Autumn and Winter

[Dawlish]

So he is still expecting a "maybe dryer than average" December - no word on snowfall yet. If he is still forecasting a much drier than average winter overall then this will be a stark contrast to the Met Office's seeming "uncertainty" over precipitation in this coming season.

It is "in contrast to the Met Office's seeming "uncertainty"", because no-one actually knows, or is able to predict, with any reasonable certainty (thank goodness) what is going to happen!

I agree with you and Mr. Currie about the drought problems, Damien. They haven't gone away. We'll need a very wet winter to solve them. We may get that and with a warming climate, very wet seasons are not unlikely, but it is getting to the stage where we could really do with some significant rainfall this Autumn and Winter.

Paul

[Glacier Point]

One thing that the UKMET may also be hedging on in their latest seasonal outlook is the transition of the westerly phase Quasi Biennial Oscillation (QBO).

http://en.wikipedia.org/wiki/Quasi-biennial_oscillation

http://www.jisao.washington.edu/data_sets/qbo/

Right now this high altitude Kelvin wave pattern is in a positive or westerly phase which started last April:

http://www.cdc.noaa.gov/Correlation/qbo.data

Westerly phases of the QBO are more strongly associated with a strong polar vortex, indeed, there is a deal of published research suggesting that the QBO has a direct influence on the stratosphere by helping to propogate aerosols and Ozone resulting in a cooling of the upper atmosphere forcing the leading mode of the Arctic Oscillation (AO) positive.

The composite anomalies for positive phase AO for the winter months look this:

http://www.cpc.ncep.noaa.gov/research_pape...DJF.z500.ao.gif

with low pressure over the pole and higher pressure bands shifted northwards delivering milder weather for the UK.

The composite anomalies for all westerly phase northern hemisphere winters (DJF) confirms this trend with positive anomalies for pressure in the Atlantic:

leading to pretty average temperatures for the UK and western Europe.

A crude analysis of AO and QBO westerly winters suggests that:

1) Decembers tend to be split between neutral, +ve and -ve phase AO;

2) Januarys favour slightly +ve AO and neutral conditions;

3) Februarys are notable for the bias towards -ve AO conditions.

This is in contrast to easterly phase QBO winters where -ve AO conditions are more strongly favoured throughout.

The QBO is also related to the solar cycle. Right now we are at the lowpoint of Cycle 23.

http://en.wikipedia.org/wiki/Image:Zurich_..._since_1750.png

You might think this was a good thing - less incoming insolation, less warmth ? Wrong. The combination of westerly phase QBO and solar minima tends to exagerate the impacts on the AO and there have been no breakdowns of the polar vortex (blocking) during westerly phase QBO winters during solar minima.

The composite anomalies for westerly QBO and low solar cycle winters looks like this....

Not great for cold prospects at all.

But there is some hope there for the cold lovers. February for example looks to be the one month where the likelihood of an easterly shot looks most favoured:

whilst the timing of the westerly phase may end anythime between January and April next year. If the QBO were to turn easterly during January or February, the prospects of some quite juicy wintry weather would be increased considerably as this has often been associated with some of the most severe winters Europe.

So it's not just El Nino that needs to be watched closely over the coming months. The QBO should be followed in detail to give a clue to our winter prospects, more particularly that January / February period.

GP

[BLAST FROM THE PAST]

GP

I remember you mentioning this way back at the time the phase changed to westerly. Did you not mention it could bode well as the phases are 'generally' 8 months in length...which times for January? Yep soory can see that you suggest it is 8-12 months

Done some digging

Why the QBO is important?

1) The phase of the QBO affects hurricanes in the Atlantic and is widely used as a prognostic in hurricane forecasts.

Increased hurricane activity occurs for westerly (or positive) zonal wind anomalies; reduced hurricane activity for easterly or negative zonal wind anomalies.

2) The QBO along with sea surface temperatures and El Niño Southern Oscillation are thought to affect the monsoon.

3) Tropical cyclone frequency in the northwest Pacific increases during the westerly phase of the QBO. Activity in the southwest Indian basin, however, increases with the easterly phase of the QBO.

4) Major winter stratospheric warmings preferentially occur during the easterly phase of the QBO, Holton and Tan (1980).

5) Predictions of ENSO use the expected wind anomalies at 30mb and 50mb to forecast the strength and timing of the event.

