Model Output Discussion - Colder but how cold and for how long?

[Lukesluckybunch]

Gfs brings the low back for Wednesday with the snow risk..

[MattStoke]

ICON 6z further south

[Harveyslugger]

Just now, Lukesluckybunch said:

Gfs brings the low back for Wednesday with the snow risk..

Why is the low tracking in a way where it misses Pembrokeshire but reaches norwich.and Pembrokeshire is much further south

[ItNeverSnowsInWindsor]

12 minutes ago, johncam said:

A poor set of ECM ens with the control one of the worst,  this is the 360 chart 

Looks like an early spring according to the control

[Mike Poole]

ECM clusters T120-T168:

For the first time in ages, more than one cluster.  Cluster 2 maintains some ridging in the Atlantic, cluster 1 has the more southerly jet.

T192-T240:

Various flavours of zonal, except for cluster 5 which only has 4 members and tries to build heights into Scandi.

T264+:

Both clusters start zonal, the first shows an inclination towards Scandi heights, the second shows an inclination towards an Atlantic ridge.  Both signals to watch as we go forward, it can’t be both of them!

[Duane S.]

History tells us getting excited 3 days out, when a model suite shows the tracking of a low like this one is optimal for your area, rarely plays out well .

Still no trends north or south, just fluctuations within the wide envelope, model to model, run to run, are still in play. And no doubt will be for a while yet.

For those on the south coast, I maintain this is our best chance of a channel runner landing in a long time. But, by like their very nature, the margin for error always involved (right down to T+0) will make it a low probability. So yes, the best in many many years, but a low Probability. It would be virtually impossible for it to be any other way.

March 2013 I think it last was? When the Channel Islands snatched it away overnight! And let that sink in to some of the newer members on here. Overnight it shifted 80 odd miles south.

High risk, high reward. Low risk, high reward rarely ever applies to the south coast receiving a decent snowfall.

10 days ago I said this low would be the big player, I also said it would likely fill and slip just south on a ESE trajectory. However, I  didn’t foresee quite such a quick breakdown just a few days later back then, so I’m open to all possibilities ref. this low, including it tracking more north. Too far north will be to the likely detriment of us far southerners though.

Often, in these situations, we have the comfort of if a system tracks too far south, the cold is at least prolonged. Yes that would apply but unfortunately only very temporarily, as a mid term warm up looks almost guaranteed now.

Edited January 14 by Duane S.

[Kasim Awan]

We needed the ICON here really. It is further South. GFS 06Z in soon.

Edited January 14 by Kasim Awan

[bluearmy]

2 hours ago, Ali1977 said:

The GFS MEAN has snow to the midlands on Wed, this is mental. I think more moves north are on the cards now 

 

A few examples, and there are plenty more 

The gefs mean also reveals that bringing the precip further north also brings less cold air with the mean precip not all shown as snow

Flicking through timeframes on the gefs members (the most excited about precip getting into s england ) reveals a hochpotch of solutions with plenty of rain involved.  So even getting the moisture in doesn’t guarantee anything. 

Meteociel - Panel GEFS

WWW.METEOCIEL.FR

 

[sunnijim]

34 minutes ago, SLEETY said:

You worry for the rest of the season though if the cold can just get pushed away so quickly. I thought cold was was hard to push away because it's dense etc and from what I have read,

Amazing to think even here on the coast we actually  have had 3 days of lying snow even on beach from the heavy snow showers from last Monday, stayed on the ground till Thursday 

This low has all the hallmarks of 2023 in March where the South Coast got a little bit of snow  but channel Isles got hammered. 

Need a big northwards movement in next 24 hours  it's rare the models are wrong with the tracks of low pressure systems 48 hours away anymore! 

You did well on Monday, saw the pix of worthing, under a streamer.Had nothing that stuck here East of you in Brighton.

I don't think you should be concerned about the rest of Winter based on next weekends cold removal.

I here what you say about the cold removal supposedly being hard to shift, that certainly has been the case from my recollection when you have had a proper battle between strong blocks to our North East and the return of unsettled Atlantic conditions.

Models often underestimate the strength of the block and the dense cold in place, so you have a two fold situation in our favour for mainataing a cold spell in the face of over progressive removal.

I can recall progged breakdowns not only being delayed for days but changed altogether in the past.

Your final point on wanting further Northward adjustments to Wednesdays system, I assume you will reside in Worthing and are not massively altruistic ?

Much further North than the GFS 00z suggests and it will be a South Coast rain fest.

[joggs]

44 minutes ago, feb1991blizzard said:

They're out to 312 already

The pain of so many winters,the Iberian high

Edited January 14 by joggs

[stewfox]

29 minutes ago, Ali1977 said:

 

Can you add comment ?

Is the 2nd chart more recent ?

Time stamps looked blurred 

 

 

[offerman]

47 minutes ago, Paul said:

If you're looking for a realistic answer, the only one as far as I'm concerned is that a gfs chart at 384 hours isn't a useful guide for that time . So, therefore attempting to extrapolate that to make a forecast for another month is impossible/pointless.

Completely agree with that post.

 

GFS or any charts that Far out are going to be so difficult and near on impossible to create a forecast from that. It’s difficult at the best of times, even 10 days out let alone that far.

 

6 minutes ago, joggs said:

The pain of so many winters,the Iberian high

Quite right, which unfortunately has become larger, stronger, more dominant and stagnant combine that with the shift north of the subtropical belt as well. ( someone posted the link not long ago to back this up about the shift Northwards) 

[SLEETY]

Models normally have the low too far north at this stage and eventual outcome it goes south, maybe they have it too far South and it goes north instead!! 

[That ECM]

6 minutes ago, stewfox said:

Can you add comment ?

