The Seasonal Forecast Thread

[Methuselah]

Very well done, Sam...I hope it comes off!

[johnholmes]

yes, thank you for that, a great deal of work has obviously gone into this; as always we have to wait and see what the outcome is.

It will be particularly interesting having used so many teleconnections to see how the result turns out.

thanks again.

[Don]

Thanks BFTV. Certainly no complaints from me if that ends up close to the mark!

[phil nw.]

Well presented Sam and good luck with it.

Interestingly similar to mine-so i hope we are both close to the actual outcome as it will please all cold lovers.

[John Badrick]

Here's my winter 2013/2014 forecast.

 

For this forecast, I looked at 10 different teleconnections for their trends and averages in the last 6 to 9 months (and forecasts for MEI), and then compared those criteria with previous years, mostly back to 1951, and created a list of the years with the most similar teleconnections to this year.

 

Below are the 10 teleconnections and the criteria used with them.

 

Teleconnections ......................  ................... Criteria 

 

Arctic Oscillation (AO): Mean of the last 6 months (May to October) close to 0, and little month to month variation.

North Atlantic Oscillation (NAO): Mean of the last 9 months (February to October) close to 0, and a moderate to large amount of month to month variation.

Multivariate ENSO Index (MEI): Winters averaging between -0.5 and +0.5 for the October to February period.

Eurasian Snow Cover: Years that show an above average increase from September to October Eurasian snow extent.

Quasi Biennial Oscillation (QBO): Positive in Autumn and falling through Winter.

Solar Activity: An 11 year monthly sunspot mean of below 70

Atlantic Multidecadal Oscillation (AMO): Mean above average over the last 9 months.

Pacific Decadal Oscillation (PDO): Mean moderately below average over the last 9 months

Arctic Sea Ice: A September sea ice area minimum of less than 4 million km² 

Globally Averaged Angular Momentum (GLAAM): Mean of the last 9 months close to 0, with moderate month to month variation.

 

After going through the data, these were the most closely matched years

 

Year ... Criteria Matches out of 10

2010/11 = 7* 

2009/10 = 6

2006/07 = 6

2004/05 = 7 

2003/04 = 6 

2002/03 = 6 

1985/86 = 6 

1978/79 = 6 

1976/77 = 6

1973/74 = 6

 

So using this, each of the years with 6 matches would get 1 place in the composite maps, and 7 matches would get 2. *An exception here is 2010/11, which had a moderate El Nino, so that will only be included once.

 

So based on the above, here's the winter forecast.

 

--------------------- ------------------------------------- ------------------------------ ------------------------------------ -----------------------

 

DECEMBER

 

A strong Atlantic ridge stretching into southern Greenland, coupled with low heights stretching from Scandinavia to the Iberian Peninsula, look to be the main features for December. An increase in northerly orientated winds could be expected with this set up, but, if the trough moves much further west, the is a chance of some milder southerly winds occurring, sourced from the western Mediterranean.

 

Precip is likely to be close to average, with a slightly higher chance of above rather than below average monthly totals.

Temperatures are more likely to be below average, with a CET estimate of close to 4C

 

 

JANUARY

Northern blocking, a west based -ve NAO and a large trough across central Europe are the main features for January. Northerly and northeasterly winds are likely to be more common during the month.

 

Rainfall is likely to be average or slightly above, with the driest weather to the south and west.

Temperatures are likely to be below average once again, with the coldest conditions further east. The CET estimate is 3.0C.

 

 

FEBRUARY

 

At this stage, February looks like featuring some very strong northern blocking, centred toward Greenland, with low heights across our south and into Europe. The set should produce much more easterly winds than normal.

 

Precip is likely to be close to or above average in the south and east, and below average further north and west

Temperatures are likely to be below average everywhere, with a CET estimate of 2.8C

 

 

OVERALL

Strong heights over southern Greenland should be a recurring feature of the first 2 months of winter, bring plenty of northerly airflows, before more general blocking takes hold, carrying more easterly winds during February. With low heights nearby and plenty of cold sourced airflows, each month has the potential for spells of cold and snow. While precip looks like being near average overall, snowfall totals may well end up above average.

The coming winter seems quite likely to be below average temperature-wise, with a good chance of all 3 winter months being below the 81-10 average.

