Model output discussion - is the beast awakening?

[tight isobar]

Eps 12z 500s \850s \@soundings!!..no complaints here...@easterly inroads...with vigor....

now let's see where the offy run goes we'll relinquish @pub run-as they are all SHUT..

Love or loathe...the hallmarks are printing for a classic beasterly✌

Edited January 31, 2021 by tight isobar

[SqueakheartLW]

After some very positive signs in the models for a cold spell back end of the coming week it is time for me to assess the 12z GFS and GEM to see if they are still on track as I put it and that the cold spell is getting closer and not staying too far away or getting watered down.

12z GFS

Here are the latest mean charts for the 12z GFS for the coldest point of the predicted cold spell. I had 3 times to choose from so went for the one in the middle at 168 hours away. 162 and 174 had the same 850hpa temperature average too.

The 12z GFS still maintains our average easterly wind at 168 hours away so still very much on track in that department anyway. The latest 850hpa average comes out at a decent -9.5 which is -6.9 below the long term mean. This is a slight 0.3 less cold than the 06z was but still in the -9's territory so fine by me. The anomaly chart maintains those blues over the UK but what makes this better is how that pink area to our east has grown since the 06z. This means a deeper cold pool to our east so even more potential to get something even colder later on if we can keep the easterly going a bit longer.

Mildest 3 charts from the GFS 12z at 168 hours away

3rd     Member 23     850hpa temp -5.0

2nd     Member 4     850hpa temp -3.3

1st     Member 6     850hpa temp -2.6

Coldest 3 charts from the GFS 12z at 168 hours away

3rd     Operational     850hpa temp -12.2

2nd     Member 13     850hpa temp -12.7

1st     Control     850hpa temp -13.4

Mildest doom and gloom chart of the GFS 12z

Member 27     +384 hours     850hpa temp 8.1

Coldest fantasy chart of the GFS 12z

Member 10     +234 hours     850hpa temp -14.5

GEM 12z

Time to now compared the 12z GEM to the 00z GEM. The latest GEM at the peak of the predicted cold spell has an average 850hpa temperature of -6.9 at 186 hours away which is -4.3 below the long term mean. This is a slight upgrade of -0.2 compared with the 00z so the GEM is coming a little bit back more on board with this idea of a cold spell.

Mildest 3 charts of the 12z GEM at 186 hours away

3rd     Member 20     850hpa temp -3.2

2nd     Member 16     850hpa temp 0.5

1st     Member 4     850hpa temp 2.0

Coldest 3 charts of the 12z GEM at 186 hours away

3rd     Member 14     850hpa temp -10.8

2nd     Member 18     850hpa temp -11.1

1st     Control     850hpa temp -12.1

Mildest doom and gloom chart of the 12z GEM

Member 16     +258 hours     850hpa temp 9.9

Coldest fantasy chart of the 12z GEM

Member 15     +216 hours     850hpa temp -14.7

[iceman1991]

1 hour ago, Penrith Snow said:

I asked the Cat to put his paw on the correct ECM solution, he chose the cold one, thats good enough for me.

Not very scientific?

Better than the ECM Computer Model Output!

Alfie says 'What Do You Mean No Cold Spell'?

Hello Alfie  nice to meet you 

[Osbourne One-Nil]

Erm....model discussion thread!

[Man With Beard]

There were more ECM ensembles similar to the op at T144 than this morning - 15 out of 51 I considered fairly similar to the op run with a low near to Scotland (1 or 2 even further NW), compared with just 3 this morning. 

Surprisingly, there's still a number of ECM ensembles that have cleared the low completely and show high pressure building down from the north as early as Saturday. 

Middle ground = easterly for most, low pressure near the south or in the north sea (think UKMO/GFS blend)

Maybe the morning will bring clarity!

[Blessed Weather]

The posts discussing the BBC weekly forecast have been moved to the Moans/Chat thread. Thank you.

[Griff]

16 minutes ago, SqueakheartLW said:

This is a slight upgrade of -0.2 compared with the 00z so the GEM is coming a little bit back more on board with this idea of a cold spell.

That's interesting and appreciated, I had a quick peak just now at the gem ensembles spaghetti plots and assumed the 12z was milder than the 00z. Thank you. Very informative post.

[feb1991blizzard]

From what i can remember (no archives) the GEM ens (upto 192) are the best they have been for a while.

 

Edited January 31, 2021 by feb1991blizzard

[SqueakheartLW]

4 minutes ago, Griff said:

That's interesting and appreciated, I had a quick peak just now at the gem ensembles spaghetti plots and assumed the 12z was milder than the 00z. Thank you. Very informative post.

