Model output discussion - into the start of Winter

[damianslaw]

4 minutes ago, Singularity said:

I think we may ‘feel’ climate change in first third Dec as we struggle to draw in cold enough air for low level snow even with decent patterns in place.

Larger-scale progress has my interest though - good steps made toward assaulting the polar vortex. Whether we can manage the elusive wave-2 or even rarer well-aligned wave-1 SSW (Usually orientates poorly for us) remains to be seen.

GFS still making much more of the MJO as it crosses the Pacific this week into next, compared to ECM. Professional consensus favours GFS when MJO is starting out where it is now, over Indonesia. This is encouraging - stronger MJO passage, bigger wave assault on polar vortex 2-3 weeks later.

MJO movement suggests La Nina struggling to make its presence felt, possibly given it isn't going into strong territory? El Nino background state at play, or is it a tug between the two enabling current output pattern. We also have the low solar energy state..

[bluearmy]

16 minutes ago, Atmogenic said:

Tbh I don't get all this excitement from models that keep getting pushed back further and further, the 20 previous pages people were getting excited about the outputs from 4-5th december and now after page 20 they're now talking about the 8th and 11th december like it is every year with snow and keeps getting pushed back. I would only get excited if its within the 5 day range and i'm not even a cold lover but snow is something that makes winter bearable and interesting. Now people are talking about interest on the 4-5th again but only on the hill tops and how many members here live on the hills i bet very few and not only that but its mainly confined in the North, it's another North/south split again like you get in the Summer with heat. Until a confident percentage of the outputs are shown giving a more widespread chance of snow, I wouldn't really be that excited.

I know this is a moan but i'm not seeing a moan thread or i'm just blind.  

You can check back if you have a week to spare but I recall posting that there was a possibility of a wintry incursion into the flow around the 7/8th dec. the timescales aren’t changing - if anything, the initial trough into next weekend is now showing some wintryness where it hadn’t before .....

we were always missing cold uppers over Europe  ........ we are still missing decent cold uppers .......but if we can get into slider territory then we don’t necessarily need proper cold uppers ....

[Scott Ingham]

19 minutes ago, Singularity said:

I think we may ‘feel’ climate change in first third Dec as we struggle to draw in cold enough air for low level snow even with decent patterns in place.

Larger-scale progress has my interest though - good steps made toward assaulting the polar vortex. Whether we can manage the elusive wave-2 or even rarer well-aligned wave-1 SSW (Usually orientates poorly for us) remains to be seen.

GFS still making much more of the MJO as it crosses the Pacific this week into next, compared to ECM. Professional consensus favours GFS when MJO is starting out where it is now, over Indonesia. This is encouraging - stronger MJO passage, bigger wave assault on polar vortex 2-3 weeks later.

Couldn't have summed it up better myself. All very encouraging 

[E17boy]

3 minutes ago, damianslaw said:

MJO movement suggests La Nina struggling to make its presence felt, possibly given it isn't going into strong territory? El Nino background state at play, or is it a tug between the two enabling current output pattern. We also have the low solar energy state..

Morning peeps ,

hope everyone is keeping well. Just a quick shorty from me just seen the weatheronline Jan and Feb outlook if that is correct then this winter is done and in the bin. 

Hopefully that is not what is waiting for us . On their outlook Jan - high pressure south low pressure north or northwest often unsettled. Feb high pressure takes over lot of fog n frost but no talk of anything wintry. Just the hint of something wintry in December but mostly on hills.

All to be taken as a pinch of salt obviously. I know Gavs weather is doing the third and final seasonal model round up today so will see what that says.

Stay safe all

kind regards

[Scott Ingham]

14 minutes ago, damianslaw said:

MJO movement suggests La Nina struggling to make its presence felt, possibly given it isn't going into strong territory? El Nino background state at play, or is it a tug between the two enabling current output pattern. We also have the low solar energy state..

When it has made its presence felt its been ever so slight (hence the mid Atlantic ridge not making it to full blown GH) but the flip side is its enabled the tropics to work its magic on the Russian High. Best of both worlds potentially if we want to see 3 good months of winter 

[Frosty.]

Ok, hardly had time to look at the models so far today but just look at this from the GEFS 0z..is that snaw I see before me?...yeah it is!!!..enjoy you’re day guys..and gals!

Edited November 28, 2020 by Jon Snow

[Laurence Hill]

42 minutes ago, Atmogenic said:

Tbh I don't get all this excitement from models that keep getting pushed back further and further, the 20 previous pages people were getting excited about the outputs from 4-5th december and now after page 20 they're now talking about the 8th and 11th december like it is every year with snow and keeps getting pushed back. I would only get excited if its within the 5 day range and i'm not even a cold lover but snow is something that makes winter bearable and interesting. Now people are talking about interest on the 4-5th again but only on the hill tops and how many members here live on the hills i bet very few and not only that but its mainly confined in the North, it's another North/south split again like you get in the Summer with heat. Until a confident percentage of the outputs are shown giving a more widespread chance of snow, I wouldn't really be that excited.

I know this is a moan but i'm not seeing a moan thread or i'm just blind.  

