Model Output Discussion - The final stretch to Christmas

[PLANET THANET]

Bizarre! Even the GFS wouldn't bring that, initially it might turn milder but even if you take the GFS low position it will still turn colder for a time.

Hi there nick

                I thought it rather strange as although I cant read the models I do listen to a lot of the comments on here from experienced members, but the forecast was on bbc1 southeast at 1855hrs this evening !!!!!

[Roger J Smith]

Would say the most likely outcome at this point is a mixed precip scenario by elevation as much as any other variable.

 

The Boxing Day low seems likely to take a sharp turn south at some point between the Irish Sea and the North Sea, but cold advection is just limited enough to give doubt about snow potential in lower elevations. Anything much above 150m above sea level is probably going to get a covering of 3-5 cm and those between 100-150m are in the marginal zone where snow may come and go during the event. Lower down would expect to see some snow mixing in at times but not lying in most cases.

 

A few north or northeast-facing hilly areas in both Ireland and the UK could see 5-15 cm falls. I suspect these will be mainly above 300m asl, as mixing issues will be found even in the 150-300m layers. With the sea surface temperatures being generally above 9 C it's going to take uppers of about -7 C to get enough sustained snowfall production in onshore flows, and -7 seems to be about the lowest value on offer (some models never go below -4).

 

The end of the year is looking increasingly anticyclonic for a few days, GFS seems to be too fast with its sinking motion to me. There won't be that much energy coming off the North American continent until maybe 2-3 January, then we'll be into a very interesting energy peak timed for 4-6 Jan when I've been expecting this winter to show its true form. Whatever regime we get into after New Years will get a major energy jolt, if it's mild then expect a big storm like last winter's parade, if it's so-so then another mixed special, and if we get into an easterly, then a snowfall-producing trough.

 

Merry Christmas and Happy New Year to all at Netweather. We're looking at a bit of a break from the mild rainy weather here, some sleet or snow could replace it tomorrow. The month has been very mild in western Canada and nearby northwest U.S., the anomaly at SEA currently +6.8 F and at DEN it was +7.0. Those are bordering on record values. A more subdued warmth in eastern North America, current anomalies in the +1 to +3 range.

[Frosty.]

5-15cm..that's it I'm off to buy a sledge..Seriously though I'm happy to see a cold outlook, if we can get a snow cover before the high moves in we will get some very low minima and struggling to get much above freezing during daylight too.. a far cry from last winter when the mild unsettled weather hardly ever stopped for 3 months.

[karlos1983]

See what you mean, but someone posted a chart earlier of Feb 1991 (the best snowstorm I can ever remember) and that occurred with low heights in Greenland. If we can tap into these Scandi heights that we keep getting glimpses of in recent output, we could be on to something more promising maybe?

That was a Scandinavia high with strong PV, different animal, and very possible.

[492]

Nice chart, cold and frosty at the surface with the Azores ridge being sheered away. As BA says, there is an undercut chance which could start to pull colder air in from the east.

Undercut achieved

Low single figure maxima for most and becoming bitter along the south coast.

Almost perfect omega shape to the block at T + 192.

Edited December 23, 2014 by 492

[ANYWEATHER]

It just shows that nothing is set in stone for this weekend. At 120 hrs the ecm/gfs  differ greatly with the low pressure system over Europe. I must say ,talking of deep snow in the southeast going by tonights  ecm is rather amusing, just remember that ecm as been very poor of late with its output.  Its only one output and more than likely be different on the 00z runs. Certainly interesting, and entertaining output, but please folks be careful at looking at one picticular model which shows what weather  you want, as it almost will be totally different tomorrow, especially given the high confusion it the model output of recent days. I love snow and cant wait to see it fall and settle, but Im very cautious with the model output that far out   :smiliz23:  :smiliz57:  

[nick sussex]

Hi there nick

                I thought it rather strange as although I cant read the models I do listen to a lot of the comments on here from experienced members, but the forecast was on bbc1 southeast at 1855hrs this evening !!!!!

I've managed to watch it now on the BBC site, I think her mild comments were in relation to just upto Saturday although it might have come across as suggestive of further.

 

Regardless of which output turns out to be correct it will turn colder, the question mark at the moment is really in terms of how long this lasts and how much snow falls.

[Stuie]

Combined with my last post, this is really knife edge on Sunday morning with the Dam thickness, 528. The ingredients are as near as dammit (no pun) there.

[karlos1983]

Combined with my last post, this is really knife edge on Sunday morning with the Dam thickness, 528. The ingredients are as near as dammit (no pun) there.

Perhaps you should be commenting in the Regionals mate as your last 2 posts have been very IMBY

[492]

http://www.wetterzentrale.de/pics/brack2.gif

 

Wave depression on T+72 FAX slightly further south than previous run as are the high cells to the south of the UK. This wave is expected to deepen rapidly as it tracks east across N England before it turns southeast.

[Stuie]

Perhaps you should be commenting in the Regionals mate as your last 2 posts have been very IMBY

I will do thanks but the scope is probably from the Humber to Kent.

[weirpig]

It just shows that nothing is set in stone for this weekend. At 120 hrs the ecm/gfs  differ greatly with the low pressure system over Europe. I must say ,talking of deep snow in the southeast going by tonights  ecm is rather amusing, just remember that ecm as been very poor of late with its output.  Its only one output and more than likely be different on the 00z runs. Certainly interesting, and entertaining output, but please folks be careful at looking at one picticular model which shows what weather  you want, as it almost will be totally different tomorrow, especially given the high confusion it the model output of recent days. I love snow and cant wait to see it fall and settle, but Im very cautious with the model output that far out   :smiliz23:  :smiliz57:  

But surely that post was only commenting on what the ecm showes.   and indeed it does perhaps show a decent covering for the south east on that run.  not to dissimilar to ukmo run infact  as ever more runs needed  but this is the model discussion thread after all  

[PLANET THANET]

I've managed to watch it now on the BBC site, I think her mild comments were in relation to just upto Saturday although it might have come across as suggestive of further.

