Model output discussion - winter proper underway

[Daniel*]

14 minutes ago, mulzy said:

The Azores High is the winter killer - always has been, always will be.  

Sometimes it can come to our aid by ridging +ve heights to our N/NE so not quite. Some cold spells wouldn’t have happened without the “winter killer”, the Euro high is the winter killer. Unlike the semi-permanent belt of high pressure to SW. With slider lows they are possible, perhaps no classic, however certainly possible as of now more likely to affect northern Britain the UKMO T+168 of yesterday gave me that slider ‘vibe’. 

Edited December 20, 2017 by Daniel*

[bluearmy]

If the Azores high wasn’t a semi permanent feature centred generally around the Azores it would be called something else ..............

cherry picking ens runs from week 2 is never a good sign ........

[mulzy]

I don't want to be pedantic but if the Azores High is displaced to the N or NE or NW, it shouldn't be called the Azores High, it should be called something else.

The Azores High is one part that contributes to a positive NAO.  Therefore in my book, it is not a good sign for cold weather in the UK.

Edited December 20, 2017 by mulzy

[ACCOUNT DELETED]

17 minutes ago, mulzy said:

The Azores High is the winter killer - always has been, always will be.  

And the Summer killer too because it can't get a good grip on the UK like it's doing now. Can't help but think if this was Summer we'd have awesome weather, blue skies, sunshine and lots of days spent in our gardens, parks & beaches! 

[mountain shadow]

2 hours ago, Singularity said:

Well, as far as I can determine, the global atmospheric angular momentum (GLAAM) budget is continuing to advance toward phase 4 of the GWO and subsequent return to positive AAM values, which flies in the face of the modelling by GEFS and perhaps even other models, which want to keep it away from that phase and even trend it a little more negative.

I can't divulge exactly what I think this will mean, but I will say that I'm not surprised the models are making such large adjustments from day to day, as the initial conditions for each run are repeatedly deviating significantly from the modelled versions.

Hi Singularity, is there a composite for GWO phase 4?

Where would the major anomaly heights and troughs be in the Northern Hemisphere in January?

Thanks in advance.

[Daniel*]

7 minutes ago, mulzy said:

I don't want to be pedantic but if the Azores High is displaced to the N or NE or NW, it shouldn't be called the Azores High, it should be called something else.

The Azores High is one part of what makes up a positive NAO.  Therefore in my book, it is not a good sign for cold weather in the UK.

Regardless if it did not exist in the first place that wouldn’t happen. You can not make Azores high disappear it can be displaced but it’s always omnipresent. 

[West is Best]

Regardless of upstream signals, I continue to have optimism. This is based on the ensembles which vary via perturbations. The operationals have been pushing on the mild side over recent runs, with increasingly cold members. We now have a 6z which is into mild outlier territory i.e. it goes outside the bounds of support from other members.

Look at these and keep faith. Soon I'm confident that an operational will switch pertubation, with exciting consequences. The more important point is that with this much uncertainty the signals appear to be unclear from around 26/12 onwards.

12z:

6z actual mild outlier:

[West is Best]

Double post

 

 

 

 

Edited December 20, 2017 by West is Best
Double post

[offerman]

34 minutes ago, swfc said:

Thats not actually true tbh.many a classic winter came about with the AH pushing way north and north east.that said I'm getting on and possibly thinking way back

Here is what i drew alluding too earlier , my upload didnt work so here it is again. and of course as i mentioned north notheast too.

 

Its not the azores high but more like the positioning of it is always wrong but agree . Back in 1980s it extended vertically right up to greenland

[JeffC]

1 hour ago, Iceaxecrampon said:

Cumbria Ensembles have scatter agreement of sorts and a ppn spike.

Something brewing and to look forward to?

Aye, but Cumbria is a big county - say 60-70 miles N-S and say 40 miles W-E and a variety of heights ASL.

How does this pick out the difference between say the top of Scafell Pike and Arnside, because the differences will be massive

[stodge]

Afternoon all

The "problem" at the moment is all the output breaks down the current HP around Christmas and this allows the jet to sink south and LP to cross the country as the Azores HP becomes displaced and suppressed but the HP quickly regain strength and moves back east into Europe turning the trough tilt positive and re-introducing milder SW'ly winds around New Year. There are, it has to be said, signs that may also be a transitory effort as the HP heads east into central Europe.

The "alternative" scenario has the Atlantic trough digging south and splitting the HP - one part retreats SW into the At;lantic while the other moves east into Europe and again draws in a mild SW'ly flow. Even if the centre of the HP is far to the west or SW, there is often a ridge thrown back toward Iberia or Western Europe to maintain the heights over Europe. 

[offerman]

28 minutes ago, mulzy said:

I don't want to be pedantic but if the Azores High is displaced to the N or NE or NW, it shouldn't be called the Azores High, it should be called something else.

The Azores High is one part that contributes to a positive NAO.  Therefore in my book, it is not a good sign for cold weather in the UK.

Agree, when it sits there in its current orientation which is more often than not its the worst. When it extends northward nforthwest northeast but to the north of British ilses it acn be amazing . Just so rare.