 

If I was to guess at a period with the highest risk of severe cold, I'd say late January and early February, as northern blocking strengthens eastward and brings a more easterly flow across the British Isles

Good forecast Sam, hope this comes off...

[Roger J Smith]

In response to the question, the actuals so far have not been vastly different from what my research model originally showed which led me to say mild first half Novemeber and colder second half, then back to mild or very mild at times in December. My attempt to fine tune this with the November update has back-fired but this is essentially just a pumped up version of mild southwesterly flow so that we're seeing considerable radiational cooling inland, temperature anomalies near west-facing coasts are not as affected. The very mild signal was somewhat weakened too by this persistent anticyclonic influence, but several days just before mid-month were in fact quite mild. So in general with the evolution in North America looking about right, I don't see any real signs of a comprehensive bust. I am covered for a colder spell in early to mid January too, so it's not a situation where my forecast is excluding any cold or snow. Maybe reality will drift towards a colder solution of all components while keeping the general up and down shape of the forecast intact, but for now I am not inclined to revise the outlook substantially.

 

I'm always looking for new factors to add to my model and have isolated two or three in the past month, they don't all phase into the existing consensus result but difficult to give them much more than 1 or 2 per cent weighting based on their weak solo performances over past three years (something I look at to assess signal strength). The problem in this business (besides it not being a business) is that you can always find some kind of pattern to support any outcome, but the requirement for success is to find enough cause to guarantee reliable effect prediction. So I just offer that as a caveat for anyone reading any forecast theory, it's not what's there in front of you but what's not known to the forecaster that may be a make or break consideration. Of course, the first place to apply that principle is right here in my own work and it is the foundation of what I'm trying to do, basically, to eliminate as much uncertainty as I can in one lifetime of effort, then hopefully have the work in some understandable format so that some other poor shmuck can take up the cause and do the same in his or her lifetime of effort. And I tend to do this with one eye on different research methods because I don't have any strong reservations about incorporating any identifiable factors in the model, I'm not on some crusade to prove that only the Moon or only the solar system or only the Sun etc etc.

 

This is a rather scary season for me, I suppose you could say, because it appears that I am swimming against the tide with this outlook and I have that unknown factor of how severe will the January cold spell turn out to be, that right there could give an appearance of a forecast bust when in fact the research model could be performing well before, during and after. On the other hand, in the risk-reward paradigm, if this winter does turn out to be similar to my forecast, very few if any others will be able to say the same. Probably the results will be some mixture, a claim of two thirds accurate implies an admission of one third inaccurate so that's the rather dismal standard (and I honestly doubt that other methods could claim anything better).

[Catacol]

 this is essentially just a pumped up version of mild southwesterly flow 

 

Hi Roger - good response. I suppose my only quibble would be this statement above, because unless the model forecasts and analogues are way off a mild SW flow isnt really what we've got. High pressure currently looks favourite to somewhere out west bringing in W/NW to occasionally N flow. Funnily enough the MetO here called a mild November presumably on the back of a belief in a Euro high that WOULD bring a SW flow - but to all observers with half an eye on teleconnections, analgues and charts it never looked likely. They are slaves to their computers down there at Exeter I think.

 

For the UK tiny shifts in pressure patterns can make massive differences to the weather type, so small an island are we - and I suppose that makes satisfactory verification over here much harder than it might be over the US continent. If the core of a Euro high moves 200 miles to the west then suddenly it is all change here. How great are the error bars on your calculations? If we pick up a NW rather than a SW people here will say - bust!! - but in fact the wave pattern could be nearly spot on. So: hard to convince a UK audience.

 

It all makes for fascinating watching though... I admire all you do and your accuracy though I must say I hope that your Jan/Feb forecast has the ridges 200 miles or so out because I want to see some snow!! Not easy here in the SW of England at low elevation. The holy grail of a long fetch easterly with an undercutting channel low hasnt hit me personally since 1996 and its a very long and impatient wait to see it happen again. We got so close on a number of occasions last winter.

[BLAST FROM THE PAST]

BFTV

Well done on producing indepth forecast....that's a strong anomaly for December!  So a sizeable difference of opinion....I prefer your outcome to mine weather-wise.  So eyes down as we enter Dec and see where we all go.

