Oops....sorry! Shud've been in the media thread.

On topic, the 18z is showing masses of cold to our north and east, so at long last, signs of the continent cooling down significantly, maybe giving us something to tap into later in the winter.

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I agree - looking forward to it, especially the dry conditions.  I'd hoped my over the top intro would be recognised as ironic!

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Can't grumble at tonights output, dry , frosty at night ( hopefully ) and chilly

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Sorry. One poster said that lake effect snow was all done by January. So I thought I'd mention January 1987, which is still the best snowfall I've ever seen in this country, caused by lake effect snow.

Q does wear his heart on his sleeve. It looks like a typical late autumn spell of weather to me. Plenty of time left.

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I didn't say lake effect snow was all done by january, mearly that more extreme lake effect snow events become less likely. The uppers in January and February, are not significantly colder than they are during December, however the SSTs are. So in order to get more extreme lake effect snow in the late winter, you need increasingly colder uppers. To get thundersnow events typically you need a gradient of more than 20C, from 850 to surface level. So in early December you might only need -11C or -12C uppers, wheras in january you would be looking more at -15C type uppers which are much harder to get. By february you would be getting on for -16C or -17C which is even harder. The effect is even more pronounced in canada, where the severe lake effect snow events all occur during the first part of the winter. 

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I've long thought the monkeys at the Met get their crayons out after the monkeys at ECM and FFS get theirs out.

Edit: Quote: Not impressed to see a few people breaking down already - it's very early days!

We look to have just had something I've seen numerous times in the past, which is some of the models showing a particular setup developing with too much haste but then having to slow it down.

In this case, GFS has been coming the other way, which is fairly typical when there's blocking to the N and NE involved.

The meeting at halfway house could be upon us soon... and UKMO will be waiting inside with a smug look on it's Right now, it seems we have a major displacement on offer from GFS and a marginal split from ECM. It may be at 192h+ range, but at this time of year that's a lot better than should ever be considered normal!. (quote)
(Quote fixed)
In Reply to Stormchaser I am also sharing this dilemma on here.

It is very common to say if the GFS gets solid runs showing the SCEURO Bartlett High for this time of November and the UKMO follows it you'd not be having a very good time enjoying the Weather after this Friday- we will see average heavy rain with near normal Temperatures Tuesday to Friday at least- make the best of the Cold mixed Arctic NW then NE flow.

Bearing this Gyres of Low Pressure go over the UK high - good work wonderer's of Winter - the UK NW Euope SCEURO just being like Brian's much endorsed Type not being wanting to move at all.

The Norway Svalbard SE Arctic Low tracks moving straight across Greenland and NE of Iceland then nose down far NE Europe - is the Zonal Positive NAO epic weather pattern- Let me also say Temporary Greenland High - does not help retrogression of SCEURO UK Anticyclone- for a few days GFS and UKMO models show no sign of a let down of it.

I see Deep Low Pressure also moving round round over Western Mid N Atlantic- not at all show resistance to push out the UK High- for now next Saturday and Sunday are just boring weather for much of the Britain mainland- but it likely could bring night frosts and lots of thick fog patches for many especially away from the cold ENE flow over SE England.

From Sunday 24th to Tuesday 26th Nov. 2013- that Low Pressure today's GFS is getting hard to move out - sat in GFS 18z run in West Mid N Atlantic- UK high could move a little west so we stay chilly with frost early and late - and of course with fog some may be freezing during overnights.

Much happy quotes of the day for all paying respect to my thoughts!.

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Good old GFS has triumphed over its European adversaries. GFS and High pressure reign supreme in the mid term...

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I wonder what Steve M thinks. He's been adamant that GFS is always wrong and plays catchup to ECM. Not had a chance to look at the charts this morning yet, so will take your word for it.

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ECM isn't as cold as yesterday but still cold and blocking with frosts and fog/freezing fog if the Sky's stay clear that is.

http://www.wetterzentrale.de/pics/Recm1202.gif

http://www.wetterzentrale.de/pics/Recm1682.gif

http://www.wetterzentrale.de/pics/Recm2162.gif

http://www.wetterzentrale.de/pics/Recm2402.gif

Met/o 00z;

http://www.wetterzentrale.de/pics/Rukm1201.gif

http://www.wetterzentrale.de/pics/Rukm1441.gif

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On the current output - it will change again.

The models are always unreliable when we leave the zonal rut - they only agree when the weather is doing what it usually does.

Sometimes GFS gets lucky, sometimes ECM gets lucky, sometimes UKMO gets lucky - it is a bit of a lottery after all.

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To be fair, the MO as a whole recently has been for a mid-latitude high around us for the remainder of November. ECM flirted Arctic/Scandi blocking for a few runs as did NAVGEM but there was little back up for this evolution from the other models. If the High hangs around as we head towards December, there's a chance of more Northerly blocking but the sinking High scenario also has to be a possibility. What we've got now is better than endless zonality and wind/rain for me.

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Not that that stopped it being ramped up as clearly the correct solution! 

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Good morning. Here is the morning report on the midnight outputs from the big 5 Computer outputs for today Tuesday November 19th 2013.

All models show a showery NW flow over the UK with a deepening Low heading SE towards NW Britain through today. This sinks further South down the North Sea and away to the South of Britain on Thursday. Spells of rain and hill snow on the highest ground will move SE tonight and tomorrow to affect all areas followed by clearer and rather cold weather with wintry showers on Thursday. These will clear away South on Friday then High pressure is shown to build across the UK with fine, cold and crisp conditions for all with widespread frost and freezing fog patches night and morning, persisting all day in places.

