Winter 2023/24 - Discussions & Forecasts

[Weather Enthusiast91]

I personally don't go for this "a warm September means a mild winter" theory. Winter is still three months away and anything can happen in that time. Plus, it's very early days as to whether or not we'll have a warm September. No doubt that the first half of the month will be warmer than average, but that doesn't mean that the second half of the month will be also.

[damianslaw]

5 hours ago, SqueakheartLW said:

You would never have thought that the cold was about to strike looking at these charts from 5th to 9th December 2009

All looks like locked in zonal and SW winds here and at this point it looks like December 2009 is written off for cold.

Then the first and important change shows itself between 10th and 12th December 2009

We start to see the first important change here with the cold uppers moving across the continent ready for what is about to happen.

Between 13th and 16th December 2009 we see the high start to pull further to our north ready to unleash the cold onto the UK

All the while this is happening even colder uppers are pushing in from the east ready to be unleashed on the 17th onwards.

The rest of the month is basically colder than average after this with an Arctic shot before Christmas before the coldest weather early in the new year.

What happened on the 10th was bizarre really. 

[damianslaw]

1 hour ago, Don said:

Whilst this is true, we are talking warm Septembers with a CET of 15C or more, not cooler Septembers.  As I've said, I suggest people look up Gavin Partridge's video analysis he did in September 2021 on his GavsWeatherVids Youtube channel, and draw their conclusions from that.

2005-06 whilst not especially cold, was consistently chilly with little mild weather. 

Our last cold September in 2015 was followed by a record breaker warm one. 

It may just be a simple coincidence most warm Septembers have been followed by no cold winters. 

The driver for the upcoming heat is ex hurricane activity, all very normal for Sept and on the back of exceptional heat over the continent. 

Edited September 1, 2023 by damianslaw

[sundog]

1 hour ago, Don said:

Whilst this is true, we are talking warm Septembers with a CET of 15C or more, not cooler Septembers.  As I've said, I suggest people look up Gavin Partridge's video analysis he did in September 2021 on his GavsWeatherVids Youtube channel, and draw their conclusions from that.

I agree with you. There are many hurdles to get past on the way to getting a decent winter especially nowadays.  I see avoiding a very warm September as the first hurdle these days. Probably a bit early yet to be worrying how warm this September could be. First half doesn't bother me, it's when the warmth extends well into the second half of the month that I worry. Regardless of the warm September = mild winter theory ( for recent times), I don't want a warm September overall anyway ,I want the autumnal feel not an extension of summer well into September. 

[northwestsnow]

CANSIPS going for a CP nino during DJF

 

[Sunny76]

1 hour ago, Don said:

Me too definitely! 

Yes, it's a shame March wasn't a cold month instead of April!

March was still chilly at times, but in all honesty, march is usually when I start looking for less cold weather and the first hints of some nice warmish days into the high teens on the odd occasion. 

1 hour ago, Weather Enthusiast91 said:

I personally don't go for this "a warm September means a mild winter" theory. Winter is still three months away and anything can happen in that time. Plus, it's very early days as to whether or not we'll have a warm September. No doubt that the first half of the month will be warmer than average, but that doesn't mean that the second half of the month will be also.

Yeah, sometimes it does happen, but I can give at least two occasions where a cold September led to a very mild winter.

1994 was one example, and 1992 was also another one. 

[sundog]

37 minutes ago, Sunny76 said:

March was still chilly at times, but in all honesty, march is usually when I start looking for less cold weather and the first hints of some nice warmish days into the high teens on the odd occasion. 

Yeah, sometimes it does happen, but I can give at least two occasions where a cold September led to a very mild winter.

1994 was one example, and 1992 was also another one. 

92 and 94 ,cases  regarding Septembers of getting past the first hurdle not the following ones.  

September 2015 was cool ,got past the first hurdle.  El nino was unfortunately a bigger hurdle down that particular track.

September 2021 fell flat on our faces at the first hurdle and what a crap winter 21/22 was.

Edited September 1, 2023 by sundog

[Metwatch]

Bit of a cherry pick but this followed a September which had +35C...

Edited September 1, 2023 by Metwatch

[damianslaw]

58 minutes ago, Sunny76 said:

March was still chilly at times, but in all honesty, march is usually when I start looking for less cold weather and the first hints of some nice warmish days into the high teens on the odd occasion. 

Yeah, sometimes it does happen, but I can give at least two occasions where a cold September led to a very mild winter.

1994 was one example, and 1992 was also another one. 

Biggest example as mentioned 2015!

[sundog]

2 minutes ago, Metwatch said:

Bit of a cherry pick but this followed a September which had +35C...

That's back in 1907 though, the point is about more recent Septembers. 

[Don]

4 minutes ago, damianslaw said:

Biggest example as mentioned 2015!

Winter 2015/16 also had a Super Nino, combined with a W-QBO which would have overridden most other teleconnections.  An average or cool September by no means guarantees a cold winter, but increases the chance over a very warm one.

34 minutes ago, sundog said:

September 2015 was cool ,got past the first hurdle.  El nino was unfortunately a bigger hurdle down that particular track.

Exactly!  

1 hour ago, Sunny76 said:

Yeah, sometimes it does happen, but I can give at least two occasions where a cold September led to a very mild winter.

1994 was one example, and 1992 was also another one. 

This isn't about cool/cold Septembers though.

[Freeze]

7 minutes ago, sundog said:

That's back in 1907 though, the point is about more recent Septembers. 

It all seems a bit too 'specific', if the correlation is correct, then why does it have to be recent? And why does it have to be 15c+ in the cet? 

[sundog]

Just now, Freeze said:

It all seems a bit too 'specific', if the correlation is correct, then why does it have to be recent? And why does it have to be 15c+ in the cet? 

