Man With Beard

Hi Skiwi1, welcome! Don't know what others think, but after several utter car crashes on the Meteociel charts this winter, the only thing I'm believing when it comes to snow is the EURO4. And it isn't pretty for the Midlands/SE tomorrow - parameters wrong when rain comes through, then once parameters are right, no precipitation. Areas around the Pennines / N Wales mountains most favoured for sure http://1.1.1.1/bmi/expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2016/03/03/basis06/ukuk/prty/16030400_0306.gif

The idea of a Scandi High on the GEFS has been dropped for the moment. No overwhelming agreement on the ensemble members on how things are going, but generally the westerly idea is favoured today, and temps maybe even above average by D10: ECM D10 mean even flatter and milder, and very probably wet for NW areas - there's fair spread over the UK, but no significant support for anything remotely cold at this stage: http://www.meteociel.fr/cartes_obs/ecmwfens_display.php?x=306&y=141&ville=Londres Both means convincingly remove low heights from Iberia, which could be significant. The effects of the SSW will have to be pretty crazy to turn these models on their head for mid-month!

Another decent Scandi High after D10 on the GEFS mean, that's two in a row...

Thanks for all the very interesting replies, and Knocker I think "strong polar vortex" summed up my thoughts better than "zonal" - anyway, better theories have been mentioned since then! Back to the here and now, after some minor snow skirmishes today, Friday is sort of coming together on the charts. Certainly areas between Birmingham, Manchester and Sheffield can keep their eyes glued to the output, as agreement is starting to emerge: and a similar story on the EURO4 http://expert-images.weatheronline.co.uk/daten/proficharts/en/euro4/2016/03/02/basis06/ukuk/prty/16030406_0206.gif The big unanswered is (1) whether the whole band will drift south during the day intact and (2) will it still be cold enough for snow later? Later in the GFS 06Z, high pressure continues to sneak in from the SW, warmer in the NW but perhaps still average in the south But VERY interestingly, a scandi-high later on from the mean chart. Honestly, has anyone ever seen such a strong signal for a Scandi High at T288??? Some of the ens members are true winter classics - even though it isn't winter anymore, some of them have just enough bite to be wintry Really unusual to see the GEFS do this in latter stages, so can only think something very interesting is about to hit our screens...

So model accuracy is actually better in the winter than summer? Or has the zonal nature of the past three winters made it easier for the models?

To be fair to John, he's simply calling a spade a spade - the Azores High will not sit over the UK by D10 (probably!) - I don't think he's saying there won't be any influence at all - we got crossed wires earlier. I believe the NOAA 8-14 trends even further this way tonight - but still a slight NW flow toward the UK so perhaps a stalemate between winter and spring coming up? Must just comment on 18Z GFS - not seen so much snow forecast by this model at just T18, normally it's disappeared by this time - are many of us about to see our first flakes of the year?

ah, but the effects of the Azores High may be getting nearer, wouldn't you agree? http://www.cpc.noaa.gov/products/predictions/814day/500mb.php EDIT: Re-reading my original post, perhaps I wasn't clear enough - clearly the Azores High is unlikely to go over the UK, but it may be close enough to affect our weather rather more - that's what I meant

(Hello my fellow Pompey inhabitant!) Glosea hasn't totally nailed things though - height rises to the west have not been to the extent they predicted - no proper Greenland High, just slight northwards ridging of the Azores High, and I do remember originally they went for well below average to the west of the UK, which I don't think has happened. As for March - it hasn't happened yet! We can easily see that the idea of a cold March/April could easily get derailed within 7 days time (see my earlier post) - still no conclusive sign of northern blocking appearing IMO - the Glosea may be right but it looks like a nervous wait to see if it actually will be - I'm smelling the Azores High coming our way by mid-month, though...

Apart from the next 5/6 days, are we looking in the wrong direction here? Spring is within touching distance according to some of the ensemble output. Starting with the D10 means: It's a close call between a slight northerly breeze and a south-westerly drift, I'd say. Uppers still slightly chilly but double figures in sunshine I'd think. And a closer study of the GEFS sees a proper breakthrough of the WSWly winds showing on many, for instance: I'd guess 15C and sunny spells in the east on this one. And this isn't the warmest ensemble member either ECM extended ensembles: cold has gone by the 10th, aside a slight frost or two So it's not a one-way street for cold on the models - just saying...

This would usually be a source of great interest, but there's just not enough bite in the cold in our side of the hemisphere. Scotland, Pennines, Lakes, Peaks and Welsh mountains probably will go white. The most interesting chart I saw today was actually the GFS 00Z chart at T384, which showed the main vortex moving to Scandi/Siberia. Now by no means am I forecasting a D16 chart, but it showed what might be possible if such an alignment could propel the cold from Siberia towards us - uppers are still in the -20C to -30C category. That would have the bite needed even in late March. But it's such a long shot it's not really worth thinking about.

5.9 please

The ECM completes its turnaround this morning, now becoming probably the most wintry model on offer for days 6-10, with a very rampable run for north of the M4. A trough gets stuck over southern Britain at T144/T168 and slowly edges south, with a weak ridge to the north bringing in another easterly. The last gasp snow chase continues, then.

Lovely charts and a fair analysis as far as the charts show ... but the 850s has been downgraded so often this year that when I see -6C, I mentally think "-4C". I think we need to see some -8C 850s to have some hope that snow would be the end result rather than cold rain.