GFS then keeps High pressure in one form or another completely dominant over the UK positioned over or just to the North. There will be fine and dry weather almost through the entirety of the second half of the run with no rain at all and mostly fine conditions with just varying degrees of frost and fog problems day to day. Temperatures at the surface will be just below average under clear conditions by day but nights will be colder than average and if fog persists through the daytime then temperatures will be held very low.

UKMO shows High pressure positioned over Southern Britain with flat calm conditions allowing plenty of frost and fog at night and variable conditions through the day's totally dependant on whether fog clears or not.

GEM too just about manages to hold High pressure over the UK throughout the latter stages of it's run though pressure on the ridge across Southern Britain is squeezed from both the North and South. It would stay rather cold overall and once again the only variance from day to day would be the extent of mist, fog and frost.

NAVGEM is the only model this morning that holds High pressure further North over Scotland maintaining an Easterly flow across England and Wales though it would be unlikely to offer any different weather other than more breeze restricting fog formation down here.

ECM has also brought High pressure further South this morning but maintaining an axis and trajectory East to West across Central Britain right out to the end of the run with fine and dry conditions for all with varying amounts of frost and fog night and morning dependant on cloud cover and airflow day to day.

The GFS Ensembles paint a dry period through the Central portion of the output today once tomorrow's Low pressure clears away South. With Britain seeing above average uppers for a time in association with a UK based High temperatures will be close to average or below at the surface with overnight frost and fog. Should fog prove reluctant to clear then temperatures at the surface would be very cold despite these higher uppers. There are tentative signs of the High pressure giving ground to more unsettled conditions very late in the run.

The Jet Stream is flowing South over the UK at the moment and is setting itself up for a blocked setup in association with a UK based High late in the week. The flow is then directed well North around the High over Iceland and Northern Scandinavia next week.

In Summary if it's static cold and calm High pressure conditions you're after then your in luck today because virtually all models with the exception of NAVGEM show a UK based High pressure offering all the ingredients for light winds and widespread night frosts and fog patches, freezing in places with the inevitable November conundrum of it's failure to clear some days, making it very cold and miserable. Outside of fog though there would be plenty of sunshine should most of the runs verify and there looks little likelihood of any significant rain anywhere and of course this applies to anything wintry also. So a very typical late Autumn and early Winter period to come with High pressure very much in control for all.

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Thanks Martin. Not a bad outlook at all - I'd certainly take a few frosty nights and sunny days. I just hope that the HP really is sunny. It's often hard to know exactly how cloudy/sunny it'll be at this distance. With the sun's weakness at this time of year, it doesn't take much to allow anti-cyclonic gloom.

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I suppose ironically, we may get colder temperatures under the severe frosts and freezing fog than we would have done had the high been at a higher latitude, dragging in North Sea muck

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Thanks, Martin. "Cold and miserable" is a very apt summary. Roll on spring.

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Thanks Martin, think you said we would end up with a UK high.

To determine the likelihood of cloud cover I tend to use the source of the High as a starting block. If it forms in rather chilly air as this one does then there is a good chance of clear skies maintained. If it drifts up from Southern latitudes it often includes a lot of Atlantic clag. You are right though that the longer it stays over us the greater chance of this fog spreading out into low stratus cloud and giving days of seemingly endless gloom. We'll have to wait and see if that's the case with this one.

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The 'blend' approach seems to be working again. It is risky, when the solutions are different, favouring one model in preference to another as the stats show the differences in performance at 5 days verification (500mb height) rarely differ by more than +/- 5%.
When for instance the three 'major' models show different solutions it is prudent to assume a mean solution and this looks like occuring again with the high lat block from ECM and the 'sinking' block by GFS resolving into what looks like a UK high situation from the weekend.

I am not one to favour one model over another (totally unbiased of course and not depenmdant on what they are showing), and only when there is unanimous agreement across the board - which happens rarely - can confidence in any particular solution be high.

I am also not a supporter of the theory that one of the four GFS runs is more 'accurate' than another. I have no evidence to support this and any of them can be as good or as bad as the other.

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Is it not the case that the four runs often have different levels of data? Or sometimes missing data? It's interesting then that there is no evidence of greater accuracy for the ones with fuller data.

When data critical to the process is missing a report is issued with details.
There is no evidence to suggest any one run has less data input that any other, although I suspect there may be variations in some of the control points dependant on time of day such as air readings on transatlantic flights or balloon dropsondes. The majority of input is actually automated from ground stations, static ships, buoys and satellite and chunks of missing data likely to affect the accuracy of the output don't get in due to input issues on initiation.

If someone can genuinely prove that the 18Z GFS run for instance performs less well compared to the 12Z then please provide the evidence. An opinion is OK, but it's not very scientific.

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http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day6_HGT_P500_G2NHX.png  ECM in the lead, followed by GFS and the UKMO. CMC = GEM, I believe.

 

EDIT, My Bad, GFS runs link should be 

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/gfs4cyc/allmodel/daily/cor/cor_day6_HGT_P500_G2NHX.png

for the 500hPa

 

Also at T+240:

http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/gfs4cyc/allmodel/daily/cor/cor_day10_HGT_P500_G2NHX.png

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http://www.emc.ncep.noaa.gov/gmb/STATS_vsdb/allmodel/daily/cor/cor_day6_HGT_P500_G2NHX.png  ECM in the lead, followed by GFS and the UKMO. CMC = GEM, I believe.