 

 

Anyone any ideas why it just sits there?  I one saw amazing BBC programe with female black presenter. She was brilliant and said around the globe there are about 6-7 areas of magnetic anomiles  from earths core that creates such strong areas of high pressure. So im assuming that is why

[ghoneym]

The Azores high Bermuda high in image) is an ever present as can be seen from the image, as is the Iceland low. The jet stream pushes and pulls these systems giving us the blocking patterns we either desire or don't. If you read up on Hadley cells @offerman you should find the answers you are looking for. Incidentally the rise in mean global temperatures will give rise to a 2 deg latitude rise in the AH, so essentially moving poleward very slowly, this brings more precipitation to the regions on the edges of the Azores high systems. What I want to know is if we are under the influence of High pressure over the UK for a prolonged period how would a SSW effect this pattern and how long would the effects take  to show? Maybe a bit off topic for the MOD thread but thought I'd sneak it in here While it is relatively quiet 

Edited December 20, 2017 by ghoneym
Name differance

[phil nw.]

A pretty mild and mundane run up to Christmas but maybe it is worth monitoring events from the big day and just afterwards as the cold air bottled up north starts to come south.We can see the kink in the jet flow as wave depressions are shown  to develop and run se across the UK with much colder air being pulled south.

This is 06 GFS take on this

Not just the GFS though a look at the ECM and UKMO

slightly different detail and timings on the exact tracking of this changeover but you get the idea ,same 500hPa/jetflow pattern.

The London ens

we can see the dip in 2mtr temperatures there too so odds on at least a 2/3 day cold snap with a good chance of some snowfall,maybe not just over higher ground.A lot depends on how much cold air we can get dragged down within this disrupting trough. .

A few days away of course to be sure of any detail but even in a +NAO pattern we can see how with just a small buckling of the jet we can get some Wintery conditions at least for a short while.

I guess it's the best we could expect with the absence of any blocking on our side of the pole currently. 

Edited December 20, 2017 by phil nw.

[Daniel*]

22 minutes ago, phil nw. said:

The London ens

we can see the dip in 2mtr temperatures there too so odds on at least a 2/3 day cold snap with a good chance of some snowfall,maybe not just over higher ground.A lot depends on how much cold air we can get dragged down within this disrupting trough. .

A few days away of course to be sure of any detail but even in a +NAO pattern we can see how with just a small buckling of the jet we can get some Wintery conditions at least for a short while.

I guess it's the best we could expect with the absence of any blocking on our side of the pole currently. 

Good post. For the most part for the cold spell just gone NAO was neutral to slightly positive. Some of the most infamous cold spells have had NAO in positive territory it isn’t a deciding factor. 

...we could quite easily see a ‘repeat’ 

[Guest]

was it not a displaced Azores high that just gave parts of the UK especially Scotland 12 day freeze?? I had 10 ice days in a row and 12 with snow cover infact we still have the odd patch of snow still here today.. if that's a killed winter then I'm Santa 

[Man With Beard]

EC clusters this morning:

At T192, cluster 4 nearly breaks through from the north, cluster 5 has broken through:

Definite potential for wintryness on these clusters by T240 - cluster 2 could develop into something too

D11-D15 - lacking a very clear signal today - but more interested in height rises to the north than some recent runs (not majority as yet, though)

 

[mountain shadow]

9 minutes ago, Man With Beard said:

EC clusters this morning:

At T192, cluster 4 nearly breaks through from the north, cluster 5 has broken through:

D11-D15 - lacking a very clear signal today - but more interested in height rises to the north than some recent runs (not majority as yet, though)

 

Whilst the Pacific ridge pushing right into the high Arctic may not benefit us much, it is at the very least a more interesting synoptic to see rather than the usual Eurotrash high.

Lets hope the 12s continue to pick up on pushing the ridge into Greenland and help sink the jet on this side of the planet.

 

[phil nw.]

25 minutes ago, Daniel* said:

Good post. For the most part for the cold spell just gone NAO was neutral to slightly positive. Some of the most infamous cold spells have had NAO in positive territory it isn’t a deciding factor. 

...we could quite easily see a ‘repeat’ 

Currently with those low heights to the north we can't really expect anything long lasting cold wise but just those minor little kinks in the jet can deliver some temporary interest.The cold air is close by at this time of year so just modest little ridging can help do this.

The Pacific high heading into the pole on the other side is at least pushing the Atlantic jet further south next week at least for a time so it will feel more seasonal with that snow possibility.

[bluearmy]

Now - following on from the ec Synoptics of pushing a polar ridge into Greenland and some mid Atlantic heights at a smiler time, the ICON model began sniffing around this on its 06z run to T120 and the 12z dribbling out is going a little further this way 

wonder if the ukmo might find this solution - would be a potential game changer if it strengthened ......

[northwestsnow]

13 minutes ago, bluearmy said:

Now - following on from the ec Synoptics of pushing a polar ridge into Greenland and some mid Atlantic heights at a smiler time, the ICON model began sniffing around this on its 06z run to T120 and the 12z dribbling out is going a little further this way 

wonder if the ukmo might find this solution - would be a potential game changer if it strengthened ......

TBH blue this is exactly what i was musing over when in discussion with Feb a few days ago- height rises behind the lows- unfortunately there appears to be too much energy modeled coming out of N America.

 

[Ali1977]

Day 4 and there's a stronger Alaskan ridge this run, hopefully it follows this mornings ECM and sends this poleward 

[bluearmy]

5 minutes ago, northwestsnow said:

TBH blue this is exactly what i was musing over when in discussion with Feb a few days ago- height rises behind the lows- unfortunately there appears to be too much energy modeled coming out of N America.

 

It’s more about the polar ridge than the Atlantic .....  that’s why even if it showed in every model this evening it would still be the least favoured outcome ! 

[bluearmy]

A very interesting set of 12z suites emerging with the anti PVTL in full swing day 5 !!!!

 

[Weathizard]

Hmmmm... arctic high much stronger on this run. Seems to be getting stronger every run