Model output discussion - heading into 2018

[knocker]

4 minutes ago, Swave Snow said:

When 

Between 12 tomorrow and 12 Sunday according the the ecm

[nick sussex]

It just shows how CET figures alone fail to tell the real picture of the month.

December is likely to come in close to average but some parts of the UK have had their snowiest December since 2010.

Its a shame more parts of the UK haven’t seen some lying snow and what’s been lacking is deep cold and there’s been a lot of marginality.

Generally La Niña years have front loaded winters but I’m not sure that will be the case this year and going forward we continue to see upstream amplitude develop after initially the outputs looking less interested .

You can see by those two ECM runs which I posted earlier the changes in just 48 hours with the upstream pattern going from flat to much more amplified.

So whilst we continue to search for the Holy Grail in terms of some HLB there’s worse patterns we could be stuck in.

[Swave Snow]

2 minutes ago, knocker said:

Between 12 tomorrow and 12 Sunday according the the ecm

Not the highlands according to people who saw the 12z output apparently although I would be happy with a real pasting 

Edited December 28, 2017 by Swave Snow

[knocker]

14 minutes ago, Swave Snow said:

Not the highlands according to people who saw the 12z output apparently although I would be happy with a real pasting 

Actually i meant to say 12 Saturday (not tomorrow) to 12 Sunday

[johnholmes]

I am not sure why there is comment at times about under +/-NAO control or whatever.

The NAO is simply what the models showing in terms of pressure differences from one place to another.

It is not the driver as some seem to be making it to be.

Or am I totally losing it?

re the models

more of the same from NOAA

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

Edited December 28, 2017 by johnholmes

[Dean E]

9 minutes ago, johnholmes said:

I am not sure why there is comment at times about under +/-NAO control or whatever.

The NAO is simply what the models showing in terms of pressure differences from one place to another.

It is not the driver as some seem to be making it to be.

Or am I totally losing it?

You're not loosing it John!

Let's give some context for some people. As you state, the NAO is the pressure differences taken from Iceland (Low) and the Azores (Azores High). From these differences, it controls the strength and direction of westerly winds and location of storm tracks across the North Atlantic.

It is closely related the AO (Arctic Oscillation).

It is not a driver but a measurement! 

[Duane S.]

11 minutes ago, johnholmes said:

I am not sure why there is comment at times about under +/-NAO control or whatever.

The NAO is simply what the models showing in terms of pressure differences from one place to another.

It is not the driver as some seem to be making it to be.

Or am I totally losing it?

re the models

more of the same from NOAA

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

I think most people here do realise that the NAO / AO  / PNA etc are just reflections (or forecasts) of pressure anomalies in certain defined areas, maybe not just always worded as well as it could be. I guess swap 'control' with 'state' in that instance.

Then again, we also talk about ENSO as ENSO state, and Nina/Nino is certainly defined as a primary driver. 

Not really sure where I'm going with this... 

[Methuselah]

33 minutes ago, johnholmes said:

I am not sure why there is comment at times about under +/-NAO control or whatever.

The NAO is simply what the models showing in terms of pressure differences from one place to another.

It is not the driver as some seem to be making it to be.

Or am I totally losing it?

re the models

more of the same from NOAA

http://www.cpc.noaa.gov/products/predictions/814day/500mb.php

If you're 'losing it', John, then so am I!

[nick sussex]

Very quiet in here given the GFS 18 hrs run is delivering an upgrade to its 12 hrs.

The weaker the low near the UK the better as this has a better chance of clearing se and allowing the ridge to the ne to develop that colder ne flow.

Could be a battle ground scenario developing , we could with a bit more trough disruption upstream but regardless this run shows what’s possible .

It’s not outlandish given it’s a variation on a theme with good agreement for the overall pattern.

The phasing with that shallow low to the east drags the pattern a bit further east but overall this is a nice run upto T240 hrs.

Edited December 28, 2017 by nick sussex

[Duane S.]

Intereting 18z. Great watching it through frame by frame. Will it won't it!? Previous few GFS OPs were game over by this stage

[bluearmy]

Avoiding the development/non development of any scandi ridging, the way the 18z pushes the trough se day 10/11 is bang in line with current  ens guidance. I expect that being the gfs it will go too much east but we'll see 

[Daniel*]

As Nick Sussex highlights battleground scenarios possible in this set up. Some very cold air off east coast..

[Duane S.]

Factor in that  Lo-res is likely being default over- progressive and the 18z is a very nice run indeed. It won't take too much of an upstream shift at all to set up a very interesting second third of the month on this basis.

[nick sussex]

I expect a good turnout in here for the morning runs given tonights GFS 18 hrs run .

A few things to look out for we must see that ne USA coastal low development as that indicates the amplified wave working east from the USA will engage the southern arm of the jet this helps to pull back nw some of the deep low heights in Greenland  . There’s still the issue of the low heights clearing quickly enough from the nw.

There must be no phasing of that deep low upstream with low heights to the nw , it’s key to clear that se as quickly as possible .

After that we need another amplified wave  from the Pacific side to run east and help carve the jet more se pulling back some of the eastwards momentum of the troughing to the west .

Apart from that we’re all set! 

Theres a chance if things fall kindly for a ne flow and a battle ground scenario and after that well  first things first !

