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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Yes, and furthermore, I think it's been mostly that way for quite some time now, with just occasional successes from GFS- when I last saw the longer-term verification scores a couple of days ago UKMO was only slightly behind ECMWF with GFS quite a bit further behind.

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Posted
  • Location: Near Matlock, Derbyshire
  • Location: Near Matlock, Derbyshire

With the excitment growing with the model outputs looking more to a snowy spell again, can anyone confirm if the charts do come off what temps we are looking because with the GFS+144 posted by Paul B shows some very deep blues and as a beginner on here I'm not sure what temps we are looking, but i'm sure if it is very cold. cc_confused.gif

Welcome! These are the forecast temperatures for T+144 from the GFS:

http://www.wzkarten.de/pics/Rtavn14417.html

Close to freezing in many parts according to the GFS model. :)

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Posted
  • Location: swansea craig cefn parc 160 m asl
  • Location: swansea craig cefn parc 160 m asl

Ty jh i was wondering about what charts they were using,because they been pretty certain for over 5days that this coldspell was going to happen.

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Eastern England would get pasted no doubt from the GFS and UKMO runs, lots of shower and more organised snow would be piling in I think, probably quite a bit inland too.

Latest GEM is interesting with a channel low, potentially major snow event for south.

gem-0-138.png

GME is similar too with a channel low, and a few ensembles show it, e.g:

gens-14-1-144.png?12

So this is a possibility too, almost no support against a cold snap now at least.

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Posted
  • Location: Near Matlock, Derbyshire
  • Location: Near Matlock, Derbyshire

The GFS ensembles continue to point towards a cold spell developing next week, with just 1 mild outlier:

http://www.wzkarten.de/pics/MT8_London_ens.png

http://www.wzkarten.de/pics/MT8_Manchester_ens.png

http://www.wzkarten.de/pics/MT8_Aberdeen_ens.png

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Posted
  • Location: Liphook
  • Location: Liphook

Good GFS ensembles, i like that little ensemble member all on its own (P17 i think) laugh.gif

Good agreement overall for a prolonged cold spell. Also looks quite snowy as well. The ECM which is also good is less snowy, but still cold. So widespread heavy snow showers on the UKMO and GFS is not guaranteed yet. Its going to turn colder. How cold and how snowy is yet to be decided smile.gif

post-6181-12653045870488_thumb.png

Yep P17 is the one run that goes for a different set-up, only a small initial change but obviously it makes a huge difference down the line, still it shows what could be the worst case but I think we have very much moved away from that solution now.

Anyway hopefully we will see a very good ECM, for now looks most likely IMO to be similar in terms of strength and possibly synoptics to the cold spell between the 16-23rd.

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Posted
  • Location: Glasgow, Scotland (Charing Cross, 40m asl)
  • Weather Preferences: cold and snowy in winter, a good mix of weather the rest of the time
  • Location: Glasgow, Scotland (Charing Cross, 40m asl)

As others have said a superb set of 12Zs so far. I said early this morning I was happy to go with the GEFS mean and the 12Z UKMO follows the GFS/GEFS very closely. Im still going to remain cautious with regards to the cold pool over Scandi backing SW until this appears within +48/+72.

I will add if the UKMO/GFS verify then the potential is far better than our previous cold spells. The cold spell in Jan started with a very slack NE,ly flow. By the time this veered E,ly the cold pool of -10Cs only lasted around 24/36hrs. This time round the convective potential could be much longer.

I remain very happy with the GEFS mean at +120 and will continue looking at this until the potential comes into the NAE/NMM range.

http://91.121.94.83/...21-1-120.png?12

Even at that timeframe TEITS convective showers will still be hard to predict in intensity and frequency - the 17th brought 2 inches here on what the NMM showed as 2 hours of light showers which turned out to be a moderate 7 hour streamer! It does give a good indication of the location of the showers, and is certainly outstanding at picking up more organised bands of snow. The best tool of course has got to be the Netweather radar!

LS

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Posted
  • Location: Hampstead / Cambridge
  • Location: Hampstead / Cambridge

With the excitment growing with the model outputs looking more to a snowy spell again, can anyone confirm if the charts do come off what temps we are looking because with the GFS+144 posted by Paul B shows some very deep blues and as a beginner on here I'm not sure what temps we are looking, but i'm sure if it is very cold. cc_confused.gif

In the height of the cold, say the mid to latter half of next week, we would be looking at daytime maxes of -1 to 1C over England and Wales and well below that in Scotland - perhaps a bit above that in Northern Ireland.

