Even after the other  thread on the quality of the posts in this thread appeared yesterday, no one is willing to engage in a discussion of my post (the post Ive taken the most care to construct over the past few months in this thread).

Perhaps teethless northerlies  are the Elephant in the room?

 

It does Tim. The NNE 'ly element is now restricted to a 12-15 hour window late Thursday / early Friday. To be honest I am pleased to maintain the NNW'ly as it means a continuation of the sparkling polar sunshine. Much more preferable to the convective rain and sleet showers expected as a result of uppers on the wet, rather than white side of marginal.

I'm hopeful for a northerly reload next week having looked at this mornings output. I'm still very dubious as to how punchy it will be though for reasons demonstrated by young Phil (Whether Idle) a few minutes ago.

 

Thursday is the day for snow if there's any pp around that is -6 -7 850s over most of the country should be ok even down south especially at night.

 Even after the other  thread on the quality of the posts in this thread appeared yesterday, no one is willing to engage in a discussion of my post (the post Ive taken the most care to construct over the past few months in this thread).

Truth be told, I'd assumed the lack of discussion is because we know the Arctic region has experienced greater warming than elsewhere on the planet - thus yes, long-fetch northerlies will by their nature be picking up less-cold air than before.

Coincidentally at the moment the Arctic region as a whole is a whopping 5C above normal. It's no wonder any northerlies on offer lack the bite we might have expected in the past! (Image from ClimateReanalyzer, click for full size).

 Even after the other  thread on the quality of the posts in this thread appeared yesterday, no one is willing to engage in a discussion of my post (the post Ive taken the most care to construct over the past few months in this thread).

Perhaps teethless northerlies  are the Elephant in the room?

Perhaps, perhaps not, but put it in its own thread and have the discussion there.

I’m more interested in what the models show currently and don’t want to have to follow several totally different discussions.

If people want to discuss it, start a new thread and you will find out.

 Even after the other  thread on the quality of the posts in this thread appeared yesterday, no one is willing to engage in a discussion of my post (the post Ive taken the most care to construct over the past few months in this thread).

Perhaps teethless northerlies  are the Elephant in the room?

I didn’t want to risk a Climate Forum type of argument but I agree that’s it's obvious that if the Arctic has warmed, as it unarguably has, that airmasses originating there will be less cold.  I see that Darren has made the same point.

That’s not to say that northerlies won’t deliver deep cold; just that the synoptics need to be more precisely set up which means it will happen less often. 

 

But you can still trace the original source of the airmass and work out where it has been and where it is going.

In the chart that CP is misreading it is perfectly clear where the air mass was situated upon which the LP draws.

So, what do you think controls the movement of air masses?

Primarily, the seasonal incidence of the sun, especially over landmasses. Hence, in Western central Asia, a cT airmass in summer is replaced in winter with a cP . Related to this would be the knock-on effects of the migration of the ITCZ,   I should think ocean currents have a role too, although I don't understand enough about these. Cyclonic development enables airmasses to 'spill' out of their homeground periodically- eg a mT incursion over the UK- but the airmass itself is still centred over the subtropical Atlantic. I would think that temporal variations in positioning of the polar vortex, and possibly zones of greatest thermal contrast might play a part. Of course, there are likely to be other factors that I haven't even heard of.

 

Truth be told, I'd assumed the lack of discussion is because we know the Arctic region has experienced greater warming than elsewhere on the planet - thus yes, long-fetch northerlies will by their nature be picking up less-cold air than before.

Coincidentally at the moment the Arctic region as a whole is a whopping 5C above normal. It's no wonder any northerlies on offer lack the bite we might have expected in the past! (Image from ClimateReanalyzer, click for full size).

Im glad its not just me that observes and accepts this.  So, I need to adjust my excitement level and expectations of northerlies.  From now on, I guess I have to accept maxes of 4 to 8 c depending on strength and almost no prospect of lowland snow. My other point being, synoptically they look good but will rarely "deliver" for many any more.  Im glad to accept their gift as clean air and fresh air and sunny skies. 

I will not pursue this, as my attitude and expectations have been suitably adjusted! 

 

Yes, more synoptic eye-candy but Im afraid even that chart flatters to deceive.

I am again left with the impression that northerlies are relatively impotent, and notably less severe than they were in past decades, particularly the latter decades of the twentieth century.  I would be very interested to see what others think about this apparant reality.  In the spirit of exploring this idea, I attach an image (and a link) of a typical northerly synoptic set up from early December 1967 - 10 uppers in fact made it into Normandy, with -15c approaching the north of Scotland.  There was a notable snowstorm in Brighton:

http://www.wetterzentrale.de/reanalysis.php?uur=1800&var=2&nmaps=24&map=1&model=noaa&jaar=1967&maand=12&dag=08

A broadly  similar synoptic picture to the early December 2017 scenario as depicted by the ECM this morning, almost 50 years later to the day:

http://old.wetterzentrale.de/topkarten/fsecmeur.html

 

Yes, I realise there are differences and no two synoptic situations are identical.  However, a not dissimilar outbreak of Arctic Air 50 years later and the -10 isotherm runs out at The Faroe Islands and the -5 isotherm gets tethered by the time it reaches the south coast.

It seems to me that the loss of ice in The Arctic and the melting of the Greenland Ice sheet are combining with positive SST anomalies and a warmer atmosphere (paricularly in high latitides) to make northerlies a much reduced force in the British Winter.  This is a pity, as they have been my favourite air mass (true Arctic Air) with its clairity and convection, and in the past, attendant chance of southern snow.

I realise that the two charts are different as the Greenalnd high is stronger in 1967 and the 2017 forecast is more of a mid Atlantic omega with a northern extension, but the differences in the reservoir of deep cold for us to tap into, are much reduced, sadly, in my opinion.

