Met4Cast

January 5

I read the forum before checking the ECM and some are acting like it’s showing raging zonality & mild weather. I think some people need a reality check.

It’s still blocked & increasingly cold. It’s also a single deterministic run, let’s wait for the ensembles shall we?

GEFS ensembles were good, I’m sure we won’t see any significant movement from the EPS either. Chill out.

January 5

Baby steps from the GFS early on then it goes on to produce a GFS classic.

UKMO/GEM are very good, GEM probably run of the day so far! Hopefully ECM follows suit and we can put the GFS into idiots corner.

January 5

GEFS so far trending more blocked compared with the 00z. James Peacock tweeted that it could be the classic GFS reverting to default bias in the extended when it struggles to handle split flows/undercutting, something which happens less frequently since the recent updates but could still be present.

If the EPS begin to back away from decent blocking on this evenings run i'll be concerned but so far away from the GFS everything is mostly the same. No real worries from me yet.

Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4996162

January 5

Ensembles not fully out yet but clustering is far more tightly packed during and just after the retrogression transition so I think we're likely back on firmer ground now.

Lets see how the rest of todays runs pan out before panicking, all good!

January 5

Just now, weathercold said:

It’s worth noting Marco (UK Met) alluded to models overdoing Greenland blocking. Have we seen this over recent days - leading us up the garden path possibly. Are recent gfs runs more realistic as to where we are heading.

With so much potential on offer I think this fail if indeed we see one will hurt more than any other. The lack of ‘pro’s’ Onboard is concerning.

To be fair he was talking more specifically about MSLP values over Greenland due to the height modelling over estimates the gap, 500hPa charts are not impacted by this issue.

January 5

GEFS so far trending more blocked compared with the 00z. James Peacock tweeted that it could be the classic GFS reverting to default bias in the extended when it struggles to handle split flows/undercutting, something which happens less frequently since the recent updates but could still be present.

If the EPS begin to back away from decent blocking on this evenings run i'll be concerned but so far away from the GFS everything is mostly the same. No real worries from me yet.

January 5

Whatever the GFS det shows it’s important to view the ensembles, we don’t want to see the trend towards increased spread (and milder members) in the extended continuing.

Fortunately the EPS has remained solid so no real dramas for me at the moment.

January 4

GFS det top of the pack in outlier territory. GEFS means remain rock solid with very little movement & certainly nothing towards the det. Steady as we go then..

January 4

1 minute ago, Neilsouth said:

Why do people keep posting the ensemble mean as that too changes as much as the models do? Such as in the case of the 18Z GFS

Because ensemble forecasting at that range is really the only way to go about things.

January 4

Very good ensemble mean so I’m afraid the “winter is over” party has been cancelled.

After two unbelievable GFS det runs it’s not a surprise we’ve had a slightly less good one. Det is also on the milder side of the ensemble pack.

January 4

Just now, mbrothers said:

Sorry I’m new to this but are people really worried about a single run at 12 days out?

Yup.. that’s generally how it goes in here though, one dodgy run and winter is over.

GEFS remain solid so far, I suspect the det will be an outlier in the extended.

January 4

If I hear “west based -NAO” one more time..

January 4

No idea how you can be anything but happy with the output at the moment.

For some perspective, this is the ECM ensemble mean for days 9 & 10. It literally does not get better than this at that range.

January 4

Here's @Tamara's shuffling high pressure on the EC46.

January 4

1 minute ago, Jason M said:

West based is the biggest risk IMHO. The sheer depth of the cold dropping into Europe could spin up a deep low which instead of sinking South ends up NW of Scotland and cuts off the flow. Kazim has been getting flack for suggesting this but if this goes per shaped it will almost certainty be via a west based set up. Not saying it will, but its going to be a risk.

I keep seeing talk about a west based -NAO and I keep seeing absolutely no evidence for it whatsoever within any output or ensemble suite..