Snow-wise, i'd be waiting until Sunday and Monday before anything get's nailed on. In terms of snow its all still in the balance. In terms of cold, we're definately heading in the right direction.

Definately a big upgrade in the last 48 (especially last 24 hours) as compared to the beginning of this week.

Lets just wait and see how long it takes for the models to gradually but surely bring that cold pool within the low resolution, T+72 hours. Then we're in business. pardon.gif

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

Even at that timeframe TEITS convective showers will still be hard to predict in intensity and frequency - the 17th brought 2 inches here on what the NMM showed as 2 hours of light showers which turned out to be a moderate 7 hour streamer! It does give a good indication of the location of the showers, and is certainly outstanding at picking up more organised bands of snow. The best tool of course has got to be the Netweather radar!

LS

Yes you're right the NMM/NAE can only give a rough guide but still remain far better than the GFS/UKMO etc. I actually find the UKMO precip forecasts rather poor especially wrt convection.

It's not actually a bad thing the models can only give a rough guide as radar watching is as much fun for me as lamppost watching. :)

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Even at that timeframe TEITS convective showers will still be hard to predict in intensity and frequency - the 17th brought 2 inches here on what the NMM showed as 2 hours of light showers which turned out to be a moderate 7 hour streamer! It does give a good indication of the location of the showers, and is certainly outstanding at picking up more organised bands of snow. The best tool of course has got to be the Netweather radar!

LS

In my experience the models often underdo convection generated over the North Sea in that kind of setup. The GFS seems to be good at simulating homegrown convection and Atlantic-generated convection, but North Sea stuff often catches it out.

For example between 5 and 8 January the progs suggested snow showers mainly over East Anglia and the southeast with the north-east of England seeing only the odd flurry after an initial snowy day on the 5th and overnight 5th/6th. The convective activity over Norfolk was fairly accurately picked out, but that over north-east England was seriously underestimated, particularly for overnight 8th/9th when aggregate depths in the Tyne and Wear area reached 20-30cm pretty widely.

I also remember the night of the 17th/18th December when the GFS suggested Tyne and Wear would be mostly dry, when in reality there were frequent short snow/hail showers and a couple of impressive snow squalls, and it similarly failed to pick up the "snow streamer" that hit the Sunderland area late on the 18th.

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Posted
  • Location: Liphook
  • Location: Liphook

Interestingly Barb there are a few GFS ensemble members that take a rather similar route to those two models so its still an option that could happen, though it seems the more likely solution is to e influenced by a developing LP thats somewhere to our east/over us...however the track of this feature could quite easily help drag in a very good ENE/E airflow as well.

Much to be sorted out but barring a major flip around I'm feeling quite confident about a cold spell now.

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Posted
  • Location: Leeds (Roundhay) 135m
  • Location: Leeds (Roundhay) 135m

Yep P17 is the one run that goes for a different set-up, only a small initial change but obviously it makes a huge difference down the line, still it shows what could be the worst case but I think we have very much moved away from that solution now.

Anyway hopefully we will see a very good ECM, for now looks most likely IMO to be similar in terms of strength and possibly synoptics to the cold spell between the 16-23rd.

Thanks, had a look but forgot which one it was. Does highlight the worst case, however does seem unlikely going by the output from the GFS, GEFS and UKMO. Awaiting the ECM now. Hopefully similar to the GFS and UKMO!

Edited by mark bayley
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Posted
  • Location: Central London near Canary Wharf
  • Location: Central London near Canary Wharf

Yes, and furthermore, I think it's been mostly that way for quite some time now, with just occasional successes from GFS- when I last saw the longer-term verification scores a couple of days ago UKMO was only slightly behind ECMWF with GFS quite a bit further behind.

Was it not the GFS that replaced it Op run with the parallel in Mid Dec to much lauding how that

Model had predicted the upcoming cold spell around 17th Dec........Seems it is not doing so well now then?

Interesting

CV

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Posted
  • Location: Lincoln, Lincolnshire
  • Weather Preferences: Sunshine, convective precipitation, snow, thunderstorms, "episodic" months.
  • Location: Lincoln, Lincolnshire

Looking at the model verification stats I don't think the GFS has got any worse- rather UKMO has got better (for whatever reasons, I don't know), moving ahead of GFS and coming a lot closer to the reliability level of the ECM. The gap between GFS and ECM is much the same as it's been generally over the last few years.