John / Mushy - would welcome a little more detail on your thoughts. We're particularly discussing the NOAA chart here: The upward kink in the lines towards Iceland indicates a tendency for higher pressure, from the Azores all the way up to the Iceland/Greenland area. The downward kink in the lines from Norway to Italy indicates a tendency for lower pressure. I have to conclude that this higher pressure in the Atlantic will mean that, as a mean over the 8-14 day period, we would expect winds to come from a northerly direction on their path to the UK. Not an Arctic northerly, but originating from the north. Now this could be a combination of N/NNW/NWlys on some days and variant directions as troughs emerge through the flow dropping from the north down to mainland Europe. And, if a trough does drop into mainland Europe, there is likely to be a period, even short, where winds veer back NEly. John/Mushy - is there a flaw in my argument?

So the current op is a warm outlier, and the parallel is a cold outlier!! The ensemble clustering not really representative of either. So should we be wary of outputs for D8 onwards??

It's been a confusing day for mid-term prospects. The ECM op remarkably consistent in flattening the pattern somewhat. But you cannot rule out another Arctic blast with anomaly charts like this: To me this shouts out Northerly, Northerly, Northerly - and if I'm wrong, North-easterly!

Hmmm ... as others have alluded, the ECM mean still gives a chance of something colder developing ala GFS - main trough to our NE, perhaps stronger heights to our west that the op suggests - can't write off a further shot of cold at the end of next week yet. But it's decidedly dodgy. Looking at the latest GEFS, the consensus is certainly to keep on the colder side - and quite confident of a flake or two in the capital before the weekend is out: http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=306&y=141&ville=Londres Yes, same on extended ECM ensembles - op is an outlier, most runs bring back the chilly weather (rather than "cold") by D9 and keep it that way till the end:

It's increasingly looking like this weekend may be the final chance of seeing flakes of some sort for many, as it just isn't working out with regards northern blocking thereafter. The ECM is particularly poor in that respect as it not only flattens out the pattern between D6-D10, but it removes deep cold from our NE too so any temporary NEly further down the line would be chilly and nothing else. In fact, the spring brigade may find the run very welcoming, as I can foresee temperatures reaching the teens with sunny spells on the east coast. The GFS attempts to build a stronger high to our West, but still not in the category of "northern blocking", so any temporary northerly is unlikely to be cold enough for snow away from the north. Still, something may develop for Sunday I feel, with a good easterly in reasonably cold uppers.

Is this another case where the models have moved on but the public forecasts have not? Here are GFS/ECM 36 hours ago for next Monday; a keen easterly wind: And here's the latest - Kent clipper maybe but not much further north (sorry!). The ops are pretty much in the middle of the ensembles, too. Saturday into Sunday looks like the best chance of getting anything off the North Sea further north:

Knocker I will add the ECM D10 mean chart: Suggests to me a re-run of the current synoptics may be on the cards next week, with another ridge towards Greenland and Scandi trough following a day or two of slightly milder. Back in the short term, these two fax charts have got my attention: What is that trough doing? Interesting for the SW, but that 528dam line is a bit further north than I expected?

Painfully close to a South West snow event on the pub run so far (T126) - parts of Ireland could do well Thames Streamer potential by Saturday: A little shortwave over Norway might help us from T138 - so often the spoiler, this time it could be the making of the cold spell as the upper flow would send it towards us in cold uppers. Not modelled or even forecast as yet, but we don't usually see them until we get inside T120!

Looking at that, Nick, shakes confidence in there being snow-sufficient cold between T120 and T168/T192. There are a number of ways that the pattern could evolve differently to the op - two possibilities are 1. the trough dropping too far SW leading to a SEly or even a Sly (early spring for a couple of days) 2. an extra shortwave developing near Iceland which I imagine would prevent the low to the SW breaking away - not sure how it would progress after that, perhaps to an even colder NEly with time as the trough may merely be held up on its journey to Europe, gathering cold from the Arctic Circle above Finland in the meantime. - but there would be a milder interlude. However - one for you MushyManRob - gettting closer to the Greenland High on the latest NOAA 8 to 14 dayer - and even an Omega block looks possible now.

This is a really important point, Tim, and I'm surprised at some people tonight taking the T120-T240 precipitation charts too seriously - we always say that when snow IS shown, so surely we should be consistent and say the same when it ISN'T shown. If one were to simply study the pressure and 850 charts tonight, you could conclude that there may not be a major snowfall, but you'd be lucky to avoid any snow showers at all for as many as 8 straight days - particularly central/northern areas. Look at it face value. No strong high pressure nearby. A deep low passing nearby to the SW, but we are well within the parameters of the depression. A strong easterly with low 850s off the North Sea. Then another depression trying to drop down from Iceland to Europe via us. You'd bet your house on that producing at least something.

Yes disappointment for snow lovers if the precipitation charts are to be believed - I just find it hard to believe that we could go through 7 days without snow with so much Atlantic activity to our north/south/east/west - this is the UK, after all! Still, maybe these charts will find a way not to verify at all!

Great post Interitus. Thanks. Onto the models, confidence is surely rising this morning in a genuine cold spell, and I must take issue with suggestions it won't be cold because we get 3 days of virtual nationwide 850s of sub -7C (as low as -9/-10 in places), and then aside a moment or two on the south coast, values never recover above -6 for almost a week - bearing in mind that once to cold gets in, it takes a mild push to get rid of it at ground level. Looking at the GFS 0.25, between this Wednesday and next Tuesday, surface maximums are between 3 and 5C but this would just be for an hour or two a day in sustained sunshine - generally, temps will be close to freezing throughout, and lower on days with cloud cover. All in all, this is what I call a proper cold spell coming up, and what's interesting is the amount of mobility in the pattern - I think snow simply has to come at some point for most. Still a chance of low pressure being too far west allowing a SEly, but this possibility seems to be receding this morning.