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Snow And Ice In The Northern Hemisphere 2017/18


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9 hours ago, Bradowl said:

I guess this isn't good news for anyone wanting the cold to spread here? Someone on here might know more than me.

http://www.severe-weather.eu/news/extreme-warming-in-the-arctic-over-the-next-10-days/

 

9 hours ago, Willsy said:

This is good news I think as it means higher pressure over the poles which in turn could bring colder weather further south for us

With regard the exact impact of a warm Arctic we appear to be witnessing a huge experiment playing out in front of us at the moment. But of interest to our little island, the scientific community do seem to agree that the reduced temperature gradient between the Arctic and the mid-latitudes will reduce the 'fuel' that drives the jet stream and increase the frequency of a meandering (meridional) jet and 'stuck' weather patterns. Here's a couple of snippets from a well written article by the Guardian newspaper in Dec 2016. Well worth a read.

It’s safe to say [the hot Arctic] is going to have a big impact, but it’s hard to say exactly how big right now. But we are going to have a lot of very interesting weather – we’re not going to get around that one.

The clearest connection so far between the melting Arctic and weather is for extreme winter conditions, such as the intense winters that hit parts of North America and northern Europe in 2009-10, 2010-11 and 2013-14, causing record snowfalls and billions of dollars of damage. In those years, the jet stream deviated deeply southwards over those regions, pulling down savagely cold air. Prof Adam Scaife, a climate modelling expert at the UK’s Met Office, said the evidence for a link to shrinking Arctic ice was now good: “The consensus points towards that being a real effect.

Full article: https://www.theguardian.com/environment/2016/dec/19/arctic-ice-melt-already-affecting-weather-patterns-where-you-live-right-now

Getting back on topic, the October snow cover index has ended up above long-term average, so as Judah Cohen says "let the games begin"!! :smile:

 

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you used to be able to run a sequence for the last 30 days on the US National Ice Centre section the NOAA Website, but it's gone. So I've created a GIF of the last 7 days. I'll do one next week f

Absolutely love this thread. Certainly my favorite of the year. And for posterity, here is what we should be aiming for....

Well, it's that time of the year again, where we can all start turning our backs from summer, and start looking north and east towards the encroaching snows of Siberia.   Lets hope that this

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On 02/11/2017 at 20:40, Blessed Weather said:

 

With regard the exact impact of a warm Arctic we appear to be witnessing a huge experiment playing out in front of us at the moment. But of interest to our little island, the scientific community do seem to agree that the reduced temperature gradient between the Arctic and the mid-latitudes will reduce the 'fuel' that drives the jet stream and increase the frequency of a meandering (meridional) jet and 'stuck' weather patterns. Here's a couple of snippets from a well written article by the Guardian newspaper in Dec 2016. Well worth a read.

It’s safe to say [the hot Arctic] is going to have a big impact, but it’s hard to say exactly how big right now. But we are going to have a lot of very interesting weather – we’re not going to get around that one.

The clearest connection so far between the melting Arctic and weather is for extreme winter conditions, such as the intense winters that hit parts of North America and northern Europe in 2009-10, 2010-11 and 2013-14, causing record snowfalls and billions of dollars of damage. In those years, the jet stream deviated deeply southwards over those regions, pulling down savagely cold air. Prof Adam Scaife, a climate modelling expert at the UK’s Met Office, said the evidence for a link to shrinking Arctic ice was now good: “The consensus points towards that being a real effect.

Full article: https://www.theguardian.com/environment/2016/dec/19/arctic-ice-melt-already-affecting-weather-patterns-where-you-live-right-now

Getting back on topic, the October snow cover index has ended up above long-term average, so as Judah Cohen says "let the games begin"!! :smile:

 

Learn't to take what Mr Cohen says with a large dose of salt and that goes for his theory as well.

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32 minutes ago, comet said:

Learn't to take what Mr Cohen says with a large dose of salt and that goes for his theory as well.

I totally agree I don't believe it makes slightest difference at all.

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8 hours ago, comet said:

Learn't to take what Mr Cohen says with a large dose of salt and that goes for his theory as well.

Actually the good news is there are a number of independent studies that have looked at Dr. Cohen’s ‘theory’ and have found there is a good correlation between Eurasian snow cover growth and extent in October and the subsequent Arctic Oscillation (AO). And I particularly like the fact that the correlation is stronger during winters with a e-QBO (expected this winter).

And as if on cue it’s interesting that current model output is suggesting the AO looks set to go significantly negative later this month, so hopefully Cohen will be proved right with his tweet “Let the games begin”. But of course, even a negative AO doesn't guarantee a snowy UK, but as the saying goes, "every little helps" for our snow starved island!!

