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Gavin Hannah

Eurasian Snow Advance and the UK / West Europe Winter....

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We're already well ahead this year than the previous 3, especially in terms of snowcover. Also, the ice is closer to the north coast of Alaska by Oct 3rd this year than it was by the 27th last year. However, that is a pretty impressive October recovery last year, start and end of month are chalk and cheese.

I look forward to see how 2013 compares to previous years in the upcoming weeks and months.

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It's going to be very interesting watching this develop. Thanks!

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Great idea as whilst we have the snow & ice across N. hemisphere thread, this one makes it easy to compare between years.

 

I suppose an interesting point is that if a rapid expansion of snow were to commence earlier than October (this year seems to be heading that way), what would any potential effects be down the line?

 

Perhaps all just starting earlier?

Or perhaps actually affecting the chances of patterns setting up against our favour (or vice versa)?

 

Interesting times..and will be one of the many factors to consider as winter progresses.

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I realise that there are very cold uppers over NE Asia at the moment, but speaking hypothetically, might a very early build up actually reduce over the coming weeks?

 

What I mean is, just because you have x sq km snow and ice on 4/10, does it follow that y sq km on say 20/10 will be larger, or might there be a degree of retreat with the changing weather?

 

If so, could it be that it doesn't keep being a much wider area than past years and in later months actually becomes smaller than past years?

 

Sorry if I've not explained this very well.

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The Ice extent should continue to grow. However, there might be the odd stagnant day in October such as yesterday. Only 5K growth i believe.  

But as you say, the snow may very well shrink if the weather warms up over Siberia. 

 

Looking at the months forecast, I'd wager the snow levels will be higher by the end of October. What is of interest to me is where exactly will that snow be??  

 

Will it be confined to East Russia / Asia, or will it be taking a higher latitude and spreading west? 

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Reading posts on the northern hemisphere thread - it is the rate of snow advancement westwards across Siberia into west russia during October which is the key feature of interest rather than the extent of snow cover early in the month.

 

Last year saw a major advancement late in the month, the same occured in 2010 - the following winters saw a lot of blocking to our north and east.

 

I first took notice of cold pooling to our NE in 1995, after a very mild October, I remember seeing the forecasts showing a strong ridge over NW Russia and sub-freezing weather whilst we sat under a moist southerly airflow, but many were saying this was a good thing for those hoping for a cold winter - late October is a pivotal time when the polar vortex ramps into gear and we traditionally see the atlantic winning out, but a strong build of heights to our NE and consequent negative AO development in late October can be a major signal for a cold blocked winter.

 

So my attention will be on what happens in the second half of October rather than the first half as development snow don't have a bearing on the winter ahead and can quickly switch to something the complete opposite in the second half of the month.

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So far, I've included snow and ice data, solar observation data and the Arctic Oscillation data. Here is some info on the North Atlantic Oscillation.

 

 

 

Posted Image

 

http://www.windows2universe.org/earth/climate/images/nao_lg_gif_image.html

 

 

post-15733-0-03719100-1380969795_thumb.p

 

 

Winter (December through March) Index of the NAO based on the difference of normalized sea level pressure (SLP) between Lisbon, Portugal and Stykkisholmur/Reykjavik, Iceland since 1864. The SLP anomalies at each station were normalized by division of each seasonal mean pressure by the long-term mean (1864 - 1983) standard deviation. Normalization is used to avoid the series being dominated by the greater variability of the norther station.

During the positive phase of the NAO, a large pressure gradient across the North Atlantic creates strong winds that drive winter storms across the Atlantic and into Northern Europe. During the negative phase, there is on a small pressure gradient. Southern Europe and Africa receive weak winter storms while Northern Europe  and the eastern United States are cold a dry.

 

https://climatedataguide.ucar.edu/climate-data/hurrell-north-atlantic-oscillation-nao-index-station-based

 

 

Current NAO Situation

Posted Image

 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ENSO/verf/new.nao.shtml

 

 

Summary

 

From the data posted so far, looking at the winter of 2010 specifically, we can take away the following observations.

 

  • Sea Ice extent is down on the mid 20th century averages.  (Relevant to Cohens Theory)
  • Winter 10/11 saw a severely negative Arctic Oscillation. - Conducive to weak polar vortex.
  • The NAO was also severely negative. -  Ideal for cold blocking.
  • The sun was spotless and in a minimum phase. Weak solar output compared with output during a maximum phase.

