Model Output Discussion - Colder spell ending, what's to follow?

[Mapantz]

Can we stick to model discussion please?

If you're not happy about certain posts, use the report function. 

[Eagle Eye]

Back on track a good low quite far out though, who knows an even Lower Low(?) could happen. 

 

[syed2878]

2 hours ago, Catacol said:

The amplification will come - momentum cycle dictates it. But just how amplified it will be is the question and just how weakened might the vortex be after wave impacts begin to fade in a week’s time. For now the vortex is under attack, and we can watch and wait and cross fingers that it gets a decent battering.

This is attack no 1. Attack no 2 will come around New Year. And then the lag impacts of that attack might possibly set us up for an interesting end of January. Having said that in a Twitter poll Amy Butler has plumped for a SSW before the first third of January is out - and she is well worth listening to. That would throw the cat amongst the pigeons and chances for earlier cold.

Lots of negativity yesterday and disappointment as amplification from the +EAMT didn’t prove enough. But it’s still early...

 

2 hours ago, Catacol said:

The amplification will come - momentum cycle dictates it. But just how amplified it will be is the question and just how weakened might the vortex be after wave impacts begin to fade in a week’s time. For now the vortex is under attack, and we can watch and wait and cross fingers that it gets a decent battering.

This is attack no 1. Attack no 2 will come around New Year. And then the lag impacts of that attack might possibly set us up for an interesting end of January. Having said that in a Twitter poll Amy Butler has plumped for a SSW before the first third of January is out - and she is well worth listening to. That would throw the cat amongst the pigeons and chances for earlier cold.

Lots of negativity yesterday and disappointment as amplification from the +EAMT didn’t prove enough. But it’s still early...

 interesting post and yet according to the Met long-range forecast January will be mild not only that but the Met office long range model glosea is not very inspiring on the December update. you talk about called but and SSW doesn’t guarantee that for the UK.

[Mike Poole]

ECM T120, I’m thinking Davros, with his head slightly tilted:

[TSNWK]

ECM 168 still having a go at those heights upstream... Please give the trough over us a boot at 192

 

[Georgina]

18 minutes ago, swfc said:

Yes lower lows do occur. I'm guessing there's a limit to how low a low can go tho

About as low as Wednesday earlier today

[swfc]

Just now, Georgina said:

About as low as Wednesday earlier today

Yes very low

[BlueHedgehog074]

What a very peculiar evening it’s been.  

Let’s remember not to get too carried away though

I do appreciate as well it’s been a hectic year for a number, which I know hasn’t helped with the mood of things. And is good to have a laugh now and then as it can help with lifting the spirits. We have, nevertheless, opened up our big storage cupboard for those of you to store ya prams in, incase there’s a temptation to throw out the dollies

Edited December 12, 2020 by DiagonalRedLine
Adding extra sentence

[MATTWOLVES 3]

I think some are misreading that Exeter update.. For me the fact things have gone from mixed signals, to very very low confidence, and any outcome is possible tells me, that perhaps a serious strat development is lurking and could throw all options onto the table... I'm now feeling the next couple or so weeks could become interesting to say the least.. You only have to view those ensembles to gather many options are on the table, and a fair few blinders an all.. And I've only viewed a quarter of em.. 

Onwards and upwards good folk.. 

Edited December 12, 2020 by MATT☀️

[lawrenk]

13 minutes ago, Mike Poole said:

ECM T120, I’m thinking Davros, with his head slightly tilted:

That photo is how old most of us in the south will be before we see settling snow again.

[Griff]

6 minutes ago, TSNWK said:

ECM 168 still having a go at those heights upstream... Please give the trough over us a boot at 192

 

Vs the mighty GEM 

Which happens to have an interesting evolution. 

Apologies if already posted previously. 

Edited December 12, 2020 by Griff

[Tim Bland]

26 minutes ago, XanderP007 said:

Back on track a good low quite far out though, who knows an even Lower Low(?) could happen. 

 

Here’s a hi high that could be cold enough for long blizzards if it gets lower ...

[swfc]

Ec looks OK imo. Not has much of a push towards Greenland but still ridging into Atlantic. And with that I'm off, feel a bit low today

[Daniel*]

Pressure higher in Atlantic but less ridging to Greenland so unsure about this.

