Model Output Discussion 1st January 2014-06z onwards.

[fergieweather]

It would be nice to have something else to say rather than SW'ly (gales)

I see their update replicates the midnight version anyway.

[Cumulonimbus Tower]

http://modeles.meteociel.fr/modeles/gfs/runs/2014010706/gfsnh-0-144.png?6

 

finally after days of GFS misery the model puts 2+2 & lands @ 4 instead of 7.

 

Wedge of high pressure into the right location.

 

S

The question is, can we get an undercut out of this GFS? Don't know too much about jet profiles but it seems to be heading deep South and East around 180h

Edited January 7, 2014 by Cumulonimbus Tower

[Timmytour]

I think the main talking point of note from this morning's output should be the concern of more disruptive rainfall likely next week which is certainly more likely than disruptive snowfall.

 

I really do admire you folks on here for continually scanning the model outputs for that elusive cold snap and the prospect of snow. I used to be much the same in my younger years. Nowadays I take the weather as it comes and enjoy it all equally, that way it has become a year round fascinating hobby and not just a hobby of bitter disappointments when the expected snow and ice doesn't materialise which let's face it is more often than not in the UK. Still keep it up guys I enjoy your banter when I get in from my workshop each evening

Gibby....first let me say your summaries I find to be brilliantly set out and an invaluable guide to what the models are actually modelling, as opposed to what they might model

I'm someone who prefers the cold weather, and I profess liking reading the posts that encourage me to think there is potential ahead. But i do so with a head on my shoulders. What I find great about some members posts, is the way they articulate what has to happen for us to be able to tap into the cold and why it might happen. Whether it materialises or not, i find it to be highly educational. Actually I rarely read them saying "this will happen"... only explain what has to happen.  of course there's too much enthusiasm at times but this is only to be expected.  there's also too much enthusiasm at times in those who rush to condemn them as soon as the potential is not realised.  Yet i will always find such analysis more useful then the "this looks just like more of the same type stuff".  Things do change eventually and it's nice to see attempts at anticipation and the rationale behind it. 

i agree the banter is great at times....save for those occasions where some get too carried away by the idea that weather forecasting is an exact science!

My take on things? it's just a "feel".  I sense that, like last year...there's a push from the East coming, but first there will be probes, unsuccesful in reaching the UK.  i don't think a first or second push and success from the East is ever a strong one...it's something for which the momentum builds. That said, i can't see this winter being anything special.  I'm looking at a bit more wintryness towards th last week of Jan (expecting snow on the 26th) and a bit of flirting during Feb and March, but nothing on last year's scale. I don't get the sense that the strength of anything to the east will be sufficient to get the push required to bring us anything sustainable.  But I do think we are now living in a period of colder winters with more potential than in the days not so long ago when we were being told our kids would not know snow!

Keep up the good work Gibby and thank you!

[Matty M]

We really need some type of trigger low over Europe to send that cold west otherwise it could be another near miss for Blighty.

[frosty ground]

The question is, can we get an undercut out of this GFS? Don't know too much about jet profiles but it seems to be heading deep South and East around 180h

http://www.wetterzentrale.de/pics/Rtavn18615.pngIt would seem it can

[nick sussex]

Yet another change from the GFS and this lack of continuity between outputs shows just how much small changes over the ne USA make a big difference for the UK.

 

I don't mind all this volatility as long as the final solution is the most amplified one!

[Paul]

Some of the bickering and point scoring in here is starting to get really tiresome again - no-one wants to stop people posting in here but if those involved want to continue then it's going to happen imminently. Please moderate your own posts before the team have to take it out of your hands..

[Cloud 10]

http://modeles.meteociel.fr/modeles/gfs/runs/2014010706/gfsnh-0-144.png?6

 

finally after days of GFS misery the model puts 2+2 & lands @ 4 instead of 7.

 

Wedge of high pressure into the right location.

 

S

 

Is that really the 06z or have you been at the control's? 

 

[Cumulonimbus Tower]

http://www.wetterzentrale.de/pics/Rtavn18615.pngIt would seem it can

It gets silly once it goes in to the low res part of the run but i've seen enough to be happier again

[SomeLikeItHot]

Good to see low pressure taking hold over southern Europe for the end of 6z run. Gives some hope that even if we don't get this bite of the cherry we are looking as a pattern change that makes a bit of decent cold more likley.

[nick sussex]

If you look at the ECM ensembles for De Bilt you can see there are still a cluster of very cold solutions for over there but we've lost some of the colder ones for earlier in the timeframe, the last 4 ECM runs in order from the earliest to the latest:

 

We can deduce from this that a blocking signal still remains, the issue I think is how far east the pattern might be and where any trough disruption might occur, I would wager that if we see a westwards correction in the ECM and more dig of energy se to the west within T144hrs that there will be an increase again in the colder solutions  from around the 13th January.

