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Upcoming winter speculation and chat - October edition

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3 minutes ago, Mike Poole said:

Hi Griff, welcome to netweather, fellow south Oxfordshire resident!

So, retrogression is relating to high pressure blocks - usually weather moves west to east, dictated by the jet stream, but retrogression is the movement of weather systems in the opposite direction, most significant on here is a high pressure block over Scandinavia moving west towards Greenland in the winter. Phasing is two areas of low pressure merging and becoming one.  Ridging is the building of an area of high pressure.  And short-waves, these are basically small areas of low pressure that mess up what we think will happen!  Air circulates round a high clockwise, and a low counter clockwise, so if we think we've got an idea about this on a larger scale dictated by high pressure, a short-wave low pressure cropping up can change the picture altogether.  

@Mike Poole thanks for the warm welcome, and taking the time to explain, much appreciated. 

FYI I'm just in the foothills of the Chilterns, but mostly stuck on the M40!

Fascinating times ahead, one last thing fi or FI... Obviously future and not to be taken seriously but what's it actually short for? Once upon a time I got my weather from metars and tafs...

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2 minutes ago, Griff said:

@Mike Poole thanks for the warm welcome, and taking the time to explain, much appreciated. 

FYI I'm just in the foothills of the Chilterns, but mostly stuck on the M40!

Fascinating times ahead, one last thing fi or FI... Obviously future and not to be taken seriously but what's it actually short for? Once upon a time I got my weather from metars and tafs...

Fantasy Island...never really understood where it came from, but in practical terms it is the timeframe when because of uncertainty the models are not worth the computer chips they are calculated on...and are therefore just spewing out nonsense. 

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1 hour ago, Griff said:

Hi all, 

Long time lurker (well since 2018) but first time posting. Fascinated by how the next few months play-out, especially considering the long range winter forecasts vs recent model runs. I feel like I've learnt so much already but continue to be baffled on a daily if not hourly basis. 

Would love to understand the following terms in no particular order... retrogression, phasing, ridging and short-wave.

Thanks, Griff. 

 

 

Hi, I will give examples of ridges (and troughs) and retrogression for you and let others explain phasing and short waves.

Ridges and Troughs

A pretty good example of this is actually from the current pattern across USA weather.thumb.png.4ca0f251d82263e08a59e4a2a23e05f3.pngRidges are associated with higher pressure and troughs with lower pressure

Retrogression 

A classic example of this was during the Beast From The East in February / March 2018 

archivesnh-2018-2-25-0-0.thumb.png.c42791e97823c8cee389a016fe5b41f8.png high pressure over Scandinavia

archivesnh-2018-2-28-0-0.thumb.png.30655e8409a19322788fc8ea128fdd59.png moved west toward Iceland / Greenland 

archivesnh-2018-3-2-12-0.thumb.png.690686730845dd32a52cea73f381634c.png completed the retrogression and ended up over Greenland 

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I hope Stewart @Glacier Point won't mind me dropping this into the thread. Hugely respected poster on here who is currently not active.

Some thoughts on this blog which I happened on this evening for folks to add into the Seasonal forecast mix.

CENTAUREAWEATHER.COM

It’s that time of year again when the energy sector, hedge funds and weather enthusiasts are deluged with long range weather forecasts, the key question – what will the winter hold ? I’ve been...

 

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18 minutes ago, lorenzo said:

I hope Stewart @Glacier Point won't mind me dropping this into the thread. Hugely respected poster on here who is currently not active.

Some thoughts on this blog which I happened on this evening for folks to add into the Seasonal forecast mix.

CENTAUREAWEATHER.COM

It’s that time of year again when the energy sector, hedge funds and weather enthusiasts are deluged with long range weather forecasts, the key question – what will the winter hold ? I’ve been...

 

As ever with GP a good read. Quite close to a few other punters. He doesn’t appear to see a split vortex scenario as likely...but otherwise I like what I read. And if actually we get that Siberian vortex split with a continued tendency for heights over Greenland then all kinds of fun and games might develop.

And another who is showing little faith in long range seasonals. Either these seasonals are about to be properly ridiculed or some of us are going to have to retire....

