Model output discussion - into the start of Winter

[northwestsnow]

Just now, Snow lover 2020 said:

What does does that mean for us then? Westerly? 

Yes, with the vortex returning home, so to speak.

[Methuselah]

And, don't the GEFS 06Z ens look spiffing? A surprise that no-one else has already posted them... not?

    

    

The Op, needless to say, is bordering on being a cold outlier...

[blizzard81]

13 minutes ago, sebastiaan1973 said:

Perhaps there's a difference in:

 

Maybe why Glosea is seeing a zonal return as we go through December. I hope it's wrong but discard Glosea at your peril. The thing that strikes me about UK Decembers is that the very few cold interludes we have ever had always seem to happen in the first half of the month only for the zonal reset button to be switched back on from the middle of the month. Just something I have noticed over the decades. 

[LRD]

19 minutes ago, sebastiaan1973 said:

Perhaps there's a difference in:

 

I thought, during the first third/half of winter, La Nina promoted mid-Atlantic ridging?

[Snowy Hibbo]

https://longrangesnowcenter.net/2020/12/01/european-winter-outlook-2020-21/

This recent more decent Late Nov/December pattern that is coming into fruition has certainly made the winter forecast more complex, with a number of factors favouring a milder winter.

So I have gone for an average to slightly above average snowfall forecast for this winter (in the UK), not expecting a horrid winter or an incredible winter, but hopefully a half decent one.

Thanks all 

Edited December 1, 2020 by Snowy Hibbo

[Froze were the Days]

33 minutes ago, MattStoke said:

Normally I wouldn't pay much attention to the GFS at such range or to the CFS at all but to have them both showing a similar (blocked, cold) outlook around Christmas, seems like more than a coincidence. 

CFS latest run shows nothing of the sort and a return to +NAO by about the 8th/10th...

[MattStoke]

5 minutes ago, Froze were the Days said:

CFS latest run shows nothing of the sort and a return to +NAO by about the 8th/10th...

I was looking at the previous run and recent trends/mean charts.

[ghoneym]

6 minutes ago, Snowy Hibbo said:

https://longrangesnowcenter.net/2020/12/01/european-winter-outlook-2020-21/

This recent Late Nov/December pattern that is coming into fruition has certainly made the winter forecast more complex, with a number of factors favouring a milder winter.

So I have gone for an average to slightly above average snowfall forecast for this winter (in the UK), not expecting a horrid winter or an incredible winter, but hopefully a half decent one.

Thanks all 

There have been many winters in the past where West based QBO and La Nina influences have been prominent.  Would I be correct in saying these parameters individually tend to bring a milder UK winter but together pose a stronger threat of a SSW and colder than average UK winter? I did have a look at the composites a few weeks back but never saved any at the time as It was a nosey out of curiosity 

[TSNWK]

31 minutes ago, northwestsnow said:

Yes, with the vortex returning home, so to speak.

and EC last night was suggesting lower heights over Europe until year end - who do we believe? is it possible to have a positive NAO Vortex over Greenland spitting out lows but on a North west / South east path, topping up the lower heights in Europe? with us on the cold side of the jet?

 

[BlueHedgehog074]

3 hours ago, Radiating Dendrite said:

@mods - perhaps time to split the thread and have one for cold searching - we had one called the hunt for cold a few years back which seemed to work.

Just feels like a battle in here between those looking for cold and those who just revert to "I told you so" posts.

Hi Radiating Dendrite, we appreciate you bringing this up. I have set up a poll for this right here:

If enough people want it, this is something we will go ahead with. I know we might not be able to please everyone, but I think there is certainly no harm in trying out the Hunt For Cold thread again to see how well it goes. We can always terminate it if it doesn’t work out, although a lot of people did seem to like it last time.

Edited December 1, 2020 by DiagonalRedLine

[ghoneym]

37 minutes ago, Snow lover 2020 said:

What does does that mean for us then? Westerly? 

As a conservative property, angular momentum in a closed system has constant total but can be redistributed within that system. For example, the atmosphere transfers angular momentum poleward in both hemispheres principally by means of transient eddies. Poleward transfers of mass however mean decreased axial angular momentum because the mass moves to a smaller radius arm from the Earth's axis of rotation. If there are no interactions with the solid Earth, a Coriolis torque will ensue, acting to increase the zonal winds, and keep the angular momentum constant. The transport of angular momentum is also accomplished vertically, carrying angular momentum as part of the Hadley and other mean meridional circulations.

[LRD]

9 minutes ago, TSNWK said:

and EC last night was suggesting lower heights over Europe until year end - who do we believe? is it possible to have a positive NAO Vortex over Greenland spitting out lows but on a North west / South east path, topping up the lower heights in Europe? with us on the cold side of the jet?

 

Angry looking Greenland purples in this chart didn't stop a superb 10-11 day-cold spell in 1991. NAO positive I would say looking at that chart

Must admit though I prefer a good old Greenland High over a Scandinavian one any day. They always look more robust than an SH even though they rarely form in the first place in winter, alas

Edited December 1, 2020 by LRD

[Snowy Hibbo]

18 minutes ago, ghoneym said:

There have been many winters in the past where West based QBO and La Nina influences have been prominent.  Would I be correct in saying these parameters individually tend to bring a milder UK winter but together pose a stronger threat of a SSW and colder than average UK winter? I did have a look at the composites a few weeks back but never saved any at the time as It was a nosey out of curiosity 

Maybe, this was my take on it:

Probably the worse analog (for snowfall) I found on the search for the outlook.

