Model output discussion 24/01/21

[Uncertainty]

The 46 is sensational 

Week 2

Week 3
 

Temps

Euro Troughing still present into late Feb

Getting BFTE vibes...

[Jarrow Posh]

4 minutes ago, Yarmy said:

I wouldn't advise going for a swim in it. It's only a couple of degrees above average. Any Easterly flow over that would be a snow machine for southern Scandinavia.

I wasnt planning on it lol but i agree,everything is relative and I do look forward to seeing a good old North Sea snowmaker spring up in the models next week

[Tim Bland]

11 minutes ago, winterof79 said:

We gave the ghost up ages ago on this. 

‘We’ being those it’s unlikely to affect? I’m sure those in west mids and Wales are still very interested ...

[Singularity]

Strange seeing ECM be the least keen to separate areas of low heights. Seems the majority of EPS don't have such hesitation but you have to wonder what drove the deterministic run to keep the two main trough areas holding hands for so long.

Its +216 chart isn't all that different to the GFS 06z at that point, but the route there was markedly different due to the lack of trough separation.

Not sure I've never seen so much Arctic and general high latitude blocking configured in a way that diverts the cold air away from the UK for so long. It's technically possible but as MWB says, cold chasers would be right to feel very unlucky if things played out that way.

Even if it did, though, it appears probably that the cold continental air would find a way across by day 12 or so, as the small low by Ireland on day 10 slides southeast and a ridge is pumped up through the UK from the southwest in its wake. It'd probably be cold and dry, though, excepting anything on the northern flank of the slider.

That last bit is probably going to be irrelevant by the 00z runs but I wanted to highlight how many routes to cold there now appear to be, be they faster or slower in nature.

[Doctor96]

Mike honestly widespread 6 C over most of lower part of north sea is usually seen in February and not January , so it is a bit colder , but if we get  super cold air in an easterly as may be comming i think we all will be happy . I recall i think 1978 or 79 with a stiff easterly mid february when Newcastle was cut off and i got stuck at school . The army was called out .  Will we see that again thi february with the modesl showing great potential 

[Mike Poole]

1 minute ago, James Maidstone said:

if the BFTE comes in and it is the right side of marginal then couldn't this aid the snow creation and subsequent precip rates?

Yes, absolutely.  If you’ve got uppers of -10 on a brisk easterly wind, then the convective activity (not related to weather fronts) will depend on the difference between -10 at 850hpa and whatever the sea temperature is, so the the higher the better in that scenario.

[MJB]

17 minutes ago, ICE COLD said:

Right at the top end of the pack and a mean easterly at days 9 and 10 . Some ens also breaching the magical -10 mark towards the end as well . Everyone breath

That can't be a surprise to anyone 

[northwestsnow]

45 minutes ago, tight isobar said:

Ecm12z..less said the better...however it's evolutionary is bordering ridiculous!!... I'm going to pretend I never even viewed it.....@non worthy imo.

Haha that made me chuckle mate I thought exactly the same thing !!

[bluearmy]

this is the best week with the low anoms in the right place 

[Mike Poole]

3 minutes ago, Doctor96 said:

Mike honestly widespread 6 C over most of lower part of north sea is usually seen in February and not January , so it is a bit colder , but if we get  super cold air in an easterly as may be comming i think we all will be happy . I recall i think 1978 or 79 with a stiff easterly mid february when Newcastle was cut off and i got stuck at school . The army was called out .  Will we see that again thi february with the modesl showing great potential 

We are nearly into February, and the warm anomaly shown is only up to 1C, so maybe it is something or nothing.  There is certainly the potential for big convective snow if the BFTE gets going though...

[Paul]

Quick look at the shorter term snow prospects, courtesy of the 15z UKV initially. Saturday's risk has moved south again following a northerly shift on the 12z, but is still keeping it to higher ground for lying snow, with Wales favoured. 

The netwx-SR (3km) is into range for Saturday and is keeping with a more northerly theme, so the south of northern England and more of the Midlands into play. 

Sunday is more of a glancing blow at the moment, with Wales again shown as the sweetspot. 

Monday looking very interesting at the moment for those in Northern England and Scotland, with lower lying areas in with a shot of seeing lying snow and higher regions potentially seeing sizeable accumulations again. There's fairly decent model agreement around this right now, but the caveat being that it's a long way off!