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14 minutes ago, Catacol said:

As ever with GP a good read. Quite close to a few other punters. He doesn’t appear to see a split vortex scenario as likely...but otherwise I like what I read. And if actually we get that Siberian vortex split with a continued tendency for heights over Greenland then all kinds of fun and games might develop.

And another who is showing little faith in long range seasonals. Either these seasonals are about to be properly ridiculed or some of us are going to have to retire....

I got to the point last weekend Catacol where I just couldn't reconcile the seasonal output with that the statistical evidence was pointing toward... hence the tweet confirming as such.

It really feels like it's an 'Us vs. Them' thing at the moment - not in a bad way - but either way it is a bit of an all or nothing situation where either the seasonal leads are defective, or, the reliability of looking back to look forward is flawed to a major degree.

Have chewed it over plenty around the fact that the seasonals, perhaps to my naivety in understanding their input matrix, to my mind I thought they must have this stuff we amateurs / speculators look at built in to the ensembles. Or, perhaps the game here is not the 'perfect evolution' but a slow build to improved skill, more improved skill, what creates better skill and improves the correlation.  Certainly having watched the symposium this week it is clear that there are hardcore questions on offer around what to 'go after' - 

1 The processes and understanding of interactions vis a vis - we have enough resolution with the models

2 Increasing either the Vertical or Horizontal capacity within the modelling -which will generate enhancements in skill.

3 Hot Topic - impacts of GWD - Gravity Wave Drag and the contest between Direct Inputs vs parametrization.

Am a Layman but if I was consulting I think I would ask the audience to Action Plan on 1 - which process the community should address, pick Horizontal to capture internal vortex vacillation and liase with MERRA for part 3, in particular their 132 level model.

So these are there real challenges in resolving predictability, then impacts and it's been a good watch to review them..

I just hope we get a strong answer either way and not a halfway house solution where the answer fits elements of seasonal and elements of statistical..

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7 minutes ago, lorenzo said:

I got to the point last weekend Catacol where I just couldn't reconcile the seasonal output with that the statistical evidence was pointing toward... hence the tweet confirming as such.

It really feels like it's an 'Us vs. Them' thing at the moment - not in a bad way - but either way it is a bit of an all or nothing situation where either the seasonal leads are defective, or, the reliability of looking back to look forward is flawed to a major degree.

Have chewed it over plenty around the fact that the seasonals, perhaps to my naivety in understanding their input matrix, to my mind I thought they must have this stuff we amateurs / speculators look at built in to the ensembles. Or, perhaps the game here is not the 'perfect evolution' but a slow build to improved skill, more improved skill, what creates better skill and improves the correlation.  Certainly having watched the symposium this week it is clear that there are hardcore questions on offer around what to 'go after' - 

 

It'll be a sad day if looking back becomes irrelevant ? I'm banking on the seasonals being wrong (again...) ?

I saw bits of a couple of the ECM Reading lectures on the livestream - are they archived or on youtube? 

Edited by Catacol
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18 minutes ago, Catacol said:

It'll be a sad day if looking back becomes irrelevant ? I'm banking on the seasonals being wrong (again...) ?

I saw bits of a couple of the ECM Reading lectures on the livestream - are they archived or on youtube? 

You can find the videos on the ECMWF vimeo page ? https://vimeo.com/ecmwf

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51 minutes ago, Catacol said:

As ever with GP a good read. Quite close to a few other punters. He doesn’t appear to see a split vortex scenario as likely...but otherwise I like what I read. And if actually we get that Siberian vortex split with a continued tendency for heights over Greenland then all kinds of fun and games might develop.

And another who is showing little faith in long range seasonals. Either these seasonals are about to be properly ridiculed or some of us are going to have to retire....

A very interesting read, and suggestive that December might well follow November pattern, which would mean cold and unsettled with quite possibly some significant snowfall events.

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It's laid out beautifully A

Monday's page updated overnight on Tuesday to include the Vimeo Link and PDF - hopefully this will continue this week and the archive remains for a bit..

KW is right they are all on Vimeo - this link lays out the vids with the presentations.

logo-2559612375.png
EVENTS.ECMWF.INT

#StratosphericWS This workshop will bring together experts to discuss and propose ways forward in representing the stratosphere in current and future numerical weather prediction models...