 

Something is preventing me from copying posts, this site doesn't half cause issues with my computer...anyone any ideas?

 

BFTV the anomaly chart for Dec ....is that a good representation of your thoughts as it suggests that High Pressure is more centred around Southern Greenland rather than ridging up there?

 

 

BFTP

Edited November 23, 2013 by BLAST FROM THE PAST

[BornFromTheVoid]

BFTV

Well done on producing indepth forecast....that's a strong anomaly for December!  So a sizeable difference of opinion....I prefer your outcome to mine weather-wise.  So eyes down as we enter Dec and see where we all go.

 

Something is preventing me from copying posts, this site doesn't half cause issues with my computer...anyone any ideas?

 

BFTV the anomaly chart for Dec ....is that a good representation of your thoughts as it suggests that High Pressure is more centred around Southern Greenland rather than ridging up there?

 

 

BFTP

 

Cheers BFTP. I just think that we'll see more in the way of ridging toward Greenland in December, rather than a high extending down from the Arctic. I'd generally the Winter 500hPa GPH composite anomalies over the Arctic with a pinch of salt when they include many recent years, just because the 500hPa level has lifted in general over the last decade and my skew the composite maps for the region a little.

[Gibby]

I have just released my long term forecast for the Winter 2013-2014 season. It can be found here:

 

http://www.norton-radstockweather.co.uk/NEW-Winter-Seasonal-Prediction(2922573).htm

Edited November 26, 2013 by Gibby

[MPG]

I have just released my long term forecast for the Winter 2013-2014 season. It can be found here:

 

http://www.norton-radstockweather.co.uk/NEW-Winter-Seasonal-Prediction(2922573).htm

Sounds like a normal UK winter forecast, more chance of snow in Feb as in most years. What models have you used to base this on or is just a guess?

Edited November 26, 2013 by MPG

[UV-RAY]

I have just released my long term forecast for the Winter 2013-2014 season. It can be found here:

 

http://www.norton-radstockweather.co.uk/NEW-Winter-Seasonal-Prediction(2922573).htm

Lol. the words lead and balloon  spring to mind with how most will view that Gibby. I'm expecting the polar opposite to yours with a significant cold spell arriving the latter half of December lasting throughout the majority of January, with the mildest month of the winter coming in February. 

[Gibby]

Sounds like a normal UK winter forecast, more chance of snow in Feb as in most years. What models have you used to base this on or is just a guess?

No it is not  a guess. I have been studying weather for the last 40-50 years and put reasoning into my interpretations. I don't think I would be able to run a successful website on 'guess work'. In answer to your comment though my methods are given in the pretext to my forecast.

I don't profess to be anymore accurate than the next guy but just because it's not what many want to read doesn't make it more likely to be right or wrong than if I was forecasting raging blizzards all Winter.

Edited November 26, 2013 by Gibby

[Summer Sun]

Thanks Gibby completely different to certain headlines in the papers, a much more realistic view IMO

[Captain Shortwave]

I have just released my long term forecast for the Winter 2013-2014 season. It can be found here:

 

http://www.norton-radstockweather.co.uk/NEW-Winter-Seasonal-Prediction(2922573).htm

Nice to have your input, I personally think your view of December will be very close to the mark. What interests me for later on is the continual trend of ridging in the Pacific and blocking over the Alaska region which the long range models are bullish about through December and even into 2014. I personally think we will start to see more wintry effects over our side of the pole once the Strat temperatures bottom out and the Westerly QBO starts to wane a bit, hence a better chance of disrupting and splitting the tropospheric polar vortex.

[MPG]

No it is not  a guess. I have been studying weather for the last 40-50 years and put reasoning into my interpretations. I don't think I would be able to run a successful website on 'guess work'. In answer to your comment though my methods are given in the pretext to my forecast.

I don't profess to be anymore accurate than the next guy but just because it's not what many want to read doesn't make it more likely to be right or wrong than if I was forecasting raging blizzards all Winter.

Thanks for replying. Are there any particular years you are using for your pattern matching? Your forecast just reads like a normal UK winter pattern, I have no preference either way myself. Just thought maybe you would produce some charts to show where your forecast has originates from, you must be using some long term data? With your wealth of weather experience, a lot more than most here, it would be interesting reading.

