Model output discussion - here comes the beast!

[Summer Sun]

ECM mean looks more marginal in the south compared to last night

[Summer Sun]

1 minute ago, Nizzer said:

Shouldn't you be comparing tonight's 96 with yesterdays 120?

It was my error I have edited the post

[Guest]

2 minutes ago, Summer Sun said:

ECM mean already shifting the cold air much further north than yesterday's run (right)

They're a day apart. In any case I think the trend to see cold air squeezed a little north by the end of the working week is pretty clear. What isn't clear is what the low does once it reaches the south coast. Does it stay to the SW and drag milder uppers over the UK a la the ECM op? Does it stall to the south giving copious amounts of snow in places before filling out? Does it stay to the south and then east of the UK prolonging the cold but reducing the chance of southerly blizzards?

This mean won't help us answer these questions just yet. More runs needed - we are in FI territory here after all.

[Eastnorthwest]

Evening each

I say again look at the next 5 days ,and all the models are more or less in agreement ,severe cold ,snow heavy for some ,and  a hint of a battle ground set up by next weekend which will see either more prolonged heavy snow for southern half of the British Isles or the north with less cold air to the south which I say will change probably change again tomorrow

The models are usually hopeless at predictING  cold continuing beyond 5 days and what we are witnessing tonight is just that

So let's enjoy the coming 5 days and ignore the beyond cos I don't believe it will be all over that quickly 

[warrenb]

Was it not last Saturday when the models had a big wobble.  Data going in will be different at weekends, different flight data and 5 day a week data sources

[Paul]

Just now, warrenb said:

Was it not last Saturday when the models had a big wobble.  Data going in will be different at weekends, different flight data and 5 day a week data sources

In all seriousness, that theory is a non-starter, there's no evidence for it, and there'd be plenty if it was even a possibility. 

[Captain Shortwave]

The trend today has been to take that cold pool through the UK at a much faster rate, this allows it to break up somewhat so we end up with two separate cold pools.

   

Todays day 6 vs yesterdays day 7 from the ECM

That separation on the low heights means we lose the clean easterly at this point and pick up less cold air from the Meditaranean and allows the low to barrel around to our south west. Ultimately we need to keep that feed of lower thicknesses to keep the easterly going and keep the low moving ENE towards France instead of spinning up towards the UK or even further west.

Still even if we see a breakdown here, it would go out with a bang with strong to gale force ESE winds whichwill likely mean that the majority of the precipitation will be of snow before less cold air tucks in behind, add to that the front could very well stall somewhere across the country with areas noth of this staying cold and of course areas underneath the run could see snow for a prolonged period of time.

A lot to be resolved here still.

Edited February 24, 2018 by Captain Shortwave

[steveinsussex]

what do the ensembles show ?

[Djdazzle]

1 minute ago, warrenb said:

Was it not last Saturday when the models had a big wobble.  Data going in will be different at weekends, different flight data and 5 day a week data sources

Isn’t that the argument that gets dragged out around Christmas every year?

ECM mean not looking as good. Is the op at the top end?

[khodds]

1 minute ago, warrenb said:

Was it not last Saturday when the models had a big wobble.  Data going in will be different at weekends, different flight data and 5 day a week data sources

Yes - I believe so. There was a fantastic post from Bring Back Winter a page or so back... have people not read it?! If not, you should!!

[ScottishSnowStorm]

Isn't there going to be a point in the models once the block pattern is in the reliable they start to look for the breakdown but it doesn't mean they are right?

[Sawel]

3 minutes ago, steveinsussex said:

what do the ensembles show ?

The EC mean shows the low being more progressive than previous suites but not to the extent of the OP run.

[Summer Sun]

Hot off the press ECM Op at the top end of the mean around the 2nd to 4th less cold possibly but not to the extent of the Op

For balance, the mean is higher than the 00z

Edited February 24, 2018 by Summer Sun

[Wilxy]

Its on the warmer side but overall most members have also gone up compared to 00Z 

[frosty ground]

1 minute ago, Summer Sun said:

Hot off the press ECM Op at the top end of the mean around the 2nd to 4th less cold possibly but not to the extent of the Op

Whats it like further north?

[TEITS]

ECM OP was much warmer than the mean but still an increase of 5C compared to 0Z.

On a different note I do feel sorry for those in the far SE though i.e Kent. Whilst the snow showers will continue during Wed onwards for N England/Scotland, the convective days for the far SE only appear to be Mon/Tues due to the flow veering ESE,ly. The likes of Norfolk, Suffolk and maybe Essex may still pick up a few snow showers.