 

 

 

 

 

The cluster of very cold solutions suggest that it might need two goes to get the cold into De BIlt, if it was that simple I'd be fine with it, however this always gives more time for another variable to pop up and either delay or derail the colder synoptics.

 

I am hoping that we will see more westwards corrections within T144hrs and also more dig of energy towards Iberia, the best cold solution is always the quickest, remembering that because cold synoptics are the exception in the UK that a lot needs to go right.

 

It does of course happen so its not always the same old story of missed opportunities but I'd like to see us take this one because with some relatively small changes  within T144hrs on a global scale modelwise the route to cold will be a lot less fraught with roadblocks!

 

I should add for newcomers to the site when you're dealing with colder patterns for the UK its best to take a view of how many things collectively have to work together to get to cold, generally blocking to the ne is a nightmare to forecast because the UK is often at the periphery of the cold, it seems that whenever this is shown it does become a stressful situation because the models will chop and change the cold boundary.

 

Its for this reason that you'll see many people hoping for a westwards correction, of course with the boundary close you can have some great snowfall where the two airmasses meet this signifies that neither mild or cold is an outright winner at that time, if the block eventually wins the fight then you'll see the energy sliding se and the ridge backing further west over the top.

Edited January 7, 2014 by nick sussex

[carinthian]

Morning all,

 Our snow computer forecasting system upgrades snowfall in our region for Tuesday and Wednesday next week with a combined reduction in temperature at all levels. Our portal forecasts indicated a fall of pressure in Southern Europe and a rise in pressure further north with a developing cold pool over West Russia. A low circulation would seem likely during this period , probable centre about 200k south of Klagenfurt.

Looking towards the British Isle, the expectancy still holds for some fall of pressure to the Southwest next week, whether this is trough alignation or cyclonic development , it still in mid- term prognosis period. The consensus from our experts is that the British Isles may become some sort of boundary ( battle ground ) against a increasing colder block further east.

Of course it is much harder to forecast snow in your location than here in central Europe. Should make for good model watching as this week progresses.

Have pictures over here on the news of the UK flooding and Mid-West Blizzards. Quite a contrast. Warmer uppers here to today, should see some snow melt after the weekends 35cm fresh snowfall.

 C

 

Morning all,

 Our snow computer forecasting system upgrades snowfall in our region for Tuesday and Wednesday next week with a combined reduction in temperature at all levels. Our portal forecasts indicated a fall of pressure in Southern Europe and a rise in pressure further north with a developing cold pool over West Russia. A low circulation would seem likely during this period , probable centre about 200k south of Klagenfurt.

Looking towards the British Isle, the expectancy still holds for some fall of pressure to the Southwest next week, whether this is trough alignation or cyclonic development , it still in mid- term prognosis period. The consensus from our experts is that the British Isles may become some sort of boundary ( battle ground ) against a increasing colder block further east.

Of course it is much harder to forecast snow in your location than here in central Europe. Should make for good model watching as this week progresses.

Have pictures over here on the news of the UK flooding and Mid-West Blizzards. Quite a contrast. Warmer uppers here to today, should see some snow melt after the weekends 35cm fresh snowfall.

 C

 

Just an update for Mountain Shadow. Yes, firming up on the low pressure circulation next week , centred North Italy/ Adriatic. Not likey to drop further south. Its influence will increase snow interest in the Eastern Alps.

Re: Shed head, I am not sure whether the latest prog is a downgrade for the British Isles. I expect main models to develop some sort of low pressure circulation next week , centred close to Southern England. Whether this taps into a cold air feed is still about 50/50 over there. If it does, certainly snow would be in the forecast. Good model watching and upgrade to a colder scenario now likely.

C

[lassie23]

Models pretty lacklustre this morning for coldies, but I am expecting some interesting developments come the evening runs. Need the USA to warm up and weaken the jet stream.

[Joe Levy]

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=310&y=140 (South-East England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=189&y=176 (South-West England)

http://www.meteociel.fr/cartes_obs/gens_display.php?ext=1&x=264&y=2 (Northern England)

 

Blocking becoming more and more widespread in the GFS ensembles, and this is starting to be reflected in the 850 temperatures, with some fantastic cold runs here. However, we have all been here before so we need to watch closely and refrain from getting too carried away. 

Edited January 7, 2014 by Joe Levy

[Summer Sun]

GFS 06z shows parts of the UK becoming cooler during the next 8 days with blues replacing the reds though the south does remain slightly above average, across the majority of mainland Europe the picture remains unchanged with temps remaining above average

 

 

Normal temps left expected temps right

 

Edited January 7, 2014 by Summer Sun

[tight isobar]

GFS 06z shows parts of the UK becoming cooler during the next 8 days with blues replacing the reds though the south does remain slightly above average, across the majority of mainland Europe the picture remains unchanged with temps remaining above average

 

 

Normal temps left expected temps right

 

thats how things are prog, at present however I think by latter this week things may look a whole lot more chilly? :

[mountain shadow]

Thanks for the update Corinthian.