January 4

Just now, Eagle Eye said:

No, a major SSW would've been better or similar. We got lucky and the minor SSW amplified the pattern setup by the rising AAM because it reflects the waves that the rising AAM is driving up towards the poles and vertically into the Strat back down to Greenland and amplifying the pattern. A major SSW would've downwelled and reversed/significantly weakened the zonal jet and probably come to a similar solution just in a different way. Proves that sometimes a minor SSW can still help in certain scenarios.

Perhaps.. but with a major SSW it wouldn't allow further attacks as Rossby waves cannot penetrate into easterly winds. In theory the dramatic weakening of westerlies caused by this minor warming may have been enough to produce the outlandish blocking being modelled anyway when combining with tropospheric led drivers.

This allows the potential for a further warming/deceleration towards mid month with some hints of a major SSW occurring which could then serve to reinforce the -NAO pattern we're seeing and 'lock in' the pattern.

Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4995074

January 4

Just now, Eagle Eye said:

No, a major SSW would've been better or similar. We got lucky and the minor SSW amplified the pattern setup by the rising AAM because it reflects the waves that the rising AAM is driving up towards the poles and vertically into the Strat back down to Greenland and amplifying the pattern. A major SSW would've downwelled and reversed/significantly weakened the zonal jet and probably come to a similar solution just in a different way. Proves that sometimes a minor SSW can still help in certain scenarios.

Perhaps.. but with a major SSW it wouldn't allow further attacks as Rossby waves cannot penetrate into easterly winds. In theory the dramatic weakening of westerlies caused by this minor warming may have been enough to produce the outlandish blocking being modelled anyway when combining with tropospheric led drivers.

This allows the potential for a further warming/deceleration towards mid month with some hints of a major SSW occurring which could then serve to reinforce the -NAO pattern we're seeing and 'lock in' the pattern.

January 4

3 minutes ago, Harsh Climate said:

Wise words, funny how many people are on full ramp charts 10+ days away .

Even though everything is saying deep cold and blocking, there is still the potential for a spanner in the works nearer the time (West based NAO) (some places being completely dry while a few lucky places get clobbered by snow streamers..) like you I'm holding back any real excitement for a few days yet.

Could you imagine if that 5/10% chance of it going the way of the pear happened, think there would be a few upset people on here.

Still though, can't ask for better charts than what we are seeing.

If you can’t take 10 minutes to enjoy the synoptic output, however unlikely then you’re in the wrong hobby

These charts are stunning regardless of their likelihood to verify or not. There is a growing likelihood of a very notable cold spell, that much is clear across all models & ensemble suites with teleconnective background forcing pointing in that direction too.

Exact detail & evolution to be determined but.. we don’t see charts like this being churned out every winter, let alone charts like this that have backing & support.

January 4

You know the modelling is good when both me and @Catacolthrow our sensible hats up into the air and just marvel at the output on offer rather than analysing.

Simply stunning 12z GFS. Lets hope the ENS remain solid. UKMO & GEM are also very good.

January 4

This chart could be plucked straight out of the archives from 1962/1963.

January 4

The lead up to 2010 was like this.

The lead up to 2018 was like this.

2009/10 was like this.

The modelling latched onto blocking & cold early and continuously upgraded until it arrived, I think that's what we're seeing now. The signal for retrogression is SOLID. The exact evolution will naturally chop & change but everything is now pointing towards cold.

January 4

Yeah I have no words,.

This is why we all do this, charts like this is precisely why we go through the pain of this every single year. Unbelievable Jeff.

January 4

Here she comes. Some genuinely cold air to the north and east of the UK on this run.

It's coming home.

January 4

17/51 EPS members show a major SSW reversal, this is up from 14 yesterday. A major SSW & downwelling easterlies super imposing onto an already -NAO would be quite something..

Still, we’ve been here once already this winter.

Original post: https://community.netweather.tv/topic/99706-model-output-discussion-into-2024/?do=findComment&comment=4994654

January 4

17/51 EPS members show a major SSW reversal, this is up from 14 yesterday. A major SSW & downwelling easterlies super imposing onto an already -NAO would be quite something..

Still, we’ve been here once already this winter.

Sign In

Forums

Blogs

Gallery

Events

Learn About Weather and Meteorology

Community guides

Posts posted by Met4Cast