The Seasonal Forecast Thread

[Interitus]

Interesting read Sebastiaan, thanks for the link. One wonders if these guys are really onto something, I guess the million dollar question is what computation is being used in their 'Telemappa' software to create the 'axis' line, the one visible Labrador > Siberia on the October composite.

 

Approfondiemento means deepening if anyone is wondering about the lines on the GPH plot. Indicating the vortex strengthening. Google translate doesn't translate the images !

 

A very specific forecast on what the expect the vortex to do, well worth a read, I suspect this forecast will be under close inspection as it takes the Cohen SAI work onto the next level.

 

 

Did anyone get to see the original leaked 'paper'?

There are a few explanations on that forum, but it's hard to work out how to replicate the results.

However, the use of axes between North America and northern Eurasia and the north Atlantic and Pacific are not without a degree of scientific credence with the contrasts between the land and sea areas.

For example this paper from 2002 - Summer snow extent heralding of the winter North Atlantic Oscillation uses very similar regions of action in North America, Eurasia and the north Atlantic to the south of Greenland.

http://discovery.ucl.ac.uk/8878/1/2002GL016832.pdf

[forecaster]

 

Did anyone get to see the original leaked 'paper'?

There are a few explanations on that forum, but it's hard to work out how to replicate the results.

However, the use of axes between North America and northern Eurasia and the north Atlantic and Pacific are not without a degree of scientific credence with the contrasts between the land and sea areas.

For example this paper from 2002 - Summer snow extent heralding of the winter North Atlantic Oscillation uses very similar regions of action in North America, Eurasia and the north Atlantic to the south of Greenland.

http://discovery.ucl.ac.uk/8878/1/2002GL016832.pdf

 

Yes, I currently have mixed thoughts regarding the OPI. On the one hand, the glimpses at the theory and approach we've been afforded do not seem completely bananas. On the other, we have to be very careful with anything in science that cannot be replicated (for whatever reason). In the meteorological sense, it would surprises me that some patterns set up in October could dominate the winter so. Does the atmosphere really become *that* heavily preconditioned? What about November, which is typically a rapid cooling month?So at the moment I am watching with interest, but prepared to be disappointed! 

[forecaster]

The newest SST-CA model run is in. If nothing else, it's consistent with its previous run:

 

[BornFromTheVoid]

Anyone know where I could find a time series of the snow advance index?

[forecaster]

Anyone know where I could find a time series of the snow advance index?

 

I thought that the index itself is proprietary (of AER) and hence is not published, but is inferred.

[BornFromTheVoid]

I thought that the index itself is proprietary (of AER) and hence is not published, but is inferred.

 

Pity. I presumed most research funded by US state bodies was made freely available. Will have to make do with the Rutgers snow data

[LomondSnowstorm]

Pity. I presumed most research funded by US state bodies was made freely available. Will have to make do with the Rutgers snow data

 

I had the same problem, had to make do with the weekly/monthly data and normalise it to get an idea of what the SAI would look like for each October

[forecaster]

I imagined the SAI as a change with respect to time....so would you approximate it by taking the (d/dt) gradient of the snow cover extent from Rutgers or elsewhere?

[Interitus]

I imagined the SAI as a change with respect to time....so would you approximate it by taking the (d/dt) gradient of the snow cover extent from Rutgers or elsewhere?

 

Strictly speaking it's typically restricted to south of 60°N though the auxiliary material to the 2011 paper shows quite a variable correlation with latitude -

http://onlinelibrary.wiley.com/store/10.1029/2011GL049626/asset/supinfo/grl28662-sup-0002-fs01.pdf?v=1&s=25752f79fe57b690307343baed987015d8cd24c4

Maybe someone could mask the latitude in the images and pixel count with paint software as is done on the Arctic Ice forum studying ice coverage?

