Model output discussion - Winter has arrived

[Skullzrulerz]

4 minutes ago, Tim Bland said:

Hmm not looking great is it. Certainly no Beast From the East that some are predicting  

I was wondering the same thing all of this of snow but yet no cold pool ?

[Weather-history]

54 minutes ago, jules216 said:

And suddenly GFS chart fot the middle od December does not look too different to last year. The period around a week before Christmas in recent years always suddenly brought Atlantic to life despite semi promising long range charts,when they flipped they did it big tíme.

Don't recall the charts this time last year looking great for winter weather, it was already looking high zonal

This was GFS 0z this time last year and look how zonal that chart looks for 240hrs

 

[alexisj9]

1 hour ago, ICE COLD said:

Unbelievable the 6z just switches at day 4 to the Atlantic ?? Just as the ECM and UKMO are a lot better this morning. What the hell is going on ? 

Shannon, as usual with these type of situations.

[jules216]

19 minutes ago, Weather-history said:

Don't recall the charts this time last year looking great for winter weather, it was already looking high zonal

This was GFS 0z this time last year and look how zonal that chart looks for 240hrs

 

Im not saying its exactly the same just pointing out that around middle of December good looking charts Can Flip suddenly with Atlantic taking over.I dont Remember when was last tíme we actualy got pre Christmas cooling in Európe 

 

[Griff]

1 minute ago, jules216 said:

Im not saying its exactly the same just pointing out that around middle of December good looking charts Can Flip suddenly with Atlantic taking over.I dont Remember when was last tíme we actualy got pre Christmas cooling in Európe 

 

Anecdotally the pros I follow on social media aren't saying it's going to flip any time soon, which means I've probably cursed it. I'm sure everyone else sees the same posts that I do... 

[offerman]

1 hour ago, ICE COLD said:

Unbelievable the 6z just switches at day 4 to the Atlantic ?? Just as the ECM and UKMO are a lot better this morning. What the hell is going on ? 

Exactly ! They are only computer models , just that. 
Gfs had massive reversal from huge blast from the east cold snow fest charts reminiscent of 2010 but then next run show blowtorch symptoms from the south. 
They will never be able to be accurate imho 

you're right it's not just F1 but in so called reliable timeframe that the weather changes so much. 

[heath]

GFS 06z operational may be flat in its early stages and may be unreliable, but a pre Christmas high would be dry and chilly. Until 2010 good cold spells came after Christmas and often after high pressure, if my ageing memory is correct. 

[NewEra21]

2 minutes ago, heath said:

GFS 06z operational may be flat in its early stages and may be unreliable, but a pre Christmas high would be dry and chilly. Until 2010 good cold spells came after Christmas and often after high pressure, if my ageing memory is correct. 

I'd actually be happy with that Chart for Christmas. I know it's not what we all want in freezing cold and snow, but at least it should be dry, seasonal and with some frost. And with the possibility of gradually evolving into something more promising cold wise.

[Frosty.]

I think it’s fair to say there’s been quite a flip from the rather cold GEFS 0z mean to a somewhat milder 6z, but as we should know, ensembles are fickle and the 12z could flip colder again, at least the 6z ends on a high note..literally!!...to be honest I’m not concerned by these variations run to run, they are to be expected...PS..I really did like the Ecm 0z op earlier..from a cold perspective!

Edited December 5, 2020 by Jon Snow

[Borei]

2 hours ago, bluearmy said:

I’m not sure what WIB is thinking but he’s just wrong. It may well be more correct to say that you generally need to have had -5c uppers in place for a period prior to the snowfall arriving 

No need to mince your words BA .

But yesterday very clearly demonstrated  that uppers less than -5 are not a pre-requisite for UK snow. I guess in this post factual world there's a tendency to ignore evidence and simply re-iterate one's mantra of choice, particularly if it can be linked to other false narratives about an alleged hemispheric absence of cold air due to global warming .  

