Model Output Discussion - Into 2024

[TSNWK]

15 minutes ago, Mike Poole said:

Just catching up this morning.  So the bottom line out to T168 on the op runs seems to be:

ECM is an upgrade on yesterday, this is a big plus in this timeframe.  It still looks messy North Greenland.  UKMO looks like a downgrade.  GEM is very good, and GFS looks decent and in keeping with recent runs.  What I would say is that there is plenty of uncertainty at a week out, the differences in behaviour North Greenland to Arctic high (or lack of it) is laughable really.

Longer term, I do think ‘whatever’ is driving this pattern, seems to be a slacker driver than was shown a few days ago.  This brings into play high risk high reward snow scenarios, at the expense of potential longevity of the spell.  But on that timescale, the Azores low needs to move east with the southern arm of the jet or it will inflate heights to our south and put southern extent of the cold in peril.  

Nice summary..  boxes it up nicely.. thank you 

[ItNeverSnowsInWindsor]

Ensembles all over the place again on the GEFS.

Nothing after T120 can be trusted.

[Weathizard]

I do find it mildly disappointing really that we are now looking out for wedges and ridges, our proper GH has slowly wained away, at day 5 it looks absolutely primed but unfortunately we don’t ever get a clean cut off high and that LP system pumps up the Iberian heights, most cold spells in the UK start with a low undercutting a ridge or HP cell and engaging cold air to our north/east, at the moment we are lacking that proper trigger because of the issues I’ve been banging on about

Don’t get me wrong we could still strike lucky, but it just shows how one ingredient out of 20 being wrong and 19 being right can still spoil the party for us.

[winterof79]

24 minutes ago, Mike Poole said:

Just catching up this morning.  So the bottom line out to T168 on the op runs seems to be:

ECM is an upgrade on yesterday, this is a big plus in this timeframe.  It still looks messy North Greenland.  UKMO looks like a downgrade.  GEM is very good, and GFS looks decent and in keeping with recent runs.  What I would say is that there is plenty of uncertainty at a week out, the differences in behaviour North Greenland to Arctic high (or lack of it) is laughable really.

Longer term, I do think ‘whatever’ is driving this pattern, seems to be a slacker driver than was shown a few days ago.  This brings into play high risk high reward snow scenarios, at the expense of potential longevity of the spell.  But on that timescale, the Azores low needs to move east with the southern arm of the jet or it will inflate heights to our south and put southern extent of the cold in peril.  

Nice post Mike.

These NH projections say no return to a PV N W of us anytime soon which bodes well for bouts of reamplification down the line

[Chesil View]

6 minutes ago, Weathizard said:

I do find it mildly disappointing really that we are now looking out for wedges and ridges, our proper GH has slowly wained away, at day 5 it looks absolutely primed but unfortunately we don’t ever get a clean cut off high and that LP system pumps up the Iberian heights, most cold spells in the UK start with a low undercutting a ridge or HP cell and engaging cold air to our north/east, at the moment we are lacking that proper trigger because of the issues I’ve been banging on about

Don’t get me wrong we could still strike lucky, but it just shows how one ingredient out of 20 being wrong and 19 being right can still spoil the party for us.

Indeed Weatherwizard just a couple of days ago we had cleaner retrogression and a cleaner southern jet taking lows into Europe.

Now its much more messy.  oh for the seventies and eighties when northern blocking was clean cut and trigger lows actually triggered something.  

Edited January 7 by Chesil View

[nick sussex]

Especially pertinent to Europe given we have the uncertainty over the Pacific Ridge from the north and any blocking towards Greenland which is impacted by the amplitude in the USA and Canada .

This from the latest NCEP extended forecast discussion.

For the next system developing across the southern Plains Friday, the GFS is slower and more amplified with the upper trough compared to the much more progressive ECMWF/CMC, and therefore considerable timing differences with the surface low track (GFS slowest and ECMWF fastest by Friday night). Both the EC and GEFS ensemble means are between these two solutions, and therefore these served as a good proxy for the expected location of the surface low. Model spread becomes high across the eastern Pacific and adjacent portions of the West going into next weekend, and this leads to below average confidence for that region. The ensemble means accounted for 40-60% of the forecast blend going into next weekend to account for the growing model differences.

 

Edited January 7 by nick sussex

[Met4Cast]

More spread than a tub of utterly butterly. 

Background forcing remains okay I think the main issue is modelling with the Pacific high & any smaller shortwave features as things move closer. 

[KTtom]

3 minutes ago, Chesil View said:

Indeed Weatherwizard just a couple of days ago we had cleaner retrogression and a cleaner southern jet taking lows into Europe.

Now its much more messy.  oh for the seventies and eighties when northern blocking was clean cut and trigger lows actually triggered something.  

Isnt this always the case though past day 10, its as if its lower resolution and everything looks clear cut, then as we head towards day 7 models pick up on nuances which effect the micro detail?

[That ECM]

I do like this. Jet stream over America going the wrong way. not suggesting icon has this right at T180 by the way.

[Man With Beard]

Looking at the individual ECM ensembles for 15 January, the cold signal is distinctively "dodgy". There are still a good number of Greenland High members but there is no ascendancy in either the cold or mild camp. We're back in a waiting game.