6) The QBO is thought to affect the Sahel rainfall pattern and is used in forecasts for the region.

Of particular note is number 1. Hurricane season has not had increased activity and indeed the official forecast now is for below average seasonal activity. As I think GP has hinted this will be only one piece of the puzzle. Pointers are leading to a mild December

BFTP

Edited September 22, 2006 by BLAST FROM THE PAST

[Dawlish]

.......whilst the timing of the westerly phase may end anythime between January and April next year. If the QBO were to turn easterly during January or February, the prospects of some quite juicy wintry weather would be increased considerably as this has often been associated with some of the most severe winters Europe.

So it's not just El Nino that needs to be watched closely over the coming months. The QBO should be followed in detail to give a clue to our winter prospects, more particularly that January / February period.

GP

That was interesting reading. Thanks GP; I'd never come across the QBO before. I don't agree with the outcomes that you derive from it, though, of course, I would never deny the possibility - especially the Easterlies in February(great odds with me, if you are swayed by that!); that really is a Long-Range very educated, guess! Have a punt, if you feel that this could well come about.

Paul

Edited September 22, 2006 by Dawlish

[Glacier Point]

4) Major winter stratospheric warmings preferentially occur during the easterly phase of the QBO, Holton and Tan (1980).

BFTP

This is the really crucial one. For major stratospheric warmings, read blocking or negative phase AO.

Timing, as in all aspects of life, will be the crucial thing here. A westerly QBO continuing throughout the winter into next Spring will signifcantly reduce the probability of -ve AO (greater +ve leading mode) which will in turn force the NAO to a +ve leading mode regardless of what the SSTA looks like.

If the QBO phase shortens markedly and say we observe a neutral value in December, then that is a totally different ball game - deep cold pooling in December over the Pole followed by two months of -ve AO conditions displacing this cold air southwards - dream scenario.

Since a very weak duration of the QBO in the 1950s (possibly related to strong solar activity), the length of the westerly QBO has been around 7 - 14 months, average 11. That woud be close but no cigar for us.

Just as an aside, analysis of the QBO / AO has, since April, called the AO correctly 4/5 times so it would appear to be running true to form so far this cycle. It didn't call June correctly but this was strongly positive perhaps consistent with the stratospheric cooling associated with westerly QBO.

Edited September 22, 2006 by Glacier Point

[BrickFielder]

The QBO also tends to affect the timing of the break up of the vortex (final stratospheric warming). An easterly phase means a late break up of vortex while a westerly phase brings the break up earlier.

The results indicate that the QBO determines the timing, rather than the existence, of the solar signal. Stratospheric warmings during the westerly phase of the QBO and during solar maximum years occur already in January, whereas they appear one month later for the easterly phase. The Holton and Tan relationship is evident during solar minimum years, whereas it is less clear for the solar maximum experiments in agreement with observations.

Details found here at Sparc

[BLAST FROM THE PAST]

GP

And your early thoughts-negative or positive?

BFTP

[Glacier Point]

Some valuable research there which would appear to support the composite anomalies suggesting a strangely more clear signal from a QBO (w) / solar maxima flux compared to the QBO (w) / solar minima:

I'm not sure about the poleward shift being less apparent during the solar minima though as the composites at sea level suggest the opposite:

Overall from punting a LRF, I would still be faced with this:-

Record of DJF QBO westerly vs easterly phases

35% of Decembers witnessed a -ve AO with QBO in the westerly phase compared to 38% for the easterly phase. In terms of AO+ve, 35% of Decembers with a westerly QBO had an AO+ve compared to 26% of QBO easterly phase.

30% of Januarys witnessed a -ve AO with QBO (w) compared to 50% with QBO (e). Slightly at odds with the early breakdown of the polar vortex theory.

26% of Jans with AO+ve were associated with QBO (w) whilst only 19% of QBO (e) resulted in AO+ve.

50% of Februarys witnesed a -ve AO with the QBO in its westerly phase compared to 51% in the easterly phase. For AO +ve, 32% of Febs with a westerly phase and 21% for the easterly phase.

In short, a westerly phase QBO is always more likely to be less -ve and more +ve compared to an easterly phase. Not a great statistical sample I acknowledge, but given the choice, which would you favour ?

GP

[Big Bear]

But there is some hope there for the cold lovers. February for example looks to be the one month where the likelihood of an easterly shot looks most favoured:

GP

In contrast to this again, the French MO have issued their early thoughts on Dec/Jan/Feb, with December being the coldest month, Jan being cold/ average and February being way above average.

