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Preliminary Winter Forecast


Paul

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

Just to add my thanks to GP. I don't often post here, but I thought I would as your work is so well laid out and explained.. actually it is pretty much brilliant. If only the Met Office had the guts to lay out there thoughts on the line in a similar manner. Couple of questions if you will.

1 - On the above quote - so basically (those of us prefering colder weather) are crossing our fingers that El Nino leavs the global weather pattern alone on those 3 opportunites & if say it breaks through mid January we may well have a cold(ish) Dec/early Jan but then Bartlett blowtorch?

2 - On last year's major stratospheric warming in Feb. Though this did cause the colder period of weather, it did not seem to have the effects that you thought it would, any thoughts as to why? (please point me elsewhere if this has already been answered).

The GLAAM plot covering the year helps to explain both.

http://www.esrl.noaa.gov/psd/map/images/aam/glaam.gif

1 - Even if El Nino starts to crank up, angular momentum moving from strong positive to negative will generate the necessary wave breaking of the stratospheric jet to support blocking. Look what happend last December when angular momentum moved strong positive negative. So long as we have negative tendencies in the atmosphere (QBO), then we are likely to see rises and falls in angular momentum which are good for cold.

2- Last year's warming event was a shot across the bows for the recent trend for a cold stratosphere. Last year was a west QBO and solar minima. That's really bad for warming events. However, we witnessed a massive warming event. It wasn't sustained, in hindsight a big fall in angular momentum impacted the pattern from February onwards was the inhibiting factor. This is very relevant to this year where the probabilities for a warming event becoming sustained are much higher.

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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

With previous posts of analysis there was nothing else to expect other than an exquisite detailed piece of work.

Stew

with the QBO and jet on southerly track possibly/probaly due to the affects of the cuurent solar state, will El Nino really influence/override this.would it be fair to say that a caveat is thrown in against past analogues/affects of El Nino because of the depth of this minima AND also where this minima may well be heading?

BFTP

Edited by BLAST FROM THE PAST
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Posted
  • Location: Glasgow, Scotland (Charing Cross, 40m asl)
  • Weather Preferences: cold and snowy in winter, a good mix of weather the rest of the time
  • Location: Glasgow, Scotland (Charing Cross, 40m asl)

Thanks GP for that brilliant enlightening forecast. It seems to be the exact opposite of the met. office forecast in both the level of content and the conclusions drawn!

Let's hope you get it right,

CW

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

With previous posts of analysis there was nothing else to expect other than an exquisite detailed piece of work.

Stew

with the QBO and jet on southerly track possibly/probaly due to the affects of the cuurent solar state, will El Nino really influence/override this.would it be fair to say that a caveat is thrown in against past analogues/affects of El Nino because of the depth of this minima AND also where this minima may well be heading?

BFTP

That's why the 1960s provide good analogues here and I have 1963/4 and 1965/6 and 1968/9 as examples [see the caveat about warming]. Low angular momentum base state but with Nino years. Obviously the world and the Atlantic in particular is warmer. However, they provide a clue as to how the pattern will pan out. A large fetch of easterlies across the tropical Pacific will result in the same hemispheric height anomalies as they did in the 1960s.

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Posted
  • Location: East Anglia
  • Location: East Anglia

With previous posts of analysis there was nothing else to expect other than an exquisite detailed piece of work.

Stew

with the QBO and jet on southerly track possibly/probaly due to the affects of the cuurent solar state, will El Nino really influence/override this.would it be fair to say that a caveat is thrown in against past analogues/affects of El Nino because of the depth of this minima AND also where this minima may well be heading?

BFTP

Spot on Fred, a very well laid out an informative post, indeed I may well print it off as a useful aide for learning more about the technical terms that I’m less familiar with.

The solar minima is fascinating and it will be interesting to see how this impacts and informs our knowledge of how climate works and whether the rule book will require some rewrites. What better than an El-Nino year for a good test.

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Posted
  • Location: Redhill, Surrey
  • Weather Preferences: Southerly tracking LPs, heavy snow. Also 25c and calm
  • Location: Redhill, Surrey

GP

Yes thanks, saw that within the body but just brought it in because as you mention is deepest since beginning of 20th century. I agree though that solar cycle wise that the period uyou highlight is more appropriate than say 2002/3 for example.

WE

Yes agreed some good testing ground upon us

BFTP

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

It's a fantastic piece of work, and agree that it is important to wait until later this month before committing to a more definite forecast.