 

image.thumb.png.79602d1ca726b94eebf3a691d7a0671f.png

 

Edited by lorenzo
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5 hours ago, lorenzo said:

 

It really feels like it's an 'Us vs. Them' thing at the moment - not in a bad way - but either way it is a bit of an all or nothing situation where either the seasonal leads are defective, or, the reliability of looking back to look forward is flawed to a major degree.

 

Is it flawed? Anthony Masiello asked on twitter how the seasonal models would hindcast Dec 1995-Feb 1996 with November '95 as input (he picked that year because conditions now are apperently very similar) . Interestingly the current EC seasonal gave a very similar output for these winter months as is does now for the coming winter 

 

https://twitter.com/WorldClimateSvc/status/1195528751536316416

 

 

Edited by ArHu3

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Manchester Winter Indices

1959-60: 68

1960-61: 47

1961-62: 100

1962-63: 520

1963-64: 59

1964-65: 88

1965-66: 71

1966-67: 43

1967-68: 126

1968-69: 141

1969-70: 129

1970-71: 62

1971-72: 32

1972-73: 50

1973-74: 27

1974-75: 22

1975-76: 38

1976-77: 141

1977-78: 86

1978-79: 233

1979-80: 63

1980-81: 81

1981-82: 155

1982-83: 87

1983-84: 84

1984-85: 139

1985-86: 158

1986-87: 100

1987-88: 37

1988-89: 20

1989-90: 26

1990-91: 119

1991-92: 40

1992-93: 43

1993-94: 78

1994-95: 45

1995-96: 135

1996-97: 72

1997-98: 25

1998-99: 47

1999-00: 42

2000-01: 77

2001-02: 50

2002-03: 44

2003-04: 50

2004-05: 47

2005-06: 59

2006-07: 21

2007-08: 37

2008-09: 105

2009-10: 197

2010-11: 119

2011-12: 47

2012-13: 102

2013-14: 7

2014-15: 82

2015-16: 28

2016-17: 37

2017-18: 93

2018-19: 37

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1 hour ago, ArHu3 said:

@Weather-history what is the winter index, same as hellmann number (accumulative of subzero average temperature) 

 

10 mulitplied by [(number of days with lying snow at 9am)+(number of days with falling sleet/snow)+(number of air frosts)] divided by the mean  maximum of that winter

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Weather history stats make for good observation, we've been draw a very short straw in recent years for cold and snow 4 out of the last 6 ranking near or at the bottom of the league..

Look at 62-63.. nearest winter 78/79 since only half the marks. 

I'd be happy with anything above 50 at least.. preferably 100, and to be greedy 150 or more..

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12 hours ago, Weather-history said:

10 mulitplied by [(number of days with lying snow at 9am)+(number of days with falling sleet/snow)+(number of air frosts)] divided by the mean  maximum of that winter

Morning WH

Where can I access these datasets by area?

Thanks

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43 minutes ago, Davegwarn said:

Morning WH

Where can I access these datasets by area?

Thanks

No idea to be honest. My data is based on my own local observations. 

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Today's update from the BBC monthly outlook.  Is it me or does that forecast potentially have shades of December 2000 about it?

og-image.png
WWW.BBC.CO.UK

Latest weather conditions and forecasts for the UK and the world. Includes up to 14-days of hourly forecast information, warnings, maps, and the latest editorial analysis and videos from the BBC...

 

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36 minutes ago, Summer Sun said:

 

And of course, he's probably right. Bloody hate the weather in this country.

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3 minutes ago, Wynter said:

And of course, he's probably right. Bloody hate the weather in this country.

This could be the 'main' cold snap of winter 2019/20! ☹️

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1 hour ago, Don said:

This could be the 'main' cold snap of winter 2019/20! ☹️

For parts of the UK, it may well be.

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1 hour ago, Sceptical said:

For parts of the UK, it may well be.

Yes, especially for the likes of southern and western areas!  How many times have we been here during the last few years when the stratosphere looks favourable, only for the polar vortex to ramp up as December arrives?  Yet we still get sucked in!

Edited by Don
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