Model thread discussion - cold spell looming

[MattStoke]

1 minute ago, JimBob said:

Not strictly true, forecasts for the South West suggesting milder air on Thursday now. 

Briefly milder air into the far west/south west before a quick return to colder conditions. Not a breakdown for the vast majority of the U.K.

[nick sussex]

A word about the GEFS .

The 850 values are misleading in terms of how many are actual mild runs versus how many keep the surface cold.

Any flow sourced with an easterly element even if the upper air temps look on the milder side will remain on the cold side at ground level  , this is the benefit of the colder uppers getting further into mainland Europe than originally forecast at the start when the models were more reluctant to do that .

[Guest]

8 minutes ago, MattStoke said:

And it was wrong about any breakdown on Thursday as no models now show this.

Well that’s not entirely accurate the bulk of the ensembles for gfs still bring a marked breakdown through the southwest on the 11/12th which never bring the cold back. A third to half of the GEM ensembles are similar.

Edited February 7, 2021 by Guest

[Battleground Snow]

Gem control and mean is a much better for what's its worth, so nick is probably correct with his assumption

[Alexis]

45 minutes ago, JoeShmoe said:

The GFS was woeful modelling the current cold spell so don’t see any reason to start backing it now it shows something good. I’ll wait to UKMO and ECM start going there ...

GFS was the first to spot the easterly, followed by UKMO! ECM wasn't having it for days and then U turned.

[Rob K]

3 minutes ago, nick sussex said:

A word about the GEFS .

The 850 values are misleading in terms of how many are actual mild runs versus how many keep the surface cold.

Any flow sourced with an easterly element even if the upper air temps look on the milder side will remain on the cold side at ground level  , this is the benefit of the colder uppers getting further into mainland Europe than originally forecast at the start when the models were more reluctant to do that .

Indeed, the 850mb ensemble doesn't look that different from the last set but the 2m temps are hugely colder (for Hampshire)

[Singularity]

 

FWIW, the UKMO 12z is a tricky one to draw conclusions from going forward.

The main Atlantic trough isn't as well behaved as on the GFS 12z but on the other hand, the shortwave west of the Azores is a little slower which would give the high more time to build north and become more capable of forcing trough disruption. On top of that, the very cold trough to the east is closer by, so the high doesn't have to take on a west-east orientation for as long to bring it to our shores.

Overall, given this is at +144 hours, I'm happy that we don't have either of these models orientating the warm air advection notably east of north.

GEM has asked a question this evening but does so via a very fast shortwave low and very deep trough - not the most convincing of queries!

[icykev]

1 hour ago, Griff said:

So who remembers my at that CFS chart the other day... 

Add the gem

Fridays GEM 

Edited February 7, 2021 by icykev

[Mike Poole]

A good time to play match the short range model predictions to the radar, here’s the last 2 hours:

EURO4 from 4pm going forward 24 hours:

 

HARMONIE:

 

ICON-EU (15z):

 

This is something that we learned in the last BFTE, the ICON really doesn’t do convective snow!  The other two make a decent fist of it, I reckon.

Edited February 7, 2021 by Mike Poole

[johnholmes]

28 minutes ago, wellington boot said:

I think it might also have led with picking the movement of the LP yesterday into today and the less impressive 850s as a result (hence my earlier question that was ignored...).

Re this next spell, I'm interested to see the EC/GFS anomaly charts are fully onboard. Less excitingly, the NOAA charts show significantly meridional flow, but at 8-14 days, it is less pronounced than at 8-10, and unlike the EC/GFS, there's no 'closed circulation' or reversal in the flow. Interested to see tonight's, and more runs probably needed. Would be good to hear @johnholmes's thoughts if he hasn't already been in.

 

ECMWF/GFS DAY 8-10 MEAN 500MB HEIGHT COMPARISON

WWW.METEO.PSU.EDU

Climate Prediction Center - 8-14 Day 500mb Outlook

WWW.CPC.NCEP.NOAA.GOV

 

I', around but not had chance to do any analysis, hopefully do something this evening if I can

[nick sussex]

6 minutes ago, Rob K said:

Indeed, the 850mb ensemble doesn't look that different from the last set but the 2m temps are hugely colder (for Hampshire)

Thanks for posting that .  Yes that is the polar opposite of what the GEFS might suggest just looking at only the 850 values .

Effectively a 26 to 5 split for the very cold to continue till at least the 15th February on the shorter ensembles .

