MOGREPS-G 00z update on 07/12 offers a lot of support for the Global model operational run. A big snow event in the southern half of the UK looks like a possibility at least.

https://www.theweatheroutlook.com/twodata/mogreps-stamps.aspx?hour=168&fvar=mslp500 

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Yes the ECM ensembles are much better this morning but they do tend to swing with the Op. The drama has a few days to run yet.
 

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ECM is actually a pretty dry run. Certainly not a big snow event in the south next week if it is correct.

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The old joke about 2 economists getting you 3 opinions applies to the models at the moment; only it's a case of N models giving you 2N opinions, as they all change come the next run. But for the moment ...

WX temps show cold air well spread across W Europe including Britain in week 1, withdrawing to E France in week 2 but intensifying, Britain still on the cold side, though; a bigger mass of extra-cold air developing over Siberia; a little milder over Spain but colder in the Balkans. Mainly dry over Britain in week 1 with pptn all around; in week 2 the pattern shifts to one patch on the N Atlantic also affecting britain, and intense rainfall separately around Greece.

GFS Op - Britain under N/NE lies resulting from LP over Scandinavia which slowly fills leaving cold air over Britain to mon 12th. This morning's treatment of the Atlantic LP leaves it W of Ireland and Britain under a weak N-S ridge of \HP (1015mb) Wed 14th. High pressure continues to be present and intensifies as part of a Scandinavian HP 1035mb Sun 18th N Sea and strong S-lies for W coasts. The Atlantic LP then diversifies into a trough moving E-wards across Britain and the final chart, Fri 23rd, shows something 'normal' for midwinter with W-lies between HP to the SW and LP over Iceland.

ECM - the coldies' favourite; from Mon 12th the Atlantic LP projects a trough into the Channel Wed 14th 995mb N France with enough cold air advected from the E to suggest the possibility of snow in S England. The LP then grows into a three-centre feature Fri 16th, 995mb Germany, 1000mb Finland and 995 mb Norwegian Sea, all with quite cold air advected over Britain. A startling difference from GFS.

GEFS - remaining v cold and mainly dry to Tue 13th after which chaos ensues; the mean is back to norm but this means very little with e.g.  selected runs in the S, Sun 18th one 10C above norm and one 10C below. Most ens members have some pptn from that Tue with snow row figures highest as the potential breakdown starts 

Other models are available, as they say.

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ECM is actually a pretty dry run. Certainly not a big snow event in the south next week if it is correct.

Yes, the precipitation only skirts the far south on the 00z op.  But given the band of rain/snow is only, what,  50-100 miles wide, any slight adjustments in the modelling will have huge consequences for any specific location.

As others have said, this will only slowly become clearer into the weekend, and in terms of precise detail not even by then. But potential, certainly.

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Someone on the other side made a good point this morning - if we could re-analyse the charts and (if they existed) ensemble data for Dec 1963, Feb 1978 and Jan 1987 for instance, we'd probably see just the same amount of uncertainty and spread leading up to those event, if not more. And actually the 2010 episode has many a wobble and variation even 5 days out. I completely accept that the scripting of NWP and the associated processing power is exponentially better than it was just 20 yrs ago, but subtle changes to starting data are introduced for a reason - because the starting data itself has error bars and is often sparse in areas where it's needed.
The skill in medium term forecasting is not in the interpreation of one chart from one model, but in looking at all available data and deriving a blended solution that (at the time) is most likely, with the caveat that it will change from hour to hour. I find the intense scrutiny of every chart entertaining, but in scientific and practical terms it is not the best approach.
 

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Indeed. 🙄

Other basic pointers are: 1) Be sure you know what chart you are looking at and make sure it isn't a cached version 2) Check the forecast variables such as precipitation before making assumptions about what it is showing 😁

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Indeed. 🙄

Other basic pointers are: 1) Be sure you know what chart you are looking at and make sure it isn't a cached version 2) Check the forecast variables such as precipitation before making assumptions about what it is showing 😁

Dry, if not very dry, for the reliable timeframe.

Midweek next week might offer some interest, on the nearer shores of Fantasy Island.

