Model Output Discussion - The Run In To Christmas

[TEITS]

I have to say with regards to the possible storm, I am more concerned with the wind strength than snowfall. At the moment it appears most of the precip would of cleared the UK by the time it is cold enough for snow. Also the models hints at a NE,ly and the warming effects of the N Sea would reduce the chance of snowfall even further for E areas. Obviously the track will make a difference but at this stage only higher ground appears at risk.

 

Moving further on and I cannot see mild returning beyond the storm. I said there is a chance of it turning much colder from the E towards the New year and I continue to believe this.

 

I don't often predict an E,ly

[EML Network]

If you run through the various outputs on the 06z you'll see that the reliable time frame sits about about 3 days out right now. 

 

Some runs keep that low pressure system well away from the UK, some don't develop it at all, some have it running through Iceland, some to the South of the UK, I expect if it does develop it will take the normal route through N.Ireland and into Scotland and the reset westerly bore fest would soon follow. 

 

IMO this will be a bog standard winter storm and by the new year we'll all be looking for the next opportunity for things to go our way. 

[Weather-history]

GFSp: If the snow storm on 27 Dec does look on I say bring it on. There is nothing more annoying on this forum than people saying "be careful what you wish for, people are travelling" - of course the weather will do what it will do and in any event people wouldn't travel if that bad boy was forecast at T12hrs.

If you are hoping a snowstorm on that GFSp run, you maybe disappointed because although it does show some snow as the colder uppers dig in, they are mixed out pretty quickly. It could a cold very breezy wet affair in the end. At least on that GFSp 06z run and at lower levels.

Edited December 21, 2014 by Weather-history

[blizzard81]

I have to say with regards to the possible storm, I am more concerned with the wind strength than snowfall. At the moment it appears most of the precip would of cleared the UK by the time it is cold enough for snow. Also the models hints at a NE,ly and the warming effects of the N Sea would reduce the chance of snowfall even further for E areas. Obviously the track will make a difference but at this stage only higher ground appears at risk.

 

Moving further on and I cannot see mild returning beyond the storm. I said there is a chance of it turning much colder from the E towards the New year and I continue to believe this.

 

I don't often predict an E,ly

I can't see an easterly developing after the storm. A transient north easterly (a blink and miss it affair) as the storm sinks south east

quickly followed by toppling ridge and the northern arm re strengthening over the top.

On a side note, something at ECM headquarters needs to be discussed with that particular model's propensity to

blow up heights to our north west. It is a real big problem for the model (both ops & ensembles) and has been for quite a few years.

It causes a hell of a lot of frustration in here, I know that much.

[IDO]

Can you post a chart / model that is showing a "Snow storm" ? GFSp is the closest I have seen but it shows sleet or rain for 90% of the uk population. It was always looking like a slim chance for the south or low ground to see snow but now only tops of Pennines etc and Scottish mountains see a decent dump. I'm praying last nights ECM resurfaces!

 

Yes despite the more amplified 06z run the chances of snow in the south from the ensembles remain about 10%: 

 

 

About 50% of the ensembles support the cyclogenesis of the LP system and its track to sink SE/S and that includes the C:

 

 

 

With such a deep storm it is likely that it will not have cold enough uppers for snow for most.

[bluearmy]

I didn't post that spread chart this morning with this in mind but perhaps if might be interesting to keep posting the timeframe until we see the spreads fall to a level where we can have some confidence in the subsequent pattern

Newest one first

[blizzard81]

Really disappointed with the models these last couple of days with the way they have downgraded the potential

cold as we approach New Year. The worst thing about them at the moment is that they do not even show any

rainbows for us to chase in the long term. I know these rainbows are generally false dawns but at least they

give us something to talk about. I guess all we can hope for is some sort of flip in the models for late next

week. Clutching at straws though I certainly am.

[J10]

Yes despite the more amplified 06z run the chances of snow in the south from the ensembles remain about 10%: 

 

graphe4_1000_306_141___Londres.gif

 

About 50% of the ensembles support the cyclogenesis of the LP system and its track to sink SE/S and that includes the C:

 

gens-0-1-150.png  gens-0-0-150.png

 

With such a deep storm it is likely that it will not have cold enough uppers for snow for most.

 

And yet on some models (GFS normal) 850Hpa uppers of -8c are forecast for Wales with NW winds giving the chance of wintry/snow streamers from the North west.

 

 

Even on the 06Hz(P) which does mix the uppers there is the chance of some front edge snow. (sub -6c for a time)

 

 

I do think though that deeper the low pressure the lower the chance of more general snow and the above run (normal GFS) makes less of the LP system hence colder uppers.

