Early run up to Winter 2021/2022 discussion

[Downburst]

On leaf fall in Autumn. A recent study is suggesting that the increase in the earlier Spring growing season is reducing the budget of energy a tree can use, such that leaf fall in Autumn is accelerating by 3 to 6 days.  Increased growing-season productivity drives earlier autumn leaf senescence in temperate trees (science.org)

Abstract

Changes in the growing-season lengths of temperate trees greatly affect biotic interactions and global carbon balance. Yet future growing-season trajectories remain highly uncertain because the environmental drivers of autumn leaf senescence are poorly understood. Using experiments and long-term observations, we show that increases in spring and summer productivity due to elevated carbon dioxide, temperature, or light levels drive earlier senescence. Accounting for this effect improved the accuracy of senescence predictions by 27 to 42% and reversed future predictions from a previously expected 2- to 3-week delay over the rest of the century to an advance of 3 to 6 days. These findings demonstrate the critical role of sink limitation in governing the end of seasonal activity and reveal important constraints on future growing-season lengths and carbon uptake of trees.

[sebastiaan1973]

1 hour ago, Uncertainy said:

Here’s the new ECM seasonal for NDJ. 
 

Cant post the monthly breakdown, would if i could.

Strong anticyclonic signal there. Not very exciting from a storm or indeed snow point of view. But, personally, I enjoy benign dry winter weather so I would welcome such an outcome and I think it’s quite plausible.

Interestingly the summer forecast in May was quite similar in the Atlantic

How many times did we see heights building between the U.K. and Iceland? Enough to make the final anomaly far stronger than that.

So so far we have:

- Cansips = flat westerly 

- ECM = U.K. high

- Meteofrance = Icelandic blocking 

Over to the UKMO for the deciding vote but an unremarkable, dryish winter seems the early form horse from a seasonal model perspective.

Thanks https://apps.ecmwf.int/webapps/opencharts/products/seasonal_system5_standard_mslp?area=GLOB&base_time=202110010000&stats=tsum&valid_time=202112020000

[Frost HoIIow]

In terms of leaf foliage they are mostly turning here. Quite a few types of tree are going yellow and leaves are now falling off on some of them. I don't think this is unusual in early October. I don't recall in the past mostly bare trees this early in the month. On average by the 3rd or last week of the month are they at that stage. So two to three weeks yet.

Edited October 5, 2021 by Frost HoIIow

[Premiere Neige]

5 hours ago, Yarmy said:

I don't really pay much attention to these monthly ensemble means at this range, but the problem there - as ever - is the above average pressure in Eastern Europe. How would the cold get here?

The November mean is ok though.

Think I kind of blocked (no pun intended) out the higher pressure over Eastern Europe. Although it's not a particularly strong signal so maybe it wouldn't be an omnipresent feature. Who knows?!

[DavidS]

I’ve been enjoying clicking through the extended CFS now it is available on Wetterzentrale.

Below are just a few highlights from today’s 6z run. Interest begins in  mid November with a  Northerly. Cold is then on/off including something chilly for Christmas and the whole thing finishes in March with a tasty Easterly. 

All JFF, but if your of a cold persuasion,  enjoy:

 

 

[sebastiaan1973]

December 2021 EC.

[northwestsnow]

10 minutes ago, sebastiaan1973 said:

December 2021 EC.

That would be cold for Europe.

[Kiwi]

16 minutes ago, northwestsnow said:

That would be cold for Europe.

Fabulous!!!.....and we're off

.....the hunt for the fabled easterlies and snowmageddon.

[skifreak]

6 hours ago, DavidS said:

I’ve been enjoying clicking through the extended CFS now it is available on Wetterzentrale.

Below are just a few highlights from today’s 6z run. Interest begins in  mid November with a  Northerly. Cold is then on/off including something chilly for Christmas and the whole thing finishes in March with a tasty Easterly. 

All JFF, but if your of a cold persuasion,  enjoy:

 

 

 

 

Hmmm I've seen that somewhere before.... 

 

 

[Simon M]

4 hours ago, Kiwi said:

Fabulous!!!.....and we're off

.....the hunt for the fabled easterlies and snowmageddon.

 

It's time for the dreaded "p-word" - potential!  

[Downburst]

Probability of 2m temps exceeding the median (1993-2016)  Nov-Dec-Jan. Of course there will be cold conditions on occasion, but it is looking very NAO+ to me with a Jet slightly more north than usual, chances of blocking of the Jet through the period and cold interludes.

[Don]

1 hour ago, Downburst said:

Probability of 2m temps exceeding the median (1993-2016)  Nov-Dec-Jan. Of course there will be cold conditions on occasion, but it is looking very NAO+ to me with a Jet slightly more north than usual, chances of blocking of the Jet through the period and cold interludes.