 

Just had a look at the surface pressure ensembles for Vienna and Madrid, remember we want the pressure to be low in these locations as an indicator that the cold air might be advected Eastwards.

 

Vienna is currently at 1020mb, the good news is, there is decent support for pressure to drop fairly significantly over the next ten days, which backs up Corinthians snow forecast for the Eastern Alps.

 

Madrid, however, is not as clear cut. Pressure is also around 1020mb at present there but there is more divergence in the ensembles although the majority do drop pressure there and a couple significantly.

 

All in all, positive signs for cold and lets hope the 12z's steady the ship.

[SMU]

Summer sun- give it 2 more days & watch a swathe of blue appear...

 

S

[Frosty.]

I think P1..GEFS 06z is what most of us would love to see evolving during the next few weeks, an emphatic pattern change with a classic winters of old look about the synoptics with the uk trough slipping south and high pressure transferring and building to the north before being forced westwards / north west towards greenland where significant height rises occur as pressure then falls sharply to the north east, so we get an easterly followed by a N'ly / Ne'ly snow fest. It's a carlsberg run if ever I saw one, reloads of very cold air and an increasing risk of snow and ice...proper winter weather instead of this sw'ly autumnal mush.P1 would trigger meltdown on here.

[Ali1977]

Well, in the last few years we have had the coldest Nov/Dec for decades, and the coldest March for a century...

I think we need the coldest ever Feb to get this forum into full swing!!! Epic cold= happy forum.

[R.P. McMurphy]

Nice to see... 35-45% building towards Scandinavia.

 

[bluearmy]

just an observation on the period post day 10 on the extended ens. they have consistently shown the northern arm strengthening and pushing through any blocking way to our west. this then restarts the strong zonality that posters have been illustrating on occasions. although consistent, i have cautioned against taking such long range output too literally. now we begin to see the signs that the jet may well amplify again in eastern america with another strong trough showing. this could well drive the ridge off the east coast and mean our colder pattern has less forcing on it in the 10/15 day range. remember that the ecm ens, the best week 2 indicator we have has a sig drop off in resolution past day 10. this drop off on the gefs at day 8. always take the post day 10 output with caution. it may well lead you in the wrong direction. not saying that its wrong now but early signs that we may see a deeper trough than looked likely in the eastern conus around day 10 and that could drive a further undercutting pattern over here.

[nick sussex]

A few charts to show how finely balanced the outputs are between good and not so good for cold. Essentially here you can correlate the amplitude of the pattern over the northeastern  USA with the low near the UK, every upstream change has indeed a consequence in terms of how much dig south we see to the jet to the west.

 

You can see from the GFS 00hrs run to 126hrs it has less of a wave of amplification working through the ne USA, now look at the tilt of the troughing near the UK positive, energy wanting to spill over the top and ne:

 

 

Now look at the GFS 06hrs run to 120hrs:

 

 

A bit more amplification over the ne USA, because of this as the low tracked it was slower and will phase at a later timeframe than the 00hrs run.

 

You can also see the tilt of the troughing to the west, its neutral, a negative would be better but at worst neutral, we must not see a positive tilt to that troughing at the key timeframe.

 

We're only talking here degrees in angle but this is the tipping point going forward, once energy is moving ne you will not get the ridge to build ahead of the low to the west.

 

Its for this reason that this could go either way, and why we're seeing this volatility in terms of the detail near the UK.

Edited January 7, 2014 by nick sussex

[Chris K]

Well, in the last few years we have had the coldest Nov/Dec for decades, and the coldest March for a century...I think we need the coldest ever Feb to get this forum into full swing!!! Epic cold= happy forum.

 

-----------------------

I will do my best.

 

Yours sincerely,

 

Jack Frost.

------------------------

 

I don't know about anyone else, but I always love a period of uncertainty in the models, as it is like searching for pieces of the puzzle to finish and witness the final outcome!

 

Hopefully that outcome is like piecing together a 3D snowman rather than a 4 piece picture puzzle of a rusty train.

 

I won't repeat what others have already have said, other than that at least we have some interesting charts to discuss and debate, rather than the inevitable chain of lows turning my garden into a pile of slurry.

[nick sussex]

If someone offered me a negative tilt trough  further to the west and even more amplification over the ne USA I will happily put my last pound on a  cold outcome for the UK. So I think you can see how important that is!

 

We are getting to the point now where we should start to see the models come together to at least decide on the upstream pattern as the key detail is really quite close.

 

We're into the T96hrs range where that amplified wave starts to move across towards the ne USA so really we should hope for agreement on that tonight. Theres still room for more amplification or less, its on a knife edge.

Edited January 7, 2014 by nick sussex