Then yes gradient of snow cover may be calculated, there are some graphs which appear on this forum, here is one from the 2011 paper -

http://onlinelibrary.wiley.com/store/10.1029/2011GL049626/asset/supinfo/grl28662-sup-0003-fs02.pdf?v=1&s=90b91a44b36a7bf8544597f158697f4bae0fe5ed

[BornFromTheVoid]

I've incorporated MEI and GLAAM into the latest composites for my winter forecast. Just waiting on the October PDO data to be released, and a little analysis on the snow cover, and the forecast will be ready.

The signal for northern blocking does appear to have increased significantly since last month.

[Roger J Smith]

Be forewarned, models will likely struggle with 8-14 day time frame next 2 or 3 days, as strong cyclogenesis takes place in central to eastern North America. At the moment the solutions look a bit puny on the outcome by days 7-9, I have the feeling that this cold spell will be scaled back somewhat and will rapidly revert to milder conditions by about 24th to 26th and beyond with a stronger low entering the picture then crossing the Atlantic.

 

I don't think there's much chance of a 2010 type outcome and continue to think December will become quite mild again, but door is open for a cold January at least for some 2-week interval most likely early to mid month.

 

Have seen similarities to 1970 (-71) in past week or two with the large temperature swings but that winter settled into a fairly bland outcome for Europe while becoming quite cold in eastern NA (a heavy snow squall winter).

 

On the other hand, there's a generally chaotic feel to the circulation as if two different patterns are fighting for supremacy, possibly it's a battle between temporary solar invigoration and longer-term solar downturn, with proxies being a mixed bag of Pacific signals and the fading mid-Atlantic ridge. All of this argues for a mixed bag of results in the season ahead with no clear trends.

[cooling climate]

Quick update to my winter forcast 2013/14 and I see no reason to

change my forcast for a very cold(severe winter) for Europe and

the UK.

[Catacol]

 

 

On the other hand, there's a generally chaotic feel to the circulation as if two different patterns are fighting for supremacy

 

I agree with this. The overall global circulation is more meridional than I would have expected with a vortex that is relatively untroubled and powered up. And yet at trop level we have strong ridging in the aleutians regularly showing its hand and an atlantic ridge that looks pretty potent next week. I still regard myself as a novice, but I have been a long time lurker for years and there is a slightly different feel to this season that I cannot quite grasp. Signals are rather contradictory. I was contemplating trying my first ever winter forecast to family and friends via Facebook or some such medium, but I am wondering whether this winter is a good one to start with! The last few seems to fit together much more easily - this one is a right pickle. CFS / Glosea4 / Jamstec updates will be interesting when they arrive. Even the sun cant make its mind up - I check Solarham daily and it has been high to low to high to low and now medium today: seems unable to make up its mind.

Quick update to my winter forcast 2013/14 and I see no reason to

change my forcast for a very cold(severe winter) for Europe and

the UK.

 

What factors have you based your forecast on primarily?

[summer blizzard]

My seasonal forecast...

 

December CET: 4.9 to 5.2 (100% confidence)

January CET: 4.9 to 5.9  (66% confidence)

February CET: 1.9 to 3.4 (66% confidence)

 

I shan't be issuing anything beyond that this year, the spread is just too large to get a distinct trend so my confidence levels are overstated as that is most likely.

[Roger J Smith]

I am adding a specific detail to my existing forecast based on research just completed this week. In an effort to develop a model that will generate weekly and daily scale maps like the CFS product, I am seeing in the prototype for that project a very strong signal for NW gales in the period 29-31 January. This would be during a temperature signal of near normal with slight retrograde index, all of which taken together would suggest a strong low in the North Sea moving east to southeast. This coincides with a new moon event around 31 Jan, so that I am adding the detail of high probability of windstorm conditions with W-NW wind directions across much of the UK and nearby parts of Europe.

