Model Output Discussion - 8th - 14th January

[Frosty.]

The latest meto update shows the atlantic will be too strong next week and overpower any threat from the north and east, just too much energy but at least it trends a bit colder later next week with a risk of wintry showers but also some mild, wet and windy spells. The danger of this is it could undo all the cold eye candy on the FI charts as the atlantic systems crash through next week, and maybe in the weeks ahead.

[VillagePlank]

Agreed, I think Sun-Mon next week probably represents FI right now and what happens at that juncture will have major implications for the pattern beyond. Perhaps the models will move more and more towards 'sliders' across the coming day or two, but it really is knife edge stuff at the moment.

Agreed; numerically, shown, here.

We all know about a butterfly flapping it's winds and create havoc elsewhere, well, the first two days of next week are critical in my view in this regard. High pressure to build up from Azores into a (sort-of) block for next weekend marks the end of this rather long zonal period and we drift into a meridional situation,

... with everything that that brings. For how long, and for how sustained is, just about anybody's guess - the block develops well into uncertainty territory. Interesting little low appears and drifts south Wedns next week in the Minorca/Majorca region. One to look out for, as that would be a sure sign that the jet-stream is behaving as forecast.

This low seems to suck the energy from the high pressure (as it fills) over Spain/France/UK and then drifts into incoherence across North Africa. This gives the "room" for Azores high to expand northwards.

Edited January 11, 2012 by Boar Wrinklestorm

[Bristawl Si]

The danger of this is it could undo all the cold eye candy on the FI charts as the atlantic systems crash through next week, and maybe in the weeks ahead.

Alternatively, it could be the start of a 'battleground' event from Winters past - the way the models have been churning out different scenarios these last few days, it would take a brave person to bet one way or the other.

Model output over next few days should firm up on the predicted situ for the next couple of weeks......maybe!

[nick sussex]

The danger zone timewise for cold and snow lovers is around 144 to 168hrs.

http://www.meteociel...=144&carte=1021

You can see the Azores high still evident to the sw, this must not link up with the high to the east, the way to stop this is for trough disruption to the west sending energy into Iberia.

Trough disruption is not the easiest thing for the models as its basically asking them to make a call as to how much energy goes north and south, the situation is finely balanced at that stage, especially as you already have some energy running ne , you can see that by the tilt, the key is that shortwave developing on the southern side of that trough, that is likely to head towards the UK, if it goes under the block game on, over game over for a quick change to colder conditions, if the latter happens then its going to take longer as we will then have to wait for the PV to pull back and further chances of trough disruption later on.

There is often no real middle ground in this type of situation, for this reason you're likely to see big splits in the ensembles, and again these are poor at handling trough disruption at that timeframe.

Edited January 11, 2012 by nick sussex

[Tim Bland]

No because the whole country would be under milder air with the continental air held out East. On a positive note, back in the 80s before we had all this NWP info, the BBC would often state 'uncertainty about whether this colder air will reach us'. It usually did, if things fall right then this can become very clear very quickly.

Which model shows this Ian? Can you post an example please?

It's funny how people are already putting a boundary on the snow area ie North of M4 east of M1 or just past the black cat roundabout Truth is we will have to wait until T+24hrs and the NAE to get a clear idea. As stated the atlantic could be hekd way out west and the uk cold and dry...It wil be at least the weekend before the scenario is clearer.

Re the Meto outlook they are stitting on the fence. They mention "relatively Mild" and "Cold setting in " for the same time frame.

[Frosty.]

Alternatively, it could be the start of a 'battleground' event from Winters past - the way the models have been churning out different scenarios these last few days, it would take a brave person to bet one way or the other. Model output over next few days should firm up on the predicted situ for the next couple of weeks......maybe!

At least there is a bit of initial interest, a frosty weekend with freezing fog becoming more of a hazard and then as low pressure pushes east early next week there could be some transient wet snow on the leading edge of the front but currently the meto expect the atlantic lows to eventually bulldoze through the uk through next week, certainly after midweek and also becoming milder again, back to square one? I really hope it's only the first skirmish of a much larger upcoming battle, by the time it occurs it will probably have a big influence on how the second half of the winter unfolds.

[Jason M]

Things looking better today. This is far from a done deal though and I wouldn't be warning friends and family yet!

I've just looked through the parallel ensembles and whilst there are a few good uns, there are a lot that are far from great.

Noticed a few people talking about 'battleground scenarios' this morning. Whilst logic dictates its better to be in the East it rarely works that way in practice. Where a situation occurs with cold air winning out its usually further west that cops the snow with the east / south east staying dry under a cloud shield.

Nice to see the better ensembles though rather than endless variations of zonality (which still isnt off the table looking at the output). Lots of interest tonight

Jason

[Cecil Hogmanay Melchett]

Well after a great morning model wise the METO update im afraid is a bit of a kick in the teeth!!

