Uncertainty

the red borders in the run up to Xmas

What now looks highly likely is for next weekend’s trough to come to a near halt adjacent to our west and slowly fill perhaps bringing quite a bit of rain, one to watch as a front could end up strung out over somewhere. What is far less certain is the strength of the ridge moving in behind it. The big 3 are presenting 3 different options. a) Greenland wedge (GEM) b) Mid Atlantic ridge (ECM) Toppling U.K. high (GFS) There is of course the option where barely a ridge appears upstream of the low in which case a long fetch south westerly would ensue. Given the time of year I’d still make this the form horse but things have got a bit interesting… If I could choose which of course I can’t then I’d want the high to eventually progress to Scandi to put the brakes on the strat but alas we can only watch and wait and see…

That’s nuts with a strong vortex up top. Must say I was, and mostly still am, expecting Atlantic oblivion, but the models are really toying with this idea of a very blocked pattern. Gfs in particular but as you say a lot of eps members and not just today. I mentioned the early murmurings on Wednesday… JMA more sobering, there are still plenty of ens members like this I wonder how many more days of the blocked to the nw charts we would need before the wording down at Exeter would shift?? Ec46 has not been keen on any of this at all.

Hmmmm

The BCC is out… DJF precip DJF heights Not bad, though it does love to go for Greenland heights… the signal is strongest in Jan. It seems to do well when it forecasts a +nao, you know the writings on the wall when that happens. It did really well with the blocking, unlike other models, in 2020/2021 but it went for it again the year after which didn’t happen. Similar to the DWD though, drier to the N wetter to the south. Aside from the cfs, every seasonal still really keen on early 2024 big time blocking. CMCC, JMA and of course Glosea to finish the set tomorrow.

6 clusters and all the colours doesn’t exactly fill one with confidence…

Surprisingly, the signal for Scandi heights in the medium range to put up more resistance than previously thought seems to be increasing tonight. The op runs, especially the gfs, have been toying with this recently but the ensembles haven’t really been interested. That has shifted a bit tonight looking at the 12z. GEFS day 10 GEPS I wouldn’t get too invested just yet, there is no mean easterly flow on the charts yet and the strengthening downwelling strat makes the above even more dubious. In my opinion scandi highs are poorly modelled and their forecast to reality ratio is (purely anecdotally) about 5:1! Nevertheless, the ec op seems to be joining in the fun in typically over excited fashion I’d still give the Atlantic 70%, but there’s a signal there to hold on to for those wanting a more settled spell (or more crucially those wishing to see the development of a longer term scandi / Ural block…)

I think that’s a massive part of what the modelling is seeing Robbie. If it were the opposite way round, like in 2018/2019, I doubt we’d be seeing the kind of prognostications we are seeing for Jan-Mar now…

Whilst we wait for Glosea to update, the latest DWD output is available. No pressure anomalies yet, but a glance at the precipitation probabilities is quite telling… This screams southerly tracking jet to me, with NW Scotland and W Norway forecast to be much drier than average and France, S England and E Europe all much wetter. Yet another consistently unusual seasonal model. Something is really telling them to go -NAO. Tripole? EQBO? Nino? All of the above? None of the above? It’s beyond me, but what I do know about is the modelling and the signal, for me, is clear. Whether we chose to believe it is another matter entirely!

Brilliant mate. I share your views and have been struck by the continued support from the seasonal modelling. The question for me now is when will the flip occur…

No argument here either Ed lad. You do realise I’m a spurs fan too? Maybe that’s why we’re both thinking we’re tetchy? When really we’re… well… I don’t know how to put it into words

Search it on Google scholar Ed, there are tonnes of journal articles around it. I think it could be part of the mid/late winter puzzle the seasonal models are unpacking. We’ll see. I’d rather have it than not have it, let’s put it that way.

There are plenty of research articles supporting it detailing the mechanism. It’s hardly the OPI - it’s a legitimate factor( should it fully manifest.)