 

If the current models are close to fruition, it is difficult enough to model at 24 hours, let alone 144 hours.

 

Edited December 21, 2014 by J10

[gottolovethisweather]

To my eyes the various NWP outputs are now suggesting a mostly quiet picture as we head towards the New Year with HP influence never far away. Get the next couple of days nuisance rainbands out of the way and we should have a settled calmer picture for all come Christmas Eve through to Boxing Day. As mentioned by many more of the seasoned forum posters and by myself here for instance, the 27th and 28th December are dates to watch. During this timescale, the current modelling suites all suggest that this could be a potential game-changing Low Pressure system, which as it pushes over our shores, it is likely to bring much rain and perhaps back-edge snow for a lucky few and more appropriately a gale to severe gale to some parts. Why a game-changer, you ask?

 

Well, heights are over Europe are stubborningly High up to then and this is never a good sign for coldies, wanting deep cold. As the depression is currently forecast to dive into Central Europe as we near the year-end, we will end up with colder air following up behind it, affecting us and also the nearby continent. This new found weather setup could well persist into the New Year in my opinion and is our best shot at cold over the next two weeks. More widely, the positives continue to be the brief pulses of  WAA pushing up towards Greenland and Iceland and added to this, a confused much weakened NH Jetstream compared to this time last year and is shown to produce a split flow at times too. The Atlantic fronts should be held at bay as we end the year too as the stubborn troughing signal has seemingly relented for now, we can and should get a very different setup in place. Mild at times at the surface then nearer Average over Christmas and a most likely colder scenario to end the year is how I view things right now.

Edited December 21, 2014 by gottolovethisweather

[Duane S.]

Looking at the Ens, factor in what is likely to occur in the States and you can see how zonal Atlantic driven weather may actually now be the favourite outcome as we head into the New Year. FAR from set in stone though. Plenty of water to get under plenty of bridges before we start getting too confident on that score! Personally I think we are heading, with blips, towards a decent cold spell in the new year

[tinybill]

http://www.meteociel.fr/modeles/gfse_cartes.php?mode=2&ech=204

 

well after  the  storm things  are  now looking much    better  for  cold  weather in the new  year  could easily  bring  snow to the  u.k.  just  in time  for  the  rush   hour  back  to work on jan  5 :smiliz64: !!

Edited December 21, 2014 by tinybill

[Mapantz]

If you run through the various outputs on the 06z you'll see that the reliable time frame sits about about 3 days out right now.

Some runs keep that low pressure system well away from the UK, some don't develop it at all, some have it running through Iceland, some to the South of the UK, I expect if it does develop it will take the normal route through N.Ireland and into Scotland and the reset westerly bore fest would soon follow.

IMO this will be a bog standard winter storm and by the new year we'll all be looking for the next opportunity for things to go our way.

Quite a few solutions have the pressure dropping some 30mb+ in under 24 hours, I'd say that's a bit more than a bog standard storm!

Disclaimer: I know it's the GFS op run but it's just an example.

1010mb to 976mb in under 24 hours..

That one of a few extreme solutions, I'm sure!

Anything involving cyclogenesis on that level will be above your average storm, and looking at it across the board, I'm not surprised the guys at Exeter are watching this with a keen eye.

Edited December 21, 2014 by Mapantz

[Frosty.]

All this talk of stormy weather is fair enough since that is what the models are showing but I just read the latest met office update and it disappointed me, transient hill snow just doesn't cut it for me. What the hell do we have to do to get a decent cold spell in this country?

Think I will take a break, still getting over the abuse I took on here last night...is it worth the abuse, nope

Edited December 21, 2014 by Frosty.

[Muffelchen]

Here on the UK channel of Weather Soap, it has been a real up and downer the last week or so and so it continues. Last week that well known spoilsport, Azores High, made a comeback to the show and, as a result, prospects were looking zonal with a mild day on Boxing day. Then came our knight on a white charger, GFS, with his girlfriend, Stella Runs, and for a few days it really began to look as though we were in for a colder period with cold moving ever nearer in the timescale, initially making Boxing day and then Xmas day cold with  snow flurries. Poor old party pooper, ECM, came in for a lot of stick at the time as he was still not playing with everyone else, except his one friend, GEM. Everyone was saying that these two had to stop ignoring everyone else and join the party.