Edited November 28, 2020 by Laurence Hill
Inappropriate, sorry

[Met4Cast]

Morning all.

Very good model runs this morning overall, the 06z Griceland ridge first picked up by the 18z last night is an interesting trend, albeit not one that's currently appearing on other models. A growing risk of a snow event of sorts around the 4-5th of December which wasn't there a few days ago, largely for northern hills at the moment but possibly down to lower levels too depending on timing/exact tracking of any slider low. 

[Sky High]

1 minute ago, Met4Cast said:

Morning all.

Very good model runs this morning overall, the 06z Griceland ridge first picked up by the 18z last night is an interesting trend, albeit not one that's currently appearing on other models. A growing risk of a snow event of sorts around the 4-5th of December which wasn't there a few days ago, largely for northern hills at the moment but possibly down to lower levels too depending on timing/exact tracking of any slider low. 

Dear God, please let it happen and get to lower levels. The Missus has pencilled that day in for Christmas Shopping. 

 

Not a bad start to winter, eh? It's only the first week of December. Lots of potential. Lots of fun on the rollercoaster.

[SMU]

37 minutes ago, Singularity said:

I think we may ‘feel’ climate change in first third Dec as we struggle to draw in cold enough air for low level snow even with decent patterns in place.

Larger-scale progress has my interest though - good steps made toward assaulting the polar vortex. Whether we can manage the elusive wave-2 or even rarer well-aligned wave-1 SSW (Usually orientates poorly for us) remains to be seen.

GFS still making much more of the MJO as it crosses the Pacific this week into next, compared to ECM. Professional consensus favours GFS when MJO is starting out where it is now, over Indonesia. This is encouraging - stronger MJO passage, bigger wave assault on polar vortex 2-3 weeks later.

Im afraid paragraph 1 in the context of the reason it may not snow in the next week is very misleading & mostly incorrect.

Could you based on your explanation inform us how much the NH air mass has been modified upwards?

How much expanse of the Nh of say the -10c isotherm has shrunk V the climatic norm.?

The bottom line here is that there is likely to be 'some' modification in the airmasses however the larger reason that you seem to have glossed over isnt climate change but the simple fact that the vast majority of any cold upper air over Europe is mixed out by warm southerlies ahead of the low - neatly obvious in the chart below-

Temperatures of 30c Theta E pushing north when we need an airmass of Sub10c from the East is the driving factor.

it cant suddenly replace itself with cold air so unless theres another cold air injection it will just hold in situ until mixed out - It takes the GFS from day 8 to day 16 to do that & most of that process is day 14-16.

 

 

[I remember Atlantic 252]

11 minutes ago, Sky High said:

Dear God, please let it happen and get to lower levels. The Missus has pencilled that day in for Christmas Shopping. 

 

Not a bad start to winter, eh? It's only the first week of December. Lots of potential. Lots of fun on the rollercoaster.

certainly would feel great living say Buxton! but not just at 100m asl, still could see wet snow here especially on the 4th

[Geordiesnow]

Ironically the ECM run initially has better ridging in the medium term but it's still like pulling hens teeth in terms of getting a northerly for the UK. 

On the flip side, would I really want the charts at 144 hours showing northerly winds when it subject to change? Maybe not so I still would not rule out a northerly flow occurring but the form horse does seem to be a low pressure system heading southwards through the UK. 

The Russian high as usual is a right pain, no potential from that, the ECM latter stages just shows what a pain it is. 

[Daniel*]

I’m interested in the models and I live on Thames floodplain in inner London, with cold spells it’s very rare we go straight into real cold and usually it takes more than one attempt, in late November 2010 the air at first wasn’t really cold it’s hard to call for patience when we have been waiting for 7 years nearly 8, but people must realise it is still November not January. I think we should all be encouraged by big picture, it looks very intriguing as we go into December and with hints of vortex disruption, opportunities will come I’m sure. 
 

+ I sort of agree with Steve remember the -10C isotherm visited Shetland in recent weeks, despite Arctic being insanely anonymously warm. And, surely climate change is irrelevant to cold generated from continent? There’s little surprise we’re struggling for cold air in early December it’s always very unusual to have such cold so early despite favourable synoptics, and furthermore this November has been very mild in Europe this is much more relevant. 

Edited November 28, 2020 by Daniel*

[phil nw.]

A few posts have strayed off model discussion and have been hidden. 

Please keep on topic please all and use other threads where appropriate. 

Ta very much. 

[kold weather]

45 minutes ago, bluearmy said:

..but if we can get into slider territory then we don’t necessarily need proper cold uppers ....

This is very true, my only concern is as Singularity said, the SSTs are higher than I'd like to see and whilst definitely cooling down, I'm not convinced that Europes surface profile is quite cold enough with a total lack of deep cold anywhere nearby. It'd extraordinarily marginal in many of the set-ups being suggested by the models. Perhaps a classic "on high ground" with an awful sleety mess lower down even in a slider situation unless we see a slightly more impressive cold signal developing at the surface over the next 5-10 days (given how close it might be, I'd not rule it out).

