Looking for winter weirdness 2

While the US East coast is preparing for an intensifying Sandy (Jeff Masters has all the info you could possibly want), Europe is being struck by a very early cold snap. According to German meteorologist Christoph Hartmann such early snows in Germany occur every 30 to 40 years (link).*

Bulgarian news ageny Novinite has some short info about the rest of Europe:

The early first snow for the new winter has already fallen in Central Europe, tragically claiming three lives in Poland.

The three victims of deadly frostbite are men aged 50-60, one of them being a homeless person.

The heavy snowfall in southern Poland has obstructed communications, and some 70,000 people have remained without power.

The situation in neighboring Czech Republic is similar, with trains delayed, roads blocked by wet snow, and trees felled.

Northern Italy and Switzerland have also been affected by the phenomenon, caused by the so-called Cassandra cyclone.

Snow has also fallen in the northern areas of southerly Croatia on the Balkan Peninsula, with the snow cover expected to reach some 20 cm by Sunday evening.

Looking at the daily snow cover maps provided by the Rutgers University Global Snow Lab (hat-tip to Hans Verbeek from the Cassandraclub blog) we see the situation up till yesterday:

The two images above show snow cover, the two images below show the anomaly. The snow in Central Europe is caused by a combination of frigid air from the Arctic and Cassandra, the cyclone in the Mediterranean pushing mild and moist air northwards. This seems to be confirmed by the National Weather Service of Switzerland, as explained in this swissinfo.ch article:

It said that in a few locations the record for the amount of snow in October had been broken. This included the capital, Bern, where records have been kept since 1931. It had received eight centimetres by Sunday morning. Bern’s previous record for October dates back to 1939, with seven centimetres.

 
The snow started on Saturday, and has continued to fall. The Swiss plateau received about ten centimetres overnight. In some places above 500-600 metres there had been up to 20 cm, MeteoSwiss said.
 
It explained that the air masses that reached Switzerland on the night of Saturday to Sunday had lain over the Arctic Ocean only four days before.

This image on the MeteoSwiss website shows the trajectory of the cold air mass at three different heights (Accuweather has a more visually appealing image in the October 25th forecast):

Here's the atmospheric situation:

On this Uni Koeln SLP map we clearly see a large low-pressure area over the Novaya Zemlya region. This cyclone - that is obviously playing a big role in the early snows in Europe and western Russia - has been stationary over this area for a couple of days now. Like Wayne Davidson wrote the other day in the first winter weirdness blog post:

Lately over the Arctic Ocean cyclones have been hanging over open water. In 2 to 3 major regions. This is no accident, they are fed in a quasi stable thermal dynamic state. This prompts the creation of adjoining Anticyclones to the South of the Arctic ocean, where ideal conditions exist, especially over snow laden lands, in particular Siberia, and Northern Canada. Highs distribute higher pressure stabilizing air towards the Cyclones (by winds) in order to fill the stubborn persistent Lows. With thicker multi-year ice Cyclones had no chance to persist long, and moved quicker wherever there was lower pressure path, a dance of moving Highs and Lows ensued. Now the Lows hang out steady well "fed" by a lot of sea energy.

This animation of SLP maps from the Danish Meteorological Institute shows how the cyclone formed, weakened and reformed in the past 10 days over the Barentsz and Kara Seas (on the lower right, blue):

And on the DMI SST anomalies map we see the power source:

The waters in the Kara and Barentsz Seas are anomalously warm, and the reason they're warm is because of the retreat at breakneck speed of sea ice this melting season, adding several weeks of solar energy to be absorbed by the dark waters. These waters are now too warm to freeze over and so release heat and moisture to the atmosphere, continuously feeding the cyclone that is pushing the cold out into Europe and Western Russia.

It's not even winter yet, and we might already be seeing some of that weirdness Kevin McKinney and I warned about in August: Why Arctic sea ice shouldn't leave anyone cold. But let's not jump to conclusions and see what else happens. What starts weird, doesn't have to stay weird.

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* I don't know on what data the German meteorologist is basing this average on. MeteoSchweiz has some more detailed info for the lower lying parts of Switzerland (translation by me):

Extensive snowfall in October in the lowland is a relatively rare occurence. The last two times it happened, haven't been long ago though: in 2008 and 2003. But for previous events one has to look far back into snow statistics: 1974, 1959 and 1939. The long-term average for first snow in the lowland is in the second half of November.

Comments

[Chris Reynolds]

Barents and Kara are well below average. However the cold weather in Europe seems to be due to the low AO - there's no indication of a Petoukhov/Semenov pattern at present.

[Jim Hunt]

The "Morris Jesup Polynia" didn't seem to have a name back in 2002 Terry. There have been some previous references by Werther to a polynia in the vicinity on the Arctic Sea Ice blog here and here. However those were in spring 2011 rather than autumn.

Is there by any chance a north Greenland polynia expert in the house?

[Werther]

Morning Jim,

I see you mention my CAD count work north of Greenland last year in relation to the present polynia near Cape Morris Jessup.

What I found then were numerous small open water spots within the anomalous lead system that had evolved out there since winter 10-11. Wayne was the first noticing that pattern on AVHRR that February.

I haven’t checked the satellite record, but my guess is someone ’s going to have a hard time finding a regular polynia that site/this time of the year.
Around the corner, SE of Flade Isblink, yes, there’s a regular one, usually April-September.

That it is there now, tells something about anomalous SW- and katabatic winds and about thin ice with many, superficially frozen leads.

[Werther]

Meanwhile, weirdness is maybe not the adequate word to describe the evolving ‘warm Arctic-cold continent’ event. That’s because we used the term specifically for consequences through the record low sea ice minimum.

It still is hard to fix a link. Chris Reynolds said that the Kara-Barentsz connection as described by Petoukhov doesn’t appear. But maybe it is part of a larger pattern, like Wayne has described. However, there are reasons why the course of action during the fall now end up in an almost fixed split Polar Vortex (any suggestions?).

While the polar jet keeps flowing along the edges of the Rossby waves, the ridges and throughs remain almost fixed (or, said in other words, constantly re-install) on their geographical locations. The lock is on the axis Bering St – Iceland. It shows in anomalous high SLP and 500Mb height. In these pics from NCEP/NCAR 0112 I marked the pattern.

Obviously the Kara-Barentsz region is part of the game.

Next is spread of built-up cold over Russian snow cover into Europe. As stated earlier (Kris?), on the leeward-side of this system, warm air will enter the Arctic along Greenland.
While the Alaskan side of the Bering Sea is cold, the Siberian side is the opposite. The Baffin Bay is portal for lows entering the Arctic. The USA doesn’t get much to welcome St Nick.

All in all turbulent times, not a usual, uniform NH winter. Sea ice extent may not be the lowest now, but all this is bound to harm volume for next year.

[Jhon Koli]

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