Model Output Discussion - 28th November

[Buriedundersnow]

I believe it is a higher resolution model which SHOULD make it more accurate, not certain how accurate it is though

thanks weathizard

[Walkinglad2013]

Currently cold and sunny but clouding over in Leeds - in terms of Model output high pressure looks like its moving in next week or the week after with very little preciptiation

[Downburst]

does anybody know how accurate the NAM is compared to the GFS

Careful there. To take 1 view and determine if it is true or not based on whether a whole model is more accurate or not is not a good call in this particular game. So many wasted posts on that over the last few years. ECM does handle lows over this point and that, then the next run "Epic" etc. etc.

[Buriedundersnow]

Careful there. To take 1 view and determine if it is true or not based on whether a whole model is more accurate or not is not a good call in this particular game. So many wasted posts on that over the last few years. ECM does handle lows over this point and that, then the next run "Epic" etc. etc.

i know was just trying to find out who is likely to have that low near greenland correct as it looks like that could be the main driver of our weather in the short term

[Frosty.]

So one week on, we are entering a half hearted cold snap, then a cool zonal outlook for early December, very little sign of wintry weather or real cold.

I disagree, it's not half hearted, it's going to be a proper cold snap with widespread sharp frosts and freezing fog, plus some areas of the north and east are going to catch a dusting of snow, even some snow showers later today on the north yorkshire moors, and a bigger risk of a few cm's of snow in parts of scotland and eastern coastal counties of england on fri/sat, and with widespread frosts, then a risk of snow on monday as fronts bump into the cold pool over the uk, followed by wintry showers and nwly winds with a chance of slider lows drawing even colder weather down from the north/ne.

[london-snow]

Interesting to just have a quick look back at the MO thread from a week ago. Lot's of hope-casting and talk of the blocking getting more established, cold NE air arriving by December, etc. To be fair, also a fair bit of challenge to this too, injecting a bit of realism.

So one week on, we are entering a half hearted cold snap, then a cool zonal outlook for early December, very little sign of wintry weather or real cold.

Re your first point highlighted - hope casting is a bit strong of a word - When we see favorable indicators set up such as the ones discussed over the past week and this early into winter. We do get exited because their is potential there. This time we have been very unlucky. And as for your point re the cold north east air arriving by December you only need to go as far to look at the posts from the more experienced posters on here to know that there will be more chances in the offering in the near future.

Re your second point highlighted - As previous stated we have been very unlucky not to receive a plunge of real cold this time & yes cool zonal may be the name of the game heading into early December however ​to suggest very little sign of wintry weather on the horizon. Well you may have to eat humble pie as it wont take too much in the way of difficulty for the pattern to change dramatically as we are not far away from real cold as things stand.

[bluearmy]

seeing as there is little obvious eye candy in the nwp, a look through the current CFS 1074 hrs run is fun. not sure many of us would survive that particular period intact on here if that verified !!

[SnowObsessor90]

Well GP's latest winter thoughts have now given me renewed hope that our next proper bite of the cherry may not be too far around the corner. Now it most likely won't happen within the period last night's ECM suggested nor would it wise to get too carried away by any future runs showing exciting looking synoptics based on recent experience but write off that man at your peril I say.

[ronan]

Perhaps I shouldve mentioned from an IMBY prospect-

I dislike cold- bar falling snow.

Which the minimal looks like happening for me-

Im tired after chasing the 1st phantom spell and think a few quieter days away will be great- thats all.

And then the 12z's come along and the roller coaster begins again! Lol! Eyes for for the next runs! Could there be anymore surprises?

[Geordiesnow]

Looks too me at least in the early part of the runs, the canadian low is a bit further Eastwards which consequently does not give rise to a massive ridge thus the whole thing collapses quickly, the ECM still looks sound though in this respect.

In terms of the trends, then I think its mixed, we are most certainly now going too see some Atlantic weather, just how they will behave is uncertain at the moment but at least there is still some cold potential. The ECM has sort of come on board with the UKMO/GFS of potentially having some cold air flooding down on the eastern side of the Arctic high which may lead to a colder Scandi down the line but of course, at this stage, detail is hard to pin down.

Overall, a little underwhelming, the chance for some snowfall in Northern Scotland is still there but any major widespread cold snowy set up does seem like it will have to wait.

[Zenarcher]

Models are still uncertain on the low to the South West of Greenland in 2 days time, some have been using the NAM model it seems a good one because it is a high res model, looking at the GFS 12z so far it does seem to move over to what the NAM model is saying it has pushed the deep low slightly more North and our Atlantic ridging has also been pushed up a bit North which is good to see.

[MR EXTREMES]

Not convinced were get a cold cold December the models are pushing back heights and bulldozing through.

Although models are volatile right now pressure systems are really full of power to much for northern heights to hold firm.

It's seems the teleconnections are for and against its hard one to call.

But things will be more clear into mid December.

But nothing very mild this is a starting point but I'm not convinced of longterm meaningful cold spell.

[Nick F]

While the 12z GFS continues to trickle out and on the subject of looking for the next opportunity for a deep cold/snowy spell - trace the flow upstream across N America and keep your eyes out for the next major amplification. Although a long way off, at t+180, 06z GEFS mean H500/slp chart shows a deep trough being carved out over eastern N America, with backing from ECM too. This IMO will be the key to the next amplification in the flow downstream over the Atlantic and may lead to the re-build of heights to our N and NW while a trough cuts off over Europe, we've seen hints of this from 06z GFS and 00z/yesterday's 12z ECM.

