but bright, if I recall, so not too bad.

Personally I am just hoping for a winter less dull, gloomy and wet, than the past two (though I was extremely lucky to be able to escape the UK for much of last winter, getting out before lockdown - for which I am very grateful).  For me that's more important than if it's cold or mild, though would be nice to see some snow and frosts.

While a cold, frosty and sunny Dec/Jan followed by a milder, and still sunny Feb would be ideal - I'd take something like 2011/12, perhaps the shortest winter of my lifetime with November being unseasonably warm and sunny until the 20th and then Feb also becoming warm and sunny by mid-month. January was also unusually sunny. A sub-three-month winter...and it still managed some severe cold and snow for a time too!

Edited October 1, 2021 by Summer8906

[damianslaw]

10 hours ago, Summer8906 said:

I hope we are not heading for an October like 1998, that's for sure.

As for the winter, Dec and Jan were grotfests, that's for sure. Feb was mild and changeable but bright, if I recall, so not too bad.

Personally I am just hoping for a winter less dull, gloomy and wet, than the past two (though I was extremely lucky to be able to escape the UK for much of last winter, getting out before lockdown - for which I am very grateful).  For me that's more important than if it's cold or mild, though would be nice to see some snow and frosts.

While a cold, frosty and sunny Dec/Jan followed by a milder, and still sunny Feb would be ideal - I'd take something like 2011/12, perhaps the shortest winter of my lifetime with November being unseasonably warm and sunny until the 20th and then Feb also becoming warm and sunny by mid-month. January was also unusually sunny. A sub-three-month winter...and it still managed some severe cold and snow for a time too!

By reference to last two winters you mean 18-19 and 19-20? Yes I wouldn't want a repeat of either, 19-20 was one long rainfest, a slightly cooler less wild version of 13-14 but nearly as bad.

17-18 and 20-21 decent though, very mixed, but some good snowy cold spells at times. 

[Cheshire Freeze]

Awaiting the updated EC seasonal...should be hot off the press in the next few days. The Oct update should give us some more substantial clues as to where we're headed...for early winter at least!

Edited October 1, 2021 by CreweCold

[Don]

17 minutes ago, CreweCold said:

Awaiting the updated EC seasonal...should be hot off the press in the next few days. The Oct update should give us some more substantial clues as to where we're headed...for early winter at least!

Squeaky bum time I think CC and perhaps more so than normal this year?!  

Edited October 2, 2021 by Don

[Fourty Point Three Degrees]

Another boring Winter looms.. It'll be the same old chesnut, with the coldest 850s really struggling due to sods law producing all sorts of complicated synoptics.  

Just seems like we will be waiting forever for that cold and snowy month. 

[Summer8906]

13 hours ago, damianslaw said:

By reference to last two winters you mean 18-19 and 19-20? Yes I wouldn't want a repeat of either, 19-20 was one long rainfest, a slightly cooler less wild version of 13-14 but nearly as bad.

17-18 and 20-21 decent though, very mixed, but some good snowy cold spells at times. 

I meant 19/20 and 20/21, rather than 18/19. I experienced 19/20 in its entirety - one of the most unpleasant autumn/winter seasons of my lifetime, constant dull, wet, unsettled Atlantic-dominated weather set in around the equinox and didn't let up for almost six months. Obviously not quite as destructive as 13/14, but I'd probably rate it even worse - the 13/14 winter seemed to have more bright spells in between the storms and didn't give such an impression of endless gloom and low light levels. Also November '13 was predominantly settled, and the settled weather returned right at the start of March '14, so it didn't go on for so long. It set in on Friday 13th (yes, really) December and was already on the way out by the end of February; the Valentines storm being the last really big one and the weekend of Feb 22/23 2014 was actually quite pleasant.

20/21 I missed part of (being overseas) but by all accounts was as unpleasant as 19/20 in this area, but colder, but bear in mind that my impression is based on others' reports. Cold at times, mild at others, and a lot of very dull, damp and wet weather is the impression I get, with little in the way of sunshine. Not cold enough for snow, here at least.  But with the low jetstream, it's quite possible the south of England had it worse than other parts of the UK. Also another year in which the poor weather extended through much of autumn and winter together.

18/19 on the other hand was one of the more pleasant winters of recent years. December 18 was a dull, wet grotfest, it's true, but Jan 19 was anticyclonic, often bright, and sometimes cold and frosty with a notable (for here) snow event at the end of the month. Then Feb had the unprecedented warm spell and 21C in London.

17/18 I would rate as the most interesting since 2013, though, culminating in the exceptional March snowfall - though the end of December 17 and most of Jan 18 was a dreary Atlantic clagfest, the early and late winter had plenty of interest.

Edited October 2, 2021 by Summer8906

[sebastiaan1973]

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2019GL084683
Our findings demonstrate that the subseasonal teleconnections from the MJO to the NAE weather regimes are strongly dependent on the ENSO background state (summary schematic: Figure 4). The NAO+ regime tropospheric teleconnection from MJO phases 1–5 is strongly enhanced during El Niño years, persisting throughout more MJO phases, while it is suppressed during La Niña years. The NAO − regime teleconnection via the stratosphere from MJO phases 7–8 is most enhanced and occurring latest during La Niña years, while it is suppressed during El Niño years. Neutral years feature aspects of both of these teleconnections. NAE regime progression, in situ development, and the differing dynamical teleconnection mechanisms also become clearer via this perspective separated by ENSO state. The ENSO circullation anomaly modifies the MJO convection, impacting the Rossby waves generated, and their teleconnection pathways to the NAE region.
The changes in the weather regime distributions present evidence of the rectification of subseasonal teleconnections onto the seasonal mean. This rectification implies that it is important to have a good representation of this subseasonal teleconnection in any general circulation model used to study climate states and their interactions.

 We have to watch MJO phase 7-8 this winter. Unfortunately there is probably not an eastern La Nina. But anyway, it's a week one.  

[SummerShower]

Hoping for a cold, snowy winter this year but if not then a truly stormy winter like 89/90 or 13/14 would be the next best option.  At least there would be some 'weather'.