Mark Smithy

Generally speaking high pressures that take residence over France / Spain / the Alps are bad news for UK winter cold.

No it's not confusing. I thought it had support from a couple of members but only a couple. But then on very close inspection it does actually head off on its own right at the end. So technically it does have an outlier couple of days to it: The main issue is that only a couple of members support the operational. The vast majority trend mild. So don't pin your hopes on something with such little support. Not unless a whole cluster of others come on board.

The ECM continues to show height rise to our south, which leaves us in alternating mild and cold meridional interludes. Ignore this at our peril. This for example at T240 isn't a pathway to cold ... at this stage:

Yep the problem comes though when people cast their subjective wishes onto model outputs and lose objectivity. It happens a lot, this morning being a case in point. Fact is, as far as this stage of the model outputs goes, that we're heading for a mild breakdown this weekend and the exciting 0z GFS operational was an outlier. Back to humdrum UK winter weather: mild and meridional cold interludes. Anything more is straw clutching.

Just before anyone gets too excited at the 0z GFS, here's a reality dose: It's not an outlier [edit - well actually it is at the end] but it sure doesn't have a huge amount of support. The likelier scenarios are the ECM. Which means mild westerlies with occasional colder incursions. Basically back to something more hum-drum. At least, until or unless more GFS members start to show what the operational did.

Run the sequence through and watch the synoptic flow left to right. That's not a cold 'set up' it's a very brief interlude in an otherwise mild flow. Check the high pressure to our south and the mild run of south-westerlies building in. It's clear right now: GFS, ECM have the UK heading mild next weekend. So does the UKMO. But see my previous comment for the detail. With a resident European High we will still get occasional colder forays esp in the far north. Make the most of this cold if you like it because the latest model outputs don't favour it sticking around.

There's perhaps a slight tendency to look for the best possible upstream signs and most obscure models or ensemble members within the mainstream ones. I think we need to recognise that the main models all now have a blocking high pressure build showing up. It's just in completely the wrong place for UK cold. If this high takes hold over southern Europe / the Alps then we will be in an Atlantic draw with occasional colder interludes for the Scottish mountains.

This isn't a synoptic cold set up from UKMO. GFS robust in a weekend breakdown and there was solid ensemble agreement in the 18z for the first mild phase. The 0z GFS doesn't deviate from the mild conditions. Looking ahead, all three main models are positing a high pressure build to our south or south-east over continental Europe. This often means no route to cold in the UK.

I'm afraid this is a classic example of straining at gnats and swallowing camels. There's a bloomin' great Euro High developing if we're not careful. You can have all the PV splits and high pressure cells over the north pole you like, but if we get a resident high over the continent (south of Scandinavia obvs) then you most certainly cannot ignore the south westerlies. The mild breakdown next weekend does now look pretty likely. All 3 big players have it coming in. Thereafter? Don't bet against the form horse winning through: mild.

Just back from a bitterly cold but beautiful 5 mile walk. Well, those of you who believe that the cold will come back after it (probably) briefly departs will be very heartened by the finale to the 6z GFS run. Scandinavian High Pressure returns and another bitter easterly sets in: Boxing Day 1962 was the start of the Great Freeze winter of 1962/3. Just saying .

Anyway, I wish you all peace. Only time will tell. Because this is a model output thread not a daily snow report

The danger here is cherry picking what we want to see versus the empirical reality of how the main model outputs are trending. There is definitely a signal to mild 6-7 days from now. That doesn't mean it's a done deal. Judging by the ensemble spread on the GEFS for instance I'd say it's somewhere between 70:30 and 80:20. Whilst the 0z operational is on the mildest side there are only a couple of members which don't trend mild at the key point:

Well clearly we're not comparing like for like and it's always dangerous to suppose how a model output might head after, erm, the model output finishes. However, this T168 final chart is not a promising set up for ongoing cold. Like the ECM, there is substantial height rise to our south building here (1024mb) and when you ally this with the west to east movement through the frames, this is not a recipe for ongoing cold:

Indeed KTom. I don't think you and I are likely to make it into the Echo Chamber thread anytime soon but the likely inconvenient truth has to be aired. It's not a done deal but it's the likeliest. The real problem would be that ECM T240 set up with a high pressure over southern France / Spain / North Africa. They can be difficult to shift and leave the UK in mild south-westerlies. Good for the pesky heating bills though.

I'm afraid the flaw in your argument lies right at the outset. There aren't really "six main outputs". There is a clear hierarchy of reliability with 3 main model outputs: GFS, ECM, and UKMO. All 3 of the main outputs suggest milder outcomes at around the 6-7 day point. It's not a done deal but once we start scrabbling around for minor model outputs to back up our preconceived wishes then we're not really being objective or empirical. Based on those 3 and the ensembles it's somewhere between 70:30 or 80:20 that it's heading milder.