Model output discussion - deep cold inbound?

[johnholmes]

4 minutes ago, WINTRY WALES said:

And computer generated models in the 21st century cannot factor in the fact that cold air is of different density to mild air?? Instead they plough through mild air as if cold doesn’t exist?

why should we have to rely on experience?? Update the god damn models

Many experienced people spend a lot of time trying to do just that, it is an incredibly complex factor to sort, be that on a local scale or globally for any of the models-believe me, honestly.

[mushymanrob]

5 minutes ago, WINTRY WALES said:

And computer generated models in the 21st century cannot factor in the fact that cold air is of different density to mild air?? Instead they plough through mild air as if cold doesn’t exist?

why should we have to rely on experience?? Update the god damn models

i would suggest the ECM has, hence the slower breakdown

[Battleground Snow]

4 minutes ago, Tim Bland said:

There’s 3-4 runs out of 34 that stay in “cold” category,  so they are telling us roughly a 10% chance ...let’s hope that improves.. if not,  I’m happy with a brief thaw before round 2

The ensembles should somewhat change when they realise that low isn't going to progress as far north east, but like you say they are clearly showing a move back to at least average conditions atm

[geordiekev]

17 minutes ago, MJB said:

OMeGa, come to Mama, how that small low out in the Atlantic behaves could bring the shift of the block to something 2010esque

[Stocksbridgesheff]

7 minutes ago, geordiekev said:

OMeGa, come to Mama, how that small low out in the Atlantic behaves could bring the shift of the block to something 2010esque

What would we be looking for the low to do to improve cold chances on this chart?

[Rob K]

Pssst.... take a look at P5 on the GEFS at around 348-360 hours. I challenge you to draw a better winter chart.

[Alexis]

21 minutes ago, WINTRY WALES said:

And computer generated models in the 21st century cannot factor in the fact that cold air is of different density to mild air?? Instead they plough through mild air as if cold doesn’t exist?

why should we have to rely on experience?? Update the god damn models

Well they do, otherwise every low pressure near the poles would be constantly in the wrong position. It's more a question of degree. Plenty of cold dense air pockets have been easily swept aside over the UK over the years, but equally others have proven very stubborn. It's just an added factor that they need to work and hence you'll get a variety of solutions until closer to the time.

[Penrith Snow]

The GFS 06z is a perfect example of how I think February will pan out, ignore the detail that will change but the theme of cold weather with short milder spells is very likely IMO and the MetO,agrees.

Its rare to get a month thats totally cold, even December 2010 had a mild spell so it is to be expected.

Indeed, the only month I can remember that was totally cold was February 1986 but was so dry and snowless a Barlett would have been preferable 

Its going to be a great month guys, enjoy it the next one might be years away.

Andy

[SqueakheartLW]

Come on 06z GFS, don't let me down by bringing the end of the cold spell closer or making the peak of the milder spell milder than on the 00z. On this run the average time for the cold spell to end is at 162 hours away, the same as it was on the 00z so that means a 6 hour extension to the colder spell already so a tick there for GFS 06z anyway

A worse looking pressure chart with stronger S to SW winds meaning despite the delay to the end of the cold spell it looks like it will be over quicker when it does happen. The 850hpa temperatures at this transition are -4.9 which is -3.1 below the long term mean and an upgrade in terms of residual cold by -0.9 compared with the 00z so colder transition and this probably means more snow in the transitional phase. The anomaly chart shows slightly deeper blues to the north and even less of the milder air has made it into the UK so a step in the right direction at least

The peak of the milder spell on 06z comes at 252 hours away. It was 240 hours on the 00z and allowing for the 6 hours later interval of the 06z this means the mildest weather has been pushed back 18 hours since the 00z, another step in the right direction.

