Model Output Discussion - 8th December Onwards

[snow drift]

Please feel free to correct me if you feel different. I am encouraged by this. The block to NE is moving west. Less energy coming from the NW. PV moved from Canada. Edited December 9, 2012 by snow drift

[SnOwFeSt]

As I predicted yesterday, the models appear to have underestimated the power of this block.

The colder air remains over the uk for longer and there appears to be a trend developing for an undercut. Loads of potential for further upgrades over the next few days.

One of those high risk/high gain patterns for snow methinks!

[Dave Kightley]

Abit better in the short term.. Long way from nailed i suspect... ECM longer term produces a lot of rain esp in the west with troughs. P.V relocates. So much going on right now. See what they look like later on.

I wouldn't be surprised if the models have pushed back the attack until the weekend by Monday.

Something tells me that getting cold here is just as hard getting rid of it. The models are making it look easy like our easterly at one point. 51 ens members fall blown. Do i believe the atlantic will come in Thursday. no i don't!

Edited December 9, 2012 by Dave Kightley

[IDO]

By 48 hours high uncertainty with that low:

In a day (T72) that increases:

Look at the uncertainty for the blocking in the NE, similar variances.

The ensembles:

http://cdn.nwstatic.co.uk/ensimages/ens.20121209/00/t850London.png

are over 85% certain of a breakdown but what type and how much snow will there be, and where, is still to be clarified. No point looking further than that, until the low is sorted there are numerous potential scenarios.

One trend is that the NW, Scotland and NE will try and hold onto the cold for the next week:

http://wxmaps.org/pix/temp4.html

Mean surface temps below 0c for them. Cool for the rest.

The GFS always looked like being to progressive with the Atlantic and with the block in more recent runs holding its ground we are close to a battle ground scenario. Push things a little further west or the low further south and things get interesting.

[Jupiters Winter]

The only correction This chart is T240 remember what happened with the Easterly at this range. Face value Xmas has potential according to the chart.

Please feel free to correct me if you feel different. I am encouraged by this. The block to NE is moving west. Less energy coming from the NW. PV moved from Canada.

[Dave Kightley]

The only correction This chart is T240 remember what happened with the Easterly at this range. Face value Xmas has potential according to the chart.

Isn't that a deep depression to our west? Hopefully heights will move over the top and then the low should sink S.E wards. Or i suspect hang around building up though's rainfall totals Edited December 9, 2012 by Dave Kightley

[tinybill]

morning all early signs on the gfs in fantasy world the uk could ,might have our first white Xmas day in years Xmas eve looks fine but at the Xmas day looking messy for the south of the UK at the moment

Edited December 9, 2012 by tinybill

[snow drift]

morning all early signs on the gfs in fantasy world the uk could ,might have our first white Xmas day in years Xmas eve looks fine but at the Xmas day looking messy for the south of the UK at the moment

To me, this is why this thread is fun. Always posts charts T200 plus always calls it F1 instead of FI. Using precipitation charts sooo far down the line. Sure you will get posts saying "come on, that’s miles in the future" but for me this is what this thread is all about. The cold spell next week was picked up by charts T240. Yes it has changed but was still picked up.

I am not suggesting that the charts you have posted will be as they are suggested but input should be welcomed. Shame IF has decided not to post anymore as it adds to the tapestry that is the thread. The thread is what it has been for years and long may it continue.

Edited December 9, 2012 by snow drift

[Tom Montalbano]

A couple of UKMo charts worth noting-

http://www.meteociel...U60-7.GIF?09-05 t 60- a large pool of -10c 850s just to the east- we are -9

then 72

http://www.meteociel...2-594.GIF?09-05

http://www.meteociel...U72-7.GIF?09-05 Snow for the SE still in -8c air & widely -7 uppers-

then at 96 we draw that continental feed up-

http://www.meteociel...96-21.GIF?09-05

more instabiltiy & possible snow-

well worth watching country file today depening on the ECM & suite + MOGREPS run.

S

Morning all,

Well the model drama continues, on the back of yesterdays ECM 12z and last nights GFS 18z, the overnight runs yet again have improved from a coldies perspective. They all seemed to have backed the pattern a little further S.W, especially GFS and UKMO.

More trough disruption evident to our S.W, with shortwaves ejecting S.E.

ECM does break through at t144 but it wouldnt take much of a further tweak S.W. to something much more favourable, considering the big swing in the models of a few days ago, that is a distinct possibility.