They clearly think the Atlantic has to much oomph in it still and are not suggesting anything from theEast at all.

I watch the models but universally look to what the pro's think and to me they have backtracked from yesterday when they mentioned the posibilty of colder weather,today they say 'a bit colder'.

Im feeling less optimistic about the 12z runs but we'll see.

[recklessabandon]

Re the Meto outlook they are stitting on the fence. They mention "relatively Mild" and "Cold setting in " for the same time frame.

I think the METO and several others will be getting very sore posteriors from all the fence sitting they will have to do in the next 48-72hours. With the models flip-flopping the way they are and with complications being borne from upstream conditions being in areas of lower data I dont think it is that surprising.

What I would say though, is that the the LP progged to cross northern Scotland in the next 24hours dragging the cold air behind, has been modelled by GFS almost continuously for a week or more now in almost every run with every track around +/-200 miles of each other, if it verifies as such, then well done GFS.

[Frosty.]

Meto clearly sitting on the fence here, they clearly arent going to stick there neck out. The truth is we really dont know. Anything from atlantic dross to -15t850s could happen in the next fortnight. Once the scandi/scalbard high begins to form, things will become much clearer.

They were sitting on the fence yesterday when they were uncertain but they seem to have jumped off the fence now and are calling for the atlantic to regain control as the jet is not weakening enough yet but a lull in the action this weekend as a ridge covers the uk.

[Shunter]

I'm not really one for pattern matching but thought this was worth posting in view of todays charts and that it is forecast only 72 hours away ( courtesy of another website forum ):-

http://www.wetterzentral...1947/Rrea00119470120.gif

http://www.wetterzentrale.de/pics/Recm721.gif

[nick sussex]

Well after a great morning model wise the METO update im afraid is a bit of a kick in the teeth!!

They clearly think the Atlantic has to much oomph in it still and are not suggesting anything from theEast at all.

I watch the models but universally look to what the pro's think and to me they have backtracked from yesterday when they mentioned the posibilty of colder weather,today they say 'a bit colder'.

Im feeling less optimistic about the 12z runs but we'll see.

The 16 to 30 day outlook has not included the longer ECM ensembles, that isn't run till tomorrow. And look at it another way at least some cold is being mentioned which is a big difference from most of the winter.

If you notice the wording about fronts moving east it looks a slow process which implies a decent ridge to the east, their outlook after that goes with troughing over the UK and a nw/se tilt to the jet which is not far from whats on show across both the ECM and GFS operational runs.

How far west or east that troughing is will be determined by how much retrogression we see in the pattern and again I'd highlight this mornings NOAA discussions, you have a better chance of that leading to much colder conditions as the PV backs west which is what they expect to happen.

[Radiating Dendrite]

They were sitting on the fence yesterday when they were uncertain but they seem to have jumped off the fence now and are calling for the atlantic to regain control as the jet is not weakening enough yet but a lull in the action this weekend as a ridge covers the uk.

It sounds like they wrote it looking at yesterdays charts.

Anyway, we have the models and do not really need to be too interested in what the meto say, that will chop and change just as much as the GFS.

The 12z could be very interesting viewing later. As Nick S has said, it is the medium time frame where this could be won or lost.

[Earth Wind and Snow]

I felt yesterday that there were still upgrades possible in the short term which could have implications for cold prospects further down the line and todays models have certainly upgraded the potential for a cold and possibly snowy spell - not allowing for the fact that things will be already turning colder from tomorrow with frost in places although Ireland will be on the western edge of this

Todays UKMO at T120 is a big upgrade on yesterdays T144

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

Todays GFS T144 is much better than anything it produced yesterday and so close to something classic

http://www.wetterzentrale.de/pics/Rtavn1441.png

Todays ECM T216 is a big upgrade on yesterdays T240

http://www.wetterzentrale.de/pics/Recm2161.gif

So short term upgrades and long term upgrades today

Roll on the 12z runs and hopefully further progress towards a cold evolution

EWS

[nick sussex]

My apologies, I did not read the 6-15 day outlook only the 16-30 day, (In which they are sitting on the fence)

As for the 6-15 day, this confuses me, as the jet is being modeled to be weaker each run. As radiating dendrite has said, they appear to be looking at yesterdays models, because the current outlook is much better than yesterday.

The jet is likely to strengthen next week as the polar front heads further south, the Arctic high is displacing colder air further south so basically adding some more energy in tandem with the strong PV.

This in itself is not a problem its where the energy goes that is.

A fast zonal flow is expected across the east Pacific through the USA and into the Atlantic the uncertainty is what happens to that as it hits the blocking high to the east and ne.of the UK.

At this point no one knows with any certainty what will happen

[Harsh Climate]

1 run goes down to -18hpa uppers in kent, anyone got a link to that perpetration member?

[Radiating Dendrite]

1 run goes down to -18hpa uppers in kent, anyone got a link to that perpetration member?