[kold weather]

Intresting to see what the Met-office are thinking and also what GP is thinking about the later easterly shot in Feb. This seems like a classic 80's type set-up and intrestingly the Pacific SSTA last month was similar to the 85-87 period which had a mild December followed by a colder second half of winter. This seems to be waht the Met-office suggests and its the way I personally think things will pan out as well, a mild and wet December. (though not sure how wet, that depends on how strong El Nino gets I feel.)

There is a very strong case for a southerly tracking PFJ this winter given how far south it already is compared to normal, however whether or not it gets itself into a decnt enough postion to give us the cold is another matter.

Edited September 22, 2006 by kold weather

[Dawlish]

Intresting to see what the Met-office are thinking and also what GP is thinking about the later easterly shot in Feb. This seems like a classic 80's type set-up and intrestingly the Pacific SSTA last month was similar to the 85-87 period which had a mild December followed by a colder second half of winter. This seems to be waht the Met-office suggests and its the way I personally think things will pan out as well, a mild and wet December. (though not sure how wet, that depends on how strong El Nino gets I feel.)

There is a very strong case for a southerly tracking PFJ this winter given how far south it already is compared to normal, however whether or not it gets itself into a decnt enough postion to give us the cold is another matter.

Whatever they think, at this distance out kold; it's a guess. Just a good, educated guess - in the case of the Met Office, a guess underpinned by some developing, but still experimental, forecasting techniques. Don't get too carried away! February is over 4 months away and there isn't an agency on Earth that can forcast what our UK weather will be with any decent accuracy, at all.

So many virtual pints waiting for you Kold, if you are pretty sure of what you are believing will happen!

Paul

[summer blizzard]

Here are the current anologues for the QBO over the past three months...

1995

I was looking for years with June and July values that are moderately positive (10 to 20) followed by a August value that was weakly positive (0 to 10).

As you can see, there was only one real anologue, the following winter onserved a weakly negative mode throughout the winter.

http://www.cdc.noaa.gov/Correlation/qbo.data

[mcweather]

Whatever they think, at this distance out kold; it's a guess. Just a good, educated guess - in the case of the Met Office, a guess underpinned by some developing, but still experimental, forecasting techniques. Don't get too carried away! February is over 4 months away and there isn't an agency on Earth that can forcast what our UK weather will be with any decent accuracy, at all.

So many virtual pints waiting for you Kold, if you are pretty sure of what you are believing will happen!

Paul

Devloping and experimental maybe but never the less good enough to pin last winter down very well.

Although the present forecast says that at the moment things are on a knife edge, it is clear from the comments about emerging signals and continuing developments that they expect it to come down on the cold side. I expect the November update to confirm this and probabay put a little more meat on the bones.

[Dawlish]

Devloping and experimental maybe but never the less good enough to pin last winter down very well.

Although the present forecast says that at the moment things are on a knife edge, it is clear from the comments about emerging signals and continuing developments that they expect it to come down on the cold side. I expect the November update to confirm this and probabay put a little more meat on the bones.

I know. The MO forecast was good, better than any other agency, however their NAO forecast, on which they based their winter forecast, at least in the greater part, was not! Now how does that tie up?

Paul

Edited September 22, 2006 by Dawlish

[pottyprof]

see what happens.. thats what i say.. :lol:

Im going for a below average CET.. more snow than last year.. and a higher gas/electricity bill.. :blink:

[Roger J Smith]

Here is the official long-range forecast of the Bi-polar Thought Society:

While nobody can predict the weather months, weeks, days or even hours in advance, and this was never going to be another 1740, it will be mild, or if not, then cold.

Snow will fall in many parts of the U.K., except where it doesn't, and this will lead to variations in snow depth.

Winds will blow from a number of directions, eight if you use that system, or sixteen if you use the other one. There will also be occasional calm periods.

This was never going to be another 1987. It was also never going to be like 1384, the year of the famous thing that happened in that place, you know, I forget where it was.

In making this forecast, we have consulted the calendar, the Ladbrokes odds on the eventual winner of the F.A. Cup, the number of slugs in Uncle Bill's garden, and some other things in a big computer that we have in the back somewhere.

This outlook is subject to change, and it will be changed, because if it wasn't, we'd be out of a job.