 

By yesterday morning on the show there was great jubilation as it appeared that they had finally done so. But had they? By last night there was utter despondency as it became apparent that all the characters had left the party and were going to ECM's house to play with that old curmudgeon, Mild Zonal, once the storm of the 27th had passed. To top it all it was thought that Mild Zonal or his twin brother Cool Zonal would take over the show for at least ten days or more and everyone would have to pin ther hopes on someone called Strat Warming, however, he has not been seen for many years on the show and his appearance is forever being forecast by Cohen and his friends, but he always seems to postpone his visits at the last minute.

 

This morning we woke up to blue skies and tuned-in to discover a renewed sense of optimism on the show. The storm on the 27th is now the saviour of our (near term) winter and, blow me down, it could even bring our long lost friend, Beast, back to the show! What a plot twist: I never saw that one coming. In view of Beast's imminent arrival it now looks as though it will not be mild at all, or will it? This, it would appear, depends on a shortwave drama showing on another channel (N America) and this holds the key to the next instalment of Weather Soap.

 

We all hate it but we can't drag ourselves away from it: compelling and frustrating with a cast of familiar characters and supporters. Beast and his friends, Greeny and Scandi High, are loved by so-called 'Rampers.' Rampers are totally committed to their 'team' and will defend their position to the death - woe betide anyone that crosses them. The Zonal Crew are less noisy but support the opposing team in this long-running drama. This team is led by Azores High and Polar Vortex: two undefeated foes who return year after year to foil the repeated attempts of Greeny and his gang to provide the UK with a snowfest.

 

With two weeks of Xmas holidays to look forward to and with four episodes daily of this gripping drama, you will not disappointed. Tune in for the latest episode, you may never sleep again!

[nick sussex]

Everyone knows by now I'm not quiet in displaying irritation at the outputs, however before this thread becomes too negative I think we need to just be a little patient but at the same time realistic.

 

It's best to work from the premise that we won't be seeing a Greenland block, the conditions at present don't support a proper high there.

 

The trend from the models is to take lower heights back across Greenland later on, there are timing differences with how quickly this occurs.

 

So I think its best to kick into touch a long lasting northerly however within the scope of whats on offer and realistically possible there are still some decent solutions in terms of a spell of colder weather.

 

It might be less snow and drier colder weather, it might also be a short northerly followed by an east/ne flow as the low slips into the Continent then high pressure close by and frost and fog type scenario, of course it could be short northerly then the high slipping much further south.

 

Much depends really on the movement of those low heights eastwards and also whether the jet digs south off the eastern USA which would of course help to keep things colder.

 

Low heights to the nw aren't always disastrous for cold but its really at this point whether the jet kicks ne with some energy going se to help keep the high in a colder position.

 

There are still disagreements between the outputs from an early timeframe, upstream regarding a shortwave over the USA, in the mid Atlantic with another shortwave.

 

We have to remember that the GEFS and ECM ensembles will include solutions that are completely wrong because what happens between T120 and T144hrs in both those key areas results in some larger scale changes further on.

 

For example the GEFS if the ensembles have got that crucial shortwave wrong at T120 to T144hrs over the USA then this changes downstream events.

 

Perhaps not enough to deliver some snow nirvana but enough to make a difference to the block and longevity of cold.

 

So until we see agreement at those timeframes then the outlook still has a level of uncertainty.

[snowking]

Perhaps we should be looking NE in to the 10-15 day period....

 

 

Split vortex and ridging tendency heading more and more towards Scandinavia over the last couple of runs

 

SK

[bluearmy]

Great post muffelchen but i'm not sure where renewed hope came from this morning ...... Yesterday's 12z runs were the last high point and it currently looks doubtful there will be more for another week.

Just read that post kris and I've been wondering about Scandi height rises - however, there has been no convincing wxtended ens evidence. Hints but no more than that.

Edited December 21, 2014 by bluearmy

[EML Network]

Quite a few solutions have the pressure dropping some 30mb+ in under 24 hours, I'd say that's a bit more than a bog standard storm!

Disclaimer: I know it's the GFS op run but it's just an example.

1010mb to 976mb in under 24 hours..

viewimage (17).pngviewimage (18).png

That one of a few extreme solutions, I'm sure!

Anything involving cyclogenesis on that level will be above your average storm, and looking at it across the board, I'm not surprised the guys at Exeter are watching this with a keen eye.

 

Yes the Op and a few other runs have this system filling and deepening as it crosses the uk. 

 

And if it came off like that then yes it wouldn't be a bog standard winter storm, I wasn't commenting on what the OP was showing, as I don't believe it will come off as modeled by the OP. 

 

If I had to pick a run to highlight my point, then try this one (just as one example of many on the 06z)

 

As I said...a bog standard winter storm...

 

[Stuie]

The jet stream starts to take a move southerly next Saturday. I wonder if this chart is what may "suck" the storm down into the UK. As it`s Christmas it throws in a free dolphin.