It seems to correlate with recent yrs much more the winters 30 + yrs ago. I can only put that down to climate change. As regarding  15c cet +that just seems to be the way, can't answer that .

[Don]

2 minutes ago, Freeze said:

It all seems a bit too 'specific', if the correlation is correct, then why does it have to be recent? And why does it have to be 15c+ in the cet? 

September 1907 only had a CET of 13.6C.

The reason why 15C and above is used as a benchmark is because no recorded winters following a September with that CET or more have been cold.

[Freeze]

4 minutes ago, sundog said:

It seems to correlate with recent yrs much more the winters 30 + yrs ago. I can only put that down to climate change. As regarding  15c cet +that just seems to be the way, can't answer that .

Surely 30years isn't enough to be considered a true correlation, there's always going to be quirks in statistics that are random, something is always going to happen more often than not somewhere and so it happens to be with Septembers and winters 

[Metwatch]

September 1961 CET 15.2C, December 1961 CET 2.2C that would do me nicely lol.

Sept 1958 CET 15.1C, Jan 1959 1.6C. Even one cold winter month with snow would be interesting. Sept 1930 with Feb 1931 another case. Not recent though.

Edited September 1, 2023 by Metwatch

[Freeze]

9 minutes ago, Don said:

September 1907 only had a CET of 13.6C.

The reason why 15C and above is used as a benchmark is because no recorded winters following a September with that CET or more have been cold.

Remember the 13th June enigma, that eventually broke, and I'm certain this theory will one year too.

[sundog]

2 minutes ago, Freeze said:

Surely 30years isn't enough to be considered a true correlation, there's always going to be quirks in statistics that are random, something is always going to happen more often than not somewhere and so it happens to be with Septembers and winters 

But climate change though imo is making the correlation. It may be only 30 yrs but how many decent winters have we had in that time ? Not many compared to the previous 30 yrs.

[Freeze]

1 minute ago, sundog said:

But climate change though imo is making the correlation. It may be only 30 yrs but how many decent winters have we had in that time ? Not many compared to the previous 30 yrs.

That's the thing though there hasn't been many cold winters in that time which means the theory hasn't really been put to the test.

[sundog]

2 minutes ago, Freeze said:

That's the thing though there hasn't been many cold winters in that time which means the theory hasn't really been put to the test.

Well I hope it doesn't have to be put to the test this yr by the time we reach the end of September.  Then we only have to worry about El Niño 

[blizzard81]

1 hour ago, sundog said:

But climate change though imo is making the correlation. It may be only 30 yrs but how many decent winters have we had in that time ? Not many compared to the previous 30 yrs.

If you go back a little further, there were hardly any cold winters in the 1920's and 30's. I suspect people back then were also wondering if they would ever experience a cold winter again. Then came the 40's.

[Mike Poole]

22 hours ago, Uncertainty said:

Cansips raising the stakes again! Incredibly consistent from this model. 
 

(thanks to World Climate Service for the chart)

The seasonals so far don’t seem to care about a strong nino or positive iod. They are insistent on this big blocking signal and are clearly ‘seeing something’.  If the Copernicus models ‘hold the fort’ over the coming days, then we will have the most consistent forecast for a cold winter since 2009. I would absolutely take a winter like that again, minus the precursor Cumbrian flood fest obviously.

Very good sign, always a bit nervous this far out that the signal could vanish, great news that it hasn’t on CANSIPS.  I’ve said before that I think this year is so far out on its own in terms of world weather patterns, especially SSTs, that we are in new territory and therefore we should trust the models rather than what any one index might suggest.

4 hours ago, Don said:

Whilst this is true, we are talking warm Septembers with a CET of 15C or more, not cooler Septembers.  As I've said, I suggest people look up Gavin Partridge's video analysis he did in September 2021 on his GavsWeatherVids Youtube channel, and draw their conclusions from that.

This September thing.  Most UK winters are mild so I’m not bought by the suggestion that a correlation exists between mild winters and warm Septembers, it doesn’t imply causation.  There might just as easily be a correlation between mild winters and the price of cheese in September.  Maybe it would be better to look at what (the much rarer) cold winters might be correlated to?  Just a thought.

And with this year being such an outlier, I’m minded to put zero weight on the weather we get in September as an indicator for winter.  

3 hours ago, northwestsnow said:

CANSIPS going for a CP nino during DJF

 

This is another interesting aspect that needs watching as we draw closer, how the Nino evolves, it is not set in stone to be a strong EP one.

Fascinating to see how all this pans out as autumn progresses…

[blizzard81]

Does anybody know when the ECM September seasonal update is?

[Sunny76]

2 hours ago, Don said:

Winter 2015/16 also had a Super Nino, combined with a W-QBO which would have overridden most other teleconnections.  An average or cool September by no means guarantees a cold winter, but increases the chance over a very warm one.

Exactly!  

This isn't about cool/cold Septembers though.

I was stating a fact that some cool Septembers don’t always lead to a colder winter. 
 

 

[summer blizzard]

4 hours ago, Weather Enthusiast91 said:

I personally don't go for this "a warm September means a mild winter" theory. Winter is still three months away and anything can happen in that time. Plus, it's very early days as to whether or not we'll have a warm September. No doubt that the first half of the month will be warmer than average, but that doesn't mean that the second half of the month will be also.

I had a look at the warmest September's recently and essentially there's no bad link overall but recent warm September's have disorted this. 

2 hours ago, Don said:

September 1907 only had a CET of 13.6C.

The reason why 15C and above is used as a benchmark is because no recorded winters following a September with that CET or more have been cold.

How are we defining 'cold'?