Model Output Discussion - Snow for some, but what else is in store?

[phil nw.]

The truth is nobody can be certain of how this evolves outside the next few days.We are in a completely non-typical NH pattern following the ssw with further warmings imminent so it's quite likely the furniture will be moved around again.

The way i see it is we have a southerly tracking jet with the UK on the borders between the deep cold  and the warmer Atlantic air masses.It's already been commented that the latest T72 fax shows a stalling front across N.England and by the looks a cleaner flow from the ne across the north.

Added to this we have all the outputs showing colder air coming south from day 5.Indeed the UKMO has the -10c upper line approaching the North of Scotland.

Now how easily will a weak southerly jet shift that cold air mass as the next Atlantic low comes across?

Mean charts are a useful guide in many setups but in this knife edge pattern for snow chances for the UK then the short term model operationals and  the UK fax- are the best guide where changes are likely to the boundary.

I certainly think we should hold back more than usual on judging anything modeled beyond the end of next week.

 

[Djdazzle]

13 minutes ago, MJB said:

Why April ? Where are your facts to support that ? 

The post I quoted mentioned that the effects may not be felt until then.

[Kentspur]

3 minutes ago, Don said:

I think you mean 2013?  

Predictive text is a pain!

[chionomaniac]

14 minutes ago, feb1991blizzard said:

I wanted the SSW (against your better judgement), reason for that is we just were not getting anywhere with uppers, cold rain from usually banker airmass sources, but only wanted a split, once that stratospheric wave was in the Atlantic and it wasn't a proper split, i thought there would be residual shortwave energy to the NW, i was wrong, there now looks to be a worse case scenario of low after low just barrelling through us, i have noticed this before with non perfect but interesting strat events, the models still promise greatness for a while but they all then back off in the space of a few runs, i wonder why this happens, even the EPS a while back had a large cluster with max's of freezing  or 1c for London.

It wasn’t against my better judgement. My concern was that if we achieved a displacement only SSW then we could be left in this type of scenario. But there was enough indication at the time to suggest a split would also occur and we wouldn’t. It didn’t and that’s c’est la vie. All throughout the SSW things have not been clear cut. And I suspect that will occur for a while. It is hardly like the strat is overwhelmingly dominating the trop. In fact, when we look at the T+240 ECM NH chart we still see one disrupted pattern, but not in our favour.

edited to show chart

Edited January 16, 2021 by chionomaniac

[Don]

3 minutes ago, chionomaniac said:

It wasn’t against my better judgement. My concern was that if we achieved a displacement only SSW then we could be left in this type of scenario. But there was enough indication at the time to suggest a split would also occur and we wouldn’t. It didn’t and that’s c’est la vie. All throughout the SSW things have not been clear cut. And I suspect that will occur for a while. It is hardly like the strat is overwhelmingly dominating the trop. In fact, when we look at the T+240 ECM NH chart we still see one disrupted pattern, but not in our favour.

Perhaps further warmings/disruptions to the pattern will place us in a better position at some point but all ifs and buts at the moment?

Edited January 16, 2021 by Don

[Vikos]

1 minute ago, chionomaniac said:

 In fact, when we look at the T+240 ECM NH chart we still see one disrupted pattern, but not in our favour.

This can change. Signals are given. And those are not yet to be found on deterministic outputs.

[Allseasons-Si]

Evening all

i must say that i am a little bit skeptical at the moment looking at the latest anomalies and they are now backing away from a  NW'ly solution to a westerly and i fear this block to our N/NW is too far N/NW  after the initial cold shot later next week

  

 

looking at the tactile you can see the block further to the SW but still maintaining a -nao,the EPS/ext EPS still shows the block to our N/NW but these also show that they are too far N/NW and we are stuck with lower heights over the UK with the added danger of ridging from the SW

  

and looking at the gefs ens it is looking increasingly unsettled but possibly turning colder as we enter Feb and this could be influenced by the MJO going into phase 6/7,so a relaxation of the cold maybe until we await the mjo cycle to push through the COD(circle of death)then into phase 6/7

this is all a bit of a guessing game as you and i know past next week and the models do change quite a lot from now until then

so stay tuned and don't have nightmares

Edited January 16, 2021 by Allseasons-si
typo

[Don]

45 minutes ago, Mike Poole said:

So either this entire ensemble suite is wrong, or the cold spell is up in smoke.  I think the entire suite is wrong and the UKMO is right, but we will find out in the next day probably. 

Just to add, knowing our luck the UKMO will probably flip to a poor outlook tomorrow while the GFS/ECM flip to something more positive!  Wouldn't surprise me lol!

[summer blizzard]

I'd not get as despondent as some are. Although it's true that SSW's can disrupt an already good pattern we would be pretty unlucky to get more than a transient period of poor weather while such winds remain weak, the bigger danger in my opinion (especially with a displacement) is that we default to the La Nina pattern afterwards (so more towards mid feb).

I would look for the current mean west based NAO to retrogress over time bringing our mean low over Scandi west, thats an unfavourable outcome in the short term but if we keep weak zonal winds it should provoke more blocking to the east.

[Mike Poole]

1 minute ago, Vikos said:

This can change. Signals are given. And those are not yet to be found on deterministic outputs.

Agreed, I think the ECM ensemble position is just wrong. And obviously prepared for the flak if it isn’t! 