When I saw the -9.8 from the GFS 06z I was hoping in anticipation that the 12z was going to break the -10 barrier but it wasn't to be. As for GEM it was initially the more keen model between the two of them on the cold spell initially then seemed to back off as GFS came more on board. With this slight upgrade on GEM maybe finally both are going to really come on board. All we need now is ECM to be fully on board too and not throw in several mild op runs to keep the chances of a total failure very much a possibility

[Lord Grogon]

1 hour ago, Stu_London said:

Amazing how quick the weather flipped after beast 2 - I recall playing golf in shorts and t shirt a week later and coming across drifts that had accumulated in the bunkers 

Funnily enough, if I recall there was very briefly a Beast number 3 popping up for the end of March. I think it ended up a Northern Hills only event though as the south began to warm up (and didn't really stop until August!). 

[Griff]

2 minutes ago, SqueakheartLW said:

When I saw the -9.8 from the GFS 06z I was hoping in anticipation that the 12z was going to break the -10 barrier but it wasn't to be. As for GEM it was initially the more keen model between the two of them on the cold spell initially then seemed to back off as GFS came more on board. With this slight upgrade on GEM maybe finally both are going to really come on board. All we need now is ECM to be fully on board too and not throw in several mild op runs to keep the chances of a total failure very much a possibility

I keep paying too much attention to eye candy op runs, so the error is all mine. I'm a bit simple that way! 

[Mike Poole]

1 minute ago, feb1991blizzard said:

From what i can remember (no archives) the GEM ens (upto 192) are the best they have been for a while.

Maybe, but I dont rate the GEM ensembles at all, they can be totally different to the GEFS which causes a problem for the NAEFS as it uses both. The GEM op has performed very well since its upgrade a year or two ago.  And has consistently predicted cold for UK - a decent pattern, apart from, obviously, the awful run this evening.  But I’d forgive it one run if the trend was right.  

[Purga]

A good time to underline the importance of the ENS rather than individual Op runs.

A good a set as you could want from ECM

And the ECM clusters after 168h are mostly showing easterly

Good to keep the balanced outlook.

Edited January 31, 2021 by Purga

[stodge]

Evening all

Just time for a quick look at the models this evening (no sniggering in the cheap seats, please).

I'll take the T+120 charts and maybe the T+180 if I've time.

12Z GEM:

Not bad - the first problem is a residue of energy is left when the initial trough moves east toward the British Isles and that phases with the next Atlantic system. The T+180 looks good for northern Britain but marginal further south through the push of heights down from the north is forcing the jet further south.

12Z GFS OP:

Very satisfactory evolution from the OP ending with a decent E'ly for most by T+180. The OP doesn't make as much of the residual energy coming out of North America.

12Z GFS Parallel:

Parallel gets there in the end but it's not as straightforward as OP and the Atlantic profiles at T+180 are very different. The energy spills out NE towards Iceland but is held by the block so will it slide south further into FI?

12Z ECM: (T+120 and T+192):

It's better than last night I suppose with the troughs inching further south against the heights to the north - it all ends a bit battleground, cold in the north, mild in the south

UKMO looks to be getting there at T+144 and JMA is fine at T+192

Conclusion: as we leave a nerve-shredding weekend for model watchers, are we there yet (as we always used to say on the journey from London to Cornwall which might explain a lot)? ECM keeps the nerve ends frayed but it's better than last night. GFS OP is fine, Parallel is okay while GEM is a bit too marginal for the south but fine for the north. Further on, and it's fascinating to see the extended FI pattern consolidating away from an Atlantic return to either a continuation of cold into mid month or a real battleground.

[Matt H]

Appreciate that it’s a dodgy model but I think it’s safe to say that the CMA 12z successfully clears the low as well. Beautiful run!

Edited January 31, 2021 by Frosty Winter

[feb1991blizzard]

3 minutes ago, Mike Poole said:

Maybe, but I dont rate the GEM ensembles at all, they can be totally different to the GEFS which causes a problem for the NAEFS as it uses both. The GEM op has performed very well since its upgrade a year or two ago.  And has consistently predicted cold for UK - a decent pattern, apart from, obviously, the awful run this evening.  But I’d forgive it one run if the trend was right.  

Hoping though (take your word that they're crap - only follow them when cold imminent), that they have now cottoned on to the right pattern just later than the GEFS although it has to be said, no later really than the eps.

[Bricriu]

1 hour ago, Catacol said:

Indeed. Lesson learned - and March 13 was none too shabby either.

