Model Output Discussion - cold spell to end Autumn

[Captain Shortwave]

Trying to fathom a route forward tonight, ECM ens

      

So with have our big East Pacific ridge, this is driven by a lot of background factors, but the usual monster Atlantic jetstreak looks unlikely to me as frankly the fuel isn't really there, so we still have the Atlantic ridge as an omnipresent feature albeit suppressed by a stronger jestream, so I suspect that we could still get north westerlies, but look what else we have coming into play here, a big block developing over Russia, So we have a potential three wave attack further down the line if we can get the Atlantic ridge to reamplify and sink the cold pool south over the US which in turn would cut off the trough over Scandinavia. The result would be blocked and cold for Europe.

So in all the route to cold is still there, but at the moment we are likely to see a brief spell of milder weather before we see at the very least a two way poleward ridge pattern emerge with the UK likely to sit on the cooler side of the jet albeit not overly cold (PM incursions because of the Atlantic ridge/Scandi trough shown in week 2). Can we see improvements in this profile to show a more wintry scenario.

[Met4Cast]

There's a lot of negativity in here and after the last couple of days, I can understand why. We went from "that 18z" which showed countrywide blizzards and the UK locked into cold to a marked movement away from a setup like that and more towards a milder, shortwave ridden yucky mess of a pattern.

The ECM ensembles show us a couple of things 

1. We will be seeing a "milder" spell starting this weekend to around the 8th December, I put milder in quotations because temperatures will still likely be in single figures quite widely, so it'll still at least feel chilly and seasonal.

2. There's a massive, massive range in the extended with many ensembles going for bitterly cold, but equally many going for mild too - The mean begins a downward trend in the extended though, so possibilities of a return to cold very much still there.

Is it as quickly as we wanted? No. This less cold spell is going to last a little longer than we were expecting. BUT! It is still November, it's very early in the season and completely losing all hope already doesn't make much sense to me.

I'm going to take a break from looking at the models for a few days to re-charge.

[Kentish Snowman in Yorks]

23 minutes ago, Ed Stone said:

Keep an eye out for the ginormous blizzard on day 10?

No that will be day 7 on tonight's run!  

[Glacier Point]

Eps seems to have refound the mid Atlantic ridge, which I think is right given the background Nina state. Temps showing a negative trend 6th - 8th onwards, but nothing special which again I think is about right given the deep trough over the US.

The thing that really takes the eye is the building ridge over the eastern Arctic. A key player long term? December heading for a very negative AO value. Is this standard Nina climo, soon to be reversed in Jan, or symptomatic of a Nina beginning to morph into something else?

[georgiedre]

9 minutes ago, Glacier Point said:

Eps seems to have refound the mid Atlantic ridge, which I think is right given the background Nina state. Temps showing a negative trend 6th - 8th onwards, but nothing special which again I think is about right given the deep trough over the US.

The thing that really takes the eye is the building ridge over the eastern Arctic. A key player long term? December heading for a very negative AO value. Is this standard Nina climo, soon to be reversed in Jan, or symptomatic of a Nina beginning to morph into something else?

Gp your winding us up here LOL. What's your pennies worth?

[Man With Beard]

Looking through the EC ensembles as you do ... Still a lot of northerlies at D8 in there. Some brutally cold members in the D12-D15 period, but no clear sign of the way forward for the UK.

[nick sussex]

The GFS gets to T90 hrs and hasn’t moved towards the ECM shortwave calamity .

Very bizarre goings on with the ECM handling things so differently in the early stages of its 12 hrs output .

 

[Duane S.]

1 hour ago, blizzard81 said:

I notice that members are avoiding any mention of the possibility of an easterly post day 10. I for one think that the chance of one has increased over the last 24 hours. The block to the east is growing and the displacement of the azores high will encourage lows to dive south east into western Europe and undercut the ever growing block to the north east. 

I've got my eyes firmly on it, Nothing showing yet on the charts, I think that will change over the next week though. It looks primed over the coming weeks, for the reasons you've stated. Good angle of and increasing jet strength off the Seaboard should increasingly steer energy through the southern arm as we go through December.

The only mild I can see is in short bursts, through waxing and waning as the theme of meridionality continues.

This remains anti zonal.

[Derecho]

GFS differs from the ECM 12z in the early stages, allowing the Greenland high to build up.... this will probably help us get a northerly later.

I reckon this will be similar to the GFS 12z, obviously underwhelming after earlier output but not as awful as the ECM. 

[nick sussex]

Quite astonishing to see the differences between the ECM and GFS at T144hrs hrs.

One would hope with an extra 6 hours of new data and the fact the chasm begins at just T96 hrs the GFS might hopefully be correct!

