Model discussion - hunt for cold - Christmas countdown

[nick sussex]

What drama!

The GFS and UKMO are converging on a shortwave ejecting across southern parts day 4 into 5.

Upstream though there are some major differences with the trough set up.

The GFS amplifies the troughing which blocks the high from escaping west , the UKMO has the flatter shallow troughing with the high moving west .

Of course given all the chopping and changing over the last few days I doubt we’ve seen the last of that .

Edited December 21, 2021 by nick sussex

[That ECM]

Remember the gem a few days back? Good output this morning.

[Kasim Awan]

Come on ecm. Do us proud just this once. Even if your 12z is mild.

 

Edited December 21, 2021 by Kasim Awan

[fromey]

4 minutes ago, Coxxy657 said:

im actually excited to if the ecm comes back in line with the others lol

That will pass! Trust me

[Chesil View]

3 minutes ago, s4lancia said:

The beauty about living on the the south coast is your expectations are so low, no matter what! Even down here there has to be back edge snow possibilities from this, notwithstanding the potential this could trend further south still, if the block has been underestimated.
Whilst this continues to be an utter bonkers period of short term model output, I remain at an utter loss as to direction of travel through the New Year period. Better signs regards longevity this morning though, long may that continue.

Certainly shows how much the charts have improved over the past 24 hours if we are worrying about mild sectors

All the best snow events tend to be marginal affairs, high fish reward and all that. Every year me and @Broadmayne blizzardI wheel out this chart to show it isn’t always about low 850 temps, now seems a good a time as any…

This reasonably innocuous looking chart produced over a foot of lying snow and monster drifts for my neck of the woods. A true battleground royale.

One other point before the ECM gets going, I’ve seen a few comments in recent days referring to wind direction that have been wrong. It’s worth remembering the general rule that winds flow into a low pressure and away from a high. The correction from the isobars is normally about an 1/8, depending on factors.

Lol. Yes S4L. I must have posted that chart at least ten times over the years to disprove some ridiculous assertions about uppers required for snow when a dry continental feed is pulled in by a channel low.

 

[Jason M]

Good charts for most this morning. I think we’re now starting to firm up on which areas will def miss out though. I think the far S and SE are now out of the game for Xmas day. Could change but but the GEFs are 100% agreed on this and I’ve barely seen any chart bringing these areas into the fray. For Boxing Day the south comes more into things but if I had to pick an area that could miss out completely it is the far SE. I think we might end up too near the low and for the area SE of London (Kent, Essex, East Sussex) we might get nearly all rain. Weirdly the last few winters have seen a lot of this and I’ve lost count of the number of times this has happened in recent years.

so looking much better for most than this time yesterday, but with proviso for the unlucky few in my area that we may be watching it on the news rather than through our windows.

[mulzy]

ECM fairly meh at day 4.  The little runner at the base of the low is very shallow.  Let's see how it pans out but I'm not that confident myself.

Edited December 21, 2021 by mulzy

[Kasim Awan]

1 minute ago, Jason M said:

Good charts for most this morning. I think we’re now starting to firm up on which areas will def miss out though. I think the far S and SE are now out of the game for Xmas day. Could change but but the GEFs are 100% agreed on this and I’ve barely seen any chart bringing these areas into the fray. For Boxing Day the south comes more into things but if I had to pick an area that could miss out completely it is the far SE. I think we might end up too near the low and for the area SE of London (Kent, Essex, East Sussex) we might get nearly all rain. Weirdly the last few winters have seen a lot of this and I’ve lost count of the number of times this has happened in recent years.

so looking much better for most than this time yesterday, but with proviso for the unlucky few in my area that we may be watching it on the news rather than through our windows.

South still fully within possibilities

[Captain Shortwave]

This should be ok by Boxing day, the Atlantic low beginning to interact with the trough to our east and will be squeezed south by the weak heights to the north. Not as good as the UKMO at this time but for reference the cold air is further south at 1am Christmas day on this run than it was at 13:00 on the previous run.

Alternatively the low could effectively just stall in situ..... 

 

Edited December 21, 2021 by Captain Shortwave

[Kasim Awan]

1 minute ago, Captain Shortwave said:

This should be ok by Boxing day, the Atlantic low beginning to interact with the trough to our east and will be squeezed south by the weak heights to the north. Not as good as the UKMO at this time but for reference the cold air is further south at 1am Christmas day on this run than it was at 13:00 on the previous run.

 

Good to see the ecm catching up to the gfs and not the other way round this morning tho.

[Duane S.]

Apples for apples comparison in just 24 hours…

[Kasim Awan]

Just now, s4lancia said:

Apples for apples comparison in just 24 hours…

Ecm is behind

[Cheshire Freeze]

ECM needs to be a tad colder. 0c isotherm for the 850s is too far N for the majority of England on 25th and into the 26th

[mulzy]

1 minute ago, CreweCold said:

ECM needs to be a tad colder. 0c isotherm for the 850s is too far N for the majority of England on 25th and into the 26th

Indeed CC, a mild (10C) is guaranteed for the south on Xmas and Boxing days if ECM verifies.  Worst of the solutions up to day 5 this morning. 

[Kasim Awan]

1 minute ago, CreweCold said:

ECM needs to be a tad colder. 0c isotherm for the 850s is too far N for the majority of England on 25th and into the 26th

Ecm trending gfs way so it's likely underdoing it as not caught up yet

[Jason M]

1 minute ago, Kasim Awan said:

South still fully within possibilities

Nothing is impossible but I’d put a 10% probability on that for Xmas day. For late afternoon Boxing Day it’s more 50%. In the far SE though I think it’s lower at perhaps 30%. The cold air will get here but I’m expecting it to be painful. The control run is fantastic and might well be where we end up. That’s just days of rain in the far SE though. Geographically we’re a tiny area but a highly populated one so it’s worth mentioning. For most though it’s looking more promising. 

I remember the good old days when we could get uncomplicated easterlies via a Scandi high. 

[smith25]

Just now, Kasim Awan said:

Ecm trending gfs way so it's likely underdoing it as not caught up yet

Should catch up tonight hopefully I think.

[Duane S.]

6 minutes ago, Kasim Awan said:

Ecm is behind

Possibly, yes, my take it is as well.

My post was more to show how much better the EC looked compared to yesterday’s 00z, trending the right way…

[jvenge]

7 minutes ago, CreweCold said:

ECM needs to be a tad colder. 0c isotherm for the 850s is too far N for the majority of England on 25th and into the 26th

Yep - ECM is giving rain for the period where GFS shows snow. 

[That ECM]

T120 and they can’t agree on the strength of the block.

[Fozfoster]

Well after Thursday Friday Saturday temperature rise (no snow for us in midlands) it’s looking like a cold snap out until New Year’s Eve. 

[Kasim Awan]

3 minutes ago, jvenge said:

Yep - ECM is giving rain for the period where GFS shows snow. 

Ecm has been allover the place

Gfs more credible atm

Edited December 21, 2021 by Kasim Awan

[mulzy]

ECM = pants.  Next!

Note:  might get some decent amplification in FI but for the period that most people are interested in, it's poor.  no point sugar coating it.

Edited December 21, 2021 by mulzy

[TSNWK]

As I said yesterday ECM is big beast!  think oil tanker.. she will turn slowly...

Todays 96 looks much better than yesterday 120 synoptic wise.  

 

[frosty ground]

2 minutes ago, Kasim Awan said:

Ecm has been allover the place

Gfs more credible atm

Why? 
 

it’s only more credible because it’s the solution you want to see, we usually meet in the middle in these circumstances.