Model Output Discussion Autumn 2024

[Mcconnor8]

Probably worth nothing but run to run consistency from the GFS 6z and 12z on a slider at Day 9 bringing lots of snow

Edited November 12, 2024 by Mcconnor8

[bluearmy]

Gfs op slips a discreet Atlantic low from upstream into the jet flow around T132 

Without  support from other models it’s evolution from there for days 6-9 is questionable 

[Derecho]

I think the slider low scenario is plausible from the GFS but it's getting a bit carried away with that deepening low.

The slider scenario isn't necessarily a bad thing if you end up with it sliding favourably to keep the cold air in place. A December 2017 scenario would be nice for early in the season.

As I expected though given the warm SSTs, a messy synoptic evolution. The GFS brings in too much in the way of less cold air and we then have to try and advect some more cold air behind the slider low to keep things interesting (though southern areas manage to get some snow later next week....).

Also of additional note, it does look as though we are set to get a late season hurricane in the Gulf of Mexico soon which may muddy things further when it eventually gets back into the North Atlantic basin after crossing Florida.

Edited November 12, 2024 by Derecho

[Polaris]

216hrs GFS gives Birmingham South snowfall.

My gut says if the pattern is sustained then the ppn will go into Northern France come  t76. Seen it so many times. 
 

In a way I wish the slider showing up at D9 was into Scotland, then would at least give my location more of a chance with the ever so sure corrections south!

[Battleground Snow]

By 168 on the ukmo you can see the little low, a bit of a difference to the gfs.

The high is probably less likely to migrate north west too.

 

[Allseasons-Si]

The UKMO at 168

miles better than the gfs.

[sheikhy]

Gimme ukmo over gfs any day right now!!!!

[Ali1977]

UKMO is awesome at 168. The GEFS mean at 132 is an upgrade from earlier - zoom in and you’ll see the cleaner flow 

Edited November 12, 2024 by Ali1977

[Mike Poole]

GEM ends up at T240 with quite extraordinary northern hemisphere synoptics. 

[Derecho]

4 minutes ago, Polaris said:

My gut says if the pattern is sustained then the ppn will go into Northern France come  t76

Same here, it's what we also saw in January. Hopefully the northern blocking can sustain itself though and we get one of these slidy scenarios with cold air entrenched.

[RJBingham]

 HarvSlugger Goes for nearly an hour, something must be happening...

[bluearmy]

 Mike Poole never going to happen Mike !

[Allseasons-Si]

 Mike Poole I was just about to post that Mike and that would set us up for round 2 from the north,...lovely chart that is.

[TSNWK]

@Mike Pooleineeded..an easterly feom Brittany all across the atlantic to newfoundland...

[That ECM]

 bluearmy apart from T240, why? TIA

[HarvSlugger]

 RJBingham are you trying to say I post too much? I'm just here watching these amazing charts

[Lukesluckybunch]

5 minutes ago, Ali1977 said:

zoom in and you’ll see the cleaner flow 

Yes Ali a better mean this time compared with the 6z.make less of that shortwave around Iceland 

[nick sussex]

Perhaps we might see some shortwave running ese into the UK but the GFS phases this with a shortwave running sw to produce that  bomb low over the UK .

It does have a known bias for over deepening.  And to even get that phasing needs perfect timing . Even before the explosive deepening.

[Polaris]

 Derecho

Yes think Paris got 4” from that. Was only T96 showing a midlands south event. 
Which is why a D9 slider for midlands south needs to be at T60 for me. 

[GokouD]

 Allseasons-Si I seem to remember the GFS was the first to show Storm Arwen a few years ago and everyone thought it was off on one, so it does get them right occasionally!

[RJBingham]

 HarvSlugger No the "deep dive" goes for nearly an hour 

[bluearmy]

 That ECM that day 10 gem NH profile is surely only ever going to appear on a computer model ! (Even moreso in November) 

of course the time frames leading up to it are also therefore v questionable 

should have view on the 12z ec op in an hour (although the experience of the 06z run would perhaps mean that we again have to wait the full hour to see the whole model run ) 

[Geordiesnow]

The blow up low on the GFS is plausible as it been hinted at by other models but how it got to it is different to the other runs.

UKMO is decent but sort of expected slightly colder 850s than it showing given it set up but what both models do show is an eastern movement of the cold pool/northerly flow so we have seen a more direct hit and 850s are more on average around -6 instead of -4 with the -8hpa touching northern Scotland. 850s between -6 and -8 from my experience well in the past should be conclusive enough for lowland snowfall away from on shore wind coasts and that is why it's important to have that eastern movement of the cold pool. 

[bluearmy]

 RJBingham can you link it please 

couldn’t find it via Google ot the met office website 

[HarvSlugger]

 RJBingham ohhhh sorry

I haven't actually watched it yet, I will soon