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Someone on the other side made a good point this morning - if we could re-analyse the charts and (if they existed) ensemble data for Dec 1963, Feb 1978 and Jan 1987 for instance, we'd probably see just the same amount of uncertainty and spread leading up to those event, if not more. And actually the 2010 episode has many a wobble and variation even 5 days out. I completely accept that the scripting of NWP and the associated processing power is exponentially better than it was just 20 yrs ago, but subtle changes to starting data are introduced for a reason - because the starting data itself has error bars and is often sparse in areas where it's needed.
The skill in medium term forecasting is not in the interpreation of one chart from one model, but in looking at all available data and deriving a blended solution that (at the time) is most likely, with the caveat that it will change from hour to hour. I find the intense scrutiny of every chart entertaining, but in scientific and practical terms it is not the best approach.
 

Surely Neil this is summed up by the fax charts, now they are in the reliable time frame these have to be the 'sense of truth', afterall they are made up are they not of all forecasts with human input 🙂

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What is wrong with Meteociel? Cant seem to get GFS

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This cold air arriving is certainly not that cold , raining here , temp goes up in showers to 1.9C , and temps in Orkney still 1.5C with rain showers 🤔, is the sea temps diluting this cold air ?

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Surely Neil this is summed up by the fax charts, now they are in the reliable time frame these have to be the 'sense of truth', afterall they are made up are they not of all forecasts with human input 🙂

👍
Perhaps others will disagree but for me, it's only when things appear in the FAX charts that they are in the reliable(and even then nothing is absolutely certain).

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The lead up to 2010 cold spell on the charts was massively different to now. 

Heavy Weather mentioned why Retron hasn't commented  onthis cold spell so far. Normally he'd do a -10 850hpa or more ens watch,  apart from the odd ens that briefly touch -10  and so far there is very little sign of much snow away from the hills and costs in the North. Any charts are still at 6+ days away that show any decent snowfall and are random with little to any ens or X model support. It may change but so far it's just a cold and mostly dry spell of Weather, nothing much to write home about for now. 

What is wrong with Meteociel? Cant seem to get GFS

Meteociel has frozen half way into the 00Z run and Wetter is painfully slow. A lot of stress of their servers.

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Fun to discuss snow potential but until the TV presenters get confident it is unlikely to be an accurate assumption but no problem in having a go. Nevertheless, sticking to the knowns, it is going to be a very cold week ahead with the risk of frosts even in the South. (None so far here). After a week or so there are a large number of models now suggesting something milder but of course with far less certainty. However we know how that usually turns out. 

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The lead up to 2010 cold spell on the charts was massively different to now. 

Heavy Weather mentioned why Retron hasn't commented  onthis cold spell so far. Normally he'd do a -10 850hpa or more ens watch,  apart from the odd ens that briefly touch -10  and so far there is very little sign of much snow away from the hills and costs in the North. Any charts are still at 6+ days away that show any decent snowfall and are random with little to any ens or X model support. It may change but so far it's just a cold and mostly dry spell of Weather, nothing much to write home about for now. 

So, pretty much what we should expect from an early December northerly - which has so far only arrived in the far north.  It was ever the case that a bone dry Arctic flow required disturbances in the flow or an incursion of less cold, moist air to get any wintry precipitation inland.

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The lead up to 2010 cold spell on the charts was massively different to now. 

Heavy Weather mentioned why Retron hasn't commented  onthis cold spell so far. Normally he'd do a -10 850hpa or more ens watch,  apart from the odd ens that briefly touch -10  and so far there is very little sign of much snow away from the hills and costs in the North. Any charts are still at 6+ days away that show any decent snowfall and are random with little to any ens or X model support. It may change but so far it's just a cold and mostly dry spell of Weather, nothing much to write home about for now. 

👍

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Literally laughing out loud at the 6z FI this time around. Bringing in almost "winter heatwave" conditions now with temperatures up to around 15c. ​​​​​​​Christmas BBQ on the cards? 😂😂😂  ​​​​​​​Just a 17c difference at 2m when compared with yesterday's 6z. 

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Literally laughing out loud at the 6z FI this time around. Bringing in almost "winter heatwave" conditions now with temperatures up to around 15c. Christmas BBQ on the cards? 😂😂😂  ​​​​​​​Just a 17c difference at 2m when compared with yesterday's 6z. 

I cant get it on Meteciel
Can someone post link

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I've been posting on this site since Brian fired it up in 2000 and experience tells me that if the GFS op shows a cold spell going t1ts up in two consecutive runs, then it will go t1ts up. I realise that there will be several days of cold before the t1ts up moment before Michael points this out!

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