arctic air Arctic air invading Europe in April - the cold part of a traffic jam!

[Vorticity0123]

A wintry spell in late April - not exactly what one would expect! Many places in Western Europe have experienced wintry temperatures and even snowfall, for instance in the Netherlands people could greet a wintry landscape with snow actually settling! This caused quite some traffic jams and accidents on the road.

 

Snowy landscape in the Netherlands on the 24th of April. Source: Weeronline.

Snow did not only reach the Netherlands, but also in low-lying areas of Switzerland some snow fell, although only somewhat higher up the landscape got a wintry white colour.

Slide of Arctic air

The main culprit of the snow can be traced down to a slide of Arctic air which has come all the way down from areas near the North Pole. Fuelled by the relatively mild waters of the North Sea, this air becomes unstable and a lot of showers and small-scale low pressure areas spin up. Couple this with the unseasonably low temperatures and the snow is there!
 

Slide of cold Arctic air envisaged by a satellite image as of 25-04 18Z. Source: Eumetrain.

The image above nicely shows the cold air reaching all the way down into Western Europe. The red colours denote polar/arctic air which is flooding down over Europe from the north. Interestingly, though, this setup has been present for a number of days. This raises the question as to what is causing this persistent northerly airflow.

A real traffic jam in the atmospere

For the solution we look at a more global picture of the Northern Hemisphere in the midtroposphere. And that is not a usual one to say the least.

Pressure at 500 hPa and anomalies (colours) as of Monday 18Z. Source: Tropicaltidbits.

The most clear feature that shows up here is very strong ridging (high pressure) at 500 hPa which extends all the way towards Greenland. This is a nice example of a block which has been present for quite some time now. This feature is what is kind of causing the atmosphere to be 'locked'; pressure systems do not move at all or barely in a couple of weeks. Think of it as a traffic jam in the atmosphere.

The counterpart of the high pressure area is located over Mid-Europe, which shows itself as a persistent trough even reaching Africa. This feature is partially responsible for the cold temperatures aloft and thereby a generation of a lot of showers. But this is not where the story ends.

The same image, but now with airflow direction indicated in white. Source: Tropicaltidbits.

The key for the cold air at low levels (and also partially at upper levels) is that between the high pressure area near Greenland, and low pressure over Scandinavia and Central-Europe, there is a deep northerly flow which starts off near Greenland and flows down all the way towards Tunesia.

More cold to come?

WIll the pressure situation remain locked, and will we continue to experience a brisk northerly airflow? The high pressure area near Greenland appears to be pulling away towards Russia, but this would still cause the cold to remain entrenched over Europe with also more unsettled weather to come. So one thing is for sure: the cold is going to stay around for some time still. Impressive for April to say the least! If we would only have had this in winter...

[Wildswimmer Pete]

Could such atmospheric "traffic jams" become more frequent given the recent signals pointing to a possible Grand Minimum?

[knocker]

More likely because of Arctic warming. See this and other papers by Dr. Jennifer Francis.

http://news.rutgers.edu/research-news/rutgers-climate-scientists-find-more-evidence-linking-arctic-warming-jet-stream-movement/20150601#.Vx81-jGgtkc

[BLAST FROM THE PAST]

Well for me 2016 was the 'tipping point' and 2017 will be volatile with real clear signs of global cooling.  The grand minima approaches and we are in stage 2 of the cooling phase.....phase 1 being the pause of warming.  Global temps in April plummeted with NH seeing the most marked drop.

More down the line.....

 

BFTP

[knocker]

As you say more down the line.....

Temperatures rose from January to March but dropped right back in April, from March's 0.566°C to 0.34°C. That makes it the coldest month since the 2016 El Nino, behind December's 0.391°C. But even so, it was warmer than the annual averages of both 2014 and 2015, each a record in its time.

The main cool places were Canada, N Europe and Antarctica. China, E Siberia and the Arctic Ocean were warms was even most of the US.

[Northernlights]

47 minutes ago, BLAST FROM THE PAST said:

Well for me 2016 was the 'tipping point' and 2017 will be volatile with real clear signs of global cooling.  The grand minima approaches and we are in stage 2 of the cooling phase.....phase 1 being the pause of warming.  Global temps in April plummeted with NH seeing the most marked drop.

More down the line.....

 

BFTP

Yes another cool /dry spring here last four years have seen cattle turnout to grass delayed from mid April to almost mid May..For the last week night time temperatures have fallen below 5c so no growth at night and quality of grass falls and cattle need supplementary silage.

[Mokidugway]

Yep same here still putting silage bails in fields 

[knocker]

7 hours ago, BLAST FROM THE PAST said:

Well for me 2016 was the 'tipping point' and 2017 will be volatile with real clear signs of global cooling.  The grand minima approaches and we are in stage 2 of the cooling phase.....phase 1 being the pause of warming.  Global temps in April plummeted with NH seeing the most marked drop.

More down the line.....

 

BFTP

If this thread is going to be expanded to a discussion on 'global cooling' it really should be in the climate area where statements like the highlighted above can be expanded upon and some scientific justification can be posted to support the statement. Otherwise it's back to unsupported opinions which is not good enough in a meteorological/climate forum . Anyway........

Nature paper on the "hiatus".

Quote

There is a new Nature paper getting discussed in various places. It is called Reconciling controversies about the 'global warming hiatus'. There is a detailed discussion in the LA Times. The Guardian chimes in. I got involved through a WUWT post on a GWPF paper. They seem to find support in it, but other skeptics seem to think the reconciliation was effective, and are looking for the catch.

I thought it was a surprisingly political article for Nature, in that it traces how the hiatus gained prominence through pressure from contrarians and right wing politics, and scientists gradually came to take it seriously. I think they are right, but the process should be resisted. There really isn't much there, and the fact that contrarians create a hullabaloo doesn't mean that it is worth serious study. I'll show why I think that.
 

https://moyhu.blogspot.co.uk/

[BLAST FROM THE PAST]

On 08/05/2017 at 06:08, knocker said:

If this thread is going to be expanded to a discussion on 'global cooling' it really should be in the climate area where statements like the highlighted above can be expanded upon and some scientific justification can be posted to support the statement. Otherwise it's back to unsupported opinions which is not good enough in a meteorological/climate forum . Anyway........

Nature paper on the "hiatus".

https://moyhu.blogspot.co.uk/

 

BFTP

[BornFromTheVoid]

The "pause" with the Met Office estimate for this year. Made by wipneus.