I had a look at all the November JFM progs on the ecm website and there’s nothing even in the ballpark as exciting for coldies as the latest one. I’ve also compared them with the actual anomaly. Apologising for comparing slp to 500mb heights I know I know but I don’t like the colours on the ec website (lol) and I can’t get the noaa anomaly builder to generate slp charts??? Anyways, I prefer to have two colourful charts to compare It’s just to give a general idea for folks… 2017-2018 Not bad, got the low heights into Europe and did well with the Nina pacific ridge. Blocking probably more extensive than progged. 2018-2019 Pretty good for our region and got the Aleutian low right. Underestimated Alaskan ridge and not great off eastern seaboard and Siberia. 2019-2020 Tbf you didn’t need a supercomputer to predict this one… A tidy job nonetheless. 2020/2021 A bit of a fail here, completed underestimated the blocking. In the end, the actual slp low anomaly was a tad to far north to allow for a famous U.K. snow season, but Scotland had a bumper year. Not terrible away from the Atlantic / euro pattern mind. I think it missed the ssw… 2021/2022 Pretty darn good. 2022-2023 Not too bad, maybe a bit more hp around Iceland but it didn’t amount to much anyway. So there you have it, recent SEAS5 forecasts have been generally good and have never even slightly predicted a favourable pattern such as what we have in today’s update. Combine that with the incredible cross model consistency I have been harping on about and perhaps you can see why I’m starting to get excited!

All true Nick but the movement back to blocking compared to the last update means we now have consistency again across the seasonal modelling for some kind of Greenie heights/S tracking jet. As ever, in that scenario the euro low heights will be key and this is where we have been stung in the recent past. SEAS5 flipping in October was frustrating and this on the other hand is reassuring for the forecast. But agree it could be even better… Encouraging to be back on track nonetheless.

Nov EC… JFM Boom!

Yeah, you can find the link to it on the Copernicus site… it links to all the contributors. Dec Jan - looks transitional Feb - oof Mar

Winter’s coming… Just not in December! Cansips was the same. Mild, wet, windy early winter transitioning to heavily blocked in Jan and beyond. Nino, weakening +IOD and plausible ssw. If it wasn’t for recent climatology, the above is what we should expect! Last year’s Meteofrance JFM for comparison: Now I’m off to hide behind a stack of sofas before the ec seasonal comes out!

I can’t post the charts yet. Will post them as soon as I can. But the extrapolation I’ve done on the charts I have seen suggest the signal for a cold blocked winter on the November run of the CANSIPS, which has been consistent for 8 months(!!!) is EVEN STRONGER! It’s on metcheck Nick. I doesn’t have the pressure anomaly so waiting for that to post. But the shape of the mean low looks even weaker than the last run and the 850s are colder than average.

Most optimistic cfs in months showing for Jan.

There are 3 solid weeks of Ural blocking preceding that rather remarkable ec 46 stratospheric temp anomaly. If the former manifests the latter could too. Easy to see then how the long time seasonal model prediction of blocking this winter could actually occur. We look east / ne with baited breath… What a chart btw! Anomaly shows how unusual it is to have a warming forecast in early dec…

I wouldn’t fret about analogues Don. For the last 3 winters the models said the Nina would go strong even super and it didn’t happen. We’re getting into sub- seasonal range of the winter and the signal for an unusual temperature profile in the strat is increasing… No one is talking about the Atlantic SSTs either which are more important imho. We are getting really close to a tripole. The coral reef chart doesn’t show it as well as others, check out Judah Cohen’s weekly blog and tell me it isn’t a tripole! IF the seasonals hold their signal (and ideally the ecm returns to the pack) then I’m calling a blocked winter. Still concerned about the cfs though. All in all more to be excited about than worried about but as ever when blocking is possible it’s a tricky call. Will put my full thoughts out after the 10th…

Great to hear your thoughts Roger... The seasonal models generally support your view. Something else to add to the mix, this little signal from the ec46 keeps getting stronger… An early December ssw… now that would be something (I realise that isn’t what the model is forecasting but the anomaly is notable nonetheless)… For balance, The cfs is still utterly diabolical for cold. It’s either very wrong, or…

Quite remarkable that the big 3 are all going for a major +SCAND. Would be a pretty big fail now if it doesn’t come off… GFS GEM Ec op EC mean Will it be transient? If it sticks around for 2 weeks or more then we could get a vortex disruption in December. This pattern is excellent for vertical wave flux into the strat. Judah will like it. We had something similar in late Autumn 2018 and did get an ssw following it but the Atlantic profile was anti-tripole and the wqbo was there so the cold never came. Anyway I’m getting ahead of myself. An interesting pattern nonetheless once Friday’s nasty rainband is squeezed out…

The big Ural high is what we want. If it manifests and lasts the vortex could pop in December. Ec46 sees it too throughout late oct early nov. Early days, but if we get 3 weeks of a giant Ural ridge (massive if) then things could get toasty up top right when coldies want it to…