But before then, we have a flattening PFJ across the Atlantic, but only briefly on Sunday do we get on the south side of it across Sern Britain. So remaining cold in the north to cool in the south, but unsettled with rain and hill snow up north.

But expect some amplification in the PFJ come early December, whether it will amplify favourably - remains to be seen!

Edited November 28, 2012 by Nick F

[PolarWarsaw]

Seems like we're going nowhere but round in circles to me at the moment-

We probably all need to leave the models to be for a week or so and then come back and see if anything has changed-

As far as I can see FI is at about t48.

All in all, a clear despondency continuing to grow amongst most after 2-3 weeks of solid chasing, all for nothing in the outcome.

Disapointing, but we move on-

[Cheshire Freeze]

Struggling to see much optimism in the model output at the moment- barring the continued weakness of the polar vortex that is. Trouble is, as Phil has alluded to, we have PV energy pushed over to the Atlantic side of the hemisphere which is stopping heights gaining a proper foothold to influence 'our patch'. Frustrating model watching at the minute for sure!

[Panayiotis]

Seems like we're going nowhere but round in circles to me at the moment-

We probably all need to leave the models to be for a week or so and then come back and see if anything has changed-

As far as I can see FI is at about t48.

All in all, a clear despondency continuing to grow amongst most after 2-3 weeks of solid chasing, all for nothing in the outcome.

Disapointing, but we move on-

But why should we do this, weather is a lot about experience, so if we can see how the models perform now, we can come to the results in future, if similar occurrences happen.

[Adam lufc]

Look at that lovely but unwelcome Azores high on the gfs.

[phil nw.]

Let`s not go down the moaning route guys.They are only weather charts.

Let`s stick to talking about them please.

There are other threads if you want to exchange general feelings or views around the start of Winter.

Thank you.

[Liam J]

It looks like we could be heading for quite a disturbed period of weather into next week as the Atlantic turns the power up. A steep thermal gradient being progged which could fuel some notable cyclogenesis.

Edited November 28, 2012 by Liam J

[Cheshire Freeze]

It looks like we could be heading for quite a disturbed period of weather into next week as the Atlantic turns the power up. A steep thermal gradient being progged with could fuel some notable cyclogenesis.

Was just thinking that. Some areas could be in for some real trouble RE rainfall amounts if we can't break out of this Atlantic based weather. Evaporation of ground water will be virtually non-existant seeing as we're approaching the shortest day.

[Geordiesnow]

It shows how things can quickly change, the UKMO has sucked away all the height rises well into the middle of the Arctic basin with more blues and lower heights appearing and of course the PV looks like forming. Who to say it can't change back but whilst I was a little bit more optimistic in my last post, it has to be said, the Atlantic is coming into play and for any cold weather, it looks like its more likely to be coming from the North West with polar maritime air from any Atlantic lows.

I think cold lovers better hope this is a blip, not good signs this afternoon unfortunately.

[Bobby]

Can't see anything other than bog-standard December weather in the charts at the moment. Chilly, rain, showers, drier interludes from ridges, some frost, deep lows, windy, occassional wintry stuff over the mountains.

Looking through the ensembles there are some attempts at blocking but the problem seems to be too much energy going into the Atlantic which just blasts any blocking away. That's what happened with this 'damp squib' cold spell this week. Think we're going to need a big block or for the Atlantic to quieten down. No proper cold spell in the forseeable future but that can easily change.

Certainly a sense of deflation around. Remember that of potential cold spells that show up, only a handful will ever become reality is my experience in my 7 or so years of model watching. I also suggest if the OP runs show a cold spell to look to the ensembles for support, there never was for this spell.

Edited November 28, 2012 by Barb-

[fergieweather]

I believe it is a higher resolution model which SHOULD make it more accurate, not certain how accurate it is though

But note of caution - higher resolution isn't a panacea to resolving model inaccuracy and higher resolution can merely amplify those errors. Often low resolution gets things right, rather than vice-versa. Regularly see this with UKMO-GM prog versus NAE, for example.

[Continental Climate]

well well well i bet none of us here were expecting these sort of charts even three days ago http://www.wetterzentrale.de/pics/Rtavn1441.png!! Everything seemed so mush more rosier back then. what I think has happened is what seems to happen quite frequently even with favourable synoptics a chunk of the displaced vortex has set up in the worst possible area for the uk just off southern greenland this means that nasty liitle low pressures will keep getting spawned in this area until the residual piece of energy moves on or dissipates.

Its just damn bad luck and if this pattern varifies then it can wipe out three weeks of winter quite easily!!!

[Nick F]

I really think some patience is required, IMO the current cold snap never looked like it would deliver much in the way of snow right from when the hints of the cold coming started to appear. The deepest, coldest air always look to stay out of reach out over Scandinavia, thanks to the low to our east, despite the odd rogue operational showing otherwise,

Sunday onwards, we have the Atlantic returning and dictating the weather across the UK and W Europe next week with a succession of depressions sliding SE, but fortunately we stay the cold side of the PFJ throughout this more unsettled spell, though the north only realistically seeing the threat of snow and probably over higher ground most the time.

It maybe not until the tail end of next week and the following weekend that we may see the PFJ amplify again to perhaps allow blocking to occur.

Edited November 28, 2012 by Nick F