Yep, not the best is it?!  However, still time for improvements.

[Mike Poole]

You know, I am feeling deja vu looking at the model output today and for the last week really.

Deja vu to winter nirvana in the past, you may ask?  No. Actually it was summer 2018, or rather the spring that preceded it.  What led me to predict a 1976 summer (see archive posts if you want to check) was that I was seeing charts I hadn’t ever seen before during spring before.  And I bet on that!  That summer was what it was, but I’m feeling the same about winter this year.  I started watching the weather models in winter after 2010, in 2011 and over the 10 year period since then they’ve been doing the same thing, but this year is different - I haven’t seen charts for the NH like this before, so by the same token I took for summer 2018, I’m lumping on a cold winter (front loaded, unsure into the later period) precisely because of that.  

Enjoy the freeze

Edited October 6, 2021 by Mike Poole

[jamesthemonkeh]

2 hours ago, Mike Poole said:

You know, I am feeling deja vu looking at the model output today and for the last week really.

Deja vu to winter nirvana in the past, you may ask?  No. Actually it was summer 2018, or rather the spring that preceded it.  What led me to predict a 1976 summer (see archive posts if you want to check) was that I was seeing charts I hadn’t ever seen before during spring before.  And I bet on that!  That summer was what it was, but I’m feeling the same about winter this year.  I started watching the weather models in winter after 2010, in 2011 and over the 10 year period since then they’ve been doing the same thing, but this year is different - I haven’t seen charts for the NH like this before, so by the same token I took for summer 2018, I’m lumping on a cold winter (front loaded, unsure into the later period) precisely because of that.  

Enjoy the freeze

How do you bet on it?

[Uncertainty]

3 hours ago, Mike Poole said:

You know, I am feeling deja vu looking at the model output today and for the last week really.

Deja vu to winter nirvana in the past, you may ask?  No. Actually it was summer 2018, or rather the spring that preceded it.  What led me to predict a 1976 summer (see archive posts if you want to check) was that I was seeing charts I hadn’t ever seen before during spring before.  And I bet on that!  That summer was what it was, but I’m feeling the same about winter this year.  I started watching the weather models in winter after 2010, in 2011 and over the 10 year period since then they’ve been doing the same thing, but this year is different - I haven’t seen charts for the NH like this before, so by the same token I took for summer 2018, I’m lumping on a cold winter (front loaded, unsure into the later period) precisely because of that.  

Enjoy the freeze

I’m with you on this Mike, but not all output is showing the charts you infer, Cansips for instance, is ‘2015’ like:

CFS isn’t much better

I think that big Aleutian ridge is practically nailed on. The Atlantic sector is all to play for. You wouldn’t expect the above ++NAO with an EQBO / coming out of low solar but the Nina could be too central based suppressing the tropical convection we really need to kick off the WAF into the strat after this odd Canadian warm up is finished.

If I had to call it I’m with you for NOV/DEC but it’s not a done deal yet. I think the latest Glosea is crucial here for more clues. A fascinating descent into winter this certainly is.

[damianslaw]

20 minutes ago, Uncertainy said:

I’m with you on this Mike, but not all output is showing the charts you infer, Cansips for instance, is ‘2015’ like:

CFS isn’t much better

I think that big Aleutian ridge is practically nailed on. The Atlantic sector is all to play for. You wouldn’t expect the above ++NAO with an EQBO / coming out of low solar but the Nina could be too central based suppressing the tropical convection we really need to kick off the WAF into the strat after this odd Canadian warm up is finished.

If I had to call it I’m with you for NOV/DEC but it’s not a done deal yet. I think the latest Glosea is crucial here for more clues. A fascinating descent into winter this certainly is.

Akin to 96-97 and 10-11 then.. 

[Mike Poole]

2 hours ago, jamesthemonkeh said:

How do you bet on it?

Only bet on it is sticking my neck out on here!  Too few decent betting opportunities available on the weather with the bookies, and those that’s there are are poorly priced so I’d avoid if I were you!

Edited October 6, 2021 by Mike Poole

[Weather Enthusiast91]

Oh look. The Sun is predicting a white Halloween this year. If that's what The Sun is saying then it MUST be true right? 

[Simon M]

1 hour ago, Weather Enthusiast91 said:

Oh look. The Sun is predicting a white Halloween this year. If that's what The Sun is saying then it MUST be true right? 

 

Time to get the old shorts and t-shirt out then.

[SqueakheartLW]

Christmas 2021 Update Number 1

Thought it would be time as we are now into October to get the Christmas updates warmed up and into gear. I plan to do one a week right up to the day before the big day itself. So far the outlook is very mixed and all over the place as is expected with a whole range of mild, average and cold Christmas's as well as wet and dry ones. Below is the current temperature data I have for week 1.