 

Regardless of which output turns out to be correct it will turn colder, the question mark at the moment is really in terms of how long this lasts and how much snow falls.

many thanks for that, lets keep our fingers crossed.

[Frosty.]

It reminds me of that famous line from planet of the apes..give me some snow you dam dirty 528 dam...All of a sudden, the models are giving new hope for a snow cover before the Atlantic / Azores anticyclone builds in strongly, if things work out, some areas could have snow on the ground for most if not all of next week, riches unheard of so far this winter.

[nick sussex]

Tonights Nick Sussex Oscars go to the following:

 

Model in a leading role for its performance in I'm Dreaming Of An Easterly.

 

 

The NAVGEM which is the best on show as it delivers a long draw easterly.

 

Model in a supporting role for its performance in Scrooge.

 

 

The GFS which throws low heights eastwards and mild mush later on.

 

 

[Banbury]

I've managed to watch it now on the BBC site, I think her mild comments were in relation to just upto Saturday although it might have come across as suggestive of further.

 

Regardless of which output turns out to be correct it will turn colder, the question mark at the moment is really in terms of how long this lasts and how much snow falls.

Regional forecasts I find are quite poor when you then watch the following National forecast

[ANYWEATHER]

Combined with my last post, this is really knife edge on Sunday morning with the Dam thickness, 528. The ingredients are as near as dammit (no pun) there.

Looking into so much detail ,that far out will result in depression! Analyize  the overall trends of the models , its gonna turn much colder, but the finer details of precip etc wont be possible to forecast to very nearer the actual timeframe....... :smiliz23:

[fergieweather]

Here's Fergie take on the weekend. Looks like the front turning to snow in Belgium, Netherlands and France. Rain for the UK.

We didn't have 12z UKMO-GM available for graphics however. Yes, some light snow around in places by Sunday in parts of S/SE (mostly uplands...snow more up northern England into Scotland on N/NW flank of low earlier in sequence) but anything in south not considered a big issue there as PPN rates will be rapidly fading by that stage (mostly dry/drying), coincidentally as the lower WBFL spreads south. Cold 'un though, for sure! MOGREPS 12z has 3-way split on low positioning / track but as per yesterday, SE'ly version remains most favoured for deterministic forecasting, with confidence growing now.

[Downpour]

Tonights Nick Sussex Oscars go to the following:

 

Model in a leading role for its performance in I'm Dreaming Of An Easterly.

 

navgemnh-0-180.png

 

The NAVGEM which is the best on show as it delivers a long draw easterly.

 

Model in a supporting role for its performance in Scrooge.

 

gfsnh-0-180.png

 

The GFS which throws low heights eastwards and mild mush later on.

Lol. Signed in on my wife's iPad just to respond.

Surely you missed the GFSp - Best Screenplay (somehow manages to get the audience to suspend their disbelief)

[ANYWEATHER]

But surely that post was only commenting on what the ecm showes.   and indeed it does perhaps show a decent covering for the south east on that run.  not to dissimilar to ukmo run infact  as ever more runs needed  but this is the model discussion thread after all  

Yes indeed this is the model discussion, but just saying going on one model and one run is pretty useless in giving any detail in forecasting

[EML Network]

Some insight as to why the models and the forecasters are struggling to deal with the evolution of the coming weekends low pressure system, highlighted well by the Jet stream

 

 

Good luck figuring that one out !!!

[Cheese Rice]

I'm surprised no one has picked up on the major snow event projected by the ECM on the 27th.

 

This is a major upgrade in snowfall potential, a good 6-9 hours of really quite heavy snow. 

 

When you consider the ECM is usually quite reserved in any snow forecast the area could easily be widened.

 

 

 

I think there's a real risk of a major snow event affecting northern England/Scotland. 

Edited December 23, 2014 by Cheese Rice

[nick sussex]

Lol. Signed in on my wife's iPad just to respond.

Surely you missed the GFSp - Best Screenplay (somehow manages to get the audience to suspend their disbelief)

Maybe we should bring in the Raspberries as they do for the worst films. The GFS would win that hands down!

 

Judging by the short ensembles for De Bilt theres a chasm between the GEFS and ECM ensembles, I'd be minded to dump the GFS tonight, it can go to the Raspberries with a rubbish table near the toilets!

 

The GFS looks far too quick with flattening the pattern, not long now to the GFS 18hrs run, I would be shocked if that doesn't at least start edging towards the Euros.

Edited December 23, 2014 by nick sussex

[Mark Neal.]

I'm surprised no one has picked up on the major snow event projected by the ECM on the 27th.

 

This is a major upgrade in snowfall potential.

 

When you consider the ECM is usually quite reserved in any snow forecast the area could easily be widened.

 

 

 

1.png 2.png

 

I think there's a real risk of a major snow event affecting northern England/Scotland. 

 

Very true, Ian F did just mention about the threat further north with the NW/N flank of the low *poss* heralding some snow. Further South some backedge sleet/snow possible with elevation could get a dusting, going on ECM/UKMO output, then as flow could turn E behind, could be a window for wintry showers to those in E/SE from the East. 

 

EDIT- Cheese Rice just seen the pictures you posted show Friday 9pm and Sat 3am, dpes it go out any further?

Edited December 23, 2014 by Mark N

[blizzard81]

ECM blue control run seems to show a snowy easterly for debilt, not heavy snow though.