But as others said in the run up to this supposed 'no snow' debacle, there are numerous parameters impacting snowfall, of which upper air temp is just one. I'm not a meteorologist, but I can read, understand and then observe post event results. You and others who explained the parameters have been proven right. The case ought to be closed. 

 

 

[jules216]

9 minutes ago, Griff said:

Anecdotally the pros I follow on social media aren't saying it's going to flip any time soon, which means I've probably cursed it. I'm sure everyone else sees the same posts that I do... 

Its all about half glass full/empty approach. If you take in to consideration very mild recent Decembers then temperature regime of 6/2C in UK seems the half full option.Though even the most blocked outputs of past few days would result in temperature regimes of 5/2C in most of European capitals like Paris,Berlín,Warsava,Budapešť,Wienna,Tallin,etc.Snow restricted Well above altitude from where majority of population lives.This is very múch half empty situation.All of this is well backed Up by ens.mean T2M. This is happening during blocked regime. We are supposed to have the most blocked Month of winter now by most of seasonal models and reward is very small for it unless you live in Alps or above arctic circle.Maybe I just have to get used to large teapot perspective to find T850 of -2/-4 as a good winter regime since it could be worse like +5C T850 in Januáry

 

[nick sussex]

So typical after the GFS was plowing ahead by itself the Euros come on board and then its 06hrs run implodes.

If the changes were out into FI it would be less concerning but the changes start early in the run.

Signs of trouble begin with the phase point of the shortwave and the Atlantic low and then it’s all over .

The UKMO today goes from zero to hero with a huge u turn , the volatility between runs has been noticeable so let’s hope the GFS 06 hrs run will switch back .

All will be revealed this evening given the timeframes involved .

[STRiZZY]

2 minutes ago, Jon Snow said:

I think it’s fair to say there’s been quite a flip from the rather cold GEFS 0z mean to a somewhat milder 6z, but as we should know, ensembles are fickle and the 12z could flip colder again, at least the 6z ends on a high note..literally!!...to be honest I’m not concerned by these variations run to run, they are to be expected...PS..I really did like the Ecm 0z op earlier..from a cold perspective!

Agreed. The variations are to be expected if you paid any attention to this years hurricane season. Wild flips and flops from the models from run to run with no consensus outside of even 48hrs. 

We have to remember that what the models try to do (predict our weather) is an extremely, extremely difficult undertaking. Our atmosphere is filled with infinitesimal swirls which makes the task even harder, not to mention the 1,000,000 other factors.   

There is still twenty days until Christmas, plenty of time for anything to happen (good or bad) with the models. 

 

[That ECM]

Nice to see new posters putting their thoughts in thread.

[I remember Atlantic 252]

15 minutes ago, nick sussex said:

So typical after the GFS was plowing ahead by itself the Euros come on board and then its 06hrs run implodes.

If the changes were out into FI it would be less concerning but the changes start early in the run.

Signs of trouble begin with the phase point of the shortwave and the Atlantic low and then it’s all over .

The UKMO today goes from zero to hero with a huge u turn , the volatility between runs has been noticeable so let’s hope the GFS 06 hrs run will switch back .

All will be revealed this evening given the timeframes involved .

I don't know much about your weather, 14 degrees off this? not good if you want it cooler

[Tim Bland]

1 hour ago, bluearmy said:

I don’t mind it - descending arctic upper high of sorts and the strat split almost to 10hpa ........all before Xmas ! 
 

and who has predicted a BFTE in the next couple weeks ????

It could be ok (very) long term, you are right. I was just lobbing some toys out of my pram to be honest, as it feels like we are always chasing rainbows. Re BFTE I think most will know who I’m referring to re their continuous ref to Xmas week which is shown end of GFS run now.

