Model Output Discussion - Colder but how cold and for how long?

[frosty ground]

1 minute ago, Mike Poole said:

 

From the runs I’ve seen, the Iberian heights pumped up by the zonal spell are part and parcel of any evolution to a Scandi high, by means of building those heights first through the UK and then into Scandi with a deep Atlantic trough providing the WAA for such an evolution.  

Standard Scandi high creation, not sure what’s so controversial about Gowons post?

 

[frosty ground]

16 minutes ago, Kasim Awan said:

That to me looks like a bog standard very mild chart with minimal scope for cold.

very mild with those uppers? 
are you sure? 

[Kasim Awan]

1 minute ago, Mike Poole said:

 

From the runs I’ve seen, the Iberian heights pumped up by the zonal spell are part and parcel of any evolution to a Scandi high, by means of building those heights first through the UK and then into Scandi with a deep Atlantic trough providing the WAA for such an evolution.  

I have no idea how suddenly the concensus is that Scandinavian heights are somehow likely.

The last 7 days has shown us that the atmosphere is very resistant to any sustained blocking signal.

No model output reliably shows a Scandinavian high building in a sustained manner. All output shows features of a phase of strong zonal winds which in El Nino late winter periods tends to be a sustained period. For me this one is complete heresay as I see nothing to suggest the possibility. This is just referring to the next 10-14 days after this options are on the table, as they are with every long term outlook.

1 minute ago, frosty ground said:

very mild with those uppers? 
are you sure? 

The overall pattern is conducive to mild weather.

[adrianh]

Definitely looks like a trend to build heights over the UK from the 24th/25th.

Whether that proves to be any use for sustained cold is another matter but at least it looks likely to bring the train of nasty looking lows to a halt.

[Ice Day]

A recurring theme over some runs yesterday and today, is a reinforcement of heights starting around the 27th/28th. The GEM shows a little potential, but far better seen on the GFS

Way too far out to treat with anything other than extreme caution, but this was the direction of travel the ECM took on yesterdays 12z.  

[Battleground Snow]

1 minute ago, Kasim Awan said:

I have no idea how suddenly the concensus is that Scandinavian heights are somehow likely.

The last 7 days has shown us that the atmosphere is very resistant to any sustained blocking signal.

No model output reliably shows a Scandinavian high building in a sustained manner. All output shows features of a phase of strong zonal winds which in El Nino late winter periods tends to be a sustained period. For me this one is complete heresay as I see nothing to suggest the possibility. This is just referring to the next 10-14 days after this options are on the table, as they are with every long term outlook.

The waa that supports a potential Scandinavian high is clearly an option in the 192-240, range.

It is dependent on how the troughs spawning off the tpv to the northwest orientate, e:g if they are sufficiently west and negatively tilted, so that they don't flatten the ridge and push it too far east.

It's an unlikely outcome admittedly on the current modelling, with only a few rogue runs going for this, but I'm not sure why you think it's not possible at all under this setup

[Kasim Awan]

Just now, Battleground Snow said:

The waa that supports a potential Scandinavian high is clearly an option in the 192-240, range.

It is dependent on how the troughs spawning off the tpv to the northwest orientate, e:g if they are sufficiently west and negatively tilted, so that they don't flatten the ridge and push it too far east.

It's an unlikely outcome admittedly on the current modelling, with only a few rogue runs going for this, but I'm not sure why you think it's not possible at all under this setup

I absolutely agree there is a signal for waa into western Scandinavia but we're missing low heights over Iberia. As a result a Scandinavian high will unlikely result in easterly winds in the UK and have very little impact on UK conditions. 

[Battleground Snow]

3 minutes ago, Kasim Awan said:

I absolutely agree there is a signal for waa into western Scandinavia but we're missing low heights over Iberia. As a result a Scandinavian high will unlikely result in easterly winds in the UK and have very little impact on UK conditions. 

Okay I understand what you are saying now,

Agreed it will be a slow burner and we need some retrogression to pull the heights up from Iberia to allow undercuts either from the west or east, ideally both!

Edited January 17 by Battleground Snow

[LetItSnow]

The latest day ten and the signal for heights pushing up from the south returns stronger. This will at least turn temperatures a little closer to normal hopefully. This is a little different than the previous run I think which had more influence from the Atlantic. It goes to show the danger of this set up. If it goes wrong it could set up a February like 1998 or 2019… conversely it could be the groundwork for something colder. Models will continue to toy with both options for some days yet so stressing over exact’s isn’t recommended by me. This is probably more what we want to see. 

Also something interesting about next week is that the minima aren’t forecasted to be exceptionally high on either the raw model data or apps. I’m not sure if they’re being undercooked or whether it’s well-timed fronts but it could mean daily mean records could be a little harder to achieve, though it will overall still be very mild. Also, speaking of minima, by day ten we are actually managing a frost in places with the raw data. This chart for the 28th is interesting. You can see that it’s really trying. 

If we can get a raise of pressure pumping some WAA into the Artic then things could align more favourable. I’d like to see more charts like this. 

[Lord Grogon]

22 minutes ago, IDO said:

The noticeable part of the next week is upcoming potential destructive storms (to D6 gusts):

 

Seems to be a bit of a reversal. Trend until yesterday was to move the low pressure centres northwards, hence restricting the severest winds to Scotland. But the GFS has now reintroduced secondary systems further south. Given GFS tendancy to overdo low pressures, be interesting to see whether the trend is followed by the other models.

Oddly enough, I like windstorms. Earliest memories of "exciting" weather I have were of the big storms in 1987 and 1990. Just a shame of course they cause such havoc!

 

[Daniel*]

GFS 12z reverts back to significant amplification to NE advancing to pole. It would be very curious what would manifest in weeks after.

Edited January 17 by Daniel*

[E17boy]

20 minutes ago, Kasim Awan said:

No I'm not too focused. They're there and they're very influential. This time I'm not backing down from my ascertions which are scientifically and evidentially supported. A cold easterly wind is not possible with a 580hpa high over Iberia, no arguing that.

I agree with the Iberian heights thinking and they have been the spoiler of many of our winters and yes whilst these heights are present down south it is almost impossible to get a deep freeze. However we got to see where these heights go I think some posters are thinking on the lines that if these heights can drift NE into Scandinavia then we can get a cut from an easterly. However for all this to happen all the jigsaw has to fall in place and at the moment no conclusion can be made. I think we got to grit our teeth and see how the pattern develops over the next 2 weeks. 
 

regards

[rwtwm]

27 minutes ago, Kasim Awan said:

No I'm not too focused. They're there and they're very influential. This time I'm not backing down from my ascertions which are scientifically and evidentially supported. A cold easterly wind is not possible with a 580hpa high over Iberia, no arguing that.

Do share any blogs or papers please. I know we look to the raising of the ridge as a spoiler, but I tend to think of the Euro ridge as a consequence rather than a cause, our weather comes from the west after all.     

But I'm just an amateur overly reliant on heuristics. Happy to see anything that contradicts me!

[Paul]

This thread is a bit long, and as we're entering a new phase in the weather, now's a good time to start a fresh thread: