Model output discussion - into the start of Winter

[BLAST FROM THE PAST]

KW

 

its late Nov into early December so yes a great run of extended cild temps, so posting a chart for 30 Dec isn’t really comparable now is it?  If I was talking about end Dec into Jan....I’d agree with you

 

BFTP

Edited November 26, 2020 by BLAST FROM THE PAST

[IDO]

Bearing in mind at no time does the UK see a cold flow, just scraps and a cold pool, not that promising, but it looks like we get caught in a static trough setup with a sustained <0c upper air reservoir. With the continental flow at times it will feel quite chilly. From the start to the depth of FI we see a static Russian HP block:

  

The Azores high ebb and flows and the UK trapped in this reverse omega-block. The enabler is the wave running through the US, amplifying the upstream for a while. Towards the end of FI this wave breaks and the pattern flattens. Taking this run for what it is, a 10 day cool period early in December, nice!

 

[Scandinavian High.]

Lovely charts cooler with frosts on way Christmas around corner and also Scandinavia high building later next week lovely start to winter .

[kold weather]

8 minutes ago, BLAST FROM THE PAST said:

KW

 

its late Nov into early December so yes a great run of extended cild temps, so posting a chart for 30 Dec isn’t really comparable now is it?  If I was talking about end Dec into Jan....I’d agree with you

 

BFTP

If it turns into the building blocks then yes, it will be fine. If this IS it, than thats a whole different story again.

I suppose my main point of view is though I don't see much realistic chance of snow from this run, I don't see any really deep cold, the surface flow is somewhat cold but is that really enough to label it as superb? 

Of course the pattern could shift subtly to become more interesting in future runs, but I'd feel far happier with any a modestly decent upper cold pool in Europe. Without that I fear any air we import will be cold, not cold enough type job. Seasonal maybe the best way to describe it, without any real prospects of snow in the medium term.

Lets hope for upgrades!

PS - its a heck of a lot better than last year though, and we keep a decent period of below average temperatures with on real sign of any milder intrusions at the surface, so I'm hoping I;m not coming across too negative with it! I'm just a bit snow starved from last few winters!

Edited November 26, 2020 by kold weather

[bluearmy]

Back end gfs ops are beginning to show something of interest  v high up 

worth monitoring given some of the ec zonal wind forecasts for dec 

Edited November 26, 2020 by bluearmy

[Methuselah]

So, what to make of the GFS 06Z? I'd guess at, apart from a brief flirtation with some possibly wintriness from the east, T850s just don't like being cold enough for anything spectacular... Temps being mostly slightly below average looks about right. And, it's nae even winter yet:

    

[TSNWK]

2 minutes ago, bluearmy said:

Back end gfs ops are beginning to show something of interest  v high up 

worth monitoring given some of the ec zonal wind forecasts for dec 

Warming I hope Blue? To help negate the inatiable coupling risk

[fromey]

I know people don’t like screenshots of Twitter on here but I think this is of relevance

 

credit to Matt Hugo

[Yarmy]

14 minutes ago, TSNWK said:

Warming I hope Blue? To help negate the inatiable coupling risk

Yep. Very early days though.

[Met4Cast]

1 hour ago, fromey said:

I know people don’t like screenshots of Twitter on here but I think this is of relevance

 

credit to Matt Hugo

Sadly he blocks anyone who even slightly disagrees with him, or even likes a tweet from someone disagreeing with him, so I'm blocked. However, this is something I've been talking about for a few days now. 

The ECM was first to pick up on potential strat disruption with the EC46 zonal winds, trending ever so weaker with each update.

It's great to see the GFS and other factors slowly coming into play now to make this more likely. No substantial sign of a solid coupling between the strat/trop at the moment though.

[kold weather]

3 hours ago, bluearmy said:

Back end gfs ops are beginning to show something of interest  v high up 

worth monitoring given some of the ec zonal wind forecasts for dec 

Also worth noting the GFS 00z extended ensembles are also starting to show more ridging occuring with decent attempts at building HP towards Greenland from the Azores in quite a few of them, to varying degrees of success.

Given all that, it is indeed something to keep an eye out for.

About time we got some luck given recent winters.

[SMU]

remember tropospheric loading can be pre strat warming as well as post....

[fromey]

The pattern is evolving in a way that will promote a stratospheric warming event over Siberia/Eurasia in late Week 2.
quoted from M Ventrice

any thoughts on this?? Anybody want to shed any light on the subject for the less informed

[sheikhy]

1 hour ago, Mr Frost said:

Met Office have just issued a warning for freezing fog.

 

Pretty rare for any rime to develop on low ground in the UK but if you can reach/live on any local high ground you may be in for a feast of a proper Winter scene! (I know...I know it is still Autumn! )

Hopefully some of you get lucky. 

Bringing it back to model discussion...tomorrow could be very chilly - once again cloud/fog/freezing fog permitting. 

Friday UKV snapshot 12:00 - Winter coat/jacket weather for many if this happens! 

All the best!

Well with the cloud cover coming down across the centre of england right now i expect it to form maybe early hours of the morning or theyve got it seriously wrong lol

[blizzard81]

A clear move towards this morning's ECM op from the latest ICON. 

[BlueHedgehog074]

In quite deep FI, but gonna compare what the 00Z models - GFS, ECMWF and GEM show at 216 hours just to illustrate a few things. Mostly though focusing on the Low Pressure 

00Z GEM
 

 

00Z GFS

 

00Z ECMWF 

 

Looks like to me that the ECMWF is on its own with its Westward placement of the Low Pressure, whereas the GEM has it to the South-South-West of the UK and the GFS directly to the South of us. The ECMWF has a deep cut off upper trough (blues and some purple) very close by over Ireland. It’s a very grumpy Low Pressure system who must have clearly got wound up by something. To be fair, since Low Pressure is more shallow and thus more Southerly placed on the other 2 operational models, it is probable that the ECMWF is over-blowing that Low. Hence its more Northerly position to the West of us. Someone posted some of the ECMWF ensemble pressure graphs that showed the operational model being an outlier in pressure towards the end of its run.

So I do feel there is a real possibility it could make adjustments East or South-East with that Low Pressure on future runs. It may still disrupt Low Pressure close by to the West of us as both the likely amplification upstream and the blocking to our North-East try to force the Low Pressure, South. But it’s destination could be more to our South rather than South-West. I guess to avoid the risk of some milder 850 hPa temperatures being dragged up from the South, then you don’t really want the Low Pressure to get stuck to the West or South-West of the UK. Edit: Looking at the 12Z ICON that was posted above, does make me realise, that sort of situation can’t be completely discarded yet. Particularly as it’s an outlook quite far away and liable to further changes, whether it ends up good or bad for cold and wintry weather.
 

Also sneaked into Nick S’s house to borrow his crayons to draw an ideal scenario for getting some very cold weather over the UK. (Blue arrow showing direction the cold weather would head in). 

 

Vortex to our North stamped out. A negative NAO pattern takes hold and the Jetstream is sent on a Southerly track. Position of both Lows and blocking High above great for bringing in a Polar Continental Easterly flow, which can bring in deep cold and heavy snow showers. And sometimes, especially with disturbances in the flow, longer spells of sleet and snow. 
 

In the close time range, and as Mr Frost and a few others pointed out, some dry, and at times, frosty and foggy, weather to come as both the Scandinavian High and ridging from the Azores High influence our weather for a time. Seasonal does feel like the word. ️

Edited November 26, 2020 by DiagonalRedLine
Adding some extra stuff

[MattStoke]

5 minutes ago, Mr Frost said:

These +384 GFS Strat charts proved to be absolute cannon fodder last Winter - how many times did we see these posted with the phrase "It's looking toasty up there" @Paul_1978 

The Stratosphere thread has tumbleweed blowing through it...apart from a few tweets and that chart you posted above. 

Would be great to hear from some of the experts - for example  @Tamara @Blessed Weather @lorenzo on what they think could happen going forward? 
Would be very much appreciated. 

Those charts were right. The warning did occur. It just didn’t have much imprint on the troposphere.

[Met4Cast]

5 minutes ago, Mr Frost said:

These +384 GFS Strat charts proved to be absolute cannon fodder last Winter - how many times did we see these posted with the phrase "It's looking toasty up there" @Paul_1978 

The Stratosphere thread has tumbleweed blowing through it...apart from a few tweets and that chart you posted above. 

Would be great to hear from some of the experts - for example  @Tamara @Blessed Weather @lorenzo on what they think could happen going forward? 
Would be very much appreciated. 

They tend to be cannon fodder in isolation, however the ECM has been trending that way too for a few runs now, coupled with the persistent Ural High/Aleutian low signal from the models, it's been almost expected that we'd begin to see the GFS picking up on some strat warming. We've also got a strong +EAMT event being modelled which can often produce patterns favourable for a trop-led attack on the SPV.

So while the GFS extended Strat charts in isolation can't be trusted, there is reason to believe they might be onto something at the moment. 

+ I believe the GFS was upgraded during the year and so far, it seems the huge bias it had last winter has been resolved.

[Duane S.]

What is very encouraging in the output is the propensity to drop energy down through the UK into Europe.

It might take a few attempts (a few weeks)  but I do think sooner or later, much good will come of this for us.

[Eskimo]

Lower heights  extending further east. Some snow across higher areas in the spine of the country. 

[bluearmy]

Anyone seen the evolution of latest gfsp run ???

 

 

[SMU]

Enjoyable 12z run > A sway towards more atlantic influence but at a very acute angle

12z Looks like 00z P at 192 lol

@bluearmy

[snowking]

A lot of sudden interest on what's happening in the stratosphere. There's two things to call out here:

1. We currently don't really have any coupling between the troposphere and the stratosphere (thankfully). If we take a look at the zonal wind cross section:

Whilst the vortex rages in the mid and northern latitudes at 1-30mb at above average levels, closer to the surface we see something slightly more serene. For as long as the vortex above rages, long may that continue. However of course such events as a sudden stratospheric warming can lead to dynamic coupling between the strat and the trop....

2. Should that happen, it may not be all that favourable. The truth about point 2 is that right now we simply don't know whether or not it will be favourable for a number of reasons:

- This is still a relatively minor warming being shown beyond day 10, which may not even come to fruition

- The potential event is really being triggered by a +EAMT event - the strength and duration of which we do not yet know, as it still remains a forecast

- We have such a strong vortex aloft that any warming events may not sink into the core of the vortex, and may simply ride the surf at the outer reaches of the upper vortex before being deflected away

But even ignoring all of these stumbling blocks before we can get to being anywhere near close to knowing what might happen - it takes a lot of work to get all of the right pieces of the puzzle in place to benefit our tiny little island. If what you are hoping for is an SSW that imprints onto the trop directly so that we have the stratosphere, rather than the troposphere, setting the tone for the global longwave pattern, then something like this from one of the previously posted tweets could be a horror show for the UK, with split vortex segments really not where we want them to be:

But to re-iterate, this is all theoretical, and should there be any stratospheric warming and subsequent impact on conditions on the ground come to fruition (but current gut instinct looking at the forecast wave activity would suggest the currently modelled attempt would not be enough to achieve such a scenario), we're looking at least 5-6 weeks away before this likely begins to impact us in any meaningful way.

In the meantime, if it's cold you're looking for, look for something tropospheric led.

[sheikhy]

Ukmo a bit meh this afternoon!!looks very different upstream as well!!

[Tim Bland]

Looks good for those with elevation away from coasts?...