Winter 2023/24 - Discussions & Forecasts

[Cheshire Freeze]

3 minutes ago, MattH said:

The October GloSea update is certainly very interesting, in terms of anomalies not being what should usually be expected. A full review of all the models will be required to determine where the Oct update of the EC sits, in terms of it shifting away from the consistent blocked pattern it had shown in recent months.

The December GloSea, in particular, is fascinating as clearly, Scandinavian high anomalies are rare and this pattern would also bring the risk of impacts on the strat as well, while January sees a pattern that is far more -ve NAO than what would otherwise be expected.

One key feature I keep looking for in all the seasonal models this year is for the European high to be, essentially, nonexistent. As we all know if we get an inflated and dominant European high that stretches from Iberia into central and eastern Europe through the winter months it often means that upstream the pattern is troughed over the N Atlantic and you've got little or no chance of colder synoptics. Winds are often from the W or SW. As the GloSea update shows, there is clearly not much evidence for a winter that is dominated by a large European high and, to me, that is potentially more of a key feature than actual blocking to the N or NW of the British Isles. Get a trough into Europe and the jet stream will naturally follow, etc.

In terms of winter synoptics and shutting off the Atlantic, then the October GloSea update for Dec, Jan and Feb is fascinating...

Regards, Matt.

 

Good post.

That’s one thing that’s stood out to me, the lack of Euro heights being shown…which as you say (and as I’ve pointed out previously) is a massive positive. It would mean a better troughed Europe and thus cold chances.

[Jacob]

10 hours ago, Cheshire Freeze said:

Latest CFS run has -14 uppers from the N in late March 

What’s the point of looking at precise models this far out? Of course it will come up with things that will never happen

[MattStoke]

13 hours ago, Bristle Si said:

Yeah fine.

But the constant dramatics - panto season soon

Oh no it isn't!

[SqueakheartLW]

11 hours ago, Don said:

The only snow event I experienced during winter 2014/15 was an un-forecast event early on the 4th February, but it had all gone by lunchtime.  However, it was an improvement on the previous year!

The main thing I remember about 2014/15 was the Eurasian October snow advance index, which created lots of excitement in the run up to winter, but ultimately failed to come off as being anything of note.  Heard very little about the October Eurasian snow advance index since!

 

10 hours ago, Don said:

I remember the snow event for the Midlands northwards on Boxing Day.  Not in the south though, instead having a not overly cold rain event!

The Boxing Day event although it looked good on the forecast melted almost as fast as it had come. By the next morning you wouldn't have even known there had been any snow the previous evening. Something similar happened in January 2018 where some snow came overnight on some cold zonality but by the next day there was nothing to see.

The best snow for me was late January / early February 2015 during that winter. Far enough north to benefit from the cold zonality at the end of Jan and also got hit by the early Feb snow as well.

[Met4Cast]

Interesting GLOSEA update but the lack of a Euro high is actually a slight concern with me. We've seen several times now GLOSEA underestimate the extent of a Euro high which does end up being evident through winter and the model just seems to "miss" it. 

It appears the model may have a bias to reduce heights across Europe.

[Don]

1 hour ago, Met4Cast said:

Interesting GLOSEA update but the lack of a Euro high is actually a slight concern with me. We've seen several times now GLOSEA underestimate the extent of a Euro high which does end up being evident through winter and the model just seems to "miss" it. 

It appears the model may have a bias to reduce heights across Europe.

Surely in that case it would be more of a concern if it was showing a Euro high?

[CoventryWeather]

2 hours ago, Met4Cast said:

Interesting GLOSEA update but the lack of a Euro high is actually a slight concern with me. We've seen several times now GLOSEA underestimate the extent of a Euro high which does end up being evident through winter and the model just seems to "miss" it. 

It appears the model may have a bias to reduce heights across Europe.

Sightly disagree here - most models are showing low heights over Europe. Surely that means all models have a bias towards that then? 

I'm not expecting a mild winter - average at best. Some zonality possible. 

[Jacob]

15 hours ago, Cheshire Freeze said:

Latest CFS run has -14 uppers from the N in late March 

Can you send the link to the website to access these charts please?

[Rain All Night]

39 minutes ago, Jacob said:

Can you send the link to the website to access these charts please?

https://www.meteociel.fr/modeles/cfse_cartes.php

[Rain All Night]

2 hours ago, Mike Poole said:

It is too early, but I am starting to like the way the chess pieces are being moved around the board.

It does not look at the moment as though a stormy Atlantic dominated second half of autumn, like some were predicting to take hold, is very likely.

I know from previous posts that in October 2016, there was a Scandi high at a similar time (though it was a little earlier, and it looked stronger than what's being forecast for next week). Did the next couple of months after this continue to have non-zonal synoptics, do you know?

I think that was a year that had had a lot of warmth in September as well.

Edited October 11, 2023 by RainAllNight

[MP-R]

1 minute ago, RainAllNight said:

I know from previous posts that in October 2016, there was a Scandi high at a similar time (though it was a little earlier, and it looked stronger than what's being forecast for next week). Did the next couple of months after this continue to have non-zonal synoptics, do you know?

16/17 was no blowtorch winter, with a lot of blocking, but mostly in the wrong place. December was anticyclonic but with a lot of southerly and southwesterly flows, book ended by frosty spells. January saw a lot more frosty settled weather with a mid-lat high extending across the middle and lower half of the country. February was more episodic. A cold easterly did try to set up early on but became a warm southeasterly then the most Atlantic spell of the winter came at the end of Feb / early Mar.