My viewpoint would be there is not enough weight paid to the recent 'form' in terms of the NAO and AO.

But the most significant comment is that GP believes that chances of a below average winter are around '1 in 3', bearing in mind some of the posts GP has issued in recent years, that is very telling.

That could change though Ian, watch those 'things to watch'.

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Posted
  • Location: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl

That's why the 1960s provide good analogues here and I have 1963/4 and 1965/6 and 1968/9 as examples [see the caveat about warming]. Low angular momentum base state but with Nino years. Obviously the world and the Atlantic in particular is warmer. However, they provide a clue as to how the pattern will pan out. A large fetch of easterlies across the tropical Pacific will result in the same hemispheric height anomalies as they did in the 1960s.

Hi GP,

I like your analogues from the 60`s .I recall some good Arctic Northerly`s then,not topplers but from Greenland High`s.

http://www.wetterzentrale.de/archive/ra/1966/Rrea00119660115.gif

http://www.wetterzentrale.de/archive/ra/1969/Rrea00119690208.gif

Hopefully we get something along those lines this Winter.

If not i will settle for a good Easterly.rolleyes.gif

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Posted
  • Location: Liphook
  • Location: Liphook

I actually think 1965-66 isn't a bad one to compare this to, milder as GP mentioned and I expect the cold to be pushed more into Feb rather then Jan, though I think that could be a decent enough month if you enjoy SE airflows I suspect...of course always the threat of LP's still being too strong and tilting winds more S/SSW in direction.

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Posted
  • Location: Lee, London. SE12, 41 mts. 134.5 ft asl.
  • Weather Preferences: Cold, Snowy Weather
  • Location: Lee, London. SE12, 41 mts. 134.5 ft asl.

Thanks Stewart for such a detailed and well thought out piece of work, and although very technical in parts, you've obviously taken great care to make it as easy to follow as possible for those of us without your knowledge of the more complicated aspects of meteorology. Thanks also for taking the trouble to illustrate this preliminary forecast with so many charts and diagrams, it helps so much in understanding your early thoughts for this winter.

Its certainly going to be an interesting couple of weeks as we head towards the start of December and just how these many pieces of the "winter jigsaw" interact. Lets hope they slot together nicely in our favour and produce some decent cold and snow events at some point during the coming winter.

I think we might be in for a milder, Atlantic driven pattern in December, rather than the anticyclonic dominated Decembers of recent years, with attendant cold inversion conditions.

After that I think a lot will depend on the strength of this winters El Nino event but certainly your early thoughts for this winters stratospheric conditions seem encouraging and the current SST situation in the Atlantic looks to be a plus too.

Regards,

Tom.

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Posted
  • Location: Faro, Portugal
  • Location: Faro, Portugal

Hi how are you ?

I dont understand much of this ... but i read the excellent piece of work of Stewart and i have a question for you !!

In the current conditions how this prediction affect the Iberian Peninsule, speccially Portugal !!

we have a normal precipitation / above normal precipitation /very above precipitation ???

Anybody can help me ???

Edited by ThunderStorms
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Posted
  • Location: The Shed of Soviets, London
  • Location: The Shed of Soviets, London

Amazingly difficult stuff - So many variables, but then so many interactions that seem to line up favourably for a cold one in respect to other cold winters.

Kirklees Council better have my loft insulation in soon - waking up to see your own breath like last year isn't good - but then I want snow...

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

Very informative post, the main message being there are many factors to consider and it really is not a clear cut case even if el nino goes into high mode, no wonder the BBC are waiting to the end of November before they issue there post.

I firmly believe it will be an average winter temp wise overall (averaged out), however, I'm expecting some cold snowy spells at times, on a par with last year and for the latter part of the winter to potentially deliver a very cold spell of weather as we see el nino weaken considerably.

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Posted
  • Location: W. Northants
  • Location: W. Northants

Theres so much information to try and and soak up from this. Excellent piece of work GP - LRF's have come a long way since I first started reading these things on the net ten years ago. Many thanks. :)

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Posted
  • Location: Broadmayne, West Dorset
  • Weather Preferences: Snowfall in particular but most aspects of weather, hate hot and humid.
  • Location: Broadmayne, West Dorset

Have just finished reading William Burroughs book Weather Cycles real or imaginary? Now I understand why GP has to take so many factors into consideration.

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Posted
  • Location: Napton on the Hill Warwickshire 500ft
  • Weather Preferences: Snow and heatwave
  • Location: Napton on the Hill Warwickshire 500ft

Am I being silly but it mentions through to Feb 2009, I assume it means throught to Feb 2010. Kind of cheating otherwise rolleyes.gif

It still has the forcast through to Feb 2009 ?

