Model output discussion - deep cold inbound?

[kold weather]

Well just for a little ramp, I present the snowiest ECM ensemble member for the majority of the country I can find out to 6pm on Wednesday:

Widespread 15-20cms, and several areas above a 1ft!

Lets get the prayer beads out and pray for this one to be a winner. Even I manage a sweet 23cms!

[Kentish Snowman in Yorks]

Two points regarding the posters commenting on the breakdown shown at the end of the ECM run.

1)  Between Sunday and Wednesday we are almost certainly looking at a stonking Easterly with bitter winds and more than likely copious amounts of snow in many areas so many of us wouldn't complain about a bit of milder weather after a spell like that?

2)  Anybody hoping for that milder weather towards the end of next week is likely to be disappointed!  It is often the case that model runs underestimate the strength of the colder air once in place and it is often harder to shift than modelled.  All the while the Met Office is calling for fronts from the West struggling to make headway across the UK I would treat any swift breakdown shown on the models with caution.  Some breakdowns get very messy (snowy) and then the milder air just admits defeat and dives South.

All in all much to be positive (excited) about if your a coldie so let's strap ourselves in and enjoy the ride!

❄?❄?❄?

[phil nw.]

23 minutes ago, nick sussex said:

This thread is a hoot. 

As night follows day this is the series of events.

Cold spell shows up , models chop and change , panic ensues , models start firming up on the cold then a few chuck in a breakdown a bit too early  , panic then ensues instead of relief that the cold spell might actually land .

 

It was ever thus Nick.Looking like we can follow this in now on the UKMO fax and raw charts and similar s/r models,as i said earlier.

It is now better to follow these little near time tweeks on these,but it is comforting to see solid agreement that by the weekend the cold will envelop the whole country with many areas seeing snow from then into next week.As i said earlier look out for future developments in this cold unstable flow,once it's establishes.I would expect short notice snow warnings.

My favourite output this evening is the UKMO out to t144.A strong easterly flow establishes with troughing to the south extending quite far east into W.Russia.

As it's day 6 it can still change somewhat but this is the best type of evolution to refresh our cold pool as this setup starts to draw the bitter Siberian cold west as can be seen on the 850's chart.

Little point in focusing further on as modeling will not be able to pin down the strength and angle of attack of Atlantic lows at this distance ,nor indeed the influence of any heights,wedges that may crop up to the north.

Let's savour what's coming up in the next week or so and enjoy.We don't see this very often.Great model watching.

[Youcan'tbecirrus]

24 minutes ago, Speedbird said:

that's exactly what i mean, Steve

Streamers are the product of convection 

I'll be happy to join in with some streamers.

[The Bevmeister]

6 minutes ago, Cold Winter Night said:

The snow and cold ultimately isn't directly the result of the SSW, but the pattern that delivers it very likely is.
In tandem with an already weak tropospheric and stratospheric polar vortex, and an MJO that helps too.

Labelling patterns with 100% certainty is not possible, but the least you could say is it is very consistent with patterns that follow SSWs about 35 days after they have happened.

So it is historically consistent with the way models have appeared after such an event then I guess.  Great answer and thank for upping my very amateur knowledge

[Speedbird]

1 minute ago, Youcan'tbecirrus said:

I'll be happy to join in with some streamers.

You should be in a good place

 

[Tim Bland]

3 minutes ago, kold weather said:

Well just for a little ramp, I present the snowiest ECM ensemble member for the majority of the country I can find out to 6pm on Wednesday:

Widespread 15-20cms, and several areas above a 1ft!

Lets get the prayer beads out and pray for this one to be a winner. Even I manage a sweet 23cms!

Are there many members that prolong the cold out to day 10? 

[chris55]

22 minutes ago, CreweCold said:

Hard to see how we deflect that Atlantic barrage without keeping some heights to our immediate N or NE

Seeing as the breakdown is at day 7, Im thinking we may need a few more runs to check and nail down the evolution of the outcome. I'm not discounting a quick return to a more Atlantic type, but it'll take a lot more runs until we can be confident.

[Kreftysoton]

35 minutes ago, Eastbourneguy said:

The low is ever to slightly too far north for coastal counties in the south on the 12Z ECM according to the raw output. But it's go time 30miles or so inland!

Been like that all winter! Actually most winters...

[Matt H]

ECM 12z ensemble mean is fantastic again this evening. We’re so close to experiencing some memorable weather now!

t96:

t120:

t144:

 

 

 

Edited February 3, 2021 by Frosty Winter

[danm]

18 minutes ago, Mike Poole said:

I really can’t see this breakdown scenario any time soon.  I know the models show it, they always do, but it will correct.  The background signals portend a longer period of cold as per my post above, that might or might not come to pass, but this is due to the SSW, and there has been close to another one since, so maybe weather on the ground will be driven by this for 4 weeks or more...those saying it is a 5 day affair are wrong in ,my opinion, but we will see...