Unlike on the 00z where the milder spell was low pressure dominated this time on the 06z it is more high pressure dominated, maybe not so bad then as we can stay mainly dry and allow the land to dry out somewhat. The 850hpa temperatures at the peak of this milder spell are 2.2 which is +3.6 above the long term mean. The bad news here is that this is a step in the wrong direction by 0.6 in the direction of milder. We want to see the milder weather watered down, not upgraded. The anomaly chart reflects this upgrade with more of those orange colours appearing over the UK.

[geordiekev]

1 minute ago, Stocksbridgesheff said:

What would we be looking for the low to do to improve cold chances on this chart?

Obvs the chart is just the ensembles, but you'd want the low to go under to prop the high up and with a squeeze from both sides would help to create the favourable Omega shape bringing cold air over the top and a more NE flow.

However on an island only 80 miles across in parts, getting it in the exact place is like hens teeth

[Cold Winter Night]

Great output this morning.
Especially for anyone looking for an extension/reload of the cold spell.

The last few days several members here, including myself, have been banging on about the models underestimating the resilience of the cold block and overestimating the Atlantic attack.
It's always a bit risky to go against what models and their ensembles are showing, but this morning we really do see the models moving towards increased Northern blocking and as a result, more resistance to the Atlantic lows.

We are talking about the edge of FI and beyond, UKMO does not go there.
EC Operational keeps hinting at stronger Scandi Heights at day 9-10, so that's good.

In deep FI, output wise we have to rely on GFS, GFS // and the ensembles GEFS and EPS.
GFS 6z shows an excellent example of a Scandi High, it did not do that before, so that's very encouraging (for coldies).
GFS // is available on and off, but it's last run had Scandi Height rises in deep FI too.
GEFS has some perturbations that stay cold.  I'd say: Watch how their company will grow. The majority brings in milder temps, but in this situation, with GFS's known weaknesses in play here, I would not take too much note of the perturbations that are even worse than their Operational run.
EPS has shown a significant increase in Northern blocking in FI, with a colder plume for De Bilt. That's what I watch with most interest. A large cluster has ice days all the way for where I live.

I am still very confident that this cold is not going to be done with us very soon.
Even if some slightly less colder weather creeps up, I don't think it will last more than 2-3 days. The farther West you go, the more you are at risk of this potential warm up, but the farther East you go, the cold might not even leave at all.

[Ninman]

It's my favorite Pert (P23) delivering the goods again!

[SqueakheartLW]

13 minutes ago, Rob K said:

Pssst.... take a look at P5 on the GEFS at around 348-360 hours. I challenge you to draw a better winter chart.

Also take a look at P8. Has the most extended cold spell of all of the GFS 06z ensembles

[Timmytour]

1 hour ago, mushymanrob said:

YES ! completely agree here, experience has shown that when we have cold air over the UK, especially deep cold, it seldom gets shunted aside as rapidly as many GFS runs have perviously suggested.

 

Experience has shown me that 99 winters out of 100 the cold air gets shunted  aside before it even steps foot in UK! :)

[geordiekev]

8 minutes ago, Ninman said:

It's my favorite Pert (P23) delivering the goods again!

Certainly resembles that 2010 omega block, the Eastern seaboard just a bit too strong, but if spawning lows were forced over the top, then game on

[The Northern Ramper]

2 hours ago, winterof79 said:

Looking good for cental northern England Saturday. There's the humber streamer that's been constantly progged early next week

 

Great to see

[sheikhy]

Wow!!!ecm 06z 850s of -12 coming in from the east across east anglia and south east!!gfs has -7 850s for the same areas!!massive difference!!....

[topo]

19 minutes ago, Ninman said:

It's my favorite Pert (P23) delivering the goods again!

What about this one  

[Battleground Snow]

2 minutes ago, sheikhy said:

Wow!!!ecm 06z 850s of -12 coming in from the east across east anglia and south east!!gfs has -7 850s for the same areas!!massive difference!!....

Certainly no marginality there, hopefully someone who has access can tell us how far west the frontal snow makes it on this run

[DavidS]

GFS 6z going for the Christmas tree formation at T288. Ok it’s February, not Christmas, but if the GFS wants to do this, I won’t complain.