Regardless the ECM did manage to get to a decent end point and so let’s hope even with different evolutions at the start we get there eventually in terms of something wintry popping up.

Edited November 30, 2017 by nick sussex

[mulzy]

ICON 18z run following the ECM.

I can bet that the others will fall into line tomorrow. 

[Ice Day]

1 minute ago, nick sussex said:

Quite astonishing to see the differences between the ECM and GFS at T144hrs hrs.

One would hope with an extra 6 hours of new data and the fact the chasm begins at just T96 hrs the GFS might hopefully be correct!

Indeed so.. at least we're seeing some inter run consistency from the GFS, with the rapidly deepening low appearing again for next Thursday.

Slightly better placed and not a 'dart board' shape.  Not a bad run this, some strong heights pushing up towards Greenland at 174.

[snowice]

At 174  Friday week  snow is back

[blizzard81]

Possible easterly coming up on this one 

[winterof79]

I do not see our high getting flattened as easily this run

18z

12z

 

Edited November 30, 2017 by winterof79

[weirpig]

Way out but again snow for quite a swathe  of the country 

[East_England_Stormchaser91]

Much better shot of WAA into Greenland on the 18z. Jet is tilted better, a major blizzard would commence on the rear flank of that low especially over higher areas of the north. Let's watch this one out. I don't see why everyone is so downbeat! It could and has been much worse in the past with an endless southwest fetch and raging PV! 

Edited November 30, 2017 by East_England_Stormchaser91

[ribster]

5 minutes ago, weirpig said:

Way out but again snow for quite a swathe  of the country 

Indeed, period 6th to 8th keeps on cropping up...

[Derecho]

Very meridional jet across the NH, quite the cold spell for continental USA, shame about the lack of heights over Greenland but pretty seasonal.

[Singularity]

Well for what it's worth, I found the 12z ECM fascinating today. The totally different path all set in motion by LP failing to transfer across to the Scandi trough on days 4-5, instead getting caught up with by the broad low to the SW, this setting up some broad (though rather weak) WAA N and NE of the UK which gives the Siberian High enough cause to extend toward us. Not only that but the polar jet continues to fluctuate wildly with no solid push from the west, just brief pushes which soon relax and allow LP systems to dive toward Europe.

It resembles the weak La Nina pattern that Tamara mentioned the other day linked to the MJO propagating eastward and bringing about some destructive interference - but I'm not sure it's expected to get far enough to achieve a lot...? I can see why the lack of phase space diagram updates is frustrating Nick!

If enough eastward progress is on the cards then maybe the ECM 12z is not so crazy... although I'm not quite sure about the 4-5 day solution that accelerates westward progress of the Siberian High compared to if we go the way of GFS/UKMO/GEM. Then again, ECM's been looking a bit wild for a few days now, yet a number of its ideas have ended up manifesting in the other models. Testament to its verification scores. Keeping doors open to all sorts of rooms but when faced with such model madness, that's about the best one can do!

[nick sussex]

I wonder if this is a data coverage issue in a key area which is causing this big difference between the ECM and GFS.

You can look at this two ways there’s a very strong signal to displace the Azores high so even with different starts both outputs want to converge eventually to that .

 

Edited November 30, 2017 by nick sussex

[johnholmes]

2 minutes ago, nick sussex said:

I wonder if this is a data coverage issue in a key area which is causing this big difference between the ECM and GFS.

 

 

Gawd not that old chestnut again. Odd it only ever gets trotted out if the output is not what someone wants or expects. Only in the winter in the chase for cold.

[Frosty.]

One word, starts with B..ends with M..yeah you guessed it

Love the snow charts on tonight's Gfs 18z☺?????

 

Edited November 30, 2017 by Frosty.

[Rocheydub]

3 minutes ago, johnholmes said:

Gawd not that old chestnut again. Odd it only ever gets trotted out if the output is not what someone wants or expects. Only in the winter in the chase for cold.

Hi John, well not really if you look at it subjectively. There is an unusually a big difference between the NWP top guys at a relatively short time frame, so to tag it as a "cold chase" has a rather disingenuous feel to it. Yes, the cold seekers far outweigh the warmies on here but you must agree, there has to be some reason for the disparities at a relatively short term on the NWP!

[blizzard81]

3 minutes ago, johnholmes said:

Gawd not that old chestnut again. Odd it only ever gets trotted out if the output is not what someone wants or expects. Only in the winter in the chase for cold.

That's an unfair assessment of Nick's post for 2 reasons. First,  his posts have been nothing but positive and informative. Secondly, he probably has more than a point about lack of data in certain areas of the northern hemisphere.