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Posted
  • Location: Lochgelly - Highest town in Fife at 150m ASL.
  • Weather Preferences: Snow and cold. Enjoy all extremes though.
  • Location: Lochgelly - Highest town in Fife at 150m ASL.

It's very helpful having something like this to refer to as these abreviations keep popping up on a daily basis on different threads. Helps me to understand things a bit better. Thanks a lot for a very well presented piece of work.

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Posted
  • Location: Seven Springs, Cotswolds 212m ASL
  • Location: Seven Springs, Cotswolds 212m ASL

The GLAAM plot covering the year helps to explain both.

http://www.esrl.noaa.gov/psd/map/images/aam/glaam.gif

1 - Even if El Nino starts to crank up, angular momentum moving from strong positive to negative will generate the necessary wave breaking of the stratospheric jet to support blocking. Look what happend last December when angular momentum moved strong positive negative. So long as we have negative tendencies in the atmosphere (QBO), then we are likely to see rises and falls in angular momentum which are good for cold.

2- Last year's warming event was a shot across the bows for the recent trend for a cold stratosphere. Last year was a west QBO and solar minima. That's really bad for warming events. However, we witnessed a massive warming event. It wasn't sustained, in hindsight a big fall in angular momentum impacted the pattern from February onwards was the inhibiting factor. This is very relevant to this year where the probabilities for a warming event becoming sustained are much higher.

Thanks GP, much appreciated you taking the time to answer. Looking forward to the main winter forecast.

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Posted
  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire

Yes I pretty much agree with most of this but there are one or two variations on the theme that I think you might not have explored. Firstly the sub surface warm anomalies have changed direction over the last few weeks.

When compared with two weeks ago, the sub-surface has warmed significantly in the central Pacific, related to a recent weakening of the Trade winds. This warming has propagated eastwards during recent weeks.

From the Bom's most recent update

Enso update

One area you might not have explored is that of mountain torque and its effects on GWO.El Nino always has its own built in ending where the jetstream crossing the large mountain ranges of the himalaya and rockies causes global wind energy to be lost. Personally I think this might come into play with GLAAM not holding up as we go into the winter months. We should probably also consider that tropopause wave breaking will most likely be concentrated around the rockies rather than towards the himalayas and the potential impact of this on the stratospheric vortex( i.e. I think it moves the vortex away rather than towards the UK)

One thing that did worry me was your up and down welling waves in the stratosphere over 6 to 9 months period. Although you said the up period was good the stratospheric warming of last winter occured in a downwelling phase. I don't personally know of any research about the longer time period upwelling and downwelling period so I would be interested in exploring this further.

Key areas for me this year are the northern atlantic to a lesser extent and the northern pacific to a larger extent. That cold anomaly in the north atlantic would typically move slowly eastwards which would tend to push a greenland high somwhat eastwards. In the north pacific that cold anomaly as it slowly moves eastwards would tend to push the el nino pattern somewhat eastwards as well. For me this pushes a typical negative AO high in the north pacific eastwards towards north west canada. You end up with a very unusual pattern in the north pacific which is why I am drawn towards similarities with winter 1986 1987, the key for me is the time of the year that the transition from la nina to el nino occurs because this determines how far advanced changes in the north pacific are.

Just a few thoughts to explore anyway.

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Posted
  • Location: Worcestershire
  • Weather Preferences: Forecaster Centaurea Weather
  • Location: Worcestershire

Hi how are you ?

I dont understand much of this ... but i read the excellent piece of work of Stewart and i have a question for you !!

In the current conditions how this prediction affect the Iberian Peninsule, speccially Portugal !!

we have a normal precipitation / above normal precipitation /very above precipitation ???

Anybody can help me ???

I bit of a mixture. There is potential for some really warm spells as the jet ripple northwards and the sea surface temperatures are above average just to the west. However, a cold or average pattern over northern Europe is also likely to feature the jet displaced south bringing cooler and unsettled spells of weather.

Yes I pretty much agree with most of this but there are one or two variations on the theme that I think you might not have explored. Firstly the sub surface warm anomalies have changed direction over the last few weeks.