[DOdo]

27 minutes ago, Cold Winter Night said:

Great output this morning.
Especially for anyone looking for an extension/reload of the cold spell.

The last few days several members here, including myself, have been banging on about the models underestimating the resilience of the cold block and overestimating the Atlantic attack.
It's always a bit risky to go against what models and their ensembles are showing, but this morning we really do see the models moving towards increased Northern blocking and as a result, more resistance to the Atlantic lows.

We are talking about the edge of FI and beyond, UKMO does not go there.
EC Operational keeps hinting at stronger Scandi Heights at day 9-10, so that's good.

In deep FI, output wise we have to rely on GFS, GFS // and the ensembles GEFS and EPS.
GFS 6z shows an excellent example of a Scandi High, it did not do that before, so that's very encouraging (for coldies).
GFS // is available on and off, but it's last run had Scandi Height rises in deep FI too.
GEFS has some perturbations that stay cold.  I'd say: Watch how their company will grow. The majority brings in milder temps, but in this situation, with GFS's known weaknesses in play here, I would not take too much note of the perturbations that are even worse than their Operational run.
EPS has shown a significant increase in Northern blocking in FI, with a colder plume for De Bilt. That's what I watch with most interest. A large cluster has ice days all the way for where I live.

I am still very confident that this cold is not going to be done with us very soon.
Even if some slightly less colder weather creeps up, I don't think it will last more than 2-3 days. The farther West you go, the more you are at risk of this potential warm up, but the farther East you go, the cold might not even leave at all.

I agree too I think there will be a few more wobbles to come. My bet is on it continuing into next weekend

[Cavehill Snow]

2 hours ago, chris55 said:

GFS is often to progressive, If we take ECM op Vs GFS 6z you can clearly see how GFS is forcing things east to easily. Those little wedges and the dense cold air can have more of an effect than it seems at face value. Steve M was always very good at reading charts like this, but as he's not here ill have a go lol.

GFS 6 z 168

Now look at ECM 168

In some ways i'm wondering if we would be better off if the major low at the end of next week didn't stall but carried on preferrably east but even northeast would do, so long as it advanced beyond the meridian. What causes this low system to stall - the temporary  ridge extending down from Iceland on ECM 168 or the surface high over Scandi? Is this an example of high latitude heights not always assisting the chase for cold. I do of course understand that without the heights around griceland in the first place, we would never be in such an exciting pattern now.

[TSNWK]

20 minutes ago, sheikhy said:

Wow!!!ecm 06z 850s of -12 coming in from the east across east anglia and south east!!gfs has -7 850s for the same areas!!massive difference!!....

Huge difference.   GFS bring weekend low in more the reason..  I still say let it hang south east with uppers like that for all there will pop up events all over and it would also indicate a more southerly tendency for pattern going forward.  Just my view

[markw2680]

There’s far to much worry about when it will end if you ask me, it hasn’t even started yet lol so let’s be excited about that before the possible breakdown? Even that if you ask me is on very shaky grounds. I’d rather think about how much snow is possible but that’s just me.

looking at the extended I’d say there’s a fair chance of the cold getting longer and longer abs possible to merge into another cold spell without any mild interlude.

stay on the roller coaster and enjoy 

[phil nw.]

52 minutes ago, Battleground Snow said:

The ensembles should somewhat change when they realise that low isn't going to progress as far north east, but like you say they are clearly showing a move back to at least average conditions atm

I think there is some, room for a switch in the gefs in particular.

We know in the situation where the Atlantic comes into blocking this model often throws too much energy ne. 

With signs of another block forming ahead we may well see the Atlantic stall before making any appreciable inroads. 

The operational runs will likely move around on this until maybe t72. 

We could well retain much of the surface cold under any ridging, although the sw quarter does seem the most at risk for some sort of warm up if only temporary. 

It does like fine margins which way the evolution goes after mid week.