 

 

Edited January 28, 2021 by Paul
Typo

[Jordan S]

Snow rather than rain is now likely for parts of the Midlands and Wales, the cold air moving south into this area of rain moving northeast into ireland, Wales and England.. this may start off as sleet and snow across wales and midlands some places beginning as rain then a transition to sleet and snow particularly for northern parts of southern England, London then possibly southeast England before it clears south.. parts of Wales and southern and western portion of the midlands likely seeing the most snow accumulation out of this. 

Arpege..

Gfs...

 

Perhaps still more snow for some parts of Wales and southern parts of England and northern Ireland on Sunday although probably lighter.

Looking at the Jetstream for Sunday you can see how it is blocked by higher pressure over us and with cold air in place..

Another area of interest is southern and looking more especially eastern Scotland for Tuesday into Wednesday with a frontal system pushing into many parts, in western parts rain but for northern particularly northeastern parts of England and especially Scotland it will probably fall as snow, possibly to lower levels at first in northern England before probably turning back to rain here. It is likely to remain as snow particularly for high ground of southern then more especially eastern Scotland significant and persistent snow quite likely here with large accumulations windy as well with a south to then southeasterly wind here..

6pm Tuesday..

6am Wednesday..

The jetstream for midweek moving through southern England with that milder weather in southern and western areas but the cold remains in Scotland.

Later next week a slow moving weather pattern as the jetstream goes to the south of us..

So after that milder weather midweek for England and Wales it will probably turn colder but somewhat drier for most or all at the end of the week, the cold air that's over Scotland and to the northeast of the uk probably moving slowly south and west.

Edited January 28, 2021 by jordan smith

[Griff]

Simon Lee recently tweeted about latest ecmwf extended range. 

Some very encouraging signs, as already noted here. 

Link to tweet on tweet thread

 

[Mike Poole]

ECM clusters T192-T240, and I like these:

It’s kind of what kind of blocking would you like, rather than is there going to to be blocking.  The borders tell a story, it’s what ECM think the wider pattern is, green is -NAO, red is Scandi block.  And red is the way they are going - this is great, at this time in late winter, a scandi block and easterly winds will deliver more than a Greenland block and northerly.  It’s the other way around in early winter.  

Keeping my eye on the strat situation, I’ve posted the NAM chart all winter, here’s today and it gives a good visual indication of the story so far:

You can see the downwelling, the blip where tropospheric conditions were not conducive, and then in the forecast the landing zone (MJO big help in that , i think) and up top the resurgent westerly winds shown in yellow will only enforce that increased likelihood of easterly winds in the troposphere for a month or more, I would expect...we will see...

[snowking]

 

Scandi Block > Atlantic Ridge > -NAO

Classic retrogressing Scandinavian high signal (even though I suspect the retrogression will be slightly slower than that)

[sebastiaan1973]

The cluster with easterly winds is growing.

[Phil Blake]

33 minutes ago, Doctor96 said:

SST  North sea 

 

i do not post much , but every month in winter I watch the north sea temperatures and tonight there have been quite a few comments on the north sea temperatures. 

I have no doubt that the SST for north sea at the moment is colder than average .  However some of you have shown graphs with anomaly warmer and others colder . you need to see what is the comparison . if the comparison is to 1971-2000 then we are about in line but for the period post 2000 we are colder no doubt.  Usually we see temps of around 5 c in  march , not in late January for parts of North sea.

I reckon with the temps being still low we will see the sst  get lower and this will make east cost weather more snowy and less marginal in february.

 

 

Current temps are about 6 or 7c. It will naturally get colder quicker closer to the coast as the sea is shallower 

Edited January 28, 2021 by Phil Blake

[Griff]

3 minutes ago, Mike Poole said:

ECM clusters T192-T240, and I like these:

It’s kind of what kind of blocking would you like, rather than is there going to to be blocking.  The borders tell a story, it’s what ECM think the wider pattern is, green is -NAO, red is Scandi block.  And red is the way they are going - this is great, at this time in late winter, a scandi block and easterly winds will deliver more than a Greenland block and northerly.  It’s the other way around in early winter.  