 

My CET numbers continue in this range:

 

Dec 5.5-6.2

 

Jan 3.0-4.5

 

Feb 3.5-5.0

 

Besides this late January windstorm, the two main features of the winter from my research output would be very mild around Christmas and snow and/or brief cold wave potential 10-15 January. Another peak of energy for a potential windstorm occurs 29 Dec to 2 Jan.

[BLAST FROM THE PAST]

Be forewarned, models will likely struggle with 8-14 day time frame next 2 or 3 days, as strong cyclogenesis takes place in central to eastern North America. At the moment the solutions look a bit puny on the outcome by days 7-9, I have the feeling that this cold spell will be scaled back somewhat and will rapidly revert to milder conditions by about 24th to 26th and beyond with a stronger low entering the picture then crossing the Atlantic.

 

I don't think there's much chance of a 2010 type outcome and continue to think December will become quite mild again, but door is open for a cold January at least for some 2-week interval most likely early to mid month.

 

Have seen similarities to 1970 (-71) in past week or two with the large temperature swings but that winter settled into a fairly bland outcome for Europe while becoming quite cold in eastern NA (a heavy snow squall winter).

 

On the other hand, there's a generally chaotic feel to the circulation as if two different patterns are fighting for supremacy, possibly it's a battle between temporary solar invigoration and longer-term solar downturn, with proxies being a mixed bag of Pacific signals and the fading mid-Atlantic ridge. All of this argues for a mixed bag of results in the season ahead with no clear trends.

Hi Roger

That funnily enough answers a question I was about to ask.  The question was 'does the current solar conditions affect the outcome of your theory model i.e. like analogues/composites for instance I don't really think that many of those during the 20th century are as valid now as say 10 years ago due to the change In Jetstream behaviour and positioning due to this low solar phase'

 

best regards

 

BFTP

I concur re cold spell in Jan though I think we are heading towards a Jan 87 situation.

Edited November 16, 2013 by BLAST FROM THE PAST

[forecaster]

New UKMO seasonal model run.

[BLAST FROM THE PAST]

New UKMO seasonal model run.

Nice

 

BFTP

[forecaster]

Nice

 

BFTP

 

Just popped one image in here because the winter thread is more high paced. Interesting to note that it seems to be going for northern blocking in Dec and Jan, then the anomaly shifted south in Feb. 

[BLAST FROM THE PAST]

Winter 2013/4 - again this year no collaberation with RJS and again I propose to do monthly outlooks with a taster of my idea for the following month.  I will post each monthly outlook around this time of the month.  Early winter?  I don't see a widespread lowland wintry outbreak for December.

 

December -

 

week 1  - Generally HP to south and LP to north.  Trough - ridge - trough set up with temps mild cool mild etc.  Deep LP to cross north of UK bringing gales to N and NW parts with winds SW'ly to NW'ly as we move from trough to ridge etc.

 

week 2  - generally cooler/colder feel to weather with NW general flow with pM source of air.  Snow for Highlands and possibly lower levels in Scotland but more likely sleet / rain.  UK generally cool and breezy and pretty wet at times with bands of rain and heavy squally showers.

 

week 3  - Pressure pattern remains with deep LP to north/NNW.  With this type of pattern I anticipate there'll be shortwaves or troughs swinging in on southern flank.  It will be very active with strong winds and snow for higher ground/mountains in North and more chance of lower levels in Scotland although unlikely to produce lying snow at lower levels for any notable duration.  The wind and windchill will be notable factor especially further N/W one goes.  Pressure rises to our E {Eastern Europe] and W [Atlantic] with over trough UK. 

 

week 4 Christmas week [22 -29] - Block holds to E and Atlantic pressure rise retreats so a situation of LP to W and HP to E possibly ESE bringing flow from southern quadrant.  No white Christmas anticipated in fact a mild and calm Christmas period but signs of a change at end of week as we approach New Year.

 

30/31 - This period I have same signal as RJS re storminess -  new moon on Jan 1st combining with a sudden and large increase in solar activity - complex and very deep and active LP to our north bringing gales to severe gales to Scotland and much cooler conditions generally.