Edited December 28, 2017 by nick sussex

[Dancerwithwings]

1 minute ago, Daniel* said:

As Nick Sussex highlights battleground scenarios possible in this set up. Some very cold air off east coast..

This evenings GFS at 240h is very much like yesterdays 0Z ECM at 240h with heights over Scandinavia.

[bluearmy]

ec 46 continues in the same vein as previous run - no doubt broadly agrees with mogreps/glosea given  the 30 dayer. Our trough into  Europe retracts nw, week by week allowing heights from the Atlantic to spread around to our south to reach the Russian ridge and give a very +nao look to weeks 3 onwards. Uppers go above normal by the end of week 3. 

Edited December 28, 2017 by bluearmy

[nick sussex]

Just now, bluearmy said:

ec 46 continues in the same vein as previous run - no doubt agrees with mogreps/glosea given  the 30 dayer. Our trough into  Europe retracts nw, week by week allowing heights from the Atlantic to spread around to our south to reach the Russian ridge and give a very +nao look to weeks 3 onwards. Uppers go above normal by the end of week 3. 

Week 3 may aswell be week 33.

The ECM op went from flat as a pancake 2 days ago to more amplified so surely that EC46 really can’t be trusted .

Thanks for giving us that news!   

I’d like to see how the current pattern evolves before getting the barbecue out! 

What do you think of the EC46 reliability BA?

[fourseasons]

Does the GFS 18 run this evening suggest that the cold air may win out tomorrow rather than the milder air? Saw a suggestion above that there has been an upgrade at 12 hours?

If this was to happen, then surely the forecast may change in the medium term too?

 

 

[nick sussex]

1 minute ago, fourseasons said:

Does the GFS 18 run this evening suggest that the cold air may win out tomorrow rather than the milder air? Saw a suggestion above that there has been an upgrade at 12 hours?

If this was to happen, then surely the forecast may change in the medium term too?

 

 

No I was talking about the post T168hrs hrs  in terms of the GFS upgrading from its 12 hrs run.

This milder interlude is unfortunately set in stone for a few days but the outputs still keep the jet track quite south after that.

And then our hopes are pinned on something from the ne. Stay tuned plenty of drama to come!

[bluearmy]

2 minutes ago, nick sussex said:

Week 3 may aswell be week 33.

The ECM op went from flat as a pancake 2 days ago to more amplified so surely that EC46 really can’t be trusted .

Thanks for giving us that news!   

I’d like to see how the current pattern evolves before getting the barbecue out! 

What do you think of the EC46 reliability BA?

Week 3 is generally worth taking notice of if it's got continuity from current week 2 eps. you can make an informed punt on whether to bother with week 4 based on what you think of week 3. Beyond that it's worthless without clusters which we don't have. As you say, the troughs east side USA and w Europe now showing at day 10 were absent just two days ago on the eps. If anyone has the inclination, the Icelandic site has all previous output available which means you can go back and view the ec46 from three and four weeks ago to see what they looked like - mind you, it's tough to picture the seven day mean upper pattern and anomolys we have seen the past three weeks. Should be obvious how much of a bust the mean ec charts are though. 

[nick sussex]

1 minute ago, bluearmy said:

Week 3 is generally worth taking notice of if it's got continuity from current week 2 eps. you can make an informed punt on whether to bother with week 4 based on what you think of week 3. Beyond that it's worthless without clusters which we don't have. As you say, the troughs east side USA and w Europe now showing at day 10 were absent just two days ago on the eps. If anyone has the inclination, the Icelandic site has all previous output available which means you can go back and view the ec46 from three and four weeks ago to see what they looked like - mind you, it's tough to picture the seven day mean upper pattern and anomolys we have seen the past three weeks. Should be obvious how much of a bust the mean ec charts are though. 

Thanks BA . 

I’ll have a look tomorrow , that change upstream also took NOAA by surprise . They made note of the much slower and more amplified trend .

[Snowy Hibbo]

EC46 500mb

Week 1 (2-8 Jan)

Week 2 (9-15 Jan)

Week 3 (16-22 Jan)

Week 4 (23-29 Jan)

If you like a mostly neutral AO profile, and a positive NAO profile from Week 2-4... then you are all set.

[Allseasons-Si]

Just a question,is the NAO/AO reflect what the models show

it looks like it to me,if so,then they will flip flop just like the NWP does.

Edited December 28, 2017 by Allseasons-si

[snowray]

Trending colder from 4th Jan on the 18z ensembles with some very chilly members in there.

[fourseasons]

40 minutes ago, nick sussex said:

No I was talking about the post T168hrs hrs  in terms of the GFS upgrading from its 12 hrs run.

This milder interlude is unfortunately set in stone for a few days but the outputs still keep the jet track quite south after that.

And then our hopes are pinned on something from the ne. Stay tuned plenty of drama to come!

It certainly is a changeable picture and milder interludes within a British Winter is to be expected. Just need to that jet to be kept South and to have a NE which will stay with us for a bit.

A NE is even colder than a Northerly, it can be really proper cold (though the next ice age will still not be coming imminently just in case anyone believes the scare stories and myths we all know who peddles, lol)

Edited December 28, 2017 by fourseasons