[BlueHedgehog074]

9 minutes ago, swfc said:

Ec looks OK imo. Not has much of a push towards Greenland but still ridging into Atlantic. And with that I'm off, feel a bit low today

Yep, it could be worse for cold weather possibilities to be fair. Quite a cool looking chart for Monday 21st December, but a bit more of an Easterly push to the pattern could bring some colder down from the North for the UK.

Hope you feel better soon. Not again been a great year at all to be honest

(Edit: Got beaten to it above)

Edited December 12, 2020 by DiagonalRedLine

[Tim Bland]

Lots of potential from here ...

[Daniel*]

I think you can say it’s an improvement at day 10 very mild southwesterlies on 00z replaced by much cooler northerly flow.

[Vikos]

Why I think that this year the setup is a lot better for cold (and maybe snow) spells is the fact, that the main cold air block this year is on the opposite side of the NH. So for me this is a big pattern change, hopefully the cold doesn't shift over the pole towards Canada this year (to initiate a very strong west drift)

 

versus last year (same date)

[Daniel*]

12 minutes ago, Tim Bland said:

Lots of potential from here ...

If we did end up in that position that developing low on east flank of ridge is going east and would likely bring some wintry weather on north flank to northern parts. I definitely see maybe this upcoming period could be of some interest to northern members with sleet/snow. 

Edited December 12, 2020 by Daniel*

[SLEETY]

1 hour ago, Mike Poole said:

No sleet on 21st that I can see, on any of the models, away from the Highlands of Scotland maybe. Anyway what’s so good about sleet?

Hadn't you thrown in the towel yesterday for the Winter?  because of the Glosea forecast?

Anyway a much improved ECM today could get very interesting if the trend continues tomorrow.

[SqueakheartLW]

A bit late today posting this but have the usual update on yesterday's GFS runs for Christmas Day itself

Temps        11/12          Precip         11/12
V Mild          0 (0)            V Dry           0 (0)
Mild             22 (+8)        Dry              20 (0)
Average      46 (-2)         Average      75 (+2)
Cold             49 (-4)        Wet              32 (-2)
V Cold          11 (-2)        V Wet           0 (0)
LEADER        AV/CD       LEADER       AV

Yet another shift in the direction of milder at the expense of colder options. My hopes of a cold or white Christmas continue to fade after the decent charts on the first day in particular. Average precipitation remains the strongly favoured option at present.

I have managed to still find a good selection of colder runs right from yesterday's 18z GFS through to the recent 12z GFS. Picked out the coldest or most likely to produce snow runs I could find

Yesterday's 18z GFS

Member 10

An Arctic northerly in time for Christmas. Snow shower threat mostly for the N and W here. The S and E probably dry and cold

Member 22

A snow maker in more central parts of the UK where the low pressure interacts with the colder air in the north and central UK

Member 23

A marginal snow event maker here. A slack low pressure pushing in from off the Atlantic is engaging quite cold uppers. Could be good in the north especially

Member 28

Let battle commence here. A frontal system pushing into cold air here could produce a transitional snow event for Christmas Day

Today's 00z GFS

Control Run

An interesting setup here with the cold Arctic air in place and that low pressure slipping down the W side of the UK. Snow risk for N Ireland, W Wales and SW England from that. Most likely snow showers in the N and down the E coast too. Everywhere else dry and cold

Member 7

A potential snow maker if only the low pressure pushes far enough north to engage the colder air in place. More likely cold rain for the south but could be a snow event if it reaches C or N UK

Member 28

This chart surprised me. At first glance at the 500mb chart my first thought was mild all the way for Christmas Day but when I saw the 850mb chart I was so surprised to see the -5 isotherm over a large part of the UK. A rather cold SW wind here for the big day. Maybe even a snow risk from a SW wind ... shocking

Today's 06z GFS

Operational Run

A dry and cold Christmas Day here for most but a risk of wintry showers in the W and N in particular, snow likely too, especially further N and over higher ground

Member 15

This could be a real snow maker if you are in the N or S. The N is exposed to the Arctic northerly so a snow shower threat here. However the south could be seeing snow from that little low just near the S coast. Central parts most likely to be dry

Member 19

Similar to the last option but less of a snow threat for the south as the uppers aren't quite as cold but the north still has a snow shower threat for Christmas Day

Member 22

General cold uppers over the entire UK here in a gentle N to NE wind. This is likely to produce a snow shower threat to the N and E for Christmas Day

Today's 12z GFS

Control Run

Yet another recent control run that looks interesting for Christmas Day. A threat of wintry showers here mostly in the N but with a trough in the flow then a chance of something a bit more persistent pushing down the UK

Member 4

Quite a deep low here for Christmas but cold uppers in the circulation too. Could produce some wintry showers even to lower levels at times.