I am however increasingly interested in what maybe coming down the line. If we can keep seeing these upper lows trying to drive  SE/S into Europe its only a matter of time before we get a stronger mid atlantic ridge and push down some much cold uppers. Once that happens we could quite easily get trapped for a 7-10 day period with cold NE/E type airflow that wouldn't be marginal. 

It might mean a 5-7 day period where things flatten, but unlike most winters where I'd be thinking that is the end of things, its clear the vortex is going to be under pressure and that leads to a good chance at getting a proper injection of cold into N/W Europe.

[northwestsnow]

2 hours ago, ALL ABOARD said:

The old saying wedges make sledges looks like it may be making a December special soon. 

06z is a good example of how small pockets of heights across Iceland can allow sliders.

Slack airflow and heavy percipation and you cant rule out a snowflake falling anywhere. 

I have the patent on wedges makes sledges....

I'm almost as possessive over it as Ian Brown and the christmas pudding thing ...!!

Anyway, lovely GFS 6Zif you enjoy cold weather !!

[northwestsnow]

Its literally all about getting low pressure established across Southern Europe.

Like a moth to a flame the jetstream will direct traffic in that direction and wedges of heights will emerge in the Griceland region...

With a strong anticyclone resident stretching from NW Russia to North East Scandy the ingredients are there for a below average first half of December IMO...

 

Edited November 28, 2020 by northwestsnow

[Methuselah]

GEFS 06z ens not three bad -- op and cont are a wee bit on the cold side of the pack; but still, daytime maxes of <5C would imply a good chance of some lucky peeps seeing some snaw:

    

    

[throwoff]

Currently looks really promising as we go into late Nov early Dec.

We did say that 2010 was a once in a decade thing, perhaps the universe took that literally 

[Blessed Weather]

2 hours ago, Singularity said:

I think we may ‘feel’ climate change in first third Dec as we struggle to draw in cold enough air for low level snow even with decent patterns in place.

(SNIPPED)

 

1 hour ago, Steve Murr said:

Im afraid paragraph 1 in the context of the reason it may not snow in the next week is very misleading & mostly incorrect.

Could you based on your explanation inform us how much the NH air mass has been modified upwards?

How much expanse of the Nh of say the -10c isotherm has shrunk V the climatic norm.?

(SNIPPED)

 

Whilst not wishing to get into a debate about available cold air with regards next week's particular synoptics, there is certainly evidence that due to climate change there is now less cold air available for the UK to draw on over the winter months. These charts from a World Climate Service report show the rise in 2m temperatures during the months of Dec to March over the period 1993 - 2016:

Source: Arctic Amplification and Extreme Weather: Controversy Lingers
https://worldclimateservice.com/2020/11/25/arctic-amplification-and-extreme-weather/

And the following report looks at the shrinking NH 850hPa temperature cold pool during winter (December-February) over the period 1948 to 2015:

Contraction of the Northern Hemisphere, Lower-Tropospheric, Wintertime Cold Pool over the Past 66 Years
Employing three different reanalysis datasets, the analysis presented here demonstrates that the 850-hPa wintertime cold pool has systematically contracted, at each of several threshold temperatures, since the mid-twentieth century.
https://journals.ametsoc.org/jcli/article/28/9/3764/106758/Contraction-of-the-Northern-Hemisphere-Lower

 

 

[Frosty.]

Just had a look at the GEFS 6z..and yeah, there’s a risk of snow / snaw later next week..get in!  ️ 

 

[SMU]

45 minutes ago, Blessed Weather said:

 

Whilst not wishing ....

 

Certainly one for another topic - it will certainly be a blend of impacts for the UK, on this occasion though I believe the main route cause is as indicated > warming the air from the south...

[Duane S.]

3 hours ago, Atmogenic said:

Tbh I don't get all this excitement from models that keep getting pushed back further and further, the 20 previous pages people were getting excited about the outputs from 4-5th december and now after page 20 they're now talking about the 8th and 11th december like it is every year with snow and keeps getting pushed back. I would only get excited if its within the 5 day range and i'm not even a cold lover but snow is something that makes winter bearable and interesting. Now people are talking about interest on the 4-5th again but only on the hill tops and how many members here live on the hills i bet very few and not only that but its mainly confined in the North, it's another North/south split again like you get in the Summer with heat. Until a confident percentage of the outputs are shown giving a more widespread chance of snow, I wouldn't really be that excited.

I know this is a moan but i'm not seeing a moan thread or i'm just blind.  

Then, with the greatest of respect, you are completely missing the point of being here in wintertime.

This forum, every winter, is all about the chase. The majority here know that more often than not we will be disappointed.

For those less familiar with the charts, trying to tell apart real potential and more wishful thinking will be tricky though at times I guess.

If you could score potential though, and of course this is subjective, I’d score the lead up to Christmas a very healthy 8.

 

[ALL ABOARD]

Icon is trying it's best slightly more amplified with the Atlantic ridge at +96

[sheikhy]

Just now, ALL ABOARD said:

Icon is trying it's best slightly more amplified with the Atlantic ridge at +96

Hmmm icon looking good at 96 hours!!move towards ukmo and gfs!!