Winter 2023/24 Chat and Discussion

[lassie23]

  @sundog so has the October Fog Index which predicted one or two snowfalls but overall winter would be a huge pile of sheeet.

[North-Easterly Blast]

  @sundog Looking at records, it is a well known fact of the British weather patterns that anomalous warmth in September (a high September CET) bodes badly for cold conditions during the following winter, in particular from high latitude blocking and northerly and easterly spells.

I have looked at Septembers over previous years and my conclusion is that a cooler or even average September CET appears to have very little bearing on the following winter's weather patterns, and it looks to be still possible in some cases to have a near or even slightly above average September CET and still have a colder winter to follow, but it is very rare, if not almost unheard of, to get a cold winter in the UK, or to get a winter that is anything other than above average, after anomalous September warmth in terms of a high CET.

It is clear that if you are hoping for a reasonable chance of cold outbreaks in the winter to follow, you do not want to see anomalous warmth in September like last year, and a number of others in the last 25 years or so.

Edited January 26 by North-Easterly Blast

[cheeky_monkey]

45 minutes ago, North-Easterly Blast said:

Looking at records, it is a well known fact of the British weather patterns that anomalous warmth in September (a high September CET) bodes badly for cold conditions during the following winter, in particular from high latitude blocking and northerly and easterly spells.

I have looked at Septembers over previous years and my conclusion is that a cooler or even average September CET appears to have very little bearing on the following winter's weather patterns, and it looks to be still possible in some cases to have a near or even slightly above average September CET and still have a colder winter to follow, but it is very rare, if not almost unheard of, to get a cold winter in the UK, or to get a winter that is anything other than above average, after anomalous September warmth in terms of a high CET.

It is clear that if you are hoping for a reasonable chance of cold outbreaks in the winter to follow, you do not want to see anomalous warmth in September like last year, and a number of others in the last 25 years or so.

q? why would the  Sept temperature anomaly on a very small location in the Northern Atlantic have any impact on the Northern Hemisphere winter that would follow ? to me is just a statistical coincidence 

[WYorksWeather]

The problem with assessing the warm September = mild winter correlation is what in statistics is known as the multiple comparisons problem.

Essentially, there are 192 month-temperature-season-temperature combinations you could test in the same way.

For example, if we look at warm January alone, you would have to test:

1. mild January vs. mild winter
2. mild January vs. cold winter
3. mild January vs. warm spring
4. mild January vs. cold spring
5. mild January vs. hot summer
6. mild January vs. cool summer
7. mild January vs. mild autumn
8. mild January vs. cold autumn

Then, the same but for cold Januaries, giving another eight, for a total of 16 January possibilities, and then multiply by 12 for the number of months.

It's hardly surprising that a few of these are notable correlations. And of course we don't comment on the ones that don't correlate.

See the great XKCD on the topic which does a far better job of explaining this in a funny way:

There are ways to adjust statistical tests and so on for this problem, but I'll leave it at that for now, as this is a weather forum, not a statistics textbook!

[Weather-history]

  @WYorksWeather
And that’s just temperatures alone,

You could factor in rainfall  as well

Wet mild January v cold wet spring

Dry mild January v cold dry spring

etc,,,

[Cheshire Freeze]

It really could be as simple as an anomalously warm September is brought about by a synoptic pattern which is part of a 6 month (etc)  circulation that we don’t yet understand.

As I said, just because we don’t yet understand the mechanism it doesn’t mean the mechanism doesn’t exist.

To assume that it’s a statistical quirk assumes that all months are independent of one another all of the time. I don’t think that’s the case…

[Harsh Climate]

So just like that, the chase for cold/snow has officially started again! . A couple days earlier than first thought (referring to my post yesterday.)

Sometimes all that is needed is a quick scan at the data over a day or so to quickly realise what's coming.

Cold/ blocking is now 7-10 days away enjoy the chase peeps!

[Weather-history]

  @Cheshire Freeze

 

I think one thing that is overlooked is that given warmth has been so dominating in the last 30 or so years, any potential signal that there may have been  is simply being swamped anyway. 

So can we trust any recent figures, given this?

Take 2016, very warm September but the following two months were not particularly warm, November was below average and the following January of 2017 wasn't a mild one, " synoptic pattern which is part of a 6 month (etc)  circulation" is struggling in this case. 

Take 2006, September was very warm but I could argue that the warmth kicked in June and September was just part of this period that ran from June 2006-June 2007, where anomalous warmth so dominated.

 

Go back to 1949, another very warm September. However that was just within a period where warmth so dominated and that September was just part of it.

September 1865, April to June were well above average so was it just part of the period?

 

Edited January 27 by Weather-history
.

[cheese]

Another chase that will most likely end in failure. Enjoy, I guess? 

I heard my first song thrush this morning which immediately reminded me of spring/summer. Really looking forward to the end of winter now.

Edited January 27 by cheese

[SunnyG]

15c forecast for Monday in London..... wow just wow....

[Snowy L]

Have to say I'm loving the current weather, not freezing in my own house and can be outdoors in comfort. My tolerance for cold without snow really is approaching zero recently.

[raz.org.rain]

  @cheese the cold runs are always at the very tail end of the outputs... we all know that means it'll either get watered down to average weather or happen in March when it has less of an impact.

[lassie23]

  @raz.org.rain or never

[Summer Sun]

Kinlochewe in north west Scotland has hit 16.9c this morning, which is provisionally the warmest January day on record for the village.

[draztik]

  @Summer Sun it’s up to 19.2C as per latest met office update. 

[Summer Sun]

The UK has provisionally recorded its warmest January day on record with 19.2c in Kinlochewe, it is also a winter record for Scotland.

[Metwatch]

Getting spoiled by some fantastic sunrises this weekend, perhaps enhanced by the Saharan dust? 

2 from Saturday:

And this morning:

[SunSean]

Amazingly, this will be the 3rd January in a row in my area that has had decent amounts of sunshine! Been a bit of a bonus month the past few years which is always nice in this normally cloudy country lol.

[In Absence of True Seasons]

  @Summer Sun  Very wild...warmer than alot of days in summer up there!

[TheOgre]

It’s like October out there today being so mild. 

[sundog]

This is lunacy.

 

[SunnyG]

16 minutes ago, sundog said:

 

Just to put things in context...

Edited January 30 by SunnyG

[SollyOlly]

 sundog Appalling, isn't it. Does not bode well.

[sundog]

 SunnyG  30c + above normal is still 30c above normal no matter what context or whatever way you want to spin it.

[SollyOlly]

 sundog Exactly, I was going to say the same thing but then couldn't be bothered...some people like to provoke (!), and I'm trying to be more zen this year! The 'mute' button works wonders...