[shaky]

Referring to the spreads bluearmy! ! What about the low confidence spread thats across england at that time (138 hours)!! Does that suggest any shortwave may take a different path to what it shows now?

[Muffelchen]

Great post muffelchen but i'm not sure where renewed hope came from this morning ...... Yesterday's 12z runs were the last high point and it currently looks doubtful there will be more for another week.

Sadly I think you may be right but it was TEITS and his 'Beast' that I was referring to here as well as Nick's shortwave drama. Both of these could well fall right for us but, if truth be known, we kinda know that this probably won't happen. In truth, after a great start last October, this winter has disappointed in spite of the potential.  Even though I hardly ever post in here, I avidly read pretty much everything that is written and have been doing so for the last 8 years or so. My view is, sadly that I think the opportunities have been lost and we may get a bit of snow prior to a toppler or two over the winter, which is quite normal here, but I am of the opinion that the Strat warming will continue to be postponed, the MJO will never quite make it to phases 7 and 8 and real heights will never arrive in Greeny. As I said; missed opportunities...

 

My gut feeling is this will be a winter of near-misses: we will run out of time before things finally fall into place. The weather is in a pattern that will need some shifting and, by the time ten more days have gone by, we will only have six weeks left of winter. After that longer days and increasing sun heights tend to make any snow cover transient.

 

So, as ever, I will live in hope but I expect to be disappointed this time around.

[492]

Perhaps we should be looking NE in to the 10-15 day period....

 

scandihigh1.gifscandihigh2.gif

 

Split vortex and ridging tendency heading more and more towards Scandinavia over the last couple of runs

 

SK

There was a chap I used to know that made a forecast for the week ahead solely from the 100mb actual charts. I cannot remember if his forecasts were accurate but he was well respected so they may well have given a good steer. The scandihigh2 chart might well give potential for cold from the east if it were to verify.  

[ukpaul]

Perhaps we should be looking NE in to the 10-15 day period....

 

scandihigh1.gifscandihigh2.gif

 

Split vortex and ridging tendency heading more and more towards Scandinavia over the last couple of runs

 

SK

 

Yes, I'm perplexed as to the modelling of the Canadian vortex lobe now, just what on earth is going on there to keep it in situ come hell or high water? With the strat in the weakened state that it is, and likely to remain so if the current elongated and suggested subsequent warmings transpire and range over the whole strat, then the likelihood of heights rising over Scandinavia becomes almost inevitable.

 

Can anyone explain why the Canadian lobe is, at the moment, seemingly immovable? 

[IDO]

As much as some may like the GFS 06z in FI, it is the 06z so anything after D6 is JFF. Looking at the op, as usual it is an outlier in FI: 

 

Dutch graph more obvious: 

 

The D16 mean is similar to the 0z and remains zonal: 

 

 

 

 

 

 

Edited December 21, 2014 by i'm dreaming of...

[Catacol]

It's been a long while since I can remember so many days of sustained model disagreement, and inability to get a hold on the hemispheric pattern. The last few days have seen all sorts of variations - not just on a theme, but on the theme or "pattern" itself. Note these differences this morning... GFSP at 192

 

 

and then ECM for the same timeframe

 

 

It's like looking at 2 different worlds, bar the signal for high pressure close to the UK. European heights different, EPO ridge different, location of most vortex energy different.

 

Frankly I dont trust anything I'm seeing at the moment. One thing is sure though - we have a pretty major wave 1 assault on the vortex underway now

 

 

But we also have strat remperatures at the pole running well below normal after a dramatic reverse earlier in December:

 

 

... and as a result a vortex that is stronger at its core than we expected it would be, leading to an ensemble mean forecast for 3-4 weeks time from JMA that looks like this:

 

 

I know that Chio is still pretty bullish on twitter about the strat forecasts, but from my more inexperienced angle we seem to be placing a lot of faith in the current wave 1 attack displacing the vortex in such a manner that it will allow heights to rise over Greenland and a consequent wave 2 attack shortly thereafter. Trouble is - the images I'm seeing this morning are not showing a consistent signal for proper height rises over Greenland, and NCEP forecast for the lower strat like this one suggest that low pressure in the atlantic will remain with us, with heights if anything sitting more over the UK in a dull omega block.

 

 

 

So - conclusion? The models are all over the place and nothing should be taken as gospel at the moment, but I'm less convinced than I was a week or so ago that we will get a proper GH... and this would be a fairly major blow to the idea of a trop lead wave 2 assault on the vortex with resultant wintry synoptics for Europe through January.