Model Output Discussion - Snow for some, but what else is in store?

[ItNeverSnowsInWindsor]

1 minute ago, Daniel* said:

Established positive NAO? It’s been negative this whole month and is set to remain so. Disruptions continue to be evident, while it’s likely it has reached a low point don’t expect vortex to be back to normal for a long while yet.
 

Weakly negative NAO with low pressure to the North East of the U.K. isn’t conducive to a severely cold spell.

[GSP]

8 minutes ago, prolongedSnowLover said:

The NH pattern is unfavourable to allow deep cold conditions over the U.K. especially in the South. Too much cyclonic between Scotland and Norway and an established positive NAO to allow anything other than normal winters weather.

The SSW has already failed to deliver with the vortex all set to recover during the remainder of the winter.

Yes, I understand that there maybe chances when this event happens, but for all the times SSW is mentioned in just about every other post and fails to deliver, makes you wonder why so many mentions are made of it. The buzz words?
There are 99 other important ingredients we need for a cold spell, that I thought by now is fairly obvious.

When I see SSW mentioned, sorry it doesn’t do it for me.

[Griff]

1 minute ago, prolongedSnowLover said:

Temperatures recovering towards normal after the spike.

Zonal winds are forecast to recover to near to or below the mean. 

The SSW has caused a displacement and forecast split. The outcome of the SSW is ongoing. 

Thanks for the chart but it just shows the original and second lesser warming. This is indicative of an SSW. It does not mean the PV has now recovered or even recovering yet. Far more unknowns regrading downwelling and coupling yet to be known. 

[Johnp]

5 minutes ago, Daniel* said:

Established positive NAO? It’s been negative this whole month and is set to remain so. Disruptions continue to be evident, while it’s likely it has reached a low point don’t expect vortex to be back to normal for a long while yet.
 

Isn't it technically a positive NAO right now?

997mb over Iceland vs 1020mb over the Azores?  Or is there a different definition?

Next week also shows a positive NAO by that definition

Edited January 17, 2021 by Johnp

[Man With Beard]

The question mark I have, having been through today's models is whether the mild SWlies really will take hold at around D8. 

The evolution in the past few days is a bit like a typical summer scenario - Azores High builds towards UK in FI, but then downgrades as another Atlantic low finds its way across when the models hit D6. Normally this happens the other way round in winter, but maybe not this time? The jet seems determined to stay south. Could lead to snow pile-ups in the north.

Further out, I can't take my eyes off that mega easterly flow just north of Scotland. We'll always be knocking on the door of cold for as long as that's in place.

[northwestsnow]

Now then ECM...

[Mike Poole]

And there is the next amplification as per GFS on ECM too at T240, lets hope for better luck with this one!

[swfc]

Ec has potential at day 10,il get my coat

[swfc]

1 minute ago, northwestsnow said:

Now then ECM...

Day 10 again

[Allseasons-Si]

On the ECM you can see the low heights drain away from day eight in the Atlantic just like the gfs did and produces this at day ten...

Edited January 17, 2021 by Allseasons-si

[Daniel*]

3 minutes ago, Johnp said:

Isn't it technically a positive NAO right now?

997mb over Iceland vs 1020mb over the Azores?  Or is there a different definition?

Quite clear it’s not positive right now. 

 

[Man With Beard]

4 minutes ago, Mike Poole said:

And there is the next amplification as per GFS on ECM too at T240, lets hope for better luck with this one!

An awful lot of ensembles have been doing this recently for months end - low pressure gets east of UK, nothing else coming off the Atlantic - this may not stay as it is, but I bet it won't be an outlier.

[nick sussex]

Just now, Mike Poole said:

And there is the next amplification as per GFS on ECM too at T240, lets hope for better luck with this one!

Encouraging but the ECM throws those lobes of deeper vorticity west which will hinder any southwards push of colder air .

At least the Azores high gets displaced so I’ll take it . I prefer the GFS op in terms of what that could lead to but after some very underwhelming outputs in recent days at least some more favourable charts are showing up .