 

Note:

I'm ignoring SSW events in this summary as I can't find any references to one in the run up to winter 2010. I may have been thinking of the SSW that occurred in Dec 09 that led to the cold and snow event in Jan 2010.

http://www.atmos-chem-phys-discuss.net/12/7243/2012/acpd-12-7243-2012-print.pdf

 

 

 

 

 

 

 

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Remember there is also a correlation with the strength & westward locale of the Siberian high as well-

 

That's part of the puzzle for a colder winter-

 

NICE THREAD BTW

Edited by Steve Murr
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I think you will find that the winter of 2009/10 had one of the

lowest AO on record with...

Dec,Jan,Feb 2009/10 recording -3.4,-2.5 and -4.2

Dec,Jan,Feb 2010/11 recording -2.6,-1.6 and +1,5

NAO reading were as follows....

Dec,Jan,Feb 2009/10 recording -1.9,-1.1 and -1.9

Dec,Jan,Feb 2010/11 recording -1.8,-0.8 and +0.7

As far as Siberian snow cover goes western advancing snow cover

is important but according to Cohen papers the SAI (snow advance

index) below 60 degrees north is one of the biggest factors

promoting a larger more powerfull than normal Siberian high.

Edited by cooling climate
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maybe when we post a few snow charts someone could artificially add on 60N would be good!

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maybe when we post a few snow charts someone could artificially add on 60N would be good!

The NOAA show the 60ºN latitude (when they are working)

 

Here is a chart borrowed from American Wx for the 1st OCT (and also 2002)

 

post-4523-0-94627200-1381095785_thumb.pn

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Posted Image

 

If this materialized there would be snow and ice moving west !

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maybe when we post a few snow charts someone could artificially add on 60N would be good!

 

here you go steve-

 

Posted Image

 

Posted Image

 

 

 

link to site for anyone who hasn't got it- http://www.natice.noaa.gov/ims/

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SSW Winter 09/10 - 9th February.

 

Ah I've misread the PDF.    If I remember correctly, we got a major snow event on Dec 20 2009. I was positive this was preceded by a SSW. The PDF mentions the following ....

A minor warming occurred around mid-December due to a wave two amplification split the lower stratospheric vortex into two lobes.

 

I've obviously interpreted that as a SSW due to speed reading lol.

 

 

Broke the 6 Million mark with sea ice. 

The latest value: 6,016,476 km2 (October 6, 2013)  

 

You need to go back to 2006 to find a year with more sea ice at this same date which recorded a value of 6,221,380 KM2

http://www.ijis.iarc.uaf.edu/seaice/extent/plot_v2.csv

Edited by IBringTheHammer
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Found this dataset in the above link, contains the weekly stats for anyone wanting a closer look. 

 

ftp://sidads.colorado.edu/pub/DATASETS/nsidc0046_weekly_snow_seaice/browse/

 

2010 really was a perfect recipe. Just look a the massive advances from Week 1 of that month to Week 4, even better in the GIF.

 

post-7292-0-21918700-1381149256_thumb.pnpost-7292-0-46555600-1381149332_thumb.pn

 

Animated

post-7292-0-27646900-1381149592_thumb.gi

 

Also this index has a nice map view of things, good for seeing how Siberia has developed.

 

ftp://140.90.213.161/autosnow/4kmNH/

 

post-7292-0-15760800-1381150117_thumb.pn

 

 

 

 

Edited by lorenzo
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Interesting blog, definately all looks better than at this point last year, will be interesting to see the pattern come November.

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Hi Recretos, nice to see you back on board.

 

Where can I find these wonderfull accumulated snowfall forecasts charts? Thanks.

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Hi Recretos, nice to see you back on board.Where can I find these wonderfull accumulated snowfall forecasts charts? Thanks.

They are available on weatherbell Sebastiaan. It is a subscription based site.

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Is this the same Cohen paper posted on other threads??Hi hammer, this is the 2011 paper, a forerunner to the latest one.There is a link in the technical papers thread to all his publications.http://www.nws.noaa.gov/ost/climate/STIP/FY11CTBSeminars/jcohen_062211.pdfI've read through this one and it's very encouraging indeed. Worth a read if you haven't read it already and are looking for potential signs of an epic winter!

Welcome back Recretos.

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