I am happy to have someone more knowledgeable than myself deconstruct my supposition, as it would be great see a similar Arctic outbreak as December 1967 brought us. Similarly, I would apprecaite some considered input from anyone knowledgeable who agrees.  Im not wanting to turn the MO thread into the climate forum! But I am irritated at the current northerlies not being what they used to be.  "The north wind doth blow and we shall have snow" could be replaced with "... and we shall have wintriness at high levels in the north".

 

Briliant post. If you look at the 00z GFS current snapshot of today’s weather however. 

http://www.wetterzentrale.de/maps/GFSOPNH00_0_2.png

There is a huge amount of extremely cold air, it just isn’t on our side of the pole. 

Remember that shortwaves, LP systems, and the extremely specific synoptic setup will determine how much cold air is at higher latitudes, and crucially how much is advected in our direction. This is also an important point. 

IIRC, both the freeze which commenced about a week before Christmas 2009 and that which began a few days before the end of November 2010 were both preceded by quiet, anticylonic spells, similar to what the models seem to be indicating for much of the time during the coming week or so. Now I'm not in any way trying to suggest that we're heading for a major freeze this time, but I guess that as long as that HP remains roughly where it is indicated to be and doesn't move either south or east, then there's always a chance. FWIW, I have a recollection of the February 1991 freeze being preceded by an anticylonoc spell also.

Pert 6 shows what happens when the reload fails and we quickly return to our default setting and the Merkel slug

Agree about the Arctic warming. If the trend intensifies, any great charts will be pointless unless you live on a northern hill. Weather watchers will rapidly lose interest in chasing snow. I'm personally not certain I will see proper settling and lasting snow again in my lifetime, in London at sea level. 

I also think a point some of you are missing is that the Arctic is currently so warm precisely because of the current weird and wonderful weather patterns, the precise patterns that could deliver some very cold weather to our shores.

If you want a freezing cold Arctic and Greenland plateau - Beast your Euroslug and Merkel High is exactly what would deliver it. 

Pert 6 shows what happens when the reload fails and we quickly return to our default setting and the Merkel slug

Agree about the Arctic warming. If the trend intensifies, any great charts will be pointless unless you live on a northern hill. Weather watchers will rapidly lose interest in chasing snow. I'm personally not certain I will see proper settling and lasting snow again in my lifetime, in London at sea level. 

 

From all the output did you honestly just pick one ensemble member of one run to suggest what may happen? 

If anything confirms the cold outlook it is that!

Regarding deep cold and not wanting to drag this more off topic, it is still currently late autumn and from lots of experience in this location, northerlies with deep and prolonged cold are unusual here at this time of year. February is the time they really hit historically and the best here have been late Feb. In terms of real prolonged cold northerlies alone are rarely enough.

Anyway on topic and the 06z GFS op run (not low-res member 6) is coming out and shows the cold moving in again on Monday with cool albeit not significantly wintry weather spreading south by Tuesday http://www.wetterzentrale.de/maps/GFSOPEU06_48_1.png 

Just to provide an example for my previous point - 

Look at the T+240 ECM chart http://www.wetterzentrale.de/maps/ECMOPEU00_240_2.png

It has the potential to give us some very cold weather, but look at all that balmy air heading towards Western Greenland. Warm air being bottled up at northern latitudes is partly caused by unusual weather patterns in the Atlantic, which conversely are the same ones which give us a good shot at colder weather. 

Thats not to say the Arctic hasn’t warmed because of climate change, of course it has, but the current Atlantic blocking patterns will also be a factor. 

I put this over the other side yest ( tried to paste it here but forum down )

Its really the reason why the models are responsing the way they are ATM -

https://www.netweather.tv/forum/topic/88576-winter-2017-2018-hopes-thoughts-and-any-early-forecasts/?page=18

Thanks

 

From all the output did you honestly just pick one ensemble member of one run to suggest what may happen? 

 

If anything confirms the cold outlook it is that!

Regarding deep cold and not wanting to drag this more off topic, it is still currently late autumn and from lots of experience in this location, northerlies with deep and prolonged cold are unusual here at this time of year. February is the time they really hit historically and the best here have been late Feb. In terms of real prolonged cold northerlies alone are rarely enough.

Anyway on topic and the 06z GFS op run (not low-res member 6) is coming out and shows the cold moving in again on Monday with cool albeit not significantly wintry weather spreading south by Tuesday http://www.wetterzentrale.de/maps/GFSOPEU06_48_1.png 

In some ways perhaps it would be better to have a ‘business as usual’ autumn, i.e. a strong PV, freezing cold Arctic, Greenland, get all the cold air bottled up, and then get the weird and wonderful blocky weather patterns once winter starts properly. 

In a bizarre way, maybe part of our problem this year is the patterns have been so unusual so early on, adding to the Arctic’s anomalous warmth in the Autumn period. 

Pert 6 shows what happens when the reload fails and we quickly return to our default setting and the Merkel slug

Agree about the Arctic warming. If the trend intensifies, any great charts will be pointless unless you live on a northern hill. Weather watchers will rapidly lose interest in chasing snow. I'm personally not certain I will see proper settling and lasting snow again in my lifetime, in London at sea level. 

 

Come on Beast, you are being far too pessimistic. Agreed that the current set of northerlies lack the punch we might have expected 50 years ago, but even then, a continental landmass will get extremely cold in the winter months, under the right circumstances. So you can see that we will always have snow potential if a Scandi High forms in January/February and advects deep cold from Russia/Siberia across the UK - that is the ideal circumstance for proper lying snow in lowland England. Even with AGW, that effect will still be there.

Sometimes I wonder if we would enjoy our weather more if we never saw models showing “what we could have won”. This week may be a prime example.