Netweather Winter Forecast - 2016/17

[Nouska]

On 25/11/2016 at 21:37, virtualsphere said:

 Does anyone know whether there were any other similarities in 1939, e.g. ENSO etc? I guess stratospheric data isn't available that far back?  

ENSO was weak Nino transitioning to moderate Nina.

Solar cycle interesting as very dramatic drop in activity just prior to onset winter 39-40.

Geomag fell off a cliff!

http://isgi.unistra.fr/data_plot.php

Stratosphere the polar opposite of this year.

You'll get strat data a long way back on this ESRL link.

http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/plot20thc.day.v2.pl

Great work on the forecast guys - and good luck!

Rather you than me trying to make sense of a very unusual picture.

Edited November 30, 2016 by Nouska
Add plot and link.

[virtualsphere]

5 hours ago, lorenzo said:

@virtualsphere Sorry, I have not looked at specific winter within that period - the lead here is around solar flux and position on the current cycle - see images attached. The NAO from cycle 17 is noted as anomalous within the paper.

...

Thanks to Anthony M for the excellent link to WSO - some great plots here http://wso.stanford.edu/#Synoptic

 

5 hours ago, Nouska said:

You'll get strat data a long way back on this ESRL link.

http://www.esrl.noaa.gov/psd/cgi-bin/data/composites/plot20thc.day.v2.pl

Excellent - thanks for the links, I didn't realise you could get such detailed data going back that far, so that's really useful.  The paper also looks interesting, thanks Lorenzo - off to read now!  Thanks for posting your methodology as well, I can see even more work has gone into your forecast 'behind the scenes'.

[The Enforcer]

I am particularly pleased to hear that there will be regular reviews - that was definitely lacking last season.

Also, for the benefit of the layperson like myself, I think it could be worth putting together a table. What I have in mind would list all the variables that have been discussed on the left hand column. Next to each of those variables, there would be a row containing that variable's possible settings and shading for each setting cell as follows: blue if it encourages blocking; green if neutral; red if discourages blocking; and yellow if unknown. Bold text could then be used to identify the settings that apply at the current time.

I believe that such a table would also enable comparison to be made with the settings of these variables that were prevalent in previous/future net weather winter forecasts issued at the cusp of winter.

 

 

[Nouska]

Just reading the MedCOF seasonal forecast statement - recommending regular updates due to uncertainty.

You are not alone in doing so.

Sub-seasonal variations, not predictable a long time in advance, may dominate at times, so regular updates to the forecast are strongly recommended. In addition, local factors (for example SSTs in the smaller basins of the region) may shape local variability at a regional level.

http://medcof.aemet.es/images/doc_events/medcof7/docMedcof7/Consensus_Statement_MedCOF-7.pdf

 

 

[The Enforcer]

9 hours ago, The Enforcer said:

Also, for the benefit of the layperson like myself, I think it could be worth putting together a table. What I have in mind would list all the variables that have been discussed on the left hand column. Next to each of those variables, there would be a row containing that variable's possible settings and shading for each setting cell as follows: blue if it encourages blocking; green if neutral; red if discourages blocking; and yellow if unknown. Bold text could then be used to identify the settings that apply at the current time.

I believe that such a table would also enable comparison to be made with the settings of these variables that were prevalent in previous/future net weather winter forecasts issued at the cusp of winter.

Well I have had a stab using my very limited understanding and made a lot of assumptions about where the variables currently sit in the range of settings so I expect there are probably quite a few errors. It will almost certainly need updating by those with more knowledge, so feel free to edit and then re-paste an updated version - change the file to v.1.1 and then v.1.2 if it is updated again and so on. There are almost certainly more variables to add (TCI is referred to under Key Considerations, but I can't see any explanation as to what it is and what it does) and definitely more settings are needed for the existing variables, particularly MJO. I am also aware that the impact of ENSO is more complex, hence leaving the impact mostly unknown. My assumption is that weak signals have limited impact on other variables, but strong signals can either override or exaggerate other variables.

I have tried to stick to variables that can be measured in their current state, rather than forecasted variables. This is why I haven't included a direct reference to SSW, which is notorious for being forecast a few weeks ahead and then failing to materialise or have any impact. I believe I have taken account of the effect of the current Canadian Warming November through inclusion of the Vortex variable.

 

Idiot's Guide to UK Winter Forecast Variables v.1.0.xlsx

[skifreak]

Interesting that the forecast expects a drier than average start to winter, last year we paid big time for a dry first 2 months to autumn and December spectacularly made up for it with crazy rainfall - particularly over the South Eastern Cairngorms as witnessed by the River Dee demolishing the A93 near Crathie. 

There seems to be some causal similarities to late 2000 going into winter 2001, late 2009 going into winter 2010 - both great Scottish Ski Seasons, but also late 2002 going into 2003 - which was a prolonged winter drought up here. CairnGorm was by and large reliant on a base on the upper mountain that fell in October for any skiing at all that year.  

My two concerns from the my back yard perspective are thus going into this winter,1 - that we will get a lot of blocking but it will be on top of Highland Scotland too much to get the snow benefit of colder than average conditions or 2 - that we will extend the dry run for another month or 2 then have an even more spectacular wet spell than last December! 

[Essan]

Aye, I have a feeling it wont be a good season for snow and ski-ing in Scotland.   The opposite perhaps of the very mild winter of 2013-14 that nonetheless produced record snow in the Highlands (at higher levels).  Hope I am wrong   

[skifreak]

19 hours ago, Essan said:

Aye, I have a feeling it wont be a good season for snow and ski-ing in Scotland.   The opposite perhaps of the very mild winter of 2013-14 that nonetheless produced record snow in the Highlands (at higher levels).  Hope I am wrong   

It's interesting to note that 2014 was milder than 2012 and 2015 warmer than 1989 and 2007 - these being right up there amongst the worst Scottish ski seasons.

Begs the question - are milder winters delivering better ski seasons than they did in the past? 

[Norrance]

5 hours ago, skifreak said:

It's interesting to note that 2014 was milder than 2012 and 2015 warmer than 1989 and 2007 - these being right up there amongst the worst Scottish ski seasons.

Begs the question - are milder winters delivering better ski seasons than they did in the past? 

Depends perhaps on how the mild average temperature occurs. In 2014 the temperature (except for a spell in December) was consistently a bit above average but still cold enough for snow on the tops. This was better for the ski slopes than wildly diverging temperatures giving a similar average. The warmer spells in those years caused thawing right to the tops.

More on topic a well thought out forecast but not an easy one to predict. What is going to occur this month is difficult enough, never mind Jan and Feb.

 

 

Edited December 1, 2016 by Norrance
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