 

 

Now looking into January -  this period around New Year is causing me angst as I see the combination of solar and lunar factors possibly leading to a 'game changer' situation and one of the reasons too why I'n not committing but mentioning what my thoughts are.  I think it could change the profile of winter and flip it on its head.  I am speculating that we could enter a cold impactual period of Jan 1987 proportions with this very deep and complex LP being part of the vortex which will get shifted/disrupted because of this external forcing.  I think the jetstream will be disrupted and become very meridional and we see a very cold push from the NE develop and move towards us. 

The flip side is that we get a short northerly blast and get a powerhouse jetstream drive through the Atlantic and return a a W'ly flow.  I will commit around 15-20th Dec.

PDO is in negative phase, perturbation cycle is in La Nina domination phase, these have affect on jetstream and increase chances of but does NOT guarantee cold synoptic setups as we have seen this autumn and as we may well see again in December if it goes the way I suggest.  However, the jet has hemispherically been very up and down and I think this is as a result of the cycles and current solar state.

 

Many things can and do happen and this current spell, which I didn't see coming, is a good example.  I have broken it up by week just to help with the 'general feel' of the month and only specific' date related weather of note is for New Year.

 

BFTP

Edited November 20, 2013 by BLAST FROM THE PAST

[UV-RAY]

I agree with you with you for the first two thirds of December Fred but thereafter I see another mid Atlantic ridge taking hold, though this time I see it ridging into Greenland and then this being the catalyst for an extended cold spell lasting throughout the majority of January at least. Then I see February being a mild and wet month proceeding a March similar to last year.

[Catacol]

Be forewarned, models will likely struggle with 8-14 day time frame next 2 or 3 days, as strong cyclogenesis takes place in central to eastern North America. At the moment the solutions look a bit puny on the outcome by days 7-9, I have the feeling that this cold spell will be scaled back somewhat and will rapidly revert to milder conditions by about 24th to 26th and beyond with a stronger low entering the picture then crossing the Atlantic.

 

I don't think there's much chance of a 2010 type outcome and continue to think December will become quite mild again, but door is open for a cold January at least for some 2-week interval most likely early to mid month.

 

Have seen similarities to 1970 (-71) in past week or two with the large temperature swings but that winter settled into a fairly bland outcome for Europe while becoming quite cold in eastern NA (a heavy snow squall winter).

 

On the other hand, there's a generally chaotic feel to the circulation as if two different patterns are fighting for supremacy, possibly it's a battle between temporary solar invigoration and longer-term solar downturn, with proxies being a mixed bag of Pacific signals and the fading mid-Atlantic ridge. All of this argues for a mixed bag of results in the season ahead with no clear trends.

 

Roger - respect. I am an admirer... but very early in season and the westerlies have not returned yet and dont look likely to do so for a week to 10 days. Even then signs of amplification ongoing and a far from flat pattern. I know that your forecast is not based on a sequence of events (at least I think not....) and the fat lady has barely started to sing - but does the hemiospheric pattern at the moment surprise you a little? I had expected it to be flatter just because of the strength of the vortex... but there is something going on. Every time it looks as though the models will flatten out we seem to get enhanced wave activity especially over the north pacific, and at the same time minor warmings in the strat are keeping the shape of the vortex variable. If the first half of December were to turn out rather more blocked and meridional than expected would that cause you to rethink?

[BLAST FROM THE PAST]

Just to add and probably touches on what C H mentions is the propensity for the HP not to really sink to far.  According to current model output this allows incursions of very cold air to flood at times into Europe.  Something to watch and if continues it does IMO bode well as we progress into winter.

 

BFTP 

Edited November 21, 2013 by BLAST FROM THE PAST

[sebastiaan1973]

New http://www.metoffice.gov.uk/research/climate/seasonal-to-decadal/gpc-outlooks/glob-seas-prob

is out.

[BornFromTheVoid]

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