[chionomaniac]

2 minutes ago, Vikos said:

This can change. Signals are given. And those are not yet to be found on deterministic outputs.

Yep. Exactly. I would not write anything off at the moment still.  It is hardly as if the strat vortex has cranked up yet giving us more reliability in the forecast. So, just because the models are offering one solution on the table, it is just one of many that could become reality. 

[Vikos]

1 minute ago, Mike Poole said:

Agreed, I think the ECM ensemble position is just wrong. And obviously prepared for the flak if it isn’t! 

We talked about ENS and their strongs and weaks already

Let's wait for those 12z EC scenarios, they will be available within one hour or so. I am quite excited....

[Vikos]

1 minute ago, chionomaniac said:

Yep. Exactly. I would not write anything off at the moment still.  It is hardly as if the strat vortex has cranked up yet giving us more reliability in the forecast. So, just because the models are offering one solution on the table, it is just one of many that could become reality. 

Well, in synoptics, one never writes anything off or on Synoptic "freaks" (try to) predict, and if they found to be false, they just say, ehh, its a chotic system, you never know, sorry

I had posted some howmöllers over to @bluearmy but got no response yet. I found them to be lets say promising. Matchday forme around 25th, after that storm low moved on.

[Mike Poole]

2 minutes ago, Vikos said:

We talked about ENS and their strongs and weaks already

Let's wait for those 12z EC scenarios, they will be available within one hour or so. I am quite excited....

No guidance from them Vikos my friend, T192-T240 has just the one cluster, and it is bad vibes when that happens:

Only comment I’d add is that the middle one looks a bit like a clown!

Point is, nobody has any idea how this is going to pan out, ECMWF included...we will see...

[Vikos]

10 minutes ago, Mike Poole said:

No guidance from them Vikos my friend, T192-T240 has just the one cluster, and it is bad vibes when that happens:

Only comment I’d add is that the middle one looks a bit like a clown!

Point is, nobody has any idea how this is going to pan out, ECMWF included...we will see...

LOL! Made my day! That clown reference

I will post those Scenarios as they give a bit more informations on NAO and stuff...

And check your PM's

EDIT: FU (not that what you think, dude!) Berlin is where I put my money on.

Edited January 16, 2021 by Vikos

[Don]

3 minutes ago, Vikos said:

LOL! Made my day! That clown reference

I will post those Scenarios as they give a bit more informations on NAO and stuff...

And check your PM's

 

All three look like clowns to me......

[chris55]

9 minutes ago, Mike Poole said:

No guidance from them Vikos my friend, T192-T240 has just the one cluster, and it is bad vibes when that happens:

Only comment I’d add is that the middle one looks a bit like a clown!

Point is, nobody has any idea how this is going to pan out, ECMWF included...we will see...

I'd be interested for the experts to add a bit more information  on the single cluster scenario from ECM.

It has shown this a few times in the last few days.

My understanding is the the spread is so wide within a smaller envelope, that the clusters just say 51 members agree?

While this may be more useful on an entire NH perspective, its essentially useless when trying to decipher a boundary line over the UK when the jet is tracking south. 

Essentially, its not a very useful forecast tool in the current set up? Right or wrong?

 

[Don]

18 minutes ago, Vikos said:

EDIT: FU (not that what you think, dude!) Berlin is where I put my money on.

Yes, there's that nagging feeling tonight.  Wonder what the pub run will give (or not)?

Edited January 16, 2021 by Don

[Mike Poole]

GFS T6:

I’m not posting this as a joke, the nothings changed gag etc.  But there are thing on this chart as it is roughly now, that are worth noting. 

• Vortex contained as far way as possible.
• Arctic high in play. 
• No strong jet across the Atlantic.
• Trough in Italy we could feed into.
• IT IS SO CLOSE.

[Don]

2 minutes ago, Mike Poole said:

• IT IS SO CLOSE.

But no cigar, soo frustrating! 

[Vikos]

5 minutes ago, Mike Poole said:

GFS T6:

I’m not posting this as a joke, the nothings changed gag etc.  But there are thing on this chart as it is roughly now, that are worth noting. 

• Vortex contained as far way as possible.
• Arctic high in play. 
• No strong jet across the Atlantic.
• Trough in Italy we could feed into.
• IT IS SO CLOSE.

That shifted azoric high...

[Mike Poole]

Just now, Vikos said:

That shifted azoric high...

I don’t think of the Azores high as a driver, it will shift when the pattern shifts!

[swfc]

OK!!! Seems things to be escalating tonight on here, very twighlite zone esq atmosphere Anyway the uncertainty for me is in a way a good thing strangley. There's no raging PV, artic high meandering, Atlantic high pushing north and a jet that's more confused than scooby doo. Plus the ramifications of a SSW to add. I'm quite optimistic that the nhp and output will be throwing many a spanner into the works but nothing is certain even in the ec envelopes ete. Changes can be swift altho the 500mb charts don't suggest it. Relax and see how it pans out

Edited January 16, 2021 by swfc

[Don]

7 minutes ago, Mike Poole said:

I don’t think of the Azores high as a driver, it will shift when the pattern shifts!

I think the latest monthly CFSv2 is showing strong northern blocking for February.  However, the downside is it's also showing heights dominating to the south too!

Edited January 16, 2021 by Don

[Matt H]

Looks like there’s the potential for a named storm next week and a lot more rain for some areas that really don’t need it at the moment after the flooding recently. Definitely something to watch.