Member 7

A nice straight northerly here with cold uppers and a snow shower threat. Even colder uppers waiting to come down from the north too as long as the pattern holds

Member 13

A cold and frosty option for Christmas Day here with decent cold uppers in the mix too. Likely to produce very low minimums too

Member 18

A nice big battle here between air masses but also the -NAO vs the Euro high. Knowing our luck the Euro high will end up dominating after Christmas Day but not without a snow event first. On the other hand the -NAO might win and leave us in the cold air with a continued risk of snow.

Member 29

The final option I have picked out is another Arctic northerly run. We have lost the beasterly runs lately but replaced them with several Arctic runs instead. Maybe that is our best hope of cold for Christmas now.

ENS update

These are the latest ENS options. Both have 1 option yet again which isn't that helpful but they do show at least above average pressure to the N and NW and below average over and to the S of the UK so some ECM options must be decent for cold at least

Look away now time if you are fans of cold and want cold for Christmas Day

I am now going to reveal the top 3 mildest options I have seen in the last few GFS runs for Christmas Day. They have all come out in today's output so far and are the 3 runs that have easily scored on my very mild option. Here they come

In 3rd position we have .............

GFS 06z Run Member 11

A very mild airmass has pushed up all the way from N Africa here with the +5c isotherm easily into the UK here. Would make for a rather balmy Christmas Day here and very much more like spring than winter

In 2nd position we have ...........

GFS 12z Run Member 12

This is an even milder option than the first one with the +5c isotherm totally covering the UK here. With the fohn effect we could be seeing upper teens in favoured spots and overnight mins could even be in the teens too in some areas .... uggghhh

Finally we have the 1st placed option and the most ridiculously mild looking Christmas Day chart I have ever seen ........

GFS 00z Run Member 21

This chart has the +5c Isotherm right through the UK and has the +10c isotherm almost onto the south coast. Lurking further south we even have the +15c isotherm showing up over France and Spain. We all know when the +15c isotherm hits us in the summer we are going to get some hot weather but to see it in winter is just so odd. This could be threatening 20c in the UK with the fohn effect in favoured locations and no doubt some locations in France and Spain will be exceeding 20c with this setup. We will likely have temperatures in the UK on a par with those expected in late Spring in this setup

 

[Anthony Burden]

Very encouraging ecm this evening,pressure rise in Atlantic good to see.

Start of building blocks to begin Christmas count down.

[Daniel*]

9 minutes ago, Vikos said:

Why I think that this year the setup is a lot better for cold (and maybe snow) spells is the fact, that the main cold air block this year is on the opposite side of the NH. So for me this is a big pattern change, hopefully the cold doesn't shift over the pole towards Canada this year (to initiate a very strong west drift)

 

versus last year (same date)

I think this is important to recognise take forecast for 19th from ECM 12z and 2019 for same date the cold is much more extensive across Eurasia. It’s always beneficial to see a colder continent.

 

[Mike Poole]

13 minutes ago, SLEETY said:

Hadn't you thrown in the towel yesterday for the Winter?  because of the Glosea forecast?

Anyway a much improved ECM today could get very interesting if the trend continues tomorrow.

Hey Sleety, no not quite.  For sure the towel is rolled and delicately scented, and ready for throwing.  But is an uphill struggle for coldies from here, with GloSea5 against us, I was hoping that the Dec 11th update would give some kind of likelihood of a SSW, but it doesn’t.  I’m hoping the MJO early timescales, and the SSW later, will bail us out.  Chance: 45% maybe.  Enough to keep washing anyway. (Edit, i meant watching, but leave it as it amused me.)

Edited December 12, 2020 by Mike Poole

[pureasthedriven]

2 hours ago, Tim Bland said:

I was just thinking the same thing?! It says any wintryness likely confined to higher ground then milder new year?

we seem to have gone from the PV shunted to the east to having it all to our North West..much harder to get cold from there 

What am I missing? The MO update half decent, no?