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Posted
  • Location: Near Matlock, Derbyshire
  • Location: Near Matlock, Derbyshire

These were probably discussed earlier, but I haven't read all the posts from today. The ECM 00z ensembles for London were a stunning set weren't they: http://www.meteogroup.co.uk/uk/home/weather/services/ensemble_forecast.html

Hopefully the 12z ECM will continue in a similar vein....and the action starts imminently!

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Posted
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.
  • Weather Preferences: Snow and storms
  • Location: Hayward’s Heath - home, Brighton/East Grinstead - work.

Quick question from a relative novice, this channel low you speak of, what exactly does this do?

The channel low nips along the channel keeping the cold air to the north. Brighton can do very well (snow) in these set ups as long as the low doesn't travel across too far north.

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Posted
  • Location: Glasgow, Scotland (Charing Cross, 40m asl)
  • Weather Preferences: cold and snowy in winter, a good mix of weather the rest of the time
  • Location: Glasgow, Scotland (Charing Cross, 40m asl)

Yes you're right the NMM/NAE can only give a rough guide but still remain far better than the GFS/UKMO etc. I actually find the UKMO precip forecasts rather poor especially wrt convection.

It's not actually a bad thing the models can only give a rough guide as radar watching is as much fun for me as lamppost watching. biggrin.gif

Sometimes if you get too interested in the radar showing a big blob of heavy snow heading right for you in a minute or two you forget to look outside to check if it's snowinglaugh.gif

Anyway, IF those sub -10 uppers can make it our way it looks like there will be quite a lot of snowfall down the eastern half of the country, regardless of what the models show PPN wise!

One thing I can see from the ensembles is that while the control and op. look very willing to bring -7 uppers in by the 7th overnight into the famous 8th, the mean is kept a bit higher http://cirrus.netweather.tv/ensimages/ens.20100204/12/t850Fife.png http://cirrus.netweather.tv/ensimages/ens.20100204/12/t850Cambridgeshire.png. Personally I think the operational and control will be right as the mean itself looks to have little support with about 7 going quite a bit above it but with more between the mean and the op or right beside the operational/control.

LS

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Posted
  • Location: Hull
  • Location: Hull

Quick question from a relative novice, this channel low you speak of, what exactly does this do?

Channel low is a low pressure system situated over the channel and parts of N France. With a very unstable flow precipitation will be very very heavy and organised. It would bring no doubt a lot of snow to Southern Counties, and it will pivot around the same areas.

Hope this helps

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Posted
  • Location: South East Cambridgeshire 57m ASL
  • Location: South East Cambridgeshire 57m ASL

JMA

What about JMA? And for some reason Meteociel are showing Yesterdays 12z, not todays 0z?

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Posted
  • Location: Dublin
  • Location: Dublin

I have just spoken to the ECM operative and he has told me it is an amazing contrast to the other outputs showing raging Zonalities

and temperatures of 10c in London next Wednesday, hold on to your hats...................

Lol lets hope for a good one.

Really the GFS and UKM are extremely good, a decent potential for something 1987esk to develop.

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Posted
  • Location: Peterborough N.Cambridgeshire
  • Location: Peterborough N.Cambridgeshire

What about JMA? And for some reason Meteociel are showing Yesterdays 12z, not todays 0z?

You won't find a 0Z im afraid. The 12Z should be updated between 19.00-20.00.

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Posted
  • Location: Milton Keynes
  • Location: Milton Keynes

In terms of which model is doing best, perhaps the one to believe over another, then the NOAA stats show that UK Met and ECMWF are well in the lead over the past 3 days, on their 6 day checks.

Yes but we were not discussing this - we were talking about the prediction of the Easterly 2 weeks ago by the GFS - there is no data for this (apart from it is probably rarely correct in any detail but can show a trend which is what happened here). All the models have been incorrect for this region of the globe for the 6 day forecasts because they have been flipping about so expect them all to dip in the next few days. When this gets brought up I would also like to point out that often we say this model or that is performing better but the difference is usually small - say 0.92 to 0.87 - so a 5% difference - what does this mean in reality (especially as they are probably considering the whole globe through the whole depth of the atmosphere - not the weather at any particular place). I also recently asked the question about how these coefficients are arrived at but no-one replied - anybody have a link to this?

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