[Catacol]

I have just released my long term forecast for the Winter 2013-2014 season. It can be found here:

 

http://www.norton-radstockweather.co.uk/NEW-Winter-Seasonal-Prediction(2922573).htm

 

If we dont get a proper assault on the stratosphere then I agree with this forecast. If we do get that assault then I see Jan and Feb rather differently - but thank you for a well set out forecast and good luck with it.

[UV-RAY]

Nice to have your input, I personally think your view of December will be very close to the mark. What interests me for later on is the continual trend of ridging in the Pacific and blocking over the Alaska region which the long range models are bullish about through December and even into 2014. I personally think we will start to see more wintry effects over our side of the pole once the Strat temperatures bottom out and the Westerly QBO starts to wane a bit, hence a better chance of disrupting and splitting the tropospheric polar vortex.

I'm not so sure that the QBO is all that relevant IMO as when one looks back at the analogues we've experienced both cold and mild winters in a Westerly QBO. For me it's no more important than any other forcing and I think this winter will catch many a good forecaster out as a result of relying on conflicting signals.

Edited November 26, 2013 by Sceptical Inquirer

[phil nw.]

I have just released my long term forecast for the Winter 2013-2014 season. It can be found here:

 

http://www.norton-radstockweather.co.uk/NEW-Winter-Seasonal-Prediction(2922573).htm

Thanks for your forecast Gibby and good luck with it.A fairly zonal Winter with the Azores high lurking nearby at times seems to be your outlook in short.

It may not be what snow lovers like but that shouldn,t detract from the work needed to put such a forecast together.

[johnholmes]

Sounds like a normal UK winter forecast, more chance of snow in Feb as in most years. What models have you used to base this on or is just a guess?

 

A trifle unfair IF you have read the output and considered the amount of effort that will have gone into producing the forecast. This kind of comment annoys me, barely a one line dig. How about you show some meteorological thought and give your idea rather than knocking someone else?

 

thanks for the output Gibby, as with everyone else the 1 March will show how close you are.

Edited November 26, 2013 by johnholmes

[Don]

I have just released my long term forecast for the Winter 2013-2014 season. It can be found here:http://www.norton-radstockweather.co.uk/NEW-Winter-Seasonal-Prediction(2922573).htm

Thanks for the forecast Martin. A very disappointing forecast if you're a coldie that's for sure! Sounds like a very typical late 90's/early 00's type Winter. I was expecting you to go for a colder Winter as I thought this is what your thoughts were hinting towards recently? Edited November 26, 2013 by Don

[Gibby]

Thanks for the forecast Martin. A very disappointing forecast if you're a coldie that's for sure! Sounds like a very typical late 90's/early 00's type Winter. I was expecting you to go for a colder Winter as I thought this is what your thoughts were hinting towards recently?

No not really. The pattern through this year has been very different with the Jet flow behaving itself in a much more normal position through the year hence the vastly drier weather this year compared to last and the favourable Summer too. The persistence of an Azores High over or displaced close to the UK is forming the basis of my early Winter thoughts though it may well become eroded later in the Winter. I know I've put my head on the block a little with the margin for error being narrow as has been touted in the Model Output thread today but I have seen nothing today to change my thoughts despite some earlier questioning my judgements in the aforementioned thread from some posters but that's fine. I am well aware that come March I could have a serious amount of egg on my face or it could end up being trumped as 'not a bad effort.' As always with weather only time will tell.

[Don]

No not really. The pattern through this year has been very different with the Jet flow behaving itself in a much more normal position through the year hence the vastly drier weather this year compared to last and the favourable Summer too. The persistence of an Azores High over or displaced close to the UK is forming the basis of my early Winter thoughts though it may well become eroded later in the Winter. I know I've put my head on the block a little with the margin for error being narrow as has been touted in the Model Output thread today but I have seen nothing today to change my thoughts despite some earlier questioning my judgements in the aforementioned thread from some posters but that's fine. I am well aware that come March I could have a serious amount of egg on my face or it could end up being trumped as 'not a bad effort.' As always with weather only time will tell.

Thanks for the reply Martin. Indeed a case of wait and see!

[keithlucky]

Met office leaning to colder than average winter?http://t.co/WAzu3F7rYl

[summer blizzard]

Anybody else go for a poor January like myself?