[ScottishSnowStorm]

More spread at the end of run compared to the 0z and mean a little less cold but the op is way off towards the end 

[Rayth]

00z 

12z

 

hmmmm ? ( this is for the north fwiw) 

[Frosty.]

Big change in the Ecm 12z ensemble mean compared to the 00z which locked the cold in for the foreseeable future. The latest mean is similar to the operational but less progressive with the deeper cold lasting longest across the far north and progressively less cold further south but with low pressure to the southwest calling the tune!

[Summer Sun]

3 minutes ago, frosty ground said:

Whats it like further north?

Central belt of Scotland ens shows it slightly less cold than the 00z past the 2nd but still nippy

12z                                                                  00z

Edited February 24, 2018 by Summer Sun

[matty40s]

3 minutes ago, khodds said:

Yes - I believe so. There was a fantastic post from Bring Back Winter a page or so back... have people not read it?! If not, you should!!

its about 6 pages back now.........doom and gloom with no sight to the long term model picture or certain models penchant to bring back Atlantic flow.

It is a brilliant post with lots of model relevance, none of this knee jerk "GFS168 has messed us up" stuff.

I do hope people get off their computers and enjoy the snow to come.

I do hope people get of their computers and help the less able and old to get some shopping in before it is too snowy and the shops run out.

....and it could well happen this week, whatever GFS/ECM and Meto say

[bluearmy]

14 minutes ago, Decemberof2010 said:

I'm still happy with that. Cold air should hold on in the north as per MO text

You shouldn’t be - once the upper cold pool heading west phases with the Azores upper low heading east, it’s likely curtains on the proper cold  all the way up to Scotland at least. Far better to keep the neg NAO away from becoming too west based as the current eps runs shows. 

 

[swfc]

14 minutes ago, ScottishSnowStorm said:

Isn't there going to be a point in the models once the block pattern is in the reliable they start to look for the breakdown but it doesn't mean they are right?

Id say the signal is already correct "with the data they have" atm.Imo the low will move towards Iberia and up into the uk.The change may come during the week in regard to heights changing there position and in turn steering the projected lows on a more southerly track.The changes over 3-4 days can alter the total flow ete and altho it may not we have seen big swings on the mo many times.The positioning of the high looks to far west towards the end of the week"west based nao" which we don't want .

Edited February 24, 2018 by swfc
missed info

[mulzy]

6 minutes ago, bluearmy said:

You shouldn’t be - once the upper cold pool heading west phases with the Azores upper low heading east, it’s likely curtains on the proper cold  all the way up to Scotland at least. Far better to keep the neg NAO away from becoming too west based as the current eps runs shows. 

 

Just shows our bad luck when it comes to the continuation of the cold spell.  I think the models have in my opinion rightly flipped to a less cold scenario.  I really hope I am wrong but that cold pool while our friend early in the week becomes our enemy at the end of the week.

Anyway, off the regional thread I go - some good stuff incoming... 

Edited February 24, 2018 by mulzy

[bluearmy]

11 minutes ago, Captain Shortwave said:

The trend today has been to take that cold pool through the UK at a much faster rate, this allows it to break up somewhat so we end up with two separate cold pools.

   

Todays day 6 vs yesterdays day 7 from the ECM

That separation on the low heights means we lose the clean easterly at this point and pick up less cold air from the Meditaranean and allows the low to barrel around to our south west. Ultimately we need to keep that feed of lower thicknesses to keep the easterly going and keep the low moving ENE towards France instead of spinning up towards the UK or even further west.

Still even if we see a breakdown here, it would go out with a bang with strong to gale force ESE winds whichwill likely mean that the majority of the precipitation will be of snow before less cold air tucks in behind, add to that the front could very well stall somewhere across the country with areas noth of this staying cold and of course areas underneath the run could see snow for a prolonged period of time.

A lot to be resolved here still.

There are a few reasons why the output has trended this way. Not least is the influence of highish heights and slp in the mid atlantic draining further nw and allowing the neg nao  to go very west based with the latest eps suite very sw/ne based on the lw trough. the acceleration of the suite to what we see now quite unusual in what is quite a short timescale for the ens. 

the cold pool ejects too quickly and too far wsw (which allows it to phase with the southern arm). I recall gfs showing som thing similar  the other evening and we all thought it had gone a bit nuts.  if it ends this way then so be it but would be a bit of a shame for it to go so quickly - after all, it’s  taken about thirty years to get it here !!