From the Bom's most recent update

Enso update

One area you might not have explored is that of mountain torque and its effects on GWO.El Nino always has its own built in ending where the jetstream crossing the large mountain ranges of the himalaya and rockies causes global wind energy to be lost. Personally I think this might come into play with GLAAM not holding up as we go into the winter months. We should probably also consider that tropopause wave breaking will most likely be concentrated around the rockies rather than towards the himalayas and the potential impact of this on the stratospheric vortex( i.e. I think it moves the vortex away rather than towards the UK)

One thing that did worry me was your up and down welling waves in the stratosphere over 6 to 9 months period. Although you said the up period was good the stratospheric warming of last winter occured in a downwelling phase. I don't personally know of any research about the longer time period upwelling and downwelling period so I would be interested in exploring this further.

Key areas for me this year are the northern atlantic to a lesser extent and the northern pacific to a larger extent. That cold anomaly in the north atlantic would typically move slowly eastwards which would tend to push a greenland high somwhat eastwards. In the north pacific that cold anomaly as it slowly moves eastwards would tend to push the el nino pattern somewhat eastwards as well. For me this pushes a typical negative AO high in the north pacific eastwards towards north west canada. You end up with a very unusual pattern in the north pacific which is why I am drawn towards similarities with winter 1986 1987, the key for me is the time of the year that the transition from la nina to el nino occurs because this determines how far advanced changes in the north pacific are.

Just a few thoughts to explore anyway.

Thanks Mark.

Those warm subsurface anomalies have shifted noticeably eastward. Cooler anomalies are also showing up towards Peru so we should see the west-based anomalies persist for a while yet.

We are in agreement about a negative tendency in angular momentum bringing about checks on any +AAM induced by El Nino. Without constant forcing, the natural ebbs and flows of zonal winds will see some scrubbing of westerlies from the atmosphere across the Himalayas and Rockies. It's noticeable how strong the negative (easterly) mean zonal winds have been across the tropical Pacific and Atlantic. Factor in the east QBO, and there some considerable obstacles for El Nino. Hence 1986/7 is a good analogue.

I think the downwelling wave / warming event last year was a west QBO type response. From my research, it would appear that upwelling and east QBO results in upper troposheric ridges.

Interesting Brick, but a Greenland High can't 'move Eastwards', as for similarities with 86/87, we are talking about a one-off event in Jan 87, involving the Arctic High, almost certainly those synoptics could not be reproduced in the christmas pudding, whatever the level of cold pooling in Eastern Europe - synoptics would direct this cold pool over Southern Europe.

Eastward motion is possible if the winds over the Arctic are easterly.

Edited by Glacier Point
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Interesting Brick, but a Greenland High can't 'move Eastwards', as for similarities with 86/87, we are talking about a one-off event in Jan 87, involving the Arctic High, almost certainly those synoptics could not be reproduced in the christmas pudding, whatever the level of cold pooling in Eastern Europe - synoptics would direct this cold pool over Southern Europe.

Don't follow this - as far as I recall the Greenland high ridged over Scandi in 1963, at times bringing in winds from NW Russia at times with easterlies pretty well right across the Atlantic.

The Net Weather LR for Jan indicates a ridging from a hign centered to SW Iceland and ridging over to Scandi as well, although this may not happen, so I do not see at as an impossible or unlikely concept.

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Posted
  • Location: Stourbridge
  • Location: Stourbridge

Don't follow this - as far as I recall the Greenland high ridged over Scandi in 1963, at times bringing in winds from NW Russia at times with easterlies pretty well right across the Atlantic.

The Net Weather LR for Jan indicates a ridging from a hign centered to SW Iceland and ridging over to Scandi as well, although this may not happen, so I do not see at as an impossible or unlikely concept.

sorry if i seem rather gloomy, but imho what the models are indicating at the moment is a pattern we have sign all too frequently in recent winters(excluding last year) with the jet really firing up now, and a lot of cyclonic activity happening over iceland and greenland, with high pressure firmly stuck across europe. it is often a very stubborn pattern, so i wonder if potential for a wintry december is on the line, as this pattern can be very hard to shift.

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Posted
  • Location: Coventry,Warwickshire
  • Location: Coventry,Warwickshire
Interesting Brick, but a Greenland High can't 'move Eastwards

Yes I would tend to agree and was hinting at the possibility of the focus for high pressure moving from greenland to scandinavia not the high pressure actually moving.

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Guest North Sea Snow Convection

Must say i dont like the sound of 1986/7,aside from THE cold spell in Jan it was a very mediocre winter.

What can be overlooked is how close we came to a repeat of the mid month freeze at the end of the month!

Rrea00219870130.gif

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