Is the 2nd chart more recent ?

Time stamps looked blurred 

 

 

Most recent op and mean.

[loafer]

1 minute ago, That ECM said:

Most recent op and mean.

No…both are 00z Mean, both 6hr accum precipitation, one for 1pm, one for 7pm.

[Cambrian]

The 0z UKMO, is a fascinating and, I feel, quite a concise run. The pressures and heights chart shows the machinations of the PV, the Siberian lobe dropping down into Northern Europe during the first 5 days, the main lobe of the PV actually brushing our shores, before spinning back around north and bridging through Svalbard and Greenland to the regathered Canadian lobe, ultimately coalescing over northern Greenland, leaving the UK and Ireland in a westerly flow by day 6. 

It’s the T850s that caught my eye though. Pulses of very cold air heading south through the UK and Ireland, cold through to day 6 before it turns milder. The first warm sector gets squeezed out to our west around day 5, before the second one manages to break through. 

 

It might be well worth keeping an eye on the shape of these warm sectors and how far north they are, this could well change over the next few days, with the scope for some chilly uppers to follow from the eastern seaboard, mixing with cold air being pushed south out of Greenland. With such a lot going on with the PV, the models might well struggle with the north-south placement of the Atlantic jet stream for a fair few days. 0z ECM / GEM / GFS ops at day 7, a wide range, particularly at our end.

  

So over the last couple of days, a more sudden curtailment of the deeper northerly flow than that being indicated previously in the models, let’s not pretend, but another good cold week in the middle of January, which we rightly saw coming for a fair few weeks.

Up here, we still have sections of solid ice where normally bubbling springs froze over a full week ago, so irrespective of if and where the snow falls over the coming days, this is quite different to many of the Januarys we have seen in the last couple of decades, an interesting spell in a winter that is far from a typical winter too.

[Harveyslugger]

Met office have now added the Pembrokeshire dangler tonight

[Ali1977]

4 minutes ago, Harveyslugger said:

Met office have now added the Pembrokeshire dangler tonight

Seen here on the GFS 

Early days but T60 the GFS has the precip a tiny bit further north!! New run bottom image 

[Ali1977]

Well I think that’s it With the ECM and UKMO not showing it , it was always v unlikely!! 
Fir those in the SE though, you could have a good snow event ️

Edited January 14 by Ali1977

[MJB]

Barely touches the UK, need it 100 miles further North, that isn't happening IMO 

Unless it pivot's 

Edited January 14 by MJB

[tight isobar]

3 minutes ago, Ali1977 said:

Well I think that’s it With the ECM and UKMO not showing it , it was always v unlikely!! 

If there’s no change on today’s 12z it’s a no - goer!!. Kent  and the south coast still in with a pretty big shout.

Edited January 14 by tight isobar

[Kasim Awan]

Yeah looking like going to the South now. Around a 15/20% chance of a more northerly track. 

Even the risk of snow showers into the Cheshire gap has reduced somewhat.

The fact is over 90% of the UK population will remain snow free from this toppler.

The risk of troughs forming in the flow is very low because it gets shunted out by Atlantic air very quickly.

Enjoy everyone  

Edited January 14 by Kasim Awan

[tight isobar]

1 minute ago, Kasim Awan said:

Yeah looking like going to the South now. Around a 15/20% chance of a more northerly track. 

Even the risk of snow showers into the Cheshire gap has reduced somewhat.

The fact is over 90% of the UK population will remain snow free from this cold snap. 

The risk of troughs forming in the flow is very low because it gets shunted out by Atlantic air very quickly.

Enjoy everyone  

Indeed snow chances evaporating every run now !!!@countrywide.

[Midlands Ice Age]

2 hours ago, offerman said:

Hi Malarkey, unfortunately they don’t at the moment. this is something I mentioned recently about due to the change in the weather we can’t rely on algorithms from whether patterns from the past as much because the weather now seems to behave in a different way and pressure. Pens have changed a lot with more stubborn high-pressure systems to our south and Southwest, and sometimes stubborn, low pressure systems, even as well, I’ve noticed but much has been controlled by high-pressure the Azores, high Iberian, high Bartlett high, and Euro slug
there was a fantastic poster recently called midnight, ice age. 

He has a vast amount of experience with working in the industry, and he said the problem is that the software needs updating. Here was his post..

 

“You can have all the modern technology you want, you are trying to predict the future, that's simply impossible on a scale you're asking for  

I am afraid that we are now getting to the point that it is now the errors and assumptions in the software are causing the greater errors.

Until you get those sorted out you will just magnify the errors, and end up with even more chaos.

Spoken after 40 years in the software industry.

MIA

Can I make this clear.. this is not quite the intended gist of my post.

They do not automatically increase just 'errors'. They increase the total amount of data (Including errors), this has the result that it increases the volatility of the output data (a larger envelope if you like). The overall effect will be more of a more chaotic output.

We are already seeing this with the models overreacting to some sorts of signals, particularly in a 'stuck' pattern where a small difference here and there can produce a totally opposite outcome.  We also see overblown lows very frequently.......   My gut  'feeling' is that this will happen more frequently if we just add in more computing power.

We will at the moment benefit more by sorting out the software glitches, than by spending many millions on hardware. Its the balance really which is important moving forward.

Midlands Ice Age   ( i don't only post at midnight?)

Edited January 14 by Midlands Ice Age

[iowpompeylee]

10 minutes ago, Ali1977 said:

Well I think that’s it With the ECM and UKMO not showing it , it was always v unlikely!! 
Fir those in the SE though, you could have a good snow event ️

If the GFS has nailed this I will put it to the top of my winter forecast charts going forward