I have highlighted the coldest max and min in blue as well as the mildest max and min in orange for the week and at present these are also the overall highest and lowest values which have their own entry at the top right of the image.

              Average Min     Average Max     Average Mean

Temp          3.61                      5.79                    4.70

Anom        +1.52                     -1.24                  +0.14

When we average out all of the max, min and mean data for the week it isn't a great start if a cold and possibly white Christmas is what you are after when we average out above average overall for the week but by only +0.14C. What will the next update bring and can we start to shift towards a colder outcome or are we going to get our more than likely mild Christmas which we tend to get most years.

[SqueakheartLW]

7th Winter 2021/2022 update based on the CFS 00z 9 monthly run dated 07/10/2021

Time for my usual weekly winter update based on the same run as always and after 6 overall colder than average runs things have looked promising so far but those who want a colder than average winter will want to put this 7th weekly run straight into the nearest bin as you are about to see in my summary of this specific run and looking at it will very much show you what I am talking about here.

December 2021

December 2021 has in general come out as the least cold month overall and in this update we continue the trend with December 2021 as this particular run puts the month milder than average overall with a mean of 6.13C which is +1.16C above the 1991-2020 average and put this update with the 2nd mildest December so far with only Update 5 being milder than this one. Not the update I was hoping to see but then we can't get every single one of them to come out colder than average can we?

January 2022

January 2022 has so far come out with a more certain chance of a colder than average outcome but this update bucks this trend completely as we come out with a mean of 5.29C which is +0.63C above the 1991-2020 mean. This is the mildest January update so far and continues the getting milder trend from last week which came out at +0.10C above the 1991-2020 mean. I hope this isn't the start of a trend towards milder updates for January and a possibility that we will be writing this month off too.

February 2022

February 2022 has so far in all of the updates come out as the most certain bet for a colder outcome with the biggest negative anomaly and as I was looking through the featured run I was hoping to see another colder than average February 2022. How disappointed I was in the end. This 7th update has gone totally the other direction with an overall mean of 6.71C which is a very mild +1.82C above the 1991-2020 mean. With this latest update I am hoping this was a one off blip and we quickly return to colder February updates from next week and hope this isn't the start of a trend to a milder February too.

March 2022

March 2022 has also been a good bet for a colder outcome and in this 7th update was in fact the only month that returned a colder than average mean with a mean of 5.60C which is -1.14C below the 1991-2020 mean. This now means that only March 2022 now has a colder than average update in every single update I have done. It is really the case of getting a shot at something a bit like winter when it is more or less too late to have any real impact.

Overall winter 2021/2022 in this 7th update

A rather disappointing update from a colder perspective overall with generally mild conditions and zonality the dominant themes of the 4 months although it does get a bit colder by March. The overall December to March mean in this update came in at 5.93C which is +0.61C above the 1991-2020 December to March mean and in fact puts this update as the mildest one so far overall. Hope this is a one off and we return to colder updates again from next week.

Summary of all updates and the latest one too

Now I will add to the table I created last week with the latest update and the new adjusted overall means of all the updates along with the change from the previous week.

                 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     -0.24C      1.95C     -2.71C         3.50C     -1.39C       4.26C     -2.48C      3.61C     -1.71C

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

Update 3  4.39C     -0.58C      3.95C     -0.71C         3.34C     -1.55C       3.89C     -2.85C      3.89C     -1.43C

Update 4  2.55C     -2.42C      2.40C     -2.26C         4.21C     -0.68C       6.21C     -0.53C      3.84C     -1.48C

Update 5  6.81C     +1.84C     4.47C     -0.19C         1.07C     -3.82C       4.98C     -1.76C      4.33C     -0.99C

Update 6  4.16C     -0.81C      4.76C     +0.10C        2.73C     -2.16C       4.90C     -1.84C      4.14C     -1.18C

LATEST

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

Update 7  6.13C     +1.16C     5.29C     +0.63C       6.71C     +1.82C       5.60C     -1.14C      5.93C     +0.61C

OVERALL 4.59C     -0.38C     3.75C     -0.91C         3.29C     -1.60C       4.82C     -1.92C      4.11C     -1.21C

Change     +0.25C Milder      +0.26C Milder           +0.58C Milder         +0.13C Milder        +0.30C Milder

[Met4Cast]

On 22/09/2021 at 15:54, Met4Cast said:

Obviously usual caveats apply given that we're in September and looking at possible weather 3-4 months away.  Usually there'd be very little to no indication or skill in forecasting for the early part of winter at this very, very early timeframe, however;

-QBO and weak La-Nina seem pretty much a given going into the early part of winter. I'm hopeful that La Nina wont destructively influence the MJO like it did last winter in that it prevented progression into the Maritime Pacific, but that's something for shorter range forecasting. 

There is a lot of agreement within the longer-term seasonal models for a weaker than average SPV going into winter, something that does have skill at this range, particularly with a majority of models seemingly in agreement. 

