Met4Cast

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.

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.

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

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!

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.

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.

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.

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..

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

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.

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.

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

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.

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

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..

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

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.

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.

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.

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

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.

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.

Here she comes. Some genuinely cold air to the north and east of the UK on this run. It's coming home.

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

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.