Model Output Discussion 12z 04/12/2012

[latitude]

Anyone think this will last until christmas

The signals are there, but the cold party hasnt even started yet. If it is showing something simular on Saturday/Sunday then game on.

[BLAST FROM THE PAST]

Anyone think this will last until christmas

No.......March

BFTP

Edited December 5, 2012 by BLAST FROM THE PAST

[Ian Brown]

Really? I thought with an easterly flow and the wind chill effect even with -7 uppers we'd still achieve very low daytime maxima (1c'ish) or is there more too this than meets the eye? Or perhaps I'm just outright wrong.

The good thing with this though is that they are trending colder every run, I've noticed this as you said, they have trended a lot colder, I am not going to worry about the 850's anyway, as long as we get the Beast in the 850's will plummet and surely the surface cold it will create over Europe will help with the cooling?

The North Sea is still (relatively) mild in December and this would modify the easterly flow, no matter how long the draw is. I don't think it would be a problem for inland areas (in terms of snow).

[phil nw.]

The main thing is the block is here and now we can watch it build and move that even colder air from the east.No need to worry about it being cold enough if the models are right.

Just for fun and this based on the 06z ensembles look at the projected 2mtr temps further east -in order

we have Moscow,Berlin,Copenhagen,Paris and good old Warks.

Looks like Europe will join Russia in the freezer-bear in mind these are projected maximum temps.

This just gives an idea what could well be coming on the Siberian Express.

[Ian Brown]

Anyone think this will last until christmas

It hasn't started yet !

[Optimus Prime]

I believe the corresponding 5000 feet to surface temperature, temperature ratio depends on where the winds blowing from. A -7c 850 hPa from the north is inheritably going to be less cold than if it were to blow from the east. Winds from the east have surface level cold that influences the air temperature whereas from the north, the sea acts as a modifier. Snowcover at ground level would also have a significant effect,

A good example would be February 1986. Constant flow of easterly winds and very cold despite the 850 5000 feet temperature never being all that low. The easterly shown mid-month (I doubt it'll ever make it to the reliable 96 hour timeframe intact) would give struggling maxima, probably below freezing in the favoured spots and around +1c or +2c elsewhere.

Edited December 5, 2012 by Optimus Prime

[Gavin Hannah]

Looks like Europe will join Russia in the freezer-bear in mind these are projected maximum temps.

This just gives an idea what could well be coming on the Siberian Express.

You can definitely see and feel the buzz in the air as it looks like another stonking winte "could" be just around the corner. The past week and a half has given us a wee taster!

[Frosty.]

Anyone think this will last until christmas

Yes I think there is a good chance it will last until at least the new year, the intial easterly and then as high pressure gets sucked towards greenland and a trough drops into scandinavia, a northerly will follow with a blocked atlantic, the more I look at these charts, the more I think we could have a similar spell to dec 2010 on our hands but with rather different snow distribution, some very low temps will be recorded if these charts come close to verifying, it will just get colder and colder until the source of the cold air is cut off, and it probably won't be cut off, there may be a temporary blip, a type of reboot between the easterly and the subsequent northerly.

[lorenzo]

It hasn't started yet !

Ian , given your experience of watching many easterlies come to fruition or not. What confidence would you have in this set up verifying. Asked the same thing of Steve earlier but no reply as yet?

[Buriedundersnow]

To answer as quickly as I can and not derail the thread, the MJO forecast on the plots above can be used in conjunction with analogue charts to present a trend for how the Northern Hemisphere will shape up in terms of key features. Couple of fact sheets on this teleconnection in MJO link. In this case the MJO phase supports the development of a Greenland high, another of our winter holy grail set ups.

thanks lorenzo i will have a look through those links and see what i can learn

[Gavin Hannah]

What I will also say is that IMO, the cold has been getting upgraded the closer we get to T.0. At least where I am, having watched the models lately, we seem to be getting slightly colder that forecast and more snow to lower levels than forecast.