Keeping my eye on the strat situation, I’ve posted the NAM chart all winter, here’s today and it gives a good visual indication of the story so far:

You can see the downwelling, the blip where tropospheric conditions were not conducive, and then in the forecast the landing zone (MJO big help in that , i think) and up top the resurgent westerly winds shown in yellow will only enforce that increased likelihood of easterly winds in the troposphere for a month or more, I would expect...we will see...

That plot show it nicely, Judah Cohen had something similar (his arrows were yellow). I didn't get what he meant about how they usually go down but in this case started down (blue) then went back up. This is more promising. 

[Nick F]

42 minutes ago, ICE COLD said:

Right at the top end of the pack and a mean easterly at days 9 and 10 . Some ens also breaching the magical -10 mark towards the end as well . Everyone breath

Odd why the EC often churns out a deterministic run that is at the mild end of the ens spread, 12z on the mild limit most of the ens spread.

12z EPS mean mslp showing a Scandi high and Genoa low at day 10, that's good enough for me ...

Oh, and while I'm at it, that's anomalously cold air at 850 hPa in the means at day 10 too

Edited January 28, 2021 by Nick F

[Griff]

2 minutes ago, Griff said:

That plot show it nicely, Judah Cohen had something similar (his arrows were yellow). I didn't get what he meant about how they usually go down but in this case started down (blue) then went back up. This is more promising. 

He also added this for further interest today... Credit Judah Cohen FYI. 

[Mike Poole]

4 minutes ago, Griff said:

He also added this for further interest today... Credit Judah Cohen FYI. 

Actually, not sure he’s showing the same thing I was, this might be the cap height?  I was showing the NAM.  There may be a correlation though!

Not sure, I haven’t read Cohen’s blog since March, the link to it is on my office computer.  I haven’t been into the office since March!

Edited January 28, 2021 by Mike Poole

[Jayfromcardiff]

32 minutes ago, Tim Bland said:

‘We’ being those it’s unlikely to affect? I’m sure those in west mids and Wales are still very interested ...

Possibly even the SW if it corrects further South. 

[Griff]

2 minutes ago, Mike Poole said:

Actually, not sure he’s showing the same thing I was, this might be the cap height?  I was showing the NAM.  There may be a correlation though!

Who knows, his was about down welling from ssw I think

 

[stodge]

Evening All

A pleasant day in lowland East London with a little afternoon sunshine and temperatures at 12-13c so very decent for the time of year. As ever, winter is the battle between colder and warmer airmasses and after recent years when the mild held sway with the cold held well to the north or east, this season has, perhaps because of the antics in the stratosphere, has seen the battleground much closer to home.

The immediate future demonstrates this with another brief cold snap at the weekend for the south while the north and especially the far north of Scotland seems set to remain cold with the milder air never fully reaching higher latitudes. Another milder push early next week but towards next weekend clear signs of another change and perhaps, just perhaps, a more significant colder spell. 

Let's see what tonight's obfuscations leaves us:

12Z GEM: T+120 takes us to Tuesday February 2nd by which time the cold snap of the weekend has receded with Atlantic frontal systems moving in ahead of two areas of LP to the west and south-west of Ireland linking back to another LP much further west. Weak heights to the north east at this time and milder air with positive uppers across most of Britain with only the far north still in colder air with 850s below -4. From there, upstream amplification develops with heights building from north to south in mid Atlantic forcing the trough east over the south of Britain with a NE'ly setting in for northern parts and a cyclonic air flow further south. Colder air has pushed south by T+180 with uppers of -4 or below over northern England and colder air over Scotland. From there, heights continue to develop to the north and by T+240 an anticyclonic cell is over Scotland with a ridge south west and LP over the northern Adriatic. Hints perhaps of the Atlantic trough trying to move round the top of the HP to the west of Iceland. 850 of -4 to -8 cover the British Isles though the coldest air has passed to the south.

A cold evolution from GEM.