[geordiekev]

15 minutes ago, Alderc said:

Well that’s not entirely accurate the bulk of the ensembles for gfs still bring a marked breakdown through the southwest on the 11/12th which never bring the cold back. A third to half of the GEM ensembles are similar.

We all know GFS will always show a west to east evolution in almost every run. Thus it's easier to call a breakdown especially on a longer range GFS & best to see if there's support elsewhere before pinning colours to one run.

It's just weather, it'll do what it wants & it's brave of those who stick their necks out to go against the norm using a wrath of sources and don't mind a bit if egg on their faces.

It's how we learn, I've been pinning hopes on an Atlantic block the same day some called a breakdown and to my relief it showed up as an evolution earlier.

Thanks to all the knowledgeable posters who help us to expand our understanding, oh & enjoy the weather 

Edited February 7, 2021 by geordiekev

[wellington boot]

2 minutes ago, Mike Poole said:

A good time to play match the short range model predictions to the radar, here’s the last hour:

EURO4 from 3pm:

 

HARMONIE:

 

ICON-EU (15z):

 

This is something that we learned in the last BFTE, the ICON really doesn’t do convective snow!  The other two make a decent fist of it, I reckon.

Really?? I mean if you're trying to match them, your radar shows the past two hours, whereas the others all start now and extend more than a day into the future. So what is being matched?

And as far as matching does go, they all show nothing for now North of the South East, whereas the actual radar shows convective activity all the way up the East coast to Scotland.

[Mike Poole]

1 minute ago, wellington boot said:

Really?? I mean if you're trying to match them, your radar shows the past two hours, whereas the others all start now and extend more than a day into the future. So what is being matched?

And as far as matching does go, they all show nothing for now North of the South East, whereas the actual radar shows convective activity all the way up the East coast to Scotland.

Depends on what your expectations of the models are as this stuff is beyond the resolution really.  And yes, I’ve edited my post to make clear that while the radar is the past 2 hours, the model GIFs are for a day ahead.  You can’t match the future predictions!!  But the position is important and the EURO4 and HARMONIE aren’t bad at that, of course the detail will be different, but models are actually getting better at this.

[Griff]

Looks further to the West than GFS 12z

[Biggin]

11 minutes ago, Mike Poole said:

A good time to play match the short range model predictions to the radar, here’s the last 2 hours:

EURO4 from 4pm going forward 24 hours:

 

HARMONIE:

 

ICON-EU (15z):

 

This is something that we learned in the last BFTE, the ICON really doesn’t do convective snow!  The other two make a decent fist of it, I reckon.

Is that a low creeping in from the SW with higher temps ?

[Howie]

1 minute ago, Griff said:

Looks further to the West than GFS 12z

This surely looks even better than the gfs

[sheikhy]

1 minute ago, Griff said:

Looks further to the West than GFS 12z

Im waiting for yours and battlegrounds 120 hour chart!!!looks further west than gfs so far!!

[geordiekev]

Not often you see all of the UK precip pink, plenty of showers making inroads on radar just now.

Remember to look out & make most of fresh air now the rain is long gone

[Griff]

1 minute ago, sheikhy said:

Im waiting for yours and battlegrounds 120 hour chart!!!looks further west than gfs so far!!

 

[Howie]

Just now, Griff said:

 

Woah!

[Mike Poole]

Just now, Griff said:

Looks further to the West than GFS 12z

Well that’s the transition to Scandi blocking nailed on if it wasn’t after the earlier runs, T96  *** what return to mild, the other day??? ***.  What is in play now is the shape, position and strength of the developing block.  How fascinating this model watching is at the moment...what word would we invent to define this addiction?  

[Griff]

1 minute ago, Howie said:

Woah!

 

1 minute ago, Mike Poole said:

Well that’s the transition to Scandi blocking nailed on if it wasn’t after the earlier runs, T96  *** what return to mild, the other day??? ***.  What is in play now is the shape, position and strength of the developing block.  How fascinating this model watching is at the moment...what word would we invent to define this addiction?  

Not really much between this and gfs 12z at this stage to be honest 

[Battleground Snow]

Just now, Griff said:

 

More importantly the low is dragging up better WAA than the Ukmo at 120, due to the low slight further north and stronger

[Mike Poole]

4 minutes ago, Biggin said:

Is that a low creeping in from the SW with higher temps ?

Low staying out there with higher temps I think!