[Tom Jarvis]

can i ask would there be allot of snow fall in east sussex from theis set up?? im just wondewring as i hope it is as much as 2010

[weatherguy]

Yes I think there is a good chance it will last until at least the new year, the intial easterly and then as high pressure gets sucked towards greenland and a trough drops into scandinavia, a northerly will follow with a blocked atlantic, the more I look at these charts, the more I think we could have a similar spell to dec 2010 on our hands but with rather different snow distribution, some very low temps will be recorded if these charts come close to verifying, it will just get colder and colder until the source of the cold air is cut off, and it probably won't be cut off, there may be a temporary blip, a type of reboot between the easterly and the subsequent northerly.

This set up, so far, has been exceptionally well modelled. I remember a few days back some people fretting about models backing away from it (UKMO specifically, although it only ever showed a delay), but the similar situation remains so; pressure building north and west, lows tracking SE over the UK, while the final trigger low becomes cut off as the high to the west and north-east link up.

This is still being shown, and is creeping closer and closer to T0. Let's enjoy it!

PS - Let's also hope for no last minute implosion that seems to plague easterly set ups...

Edited December 5, 2012 by weatherguy

[Cheshire Freeze]

Ian , given your experience of watching many easterlies come to fruition or not. What confidence would you have in this set up verifying. Asked the same thing of Steve earlier but no reply as yet?

Here is a PM he sent me earlier. I'm sure Ian won't mind me outing him as a secret ramper...

Hi CC

I think it looks very promising - the height anomaly charts strongly support a High latitude block and I'm more optimistic than last night. I would just like to see model agreement on getting the core of heights far enough North in the almost reliable timeframe because although we get a second bite on the 06z (which I never really rate anyway), there is more time for things to go wrong between T144-192.

I would say very worst is a High on top of us, possible retrogressing later which would be a disappointing outcome based on this mornings output !

From our IMBY view for an easterly, there are no guarantees. Jan 87 was good, Feb 91 was not so good, Jan 96 was good.

Regards

Ian

[Rollo]

No.......March

That must have been written "tongue in cheek" but I suppose anything is possible with our weather.

BFTP

[snow drift]

Here is a PM he sent me earlier. I'm sure Ian won't mind me outing him as a secret ramper...

Hi CC

I think it looks very promising - the height anomaly charts strongly support a High latitude block and I'm more optimistic than last night. I would just like to see model agreement on getting the core of heights far enough North in the almost reliable timeframe because although we get a second bite on the 06z (which I never really rate anyway), there is more time for things to go wrong between T144-192.

I would say very worst is a High on top of us, possible retrogressing later which would be a disappointing outcome based on this mornings output !

From our IMBY view for an easterly, there are no guarantees. Jan 87 was good, Feb 91 was not so good, Jan 96 was good.

Regards

Ian

Interesting. Not sure you should post a pm without checking tho.

[Cheshire Freeze]

Interesting. Not sure you should post a pm without checking tho.

It's hardly top secret stuff!

Only sent a PM in the first place as not to clog the model thread up!

[Ian Brown]

Lorenzo, I’ve got high confidence of the loop of High pressure forming from near the British Isles towards Scandinavia bringing an easterly flow of some sort, everything else that I’ve seen this morning then supports an established High pressure. What we didn’t want was an ‘end of the line’ easterly such as Xmas 2005 where no sooner has the flow become established, the Atlantic is banging the door down.

The only doubts concern orientation of the High going forward from around the day 6/7 timeframe. Shortwaves could appear that result in the block not being able to get that crucial orientation, but that is just speculation. Importantly we are not relying on the Arctic High to get where we want to be – we look back at Jan 87 and saw what a part that played, but since then relying on it to intervene as always ended in tears for future cold spells.

Looking good, but the next 36/48 hours are important for the models, and I think that, worn down by so many failures, if 2009-11 had not happened, nobody would believe that this was going to happen until it is T72.

[Frosty.]

This set up, so far, has been exceptionally well modelled. I remember a few days back some people fretting about models backing away from it (UKMO specifically, although it only ever showed a delay), but the similar situation remains so; pressure building north and west, lows tracking SE over the UK, while the final trigger low becomes cut off as the high to the west and north-east link up.

This is still being shown, and is creeping closer and closer to T0. Let's enjoy it!