GEFS show zero chance of anything wintry south of Pennines with most going above average. I’m going to take a break and hopefully come back soon with a a renewed optimism if the models improve 

Edited December 5, 2020 by Tim Bland

[bluearmy]

4 minutes ago, Tim Bland said:

It could be ok long term, you are right. I was just lobbing some toys out of my pram to be honest, as it feels like we are always chasing rainbows. Re BFTE I think most will know who I’m referring to re their continuous ref to Xmas week which is shown end of GFS run now

The sypnotics are feasible but it’s currently a stretch to imagine how a deeply cold pool gets into the circulation and then arrives here !

[Scott Ingham]

1 hour ago, heath said:

GFS 06z operational may be flat in its early stages and may be unreliable, but a pre Christmas high would be dry and chilly. Until 2010 good cold spells came after Christmas and often after high pressure, if my ageing memory is correct. 

This is exactly the chart I was expecting back end of December. And the strat is almost what I expected back end of December. I've called for a ssw end of December or beginning of January and the best cold spell of the winter at the end of January and all of February 

Edited December 5, 2020 by Scott Ingham

[feb1991blizzard]

11 minutes ago, Scott Ingham said:

This is exactly the chart I was expecting back end of December. And the strat is almost what I expected back end of December. I've called for a ssw end of December or beginning of January and the best cold spell of the winter at the end of January and all of February 

Agree in the main but think we might have to wait until back end of jan for a split SSW (ie - the type that is likely to benefit us). - Still the QBO worries me, will the westerlies in the tropics be weakening in the mid-lower strat (30-70mb) by then?

[Starsail]

West is Best taking a battering for his comments on the - 5 850's but I don't think his comment was unreasonable. 

-5C is not needed in all situations as the last few days have shown but it is an excellent benchmark. 

I happen to live in what I would imagine is one of the most marginal locations in the UK for snowfall. I live on the edge of the Southern Uplands (Leadhills is 15 miles up the road) in Scotland at an altitude of 192m.

Many is the time that I can look out of my window to see the snow settle at the magic 200m line whilst there is sleet or rain on my doorstep. This is very often with 850's of - 5 so I always look to < - 5C to get settling below 200m.

John Holmes excellent snow forecasting guide (I think he posted it a few days back/ well worth a read) shows how complicated the forecasting of snowfall is. 

So as a very very rough start point - 5 850's (or lower) is a good place to start so WIB's comment seemed reasonable to me.  

 

Edited December 5, 2020 by Starsail

[bluearmy]

6 minutes ago, Starsail said:

West is Best taking a battering for his comments on the - 5 850's but I don't think his comment was unreasonable. 

 

WIB is still owed from comments made fifteen years ago

I’m sure he will cope !

[northwestsnow]

Just now, bluearmy said:

WIB is still owed from comments made fifteen years ago

I’m sure he will cope !

Methinks we will have lots to digest over the coming days Nick !!

[Scott Ingham]

22 minutes ago, feb1991blizzard said:

Agree in the main but think we might have to wait until back end of jan for a split SSW (ie - the type that is likely to benefit us). - Still the QBO worries me, will the westerlies in the tropics be weakening in the mid-lower strat (30-70mb) by then?

The models aren't picking up the pacific forcing they keep reverting to a nina base state when the atmosphere is behaving as though we're in a nino base state. As the forcing continues to drip feed into the models in the next 10 days I expect the Ural high and Russian high to continue to be more stubborn than is predicted and a consequence of that being more warming than is forecast into the strat. Every day we get a little closer to a ssw at the end of December. You could be right but I believe there is a 40% chance we hit a ssw before that which with lag will mean a winter bite right in the heart of winter for a change 

[Bricriu]

1 hour ago, bluearmy said:

The sypnotics are feasible but it’s currently a stretch to imagine how a deeply cold pool gets into the circulation and then arrives here !

In years gone you might have said the same thing. In some winters, winters that have entered snow lore, from less than fantastic looking charts things evolved very nicely for snow fanatics.

Edited December 5, 2020 by Bricriu

[SLEETY]

Gfs was right at the top of the pack, lots of colder runs in their, think we can bin the 06z run, it's always the most progressive of the four daily runs.