For those interested, some snippets and links from a couple of supporting studies:

1. An Analysis of Eurasian Snowfall and the AO
The statistical analysis reveals that the highest correlation to the AO is the combination of the cumulative weeks 41-45 snowfall extent with the week 39-46 rate of snowfall expansion.
Adam Turchioe 2013

I quite liked this simple Cohen diagram included in the above study that shows the sequence of impact of snow cover:

59ff866a15f17_SiberianSnowCoverImpact.thumb.jpg.b3db1f693bcfa90d6f7586f55ca6e2f6.jpg
 

http://www.atmos.albany.edu/student/aturchio/Presentations/Snow Presentation.pdf

2. How stationary is the relationship between Siberian snow and AO over the 20th century?

Both observational and numerical studies suggest that fall (autumn) snow cover extent over Eurasia is linked to subsequent winter variations in the predominant Northern Hemisphere teleconnection pattern known as the Arctic Oscillation (AO). The present study uses the recent 20th Century Reanalysis to explore the snow-AO relationship over the entire 20th century for the first time.
Over 1976–2010, the well-documented snow-AO mechanism is found; positive snow anomalies enhance the stationary wave activity from the surface into the lower stratosphere, and this wave momentum deposition weakens the polar vortex, leading to an AO response that propagates downward in winter.

Y. Peings et al 2013.

http://onlinelibrary.wiley.com/doi/10.1029/2012GL054083/full

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I don't take too much notice of the theory, as although it is built on something real, I just don't think it is enough to change more important drivers (ENSO, QBO, Solar) and so the situations where it might be useful are few and far between.

That said, before people trash the theory and the guy, have a detailed read of http://www.aer.com/science-research/climate-weather/arctic-oscillation and understand exactly what his thinking and logic is for this coming season. Just to be sure you don't misunderstand where he is actually sitting on this season.

 

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First area of white showing on west side of Scotland, long may it last. Looking at models we should (fingers crossed) see whiteness develop over northern uk in coming weeks.

cursnow_asiaeurope.gif

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11 hours ago, jvenge said:

I don't take too much notice of the theory, as although it is built on something real, I just don't think it is enough to change more important drivers (ENSO, QBO, Solar) and so the situations where it might be useful are few and far between.

That said, before people trash the theory and the guy, have a detailed read of http://www.aer.com/science-research/climate-weather/arctic-oscillation and understand exactly what his thinking and logic is for this coming season. Just to be sure you don't misunderstand where he is actually sitting on this season.

 

Dr. Cohen has updated his blog today (6th Nov) and has taken on board the negative trend in the AO that the models have been forecasting this last few days. As a result his prognosis for the upcoming season is much more encouraging. Some snippets (my emphasis in bold):

For me the most important recent development in the large-scale circulation is the weather model consensus that ridging/positive geopotential height anomalies will consolidate across the high latitudes of the Eurasian sector stretching from Northern Europe to the dateline next week.  With the ongoing positive AO, a relatively mild pattern has become established across Eurasia with just localized pockets of below normal temperatures across the entire continent.  As a result snow cover advance across Eurasia has once again stalled and Eurasian snow cover extent is significantly less than a year ago on this date.

However based on model forecasts, that is about to change dramatically.  Currently the only region with ridging/positive geopotential height anomalies at high latitudes across Eurasia is northwest Russia.  However those positive height anomalies are predicted to move east while ridging/positive geopotential height anomalies now centered near the dateline are predicted to move west.  Next week the two areas of positive height anomalies are predicted to merge forming a bridge of above normal geopotential height anomalies stretching from Northern Europe to Eastern Siberia.  This will force below normal geopotential height anomalies further south across the mid-latitudes of Eurasia.  Low heights and northerly flow will usher colder temperatures across the mid-latitudes of Eurasia including Europe and especially East Asia.  Longer term I do believe that this pattern of northern Eurasia blocking increases the probability of more active poleward heat flux and a weakening or disruption of the stratospheric PV.  Severe winter weather across the NH is more likely following a PV disruption.

.......the model forecasts also suggest the building of Greenland blocking mid-month and possibly beyond.  Greenland blocking favors cold temperatures not only in Europe but in the Eastern US as well.

http://www.aer.com/science-research/climate-weather/arctic-oscillation

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It would be interesting to correlate the SAI with the ENSO state and essentially see if it has a larger effect in neutral years. 

That being said we have a weak SAI signal this year (slightly negative which is slightly bad for us). 

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Very interesting growth of ice this year.

Comparing this year to last you would be forgiven for being concerned, the snow was much further spread by this point last year resulting in some serious excitement (admittedly from myself included) but the ice was nowhere near where we are now.

image.thumb.gif.480d82312f71a83be32b0c69db32bc2d.gifimage.thumb.gif.5508d22961684b4b5ced9fa9b1b7ebd5.gif

Now compare to 2010.. Much more similar picture to now.

image.thumb.gif.4db724ac5a103f3606b64767c8699ddc.gif

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46 minutes ago, craigusp said:

Any new updates on the snow and ice charts this week?

Westward advance seems to have slowed up, although snow cover across Scandinavia continues to grow.

cursnow_asiaeurope.thumb.gif.ba1d0c90db7069d962abc8e36671b8cd.gif

 

Edited by karlos1983
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