At the moment, my current thinking is that the best chance of snow this winter will be during December with the first half of winter most likely to be below average featuring a -NAO more often than not. 

Into the later part of the winter, models see a connect between the Strat & Trop perhaps indicating of a more westerly, +NAO dominated second half, La Nina possibly strengthening by this point too could help prevent cold patterns becoming established over NW Europe/UK , similar to last winter. 

Front loaded winter for me. But these are some very very early musings, October is an important month in terms of snow expansion across the NH and of course seeing how the SPV begins to take shape.

It's been a few of weeks since my last post in here, so where are we at?

If anything my thoughts have remained the same and I'm now a little bit more confident on them, i.e colder weather is most likely during the first half of winter with things more likely to be mild into the second half. The bias-corrected CFS forecast is perhaps one of the best I've seen in terms of early winter SPV forecasts.

It keeps the vortex way below average through into January, most notably late November into early December where we get very close to a reversal, I tweeted a few days ago but I'm marking November 20th - December 15th for a potential SSW. 

The un-corrected version of the CFS is even more nuts, but given it has a huge -ve bias at longer ranges I'm really only posting this one for fun.

A weak vortex (possible SSW) into early winter with an -QBO and La Nina almost overwhelmingly favours blocked conditions in our part of the world. The latest EC Seasonal supports this idea with a huge signal for European blocking during December.

Whether these variables translate to cold weather reaching the UK or not is a question that can't be answered until the short term, when we see patterns playing out in real time, however at this very early stage in the still very much developing forecast, late November and through December is looking very, very interesting. 

 

[Mike Poole]

I think that this year is the best chance since 2010 of a really cold spell, probably in the early to mid part of winter.  So many factors at play but one that is particularly well aligned is solar activity - this screenshot from spaceweather.com:

We are coming off the back of a solar minimum, as we were 11 years ago in 2010 (my markings).  

We have east QBO.  

We have, I think a residual NH impact from last year’s largely blocked (but ultimately slightly disappointing winter, particularly further south in the UK), it has been there all summer.   Remember that Dec 2010 came on the back of a half decent winter in 2009/10.  And others have commented as well as me on the similarities to 2010 as we have approached autumn.  

Strat vortex, all signs are it will be very hampered in getting going, an early SSW not out of the question, but whether that happens or not, there is a reasonable chance this year, that it doesn’t get going and couple with the trop in a vortex intensification event until January in my view.  So many years we say this but they couple in mid December and write off the heart of winter, so this bit is crucial, so even though the early part of winter may be trop led, an eye on the strat will be vital.  

Anyway, bring it on

Edit I should add, that I’m not aware of any big negative factors that can totally override the ones I’ve talked about this year.  Still got nightmares about the Indian Ocean Dipole event that scuppered any chance of cold in 2019/20, despite other favourable indicators .  

Edited October 8, 2021 by Mike Poole

[Premiere Neige]

1 hour ago, Mike Poole said:

I think that this year is the best chance since 2010 of a really cold spell, probably in the early to mid part of winter.  So many factors at play but one that is particularly well aligned is solar activity - this screenshot from spaceweather.com:

We are coming off the back of a solar minimum, as we were 11 years ago in 2010 (my markings).  

We have east QBO.  

We have, I think a residual NH impact from last year’s largely blocked (but ultimately slightly disappointing winter, particularly further south in the UK), it has been there all summer.   Remember that Dec 2010 came on the back of a half decent winter in 2009/10.  And others have commented as well as me on the similarities to 2010 as we have approached autumn.  

Strat vortex, all signs are it will be very hampered in getting going, an early SSW not out of the question, but whether that happens or not, there is a reasonable chance this year, that it doesn’t get going and couple with the trop in a vortex intensification event until January in my view.  So many years we say this but they couple in mid December and write off the heart of winter, so this bit is crucial, so even though the early part of winter may be trop led, an eye on the strat will be vital.  

Anyway, bring it on

Edit I should add, that I’m not aware of any big negative factors that can totally override the ones I’ve talked about this year.  Still got nightmares about the Indian Ocean Dipole event that scuppered any chance of cold in 2019/20, despite other favourable indicators .  

From what I've heard, the IOD will be neutral at worst (from a cold lover lovers perspective) so hopefully we can remove that one from the list of "could go wrongs" for this winter

[Mike Poole]

3 minutes ago, Premier Neige said:

From what I've heard, the IOD will be neutral at worst (from a cold lover lovers perspective) so hopefully we can remove that one from the list of "could go wrongs" for this winter

Yes, that should not worry us this year!  List of things that could go wrong diminishing, while things that could go right in the ascendency - but these days we practically need the whole damn lot to go in our favour for winter UK cold, this year the best chance since 2010.