I noticed during the 00z GFS run that temps stayed sub-zero not far to our east over Germany, right throughout the high-res part of the run, confirmation that this model has started to back the pattern gradually further back south west.

So plenty to be encouraged by on waking this morning and just as a "week is a long time in politics", its also an eternity in computer weather modelling.

Just about to get ready for work, hope I return to a more relaxed and happy Model Thread tonight. Hope to keep tabs on how things are shaping from work though, when time permits.

Enjoy the day!

Regards,

Tom.

[Dave Kightley]

Still way below Average by next Sunday. Only the far south and west temps recover on this run. You could still class this as a cold spell without the snow except Scotland and Northern England. Still 4/5/6 is what we have had most of this week Edited December 9, 2012 by Dave Kightley

[Tom Montalbano]

Just a further quickie,

Latest Fax for midday Weds shows that front S.W of Ireland stalling. Below the old and new Fax for Weds.

http://cdn.nwstatic.co.uk/fax/PPVM89.png

http://cdn.nwstatic.co.uk/fax/PPVL89.png

Regards,

Tom.

[snow drift]

Just a further quickie,

Latest Fax for midday Weds shows that front S.W of Ireland stalling. Below the old and new Fax for Weds.

http://cdn.nwstatic..../fax/PPVM89.png

http://cdn.nwstatic..../fax/PPVL89.png

Regards,

Tom.

And who is to say that the current trend wont continue and it improves further!! Come on Frosty, give us your thoughts.

[Tom Montalbano]

And who is to say that the current trend wont continue and it improves further!! Come on Frosty, give us your thoughts.

Morning sd,

Yes, I would say thats a distinct possibility, given the volatility of the models at the moment but I must balance that out by saying they could also revert back to show a more dominant Atlantic driven pattern too. Fascinating model watching at the moment!

Regards,

Tom.

[Severe Siberian icy blast]

Well well well . . . . . Upgrade , upgrade, upgrade !! That's my rant ! I said yesterday I thought I was seeing small signs of a backtrack , and I'm so pleased to see the models getting to grips with the pattern , sliders the theme this morning , and I feel we will now have a succession of upgrades , as like I said yesterday I felt we had reached the tipping point in the models 36hours ago.

Remember what Iv been ranting on about , the false dawn ? Aka gp warnings to us 10 days ago of a false dawn with the Atlantic express??

For me the chart of the day goes to ukmo 144z , look at the retrogression of the high pressure from scandi to greenlands . The way gp expected things to go is just that . I feel we are back on track now , or will be in another 24 hrs. Very happy this morning.

[cooling climate]

Ah nice turn around in the models this morning with a much more favorable outcome for us

snowgeese perhaps.If the runs today continue this trend then its game on but one word of

caution some times the models overdo a sudden shift south and west like we have seen

this morning and slowly pull the pattern back north and east. Hopefully this will not be the

case this time.

Very encouraging though together with the fax that Tom showed not sure what the 06z

run will show but certainly looking forward to this evenings runs.

[Bolton67]

Just a further quickie,

Latest Fax for midday Weds shows that front S.W of Ireland stalling. Below the old and new Fax for Weds.

http://cdn.nwstatic.co.uk/fax/PPVM89.png

http://cdn.nwstatic.co.uk/fax/PPVL89.png

Regards,

Tom.

. Also the 528 dam line on the fax for midday Wednesday is more inland

[Snow Obsession]

This is my first post here so please be kind!

It has been said in the past that the data at the weekends is not as reliable as during the week. I'm really hoping this is not the case, but could this slight improvement for cold prospects be due to this? Whenever there is a wobble towards mild at the weekend in an otherwise cold scenario, there are lots of posts about things being different at the weekend...

[DanDorsetUK]

My word i wasnt expecting to see that this morning so much chopping and changing they got a right problem with there weekly forecast today on bbc lol be interesting how they word this one. Already the atlantic attack has been pushed back by 24hrs! very interesting

[bluearmy]

The 00z show whats possible with some cold in place and the initial trough disrupts and the energy heads se. Now the second depression seems to be a little slower (somewhat deeper which has likely forced it more ne into more resistance from the ridge to its nw) than previously forecast. It wouldnt take too much more change in this track to make bigger downstream differences. That said, the pendulum swung quite a way overnight so for it to move even further today would be quite something. whatever, the size of the russian ridge seems to be similar to what we saw a few weeks ago. We do have some embedded cold to our east now so a broad repeat of the pattern might be more rewarding this time around.

[Severe Siberian icy blast]

The 00z show whats possible with some cold in place and the initial trough disrupts and the energy heads se. Now the second depression seems to be a little slower (somewhat deeper which has likely forced it more ne into more resistance from the ridge to its nw) than previously forecast. It wouldnt take too much more change in this track to make bigger downstream differences. That said, the pendulum swung quite a way overnight so for it to move even further today would be quite something. whatever, the size of the russian ridge seems to be similar to what we saw a few weeks ago. We do have some embedded cold to our east now so a broad repeat of the pattern might be more rewarding this time around.

Agreed, this time Europes in the freezer so any feed off the continent will be bone chilling, Novembers not a good time to have an easterly.

I look to further upgrades . . . Watch this space.

[loafer]

As a couple of posters last night said, the GFS often seems to backsolve to an Atlantic breakthrough for good statistical reasons, in that, for us, the Atlantic usually wins.

However, when there is a decent block it just blows up the incoming low beyond credible proportions before backtracking as T0 approachez.

This seems to be what has happened here, and the next question is how overdone was the low, and therefore how much further West the cold will remain...

[smith25]

This is what I was expecting small upgrades when we get closer to the event. I remember something similar happening during the past 2 winters where the breakdown kept getting pushed back on every run. Hopefully the same will happen this winter

[nick sussex]

I have to agree with SM here, this is a huge turnaround.

The models looked like they overplayed the amount of energy moving east and we have better trough disruption.

I first looked at the GFS this morning and thought what!!!

Really I don't think i've seen this many changes in output for many years, I think we should wait to cement this with one more run but if the models continue to trend as they have done so far then hard to know what will appear in later timeframes.

Edited December 9, 2012 by nick sussex

[Polar Continental]

A couple of UKMo charts worth noting-

http://www.meteociel...U60-7.GIF?09-05 t 60- a large pool of -10c 850s just to the east- we are -9

then 72

http://www.meteociel...2-594.GIF?09-05

http://www.meteociel...U72-7.GIF?09-05 Snow for the SE still in -8c air & widely -7 uppers-

then at 96 we draw that continental feed up-

http://www.meteociel...96-21.GIF?09-05

more instabiltiy & possible snow-

well worth watching country file today depening on the ECM & suite + MOGREPS run.

S

Morning Steve, everyone...

Absolutely spectacular, I think this has to be the most intense roller coaster since the famous easterly fail in February 2005. I saved all the links to that, we all said we had learned a big lesson afterward!!! Lol.

Feb 01 2005

Feb 02 2005

Feb 03 2005

Feb 04 2005

Feb 04 2005

Feb 05 2005

Feb 06 2005

Feb 07 2005

Feb 07 2005

Feb 07 2005

Feb 08 2005

Feb 08 2005

Feb 09 2005

Feb 10 2005

Feb 11 2005

Feb 12 2005

Feb 12 2005

Anyway back to today’s models, they have certainly picked up on something overnight, though after last nights ECM 12z run, I was half expecting a slowdown of the Atlantic push. Was the no gaps right all along, I think Nick S mentioned it would throw a double 6 eventually?

The 0z GFS is delaying the Atlantic by a couple of days and now shows a very cold south easterly by Saturday.

http://cdn.nwstatic....138/h500slp.png

Edited December 9, 2012 by Polar Continental

[Frosty.]

The latest models are showing signs of backtracking from the relatively swift breakdown to milder zonal weather they were showing yesterday, the residual cold pool in the week ahead looks more entrenched and the angle of attack for approaching depressions is more favourable for an undercut, it's still not good enough but it's trending in the right direction, especially the gfs 00z, the ecm 00z is synoptically not as good as the gfs but better than yesterday. What it means is, even though the cold uppers are gone by next weekend, it's still cold at the surface with temps of 2-4c away from the far south/southwest. So, the models have changed in favour of holding on to the cold air for longer, widespread frosts all week but inland looks mainly dry and sunny, probably some snow showers to n/e coasts and then as pressure begins to fall after midweek, a real chance of rain turning to snow for longer as a raw SEly flow develops, even some wet snow for the south but a chance of disruptive snow from the midlands north after midweek with drifting in the strengthening SEly flow and especially for scotland towards the end of the week, the hills in northern britain could become very snowy towards next weekend, a step in the right direction this morning.