12Z GFS OP - at T+120 not hugely different from GEM - slight difference in the orientation of the Atlantic trough and heights a smidgen more pronounced to the south. As with GEM, positive uppers over the south and west of Britain with colder air confined to the north at this time.  Moving on and the impact of the upstream amplification becomes clear as the trough is pulled east and south and by T+180 is to the west of Brittany with a NE'ly airflow over the British Isles. Cold air with uppers below -8 for many areas with the mildest air confined to the far south.  Moving on and the NE'ly flow eases away south as heights build across the British Isles with HP centred over England by T+240 but clear signs of the Atlantic trough trying to push back towards Iceland trying to re-introduce a milder air flow. Uppers below -8 confined to southern and eastern areas by this time.

GFS OP brings in the cold but it looks a short-lived snap rather than a prolonged spell unless we see the ridge head into Scandinavia.

12Z Parallel - at T+120 small variations against the OP but nothing too significant to my eye. Again, we see the push of milder air to most parts of the British isles but colder air hangs on in north and north east Scotland as well as the northern isles.  From there, as we've seen elsewhere, heights build from the north and the trough is pushed east and south - by T+180 a weak LP is over south-east England and the HP to the north ridges south west against the new Atlantic trough. The lost of the positive 850s have eased away from the south and uppers of -4 or below for northern areas and even colder air trying to come into Scotland on an ENE'ly air flow. Moving on from T+180 and heights continue to develop to the north and by T+240 a block has formed over Scandinavia with a ridge to Iceland and Greenland. Between that and residual LP over Europe, a strong E'ly flow has established over the British Isles albeit with the origin further south. That means the coldest air is over the north of the British isles with positive uppers approaching from the east and south east (strange as it may seem).

Parallel brings in synoptics which by T+140 you'd think would be nirvana for coldies but the air isn't sourced from Siberia but from the Middle East so it's significantly warmer than you might imagine. Curious but fascinating synoptics - a warm E'ly in February - who'd have thunk it?

12Z ECM - by T+120 the trough is less elongated than on other models and orientated slightly more positive but the upstream amplification looks to be in place. The 850s look similar, +4 uppers across parts of the south but uppers below -4 in the far north and north east. From there, ECM goes off on its own - the trough starts to move east but the upstream amplification struggles as the two Atlantic troughs try to phase and a residual LP sits to the west of Iceland as heights build from the Azores and over Scandinavia. 850s of zero to -4 for all parts of the British Isles by T+192. It's a messy evolution if I'm being honest and I don't quite see how this small residual LP holds against the heights moving down from the north. From there, we reach T+240 with a chart more like midsummer than February. Heights over Scandinavia and Greenland but somehow the British Isles dodges a cold evolution with milder uppers coming back over Ireland as colder air sits to the east but there's no real momentum for anything on that chart.

I'll be honest - I just don't understand the ECM evolution at all so it's the bin for this in my view.

Looking at the T+312 (Feb 10th) and T+384 (Feb 13th) charts for both GFS OP and Parallel tonight:

Both interesting in their own way - GFS OP keeps a blocked pattern throughout and threatens a N'ly incursion at the very end while Parallel collapses the block and goes back to a more stormy pattern but with the jet running close to southern Britain so the north stays cold even as the south becomes a little milder. Control is horrible for cold fans with northern blocking shifting south and forming a European HP allowing a long-fetch SW'ly to set up.

The 10 HPA charts show little interest in further warmings into February as the PV consolidates albeit much warmer than usual.

Conclusion: It does look as though after next week's brief milder spell we will see another push of colder air from the north at the end of the first week of next month. How long that lasts and how severe that might be are all very much up for grabs. GEM and GFS OP are quite promising and Parallel does well for a while but ECM isn't convincing and GFS Control rapidly collapses any block for a European HP so it's all very much in the balance tonight. I really don't know whether we'll see a snap or a spell - can the HP either build NE or NW or will it sink?

 

 

 

[Allseasons-Si]

A look at the anomalies...

WHOOOOSH!!...

but we have to be careful of those SE'ern European heights?

the De-built ecm ens

this morning v's this evening's and there is more NE'ly ens showing in the ext

the tactile shows that there was a push towards the UK with heights the other day but now they are starting to move to the NW,remember these only go out to 192

The EPS ext has mostly all blocking(red boxes)

and,...the ECM was somewhat a mild outlier

lets see if this traction can be maintained or even upgrade

 

 

Edited January 28, 2021 by Allseasons-si