[Rollo]

Here is the official long-range forecast of the Bi-polar Thought Society:

While nobody can predict the weather months, weeks, days or even hours in advance, and this was never going to be another 1740, it will be mild, or if not, then cold.

Snow will fall in many parts of the U.K., except where it doesn't, and this will lead to variations in snow depth.

Winds will blow from a number of directions, eight if you use that system, or sixteen if you use the other one. There will also be occasional calm periods.

This was never going to be another 1987. It was also never going to be like 1384, the year of the famous thing that happened in that place, you know, I forget where it was.

In making this forecast, we have consulted the calendar, the Ladbrokes odds on the eventual winner of the F.A. Cup, the number of slugs in Uncle Bill's garden, and some other things in a big computer that we have in the back somewhere.

This outlook is subject to change, and it will be changed, because if it wasn't, we'd be out of a job.

I like it Roger,however you forgot to mention that it would rain somewhere everyday and Lutoons would get snowed in on the 31st of february 2007.

[Roger J Smith]

Don't enter any car rallies that go through Scotland on 5 January, that's all I am allowed to say at this point.

[North-Easterly Blast]

The models are now hinting at low pressures crashing over us as we go into early October, so another wet October could well follow this warm September. I just wonder why we just get September warmth year after year, followed by very wet weather in October. I would just love to see an October like 1995, or even 1985 which was very dry as well. Dry blocked Octobers have been almost entirely absent in recent years.

[The PIT]

Well I can only answer for the Sheffield area. October has been getting wetter over the last fews year which probably explains why you think that September is always followed by a Wet October.

http://www.sheffieldweather.co.uk/MONTHLYRAINAVERAGE.htm

Grapth showing the trend

http://www.sheffieldweather.co.uk/MONTHLYRAINAVERAGE.htm

However for the year nothing much has changed.

http://www.sheffieldweather.co.uk/MONTHLYRAINAVERAGE.htm

Of course this is only for Sheffield

Edited September 24, 2006 by The PIT

[mcweather]

I know. The MO forecast was good, better than any other agency, however their NAO forecast, on which they based their winter forecast, at least in the greater part, was not! Now how does that tie up?

Paul

Fair point to make there Dawlish but the NAO was only one factor in a number used to put the forecast together. Presumably If the other factors are strong enough then being a tad out one will not automatically invalidate everything else.

In a similar vein, all those who say it is impossible for us to have another half decent winter in this country seem to forget that if the wind blows from the east or north east for long enough at the right time of the year then GW

man made or otherwise will have very little bearing on what happens.

[Bham Chris]

The models are now hinting at low pressures crashing over us as we go into early October, so another wet October could well follow this warm September. I just wonder why we just get September warmth year after year, followed by very wet weather in October. I would just love to see an October like 1995, or even 1985 which was very dry as well. Dry blocked Octobers have been almost entirely absent in recent years.

Well October 2003 wasn't wet though it was a cold month,I'd gladly settle for some crisp autumn sushine this october as well,rather much have that than the October we experienced last year which was wet and very warm.

[Dawlish]

Fair point to make there Dawlish but the NAO was only one factor in a number used to put the forecast together. Presumably If the other factors are strong enough then being a tad out one will not automatically invalidate everything else.

In a similar vein, all those who say it is impossible for us to have another half decent winter in this country seem to forget that if the wind blows from the east or north east for long enough at the right time of the year then GW

man made or otherwise will have very little bearing on what happens.

I don't know of anyone that has said that it is impossible for us to have another half decent winter in this country mc. Anyone that does, has little understanding of probabilities and is much more likely to be proved wrong than right!

Paul

[BLAST FROM THE PAST]

Don't enter any car rallies that go through Scotland on 5 January, that's all I am allowed to say at this point.

Roger

That reads very zonal to me :huh: However, I must agree that the first week to 10 days of Jan will be very interesting. My early indicators are for an attempt at retrogression against the LPs...but it may be that the n/nw areas get the snow :o

BFTP

Edited September 24, 2006 by BLAST FROM THE PAST

[summer blizzard]

Personally, am not particulay bothered if my area were to miss out on such an event because looking at the data and listening to the reports from other people was almost as exiting as the event itself, taking March 12th as an example, while i only got 6cm of snow, listening to the reports from Glasgow and reveiwing my snow depth forecast for them was equally exiting.

Does anybody know where the March 12th snowfall threads are kept??????