Certainly the QBO is the biggest trouble for this winter, but then again it has been all over the shop in the past few cycles, one cannot really know where it will go.

[bluearmy]

just a note that if we retain euro low heights then a pos NAO doesn't necessarily mean mild for nw Europe if the jet heads to our south.  there are other factors to then take into account. i also doubt glosea (or any longer range model) would get a handle on any wedges - and finally, it could be that the expected slow down in the upper strat may actually flush a more zonal flow into the trop for a period - short term pain = long term gain 

[ICE COLD]

10 minutes ago, bluearmy said:

just a note that if we retain euro low heights then a pos NAO doesn't necessarily mean mild for nw Europe if the jet heads to our south.  there are other factors to then take into account. i also doubt glosea (or any longer range model) would get a handle on any wedges - and finally, it could be that the expected slow down in the upper strat may actually flush a more zonal flow into the trop for a period - short term pain = long term gain 

And the meto update outlook looks pretty good . Sounds like high pressure to the north of the UK reading between the lines ? 

[lassie23]

5 hours ago, Paul_1978 said:

Is this the "will it snow" thread or the "model output discussion" thread?

At least there haven't been any posts asking whether it will be snowing at 3.33pm on the 14th December

[bluearmy]

2 minutes ago, ICE COLD said:

And the meto update outlook looks pretty good . Sounds like high pressure to the north of the UK reading between the lines ? 

Exeter's update from 4am looks EC46. i don't know when glosea ran - perhaps look for an adjustment in the 30 dayer tomorrow ??

[Methuselah]

1 minute ago, lassie23 said:

At least there haven't been any posts asking whether it will be snowing at 3.33pm on the 14th December

Give it time?

[Met4Cast]

6 minutes ago, bluearmy said:

Exeter's update from 4am looks EC46. i don't know when glosea ran - perhaps look for an adjustment in the 30 dayer tomorrow ??

The latest GLOSEA run was yesterdays 00z, or at least that's the latest I've seen. It does indicate some blocking out until the 10th December  (albeit not as strongly as the EC) but tends to relax the signal beyond that in favour of a more mobile pattern for the remainder of the month, though worth noting it didn't pick up the current blocky pattern until about a week beforehand. It does seem Exceter have favoured EC46 over GLOSEA, though mention of "milder interludes" in the update does highlight the uncertainty given differing signals between the two models.

Edited December 1, 2020 by Met4Cast

[Chesil View]

29 minutes ago, bluearmy said:

just a note that if we retain euro low heights then a pos NAO doesn't necessarily mean mild for nw Europe if the jet heads to our south.  there are other factors to then take into account. i also doubt glosea (or any longer range model) would get a handle on any wedges - and finally, it could be that the expected slow down in the upper strat may actually flush a more zonal flow into the trop for a period - short term pain = long term gain 

Indeed so Blue if one looks back at cold and snowy spells through the years on the NOAA reanalysis charts you won't find Greenland covered in yellow and orange all the time. It's perfectly possible for the PV to be roaring away in that region with a stubborn block downstream. Glosea is I feel not a great guide to nuances that can occur in our locale. It's really a rather blunt instrument in that regard.

Edited December 1, 2020 by Broadmayne blizzard

[damianslaw]

38 minutes ago, bluearmy said:

just a note that if we retain euro low heights then a pos NAO doesn't necessarily mean mild for nw Europe if the jet heads to our south.  there are other factors to then take into account. i also doubt glosea (or any longer range model) would get a handle on any wedges - and finally, it could be that the expected slow down in the upper strat may actually flush a more zonal flow into the trop for a period - short term pain = long term gain 

If the short term pain can wait until early Jan, and last no more than a couple of weeks, then I'd be happy. Too much to ask?

[Bogman]

24 minutes ago, lassie23 said:

At least there haven't been any posts asking whether it will be snowing at 3.33pm on the 14th December

Well, will it?!!!!!!!!!!!!!!!

 

(asking for a friend)

[jules216]

1 hour ago, Snowy Hibbo said:

Maybe, this was my take on it:

Probably the worse analog (for snowfall) I found on the search for the outlook.

Certainly the QBO is the biggest trouble for this winter, but then again it has been all over the shop in the past few cycles, one cannot really know where it will go.

Nice forecast @Snowy Hibbo although not looking to good for me in central Europe,better towards west in December. Interestingly seen today VP charts from M.Ventrice that might suggest MJO forcing towards phases 5 and 6 which kind of ties with the latest UKMO long rage text forecast towards the end of the month. MJO phases 5 and 6 for January are very close to what they see - settled weather from NW. This might be a go ahead pattern for Christmas to New Year period.

[lassie23]

12 minutes ago, Bogman said:

Well, will it?!!!!!!!!!!!!!!!

 

(asking for a friend)

lol computer says no

[STRiZZY]

8 minutes ago, jules216 said:

Nice forecast @Snowy Hibbo although not looking to good for me in central Europe,better towards west in December. Interestingly seen today VP charts from M.Ventrice that might suggest MJO forcing towards phases 5 and 6 which kind of ties with the latest UKMO long rage text forecast towards the end of the month. MJO phases 5 and 6 for January are very close to what they see - settled weather from NW. This might be a go ahead pattern for Christmas to New Year period.

What do MJO phases 5 and 6 mean for Central Europe?