[Johnp]

4 minutes ago, northwestsnow said:

Now then ECM...

I've no idea how that day 9 chart leads to the day 10 chart, but I'm not complaining.

On the chase we go again. 

[Vikos]

8 minutes ago, Mike Poole said:

And there is the next amplification as per GFS on ECM too at T240, lets hope for better luck with this one!

Far too weak I would say, gets overrun easly. But Didi-land, anyways....

[sebastiaan1973]

There is still time to improve

The high at the Northpole is not well positioned. We see this at 168h, the coldest air is blown in the Norwegian Sea instead of NW-Russia. So at day 10 there is not much cold air in Scandinavia and NW-Russia. It reminds me of december, when it was mild in Eastern Europe, NW-Russia and Scandinavia. Hopefully we will see some change. But I doubt it. There must change quite a lot. And the EC/GFS plume at day10 show day show little progress of the cold coming south. But who knows.

[Johnp]

11 minutes ago, Daniel* said:

Quite clear it’s not positive right now. 

 

Hmm you learn something new every day! I thought the definition was the difference in pressure between Reykjavik and the Azores (if higher in Reykjavik then it's a negative NAO, if higher in Azores then it's a positive NAO). 

However having read more I think it is in fact related to the difference in pressure anomoly at the two locations. Apologies for my confusion (that I've been carrying for years). 

Edited January 17, 2021 by Johnp

[Singularity]

Maybe a classic case of erroneous persistence unfolding; modelling initially keen to persist the Iberian high for a bit but now it appears it could be fleeting.

More runs needed of course!

[bluearmy]

The strat has been rock solid on the ridge establishing around the n Atlantic sector from the north  in week 2 ....perhaps the 12z runs are beginning to sniff that imprinting onto the trop ..... let’s see how many eps members drift that way - mwb has indicated that this isn’t a completely left field option ...

[sebastiaan1973]

13 minutes ago, Mike Poole said:

And there is the next amplification as per GFS on ECM too at T240, lets hope for better luck with this one!

The low pressure west of the little amplification is round, this is not ideal for good WA. Preferably we need a stretched cyclone in direction south -> north.

[Mike Poole]

4 minutes ago, Vikos said:

Far too weak I would say, gets overrun easly. But Didi-land, anyways....

I think it could link with the previous high, as per:

Which would give a stronger ridge upstream of the UK, less sure re your location!

[northwestsnow]

2 minutes ago, bluearmy said:

The strat has been rock solid on the ridge establishing around the n Atlantic sector from the north  in week 2 ....perhaps the 12z runs are beginning to sniff that imprinting onto the trop ..... let’s see how many eps members drift that way - mwb has indicated that this isn’t a completely left field option ...

We need this trend to strengthen..

Clearly.

[Tim Bland]

Early Feb often delivers a cold spell so wouldn’t be surprised if day 12-14 sees a ridge. It will probably be last chance saloon. Just gutted that after the promising start in Dec (PV never really got going ) followed by an early SSW, we still couldn’t get a decent cold spell in the heart of winter  

[Daniel*]

Just now, Johnp said:

Hmm you learn something new every day! I thought the definition was the difference in pressure between Reykjavik and the Azores (if higher in Reykjavik then it's a negative NAO, if higher in Azores then it's a positive NAO). 

However having read more I think it is in fact related to the difference in pressure anamoly at the two locations. Apologies for my confusion (that I've been carrying for years). 

When it is positive NAO there is a stronger than usual difference it doesn’t mean pressure needs to be higher in Iceland than Azores region that’s very rare, of course with climatology pressure in Iceland is much lower than in Azores and therefore 1000mb for them in middle of winter is actually on cusp of higher pressure. The anomalies are useful to look at! 

[Anthony Burden]

ECM from 96 hrs very interesting for cold weather fans,showing a mild plip for the south at 216 hrs 

before Atlantic low tracks over southern England to the east of the U.K. dragging north/northeast 

winds behind,but perhaps more important signs of pressure rise to the west all of course in 

fantasy island but good to see,also GFS 12z showing the same principle in fantasy island of course.