[Frigid]

29 minutes ago, RainAllNight said:

I know from previous posts that in October 2016, there was a Scandi high at a similar time (though it was a little earlier, and it looked stronger than what's being forecast for next week). Did the next couple of months after this continue to have non-zonal synoptics, do you know?

I think that was a year that had had a lot of warmth in September as well.

Interesting observation. Autumn 2016 also had a pretty chilly November, which is also being hinted in the models this year. 

[LRD]

Met Office Probabilistic charts are now out for October. I assume this is derived from GLOSEA?

Global long-range model probability maps - Met Office.url

Global long-range model probability maps

WWW.METOFFICE.GOV.UK

---

Model probabilistic guidance for temperature and rainfall up to six months ahead. Updated monthly.

1) It shows a higher probability for below average precipitation to our north and NE from Nov-Jan.

2) It also shows a better chance of above average pressure to our north and NE for the same period. Potential for high pressure and low precip over Scandi and the Norwegian Sea

3) Above normal precipitation to our south has a greater probability than normal or below normal

4) And, it follows, that it also forecasts a higher probability of below average pressure to our south

In summary - there are higher probabilities for a Euro low than a Euro High. And higher probabilities for a Scandi/Norwegian Sea High than not. But if it's the same data as GLOSEA then that stands to reason after yesterday's update

Edited October 11, 2023 by LRD

[Don]

1 hour ago, RainAllNight said:

I know from previous posts that in October 2016, there was a Scandi high at a similar time (though it was a little earlier, and it looked stronger than what's being forecast for next week). Did the next couple of months after this continue to have non-zonal synoptics, do you know?

I think that was a year that had had a lot of warmth in September as well.

Winter 2016/17 was a borefest and not something I would like to see a repeat of! 

[Rain All Night]

3 minutes ago, Don said:

Winter 2016/17 was a borefest and not something I would like to see a repeat of! 

It sounds like it was dry though with lots of HP around - that would do me!!

[Don]

20 minutes ago, LRD said:

Met Office Probabilistic charts are now out for October. I assume this is derived from GLOSEA?

Global long-range model probability maps - Met Office.url 119 B · 0 downloads

Global long-range model probability maps

WWW.METOFFICE.GOV.UK

---

Model probabilistic guidance for temperature and rainfall up to six months ahead. Updated monthly.

1) It shows a higher probability for below average precipitation to our north and NE from Nov-Jan.

2) It also shows a better chance of above average pressure to our north and NE for the same period. Potential for high pressure and low precip over Scandi and the Norwegian Sea

3) Above normal precipitation to our south has a greater probability than normal or below normal

4) And, it follows, that it also forecasts a higher probability of below average pressure to our south

In summary - there are higher probabilities for a Euro low than a Euro High. And higher probabilities for a Scandi/Norwegian Sea High than not. But if it's the same data as GLOSEA then that stands to reason after yesterday's update

The pressure height probabilities look pretty good, but still a strong signal for above average temperatures all the way.

[Cheshire Freeze]

2 minutes ago, Don said:

The pressure height probabilities look pretty good, but still a strong signal for above average temperatures all the way.

There always is.

I was looking at temperature anomaly charts on various long rangers yesterday and where you’d expect lower than average temperatures (due to the set up) it was shown average at best.

My advice is to look at the context. If you see areas of higher than average and a couple of patches of average, then the average is likely to be where the signature for cold is.

Edited October 11, 2023 by Cheshire Freeze

[LRD]

Just now, Don said:

The pressure height probabilities look pretty good, but still a strong signal for above average temperatures all the way.

Wouldn't take TOO much notice of the temps at this stage but, yeah, it is above average temps

[Don]

Just now, RainAllNight said:

It sounds like it was dry though with lots of HP around - that would do me!!

It was dry and frosty at times (particularly January), but with very little in the way of wintry weather, so a tedious season, a bit like those winters of 1991/92 and 1992/93.

1 minute ago, Cheshire Freeze said:

There always is.

I was looking at temperature anomaly charts on various long rangers yesterday and where you’d expect lower than average temperatures (due to the set up) it was shown average at best. 

Very true!

[northwestsnow]

Really positive Meto pressure maps for N/D/J..

I'll be scrutinising ec46 for the next number of weeks looking for Blocking to the NE ..

[LRD]

5 minutes ago, northwestsnow said:

Really positive Meto pressure maps for N/D/J..

I'll be scrutinising ec46 for the next number of weeks looking for Blocking to the NE ..

Even Dec-Feb isn't bad but the signal, understandably, weakens

[SqueakheartLW]

25 minutes ago, Don said:

It was dry and frosty at times (particularly January), but with very little in the way of wintry weather, so a tedious season, a bit like those winters of 1991/92 and 1992/93.

Very true!

Wasn't 2016/17 the winter where we got that bizarre day where surface temps were below freezing all day whilst the 850hpa temps were nearly +5C on a continental SE wind?

[Don]

13 minutes ago, SqueakheartLW said:

Wasn't 2016/17 the winter where we got that bizarre day where surface temps were below freezing all day whilst the 850hpa temps were nearly +5C on a continental SE wind?

Possibly.  A typical example of ‘faux’ cold when we get cold surface temperatures with mild upper temps!

[seabreeze86]

Good effort by the GFS just 6-8 weeks to early 

[Rain All Night]

7 minutes ago, Don said:

Possibly.  A typical example of ‘faux’ cold when we get cold surface temperatures with mild upper temps!

You'd take that though, right?