But I think it is really important that folk realise the context this year is not (yet) anything like 2018. The Beast in 2018 was a direct creation of a significant vortex split, and such was the magnitude and angle of that split and the very swift downwelling response that it became very difficult NOT to end up with a massive easterly. It was an extraordinary event. I had half hoped for something similar earlier this month, but the warming wasn't quite strong enough.

What we have coming up is a tropospheric led pattern with a vortex up top that is forecast to recover a bit - and isn't split. That isn't to say that we won't end up with an easterly - I'm pretty sure at stages this coming month we will have that easterly....but we are also going to have Atlantic influence and that means battleground events a plenty. Different setup, less chance of that long draw easterly. In 2018 do people remember how one phase of cold ended? A low pressure travelling east to west actually shot too far out into the Atlantic from Spain. It was utterly bizarre. The vortex split caused the entire circulation to travel the wrong way, and as that low ended up in the Atlantic against the initial forecast it was a bit of a sickener. It was still awesome....but by golly it could have been drifts up to the armpits had that low held fast.

I don't think we are going to get anything like that this time around, but the longevity of snow opportunities looks striking. Warm bumping and sliding into cold....brief warm up.....cold digging back in.....more bump and slide. Chances for an easterly to hold fast for a few days certainly possible too.

I'm seeing chances for Feb 91 and Feb 96 in the approaching mix. I'm not seeing a 2018 style vortex split in the forecast for this season now. Would love to be wrong though - 3 cold months on the bounce would be awesome.

 

I am not sure this is all that much different from we've had so far, so i can see how some posters in locations that have been the wrong side of the boundary between the cold and mild air might not be that excited by this prediction. They would much prefer a deep push of cold air from the east or north east rather than glancing blows, which risks everything being marginal when the Atlantic comes in.

The UK Met do hold out the possibility that snowy cold digs further south during February, but it could easily be that it does not and the milder air pushes further north than expected to just leave the usual places favoured to get snow.

Edited January 31, 2021 by Bricriu

[phil nw.]

Apart from the GEM the 12z all show cold heading south by the weekend.

All 4 at t144

The delay on the GEM showing and colder uppers never really make it south of the border. 

GFS with the quicker sinking of the low and then the bitter easterly with snow likely in showers down the east and with the low over France every chance of more prolonged snow for the south.

ECM/UKMO similar in a slower movement of the uk low south but both have a wrap around of cold from the ne as it slowly drifts away.No classic easterly on the latter 2 but looking more battleground again with the next Atlantic attack looking like sliding se.

The important difference is the boundary seems likely to be further south which would bring snow starved areas into the picture.

In spite of small differences in the movement of the low complex  the end result overall is ok.

Certainly a better set overall and I feel by 12z runs tomorrow we should have a much firmer pattern up to the weekend with the fax's for support as well.

[Mike Poole]

3 minutes ago, feb1991blizzard said:

Hoping though (take your word that they're crap - only follow them when cold imminent), that they have now cottoned on to the right pattern just later than the GEFS although it has to be said, no later really than the eps.

My concern with the ensembles (all of them, but particularly GEM/CMC) is that the current dilemma seems to be troubling the highest resolution op runs at short range, so the lower res ensembles could be collectively leading us up the garden path.  Anyway, raise a glass to you all for the pub run

[Mark wheeler]

8 minutes ago, Frosty Winter said:

Appreciate that it’s a dodgy model but I think it’s safe to say that the CMA 12z successfully clears the low as well. Beautiful run!

Has been consistent the last 3 days in showing this as posted yesterday

[Battleground Snow]

Icon even better than its 12z run at 102,

Low weakening fast on this run. Cold almost in.

 

[Mike Poole]

ICON 18z T90 v 12z T96:

The low west of Ireland is shallower on this run and ‘closer’ in a sense I’m not sure what I mean (!) to the one to the SSW, so hopefully it won’t go the way of the 12z run.  

Edited January 31, 2021 by Mike Poole

[ICE COLD]

Icon is an upgrade T114  

Edited January 31, 2021 by ICE COLD

[chris55]

One of the coldest means of the winter so far on the gfs 12z ensembles, 06z mean was marginally colder, but a min average of circa -9 is pretty cold. Still to much scatter for a really confident forecast but very good nonetheless. Will be interesting to see how the 18z compares.

Operational slow getting the cold in and on the milder side from the 5th. 

 

Edited January 31, 2021 by chris55

[kold weather]

Yep can't complain about the 18z ICON indeed. Hopefully the 18z GFS holds its trigger and doesn't decide to make things somewhat more uncertain than they already are.