Even if it were just a 5 day event - five days of bitterly cold and snowy weather? I’d be over the moon with that. A December 2010 style extended big freeze is exceptionally rare in this country. 

[Youcan'tbecirrus]

3 minutes ago, Speedbird said:

You should be in a good place

 

If I am I'll look out my front window and wave. I can see Leigh from here.

[Bricriu]

40 minutes ago, bluearmy said:

It’s generally like that ..... understandable because that’s what the models are showing 

Never understood why people look forward to a snow to rain event ....even if it stays as snow the positive Dp’s that follow mean the snow so. becomes slushy and drip drip drip

the renewed easterly delivers some troughs and snow plus more to follow ....

It's not a question of looking forward to it as such, but if you live in a region that gets next to nothing from an easterly, you'll welcome the chance for snow even if it will drip drip afterwards. Also these frontal situations can lead to significant snowfall before the thaw sets in.

Edited February 3, 2021 by Bricriu

[kold weather]

So remember that ensemble member I couldn't resist showing a short while ago...

Yeah...it gets better!

Just for reference, the area from Sheffield down to London and across to Bham is 30cms!

Peak depth is around 50cms!

Well, thats my ramp for the day done!!

[sparky1972]

hi guys, great to read the positive vibes regarding the potential upcomming cold spell, we all know though that if it can go wrong it will go wrong so what potential flies in the ointment if any are the models showing that could scupper the uk getting the cold in? 

[sunnijim]

12 minutes ago, kold weather said:

Well just for a little ramp, I present the snowiest ECM ensemble member for the majority of the country I can find out to 6pm on Wednesday:

Widespread 15-20cms, and several areas above a 1ft!

Lets get the prayer beads out and pray for this one to be a winner. Even I manage a sweet 23cms!

Allow me some imbysm here,but no thanks! I have a particular set of requirements for snowfall on the Sussex coast and that scenario ain't one of them!

Imo highly unlikely to come off anyway,as has been said already,the blocking is being underestimated tonight and probably will be for a couple more days.

Edited February 3, 2021 by sunnijim

[Mike Poole]

ECM 144 and T240 mean:

T144 is what we know, but the signal is lost in the T240, so I looked at the uncertainty, the spread, and it is massive, and everywhere, the models just don’t know what to do beyond day 6. Apart from the high lat block regions of course...

[Scandinavian High.]

Is there any chance of a thames streamer setting up across south London we normally do quite well thanks.

[jacke]

48 minutes ago, mbrothers said:

Suddenly this thread had become the ‘when will the cold spell that hasn’t arrived yet breakdown thread’ .

Please let's have a bit of the cold before all discussion on here relates to the breakdown! Goodness,still looking at ever changing charts for the next 4-5 days first.

[bluearmy]

 

Not a bad day 6 mean .....

[Paul_1978]

1 hour ago, DAVE_ALLEN said:

Just imagine.... If this did that  

If you look at the 0z ECM from last night it pretty much did that. Alas not on the 12z though.

Edited February 3, 2021 by Paul_1978

[rug]

4 minutes ago, kold weather said:

So remember that ensemble member I couldn't resist showing a short while ago...

Yeah...it gets better!

Just for reference, the area from Sheffield down to London and across to Bham is 30cms!

Peak depth is around 50cms!

Well, thats my ramp for the day done!!

Oh my, that is just beautiful.

[chris55]

51 minutes ago, nick sussex said:

This thread is a hoot. 

As night follows day this is the series of events.

Cold spell shows up , models chop and change , panic ensues , models start firming up on the cold then a few chuck in a breakdown a bit too early  , panic then ensues instead of relief that the cold spell might actually land .

 

No Panic here Nick, just a few charts and some commentary.  

 

Edited February 3, 2021 by chris55

[Lukesluckybunch]

2 minutes ago, sparky1972 said:

hi guys, great to read the positive vibes regarding the potential upcomming cold spell, we all know though that if it can go wrong it will go wrong so what potential flies in the ointment if any are the models showing that could scupper the uk getting the cold in? 

Well that risk appears to be diminishing as we are getting closer to the cold arriving.but wrap around from the lows to the South could become an issue in pulling up warmer air from southern Europe this is most likely to affect the southeast.but this is looking not likely currently.

[Speedbird]

2 minutes ago, Scandinavian High. said:

Is there any chance of a thames streamer setting up across south London we normally do quite well thanks.

Yes, there is every chance provided there is a sufficient ene/e feed (which there is forecast to be)