Look at post 1203.

[Harsh Climate]

Found it, god if that run came of, the south east would be burried

[Frosty.]

The jet is likely to strengthen next week as the polar front heads further south,

Yes nick that's why the uncertainty issue yesterday has been removed with a return to atlantic driven milder weather after a cold start to next week with a bit of wet snow in the east/southeast, it may seem as though we will be heading back to square one but it's probably just a delay in the natural progression to all cold fans main event.

[ITSY]

only 3 runs above freezing by the 22nd. certainly something noteworthy IMO, given that nearly half the runs are below -5 at the 23rd. Not dead on or certain by any means, but if that continues then we're in the right direction. Bare in mind though that originally it was the 15th, then the 19th, now the 22nd/3rd. If it keeps being pushed back in a few days it could be one of those illusive close but no cigar type affairs, if it materialises at all. I'm not guna do this, but if one has any sense they'd return here only every 48 hours and check the progress - at this stage its silly looking for pattern changes or cold that remains over 10 days away.

[nick sussex]

Yes nick that's why the uncertainty issue yesterday has been removed with a return to atlantic driven milder weather after a cold start to next week with a bit of wet snow in the east/southeast, it may seem as though we will be heading back to square one but it's probably just a delay in the natural progression to all cold fans main event.

The uncertainty yesterday was more in relation to the shorter term ie how long the initial ridge to the east lasts.

Their outlook suggests a mixed bag of conditions and is perfectly plausible with a nw/se tilt to the jet, you'll get some milder conditions mixed with colder ones,but they're not saying just mild.

Both the ECM and GFS operational runs suggest this to be the case if the troughing sits over the UK, to get locked into the cold you'd need the pattern further west.

Those UKMO forecasts are liable to change as quickly as the models do so although people want to know whats going to happen theres no way of knowing until the models decide what to do at 144 to 168hrs regarding where the energy from the jet goes and how far west the PV backs.

People want answers unfortunately unless someones got a crystal ball then at the moment this sums it up.

?????

[tinybill]

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

nick looking in to my crystal ball looking on the maps here it could start on the jan 19 th -jan 29 the south and east anglia might need huskies by then!! mind ypu this fantasy land and it could go all xxxxx s up!!

[penicuikblizz]

There again it could end up mild!!!!

[Zenarcher]

Review on the weather models this morning,

GFS

It has good model agreement up to 96 hours where again it seems to struggle. Yesterday it took a different path after 72 hours then later on changed to what other models were saying. The GFS still seems to be struggling at the moment. Between 96 hours and 120 hours four other models show the low to our South West cut off and basically disappear. The GFS isn't to keen on this but after the last few runs seems to be falling more into line with the other models. The GFS no longer has a deep depression situated to the West coast of Scotland however it still brings up some Atlantic lows for the start of next week they do look to miss the UK though it may get a bit windy on the coasts of Scotland. In 9 days the GFS still wants to bring a change at the moment it wants to weaken the Atlantic and bring down high pressure from our North East.

ECM

It has good agreement all the way up to 144 hours. It wants to like three other models is to let the low at 96 hours sink down South allowing high to build up over the UK. On its further outlook to early next week it still has settled conditions for the South and unsettled conditions at times for the North. Again the ECM has good agreement with this outlook. Looking into the long term it still wants to make a change in about 9 days time however what this change may bring is unknown at this time at the moment it does want to weaken the Atlantic and build high pressure to our North something the GFS has shown.

GEM

Pretty much backs up the ECM showing settled weather for the South and unsettled for the North over the next 6 days. It's longer term in 9 days time brings a change as well but probably not to great or cold lovers because its looking mild for the UK.

NOGAPS

Another model agreeing with the ECM which is good to see because its mostly been on its own recently with its solutions.

UKMO

Yet another model agreeing with most and the ECM. However it isn't too keen to bring much high pressure over the UK at 144 hours just very far South of England would see settled conditions meanwhile the rest of the UK may be unsettled.

Overall from today to Sunday it will be mostly settled for the UK perhaps getting colder over the weekend and a bit windy at times for Western areas. At the start of next week settled for the South and unsettled for the North. In the longer term the models are still keen to bring a change around the 20th in about 9 days time and this change could lead us to colder weather. Overnight we see excellent agreement with ECM, GEM, UKMO and NOGAPS meanwhile the GFS still seems to be lagging behind usually around 96 to 120 hours.

[DubWeatherAddict]

Very interesting situation going on indeed. GFS seems to take more notice of a weakening in the westerly zonal flow and the ECM more of the opposite.

If anything though the ECM could just be delaying a potential cold snap further by a few days but things are loking positive IMO . COld pool building on the continent is the overall runner. How far its kept east will be the " battle"

12 z will once again be interesting . Will there be an increase of the number of possible -18 850s? We shall see!!!