[feb1991blizzard]

2 minutes ago, Met4Cast said:

More spread than a tub of utterly butterly. 

Background forcing remains okay I think the main issue is modelling with the Pacific high & any smaller shortwave features as things move closer. 

unfortunately the low 10th percentile is where we need to be for a proper cold spell.

[Mike Poole]

1 minute ago, KTtom said:

Isnt this always the case though past day 10, its as if its lower resolution and everything looks clear cut, then as we head towards day 7 models pick up on nuances which effect the micro detail?

I don’t think any of the models drop resolution part way through the run anymore.  I know the GFS used to, was it post day 8 or day 10?  But since the FV3 upgrade it has been the same resolution throughout.  

[ItNeverSnowsInWindsor]

49 minutes ago, northwestsnow said:

Yes, hopefully the South will do well tomorrow ..

We've not had much snow here but down south the lads and lassies defo deserve a change of luck.

Fingers crossed ...

Is unlikely to be widespread unfortunately. Not expecting anything more than a sleety shower here.

[winterof79]

31 minutes ago, winterof79 said:

Nice post Mike.

These NH projections say no return to a PV N W of us anytime soon which bodes well for bouts of reamplification down the line

In fact i wonder if a Canadian PV will be awol for this winter

Edited January 7 by winterof79

[nick sussex]

The ICON EU 03 hrs run to T30 hrs shows a slight increase in the precip towards the se . Also  a slight northwards adjustment in the -10 850 cold pool.

[Met4Cast]

There’s no two ways about it really, this is a poor set from the EPS. 

[Ali1977]

Just now, Met4Cast said:

There’s no two ways about it really, this is a poor set from the EPS. 

Yeah I was just looking through the individual members, around 10/50 show something decent at day 10 , and by day 12 that drops to about 3/50. This is a real kick in the ****!!! An interesting METO update today, going off the models we see they will have to change their long term to standard Jan type weather, although if they don’t then their supercomputers must be seeing something much better for coldies - and we should expect a flip back to to a better set of ENS later today!! 

[That ECM]

4 minutes ago, nick sussex said:

The ICON EU 03 hrs run to T30 hrs shows a slight increase in the precip towards the se . Also  a slight northwards adjustment in the -10 850 cold pool.

I’m watching it as it ticks out hourly.

[Anthony Burden]

Morning all,models are struggling post 168 hrs with a changeable weather pattern temperatures will the northerly find it’s way through the whole of the UK or will the south especially,be under attack from the Atlantic lows.Nothing resolved as yet until then snow showers looks a good bet in the southeast possibly pushing into central southern areas as well with -10 hpa going to feel very cold Monday and cold for the rest of the week with just a short pick up of single digit temperatures end of the week,so lots to enjoy and hopefully longer term.

[nick sussex]

3 minutes ago, That ECM said:

I’m watching it as it ticks out hourly.

The main risk for any showers should be as the coldest 850s start crossing the southern North Sea .

Theres not much instability available that’s why it’s important to squeeze the coldest possible 850s out of that cold pool moving west .

I think it will really come down to a nowcast situation.

Edited January 7 by nick sussex

[Methuselah]

4 hours ago, dallas said:

Latest Meto update, talking snow showers [. . .]

Now, there's something you don't see very often! 

[northwestsnow]

5 minutes ago, Met4Cast said:

There’s no two ways about it really, this is a poor set from the EPS. 

You'd have to say the wheels are falling off mid term ..

If anything it's beginning to look like a mediocre toppler for the south  and it might not be great north of Manchester..

I hope we see a change of direction this evening ...

[January Snowstorm]

The ecm almost always gets to a boom chart by 240hrs. It's at it for over a week now and does some this morning. Of course the other models aren't any better in their chopping and changing. A couple of signals that have grown the last 24 hours or so

- Weaker heights over Greenland and also further East which in turn are shoving the Northerly further East.

- Remaining cold at the surface out to day 10 so quite a frosty week where skies are clear.

- Very dry with little chance of snow throughout.

- A shortening of the cold spell looks inevitable with some sort of Atlantic breakdown during week 2.

For me the Met Office have done a very good job. Called it cold very early, said it would be mainly dry which it is, and we're stand offish long term. Folks other than us on here, there is almost no talk of a cold snowy spell in the public domain and for now that remains the correct outlook

[Hotspur62]

4 minutes ago, Met4Cast said:

There’s no two ways about it really, this is a poor set from the EPS. 

Yes gradually over last 36 hours been a general trend from the models to back away from a GH which is a real disappointment.Think what has been popping up in Met office outlook will be on the money and reckon push of cold air from north will stall sadly so the South and maybe South midlands may miss out and here more rain could be on the cards w/c 15th January.Think Scotland northern England and North wales should see some wintry precipitation though.Still time for some upgrades but looking less likely though as time moves on.In the short term may see some snow in SE tonight and tomorrow with streamer activity

[WINTRY WALES]

Gong to be some right pants pulled down here unfortunately if this does turn out to be standard January weather from mid month. That’s not a dig or anything like that as all the teleconnectiins etc pointed towards that. More so points to the fact that nearly all most understood drivers were lining up in a positive way and the technical guys feeling comfortable yet “maybe” the blinking wheels are still falling off .