Model output discussion - cold spell approaching?

[Tim Bland]

1 minute ago, weirpig said:

Arp is different though tim   further west   and south

I think those always look more dramatic as it shows fallen sleet / snow, it’s not accumulated / measurable snow fall. I wouldn’t expect much accumulation south of north Lincs.  My French isn’t that great (perhaps Nick can help?) but it says something like ‘Attention this is not the snow on the ground but total falling’ 

[Battleground Snow]

The para is not going to phase, either.

The UKmo is ever so slightly better than it's 00z run.

If you look on wetter Europe view it's easier to see at 120 that they come close but don't phase

I'd expect the Ukmo to adjust more to ECM and GFS by tomorrow

Edited January 12, 2021 by Battleground Snow

[frosty ground]

Link to the artic high on this run

[Singularity]

UKMO sure made a lot of that little low running across the south on Sunday.

Whole progression is slower, more amplified. Quite unusual from a model that's usually among the fastest to move lows around in the 5-6 day range.

The +144 chart reminds me of those times in summer when we see a short heatwave followed by a dramatic capitulation as a ridge to the west takes over.

Not sure about how vigorous it makes that low, though - seems a little OTT?

[weathermadbarnsleylad]

Nice 1040mb greenland  high blocking the Atlantic. Primed low moving east to allow winds to become N/NE. How cold will this run get. I'm quite happy to be fair. 

[JoeShmoe]

11 minutes ago, MJB said:

Why  do you say that Joe 

Because this mornings output rang alarm bells with the spoiler low and Iberian heights and that run hasn't backed away from it ... 

[bluearmy]

We are struggling to bring cold air south for the first northerly .... I assume the meandering weak zonal pattern responsible - nothing to drive the cold uppers south. 
 

so any initial runners into the trough will likely be wet 

this assumes we get 

a) a trough

b) a runner 

 

[Tim Bland]

Saturday night is similar to Thursday with a. Marginal snow situation, some models have it and some don’t. GFSp is really going for it ..

[jam]

22 minutes ago, Djdazzle said:

Sorry mate but that's setting people up for more disappointment. It looks highly marginal to me.

Tbf it’s a forum not a formal met office forecast ! A little licence and excitement is allowed especially with such interesting model watching 

 

[sebastiaan1973]

This is what I'm looking for. The extreme cold air pushing southwards over land, instead of the Norwegian sea. 

[frosty ground]

3 minutes ago, JoeShmoe said:

Because this mornings output rang alarm bells with the spoiler low and Iberian heights and that run hasn't backed away from it ... 

Those height at that time frame are shown on all models.

[Captain Shortwave]

Digging deeper around the day 4/5 mark, major disagreements in terms of a front moving through the U.K.

There is the risk of another area of snow on this front, the GFS (p) most positive about this. The UKMO as a similar set up of trough disruption but with a more significant area of low pressure. The GFS (op) pushes through quicker and mostly of rain.

Beyond this, the output looks very messy. The GFS with the cleanest evolution of the Greenland high.

 

Edited January 12, 2021 by Captain Shortwave

[Kentspur]

8 minutes ago, Tim Bland said:

I think those always look more dramatic as it shows fallen sleet / snow, it’s not accumulated / measurable snow fall. I wouldn’t expect much accumulation south of north Lincs.  My French isn’t that great (perhaps Nick can help?) but it says something like ‘Attention this is not the snow on the ground but total falling’ 

Correct I'm half Mauritian French mon deuxieme langue it does indeed say that I have my uses

[nick sussex]

7 minutes ago, Tim Bland said:

I think those always look more dramatic as it shows fallen sleet / snow, it’s not accumulated / measurable snow fall. I wouldn’t expect much accumulation south of north Lincs.  My French isn’t that great (perhaps Nick can help?) but it says something like ‘Attention this is not the snow on the ground but total falling’ 

Basically that chart shows what would happen if all the snow falling accumulated but it doesn’t take into account any melting or difficulty laying . 

Still it’s encouraging regardless , hopefully this gets upgraded .

[Cold Winter Night]

GFS +192h takes the Greenland High and therefore the cold West, mainly to the Atlantic, as per previous concerns.

The development of the Arctic High, near Svalbard is encouraging though. Fits in with some clusters on EPS, bringer deeper cold, but later.

[phil nw.]

Looks ok with GFS and UKMO showing the initial retrogression of the ridging towards Greenland now at day 6 ie.18th.This date has been on modeling for a number of runs now.

It will be few days before the mists clear on how cold the uppers will be.The main thing is the 2 features ie Scandi.trough and G.heights are being developed pretty much consistently  now and within the expected time scale.

Remember when these features were first shown 10 days and beyond -the trend to cold is still good.Details for later.

 

[Tim Bland]

GEM is the camp for more widespread snow Thursday eve 

[Valleyboy]

1 minute ago, phil nw. said:

Looks ok with GFS and UKMO showing the initial retrogression of the ridging towards Greenland now at day 6 ie.18th.This date has been on modeling for a number of runs now.

It will be few days before the mists clear on how cold the uppers will be.The main thing is the 2 features ie Scandi.trough and G.heights are being developed pretty much consistently  now and within the expected time scale.

Remember when these features were first shown 10 days and beyond -the trend to cold is still good.Details for later.

 

Latest charts underwhelming  and a step backwards.  I think we’ll get there, but need to see timescale reducing.  This 10 day stuff will take us to spring time if this carries on

[Ben Sainsbury]

Cracking run so far from the GEM, doesn't come close to phasing the lows.

[Battleground Snow]

Gem is the best run of the day so far... Phasing doesn't get close and more WAA into Greenland. Hopefully the ECM is like this too

Ben beat me to it ^^

Edited January 12, 2021 by Battleground Snow

[phil nw.]

Just now, Valleyboy said:

Latest charts underwhelming  and a step backwards.  I think we’ll get there, but need to see timescale reducing.  This 10 day stuff will take us to spring time if this carries on

If you read my post i commented how the changes to the 500 pattern have been counting down to within 10 days now.The switch to cold will develop from there but a step backwards it ain't.

[Kasim Awan]

1 minute ago, phil nw. said:

If you read my post i commented how the changes to the 500 pattern have been counting down to within 10 days now.The switch to cold will develop from there but a step backwards it ain't.

The forecast of "cold" is still very much a likelihood, it's the magnitude of cold during day 6 to day 8 which has been steadily downgrading recently.

[swfc]

Comparing the 6z to the the 12 z gfs there is a downgrade without doubt. Low heading under the block to phase with the UK low. One run but can't ignore it

[warrenb]

Now what is interesting is the high is getting a positive tilt and is heading west, could get a very cold easterly out of this.

SSW always for me = Easterly.

[mountain shadow]

1 minute ago, swfc said:

Comparing the 6z to the the 12 z gfs there is a downgrade without doubt. Low heading under the block to phase with the UK low. One run but can't ignore it

I would advise you not to look at the PARA GFS then swfc.