PS - Let's also hope for no last minute implosion that seems to plague easterly set ups...

i'm even more encouraged now that the meto update has upgraded the easterly potential after next mon/tues (in line with the latest ensemble support)..it seems to me we are all heading head first into the freezer during the second half of next week

[weatherguy]

Indeed, music to my ears! (or...good stuff to my eyes!)

[snowking]

(or...good stuff to my eyes!)

Balanced salt solution...

The most encouraging thing for me at the moment is the ensemble mean support.

Havnt had a chance to see the individual pets. yet (having taken me 2 1/2 hrs to get to work this morning I'm a bit behind!) but should be plenty of eye candy on offer

As for Ian's comments re: MOGREPS, could be just me, but it seems to take ages for it to drop an idea in its ensembles - that was certainly the case with the precious really deep cold that was suggested last week (and consequently took the met office further outlook some time to be altered)

Obviously without access to the model I can't say that with absolute certainty but that's what it seems like to me. I guess we shall see in the coming days if it moves further towards the ECM

SK

[london-snow]

The main thing is the block is here and now we can watch it build and move that even colder air from the east.No need to worry about it being cold enough if the models are right.

Just for fun and this based on the 06z ensembles look at the projected 2mtr temps further east -in order

we have Moscow,Berlin,Copenhagen,Paris and good old Warks.

Looks like Europe will join Russia in the freezer-bear in mind these are projected maximum temps.

This just gives an idea what could well be coming on the Siberian Express.

Great post there Phil,

I am very impressed with the amount of agreement in the general pattern up to day 8 over the past few days we have seen a lot of scattered ensembles in the pack but now coming more inline as we edge closer.

Two main points for me to add to the day so far -

1. Ensembles not only supporting each other hence less scatter but also trending colder than previous. Lets hope it trends even colder as things begin to firm up.

2. Much much better agreement with the models, I am expecting the 12z UKMO to come further inline with the GFS & ECM. We have seen over the past 36 hours that the UKMO is starting to come around to the GFS i expect a big push towards the GFS this afternoon.

Very happy thus far now let's see how the 12s go but i am expecting a UKMO to come more inline this evening.

[nick sussex]

Lorenzo, I’ve got high confidence of the loop of High pressure forming from near the British Isles towards Scandinavia bringing an easterly flow of some sort, everything else that I’ve seen this morning then supports an established High pressure. What we didn’t want was an ‘end of the line’ easterly such as Xmas 2005 where no sooner has the flow become established, the Atlantic is banging the door down.

The only doubts concern orientation of the High going forward from around the day 6/7 timeframe. Shortwaves could appear that result in the block not being able to get that crucial orientation, but that is just speculation. Importantly we are not relying on the Arctic High to get where we want to be – we look back at Jan 87 and saw what a part that played, but since then relying on it to intervene as always ended in tears for future cold spells.

Looking good, but the next 36/48 hours are important for the models, and I think that, worn down by so many failures, if 2009-11 had not happened, nobody would believe that this was going to happen until it is T72.

Good post Ian

Your last sentence sums up why I shall be refraining from even the slightest ramp!

Regarding the orientation of the high that really is anyones guess however I think what complicated the 06hrs was the residual energy to the north in Scandi which stopped the high from extending its ridge earlier.

Luckily the upstream pattern remained amplified sufficiently to help cut the shortwave south with the block ridging over once again.

That low exiting the eastern USA is our extra insurance in sharpening any troughing to the west.

Theres still some uncertainty with how quickly that low moves east and engages the PV but it was good to see the GFS 06hrs run show no support for the UKMO's much slower solution.

Edited December 5, 2012 by nick sussex

[Gavin Hannah]

Ok, so I posted this over in the chat thread too. It is at t.192 but, it does have a flavor of 2010 about it.

[Summer Sun]

Looking at the models today the the potential for a cold snowy period does seem to be increasing ever so slowly from mid next week its at t186 so as ever caution is needed but with today's met office forecast update there is a good chance this may happen

The snow gets going during the early hours of next Thursday (13th) in the north parts of Yorkshire, wales and the midlands sleet even in the south

But look what happens by 06:00

Even into the weekend the snow risk remains

So don't give folks when we get one bad run from the models there will be many up's and downs over the coming days but those who stay patient will get rewarded in time