Model output discussion - Closing in on Christmas

[northwestsnow]

Just now, CreweCold said:

Control at D10!

long long way to mild ...

Euro heights nuked.

[Uncertainty]

2 minutes ago, Scott Ingham said:

Yeah I take your point on board. Im getting carried away with looking for the Jackpot scrnario. If we did have a split falling in the right place though theres no doubt wed have 4 weeks minimum in a stuck pattern like that. But your senseible head is completely correct. It could indeed scupper this as could the flushing down of zonal winds in the right place which i did call for after the greenie high with a colder shot end of jan

I think you’re both right here. The dream scenario this winter always was the blocked December predicted by the seasonals verifying then we get the big mid Jan SSW with correct split location etc and a Feb91/10/18 redux. The fact this scenario remains possible is wonderful in itself. In my view if we don’t get the SSW we get VI which means zonal winds get flushed down followed by zonal winds getting flushed down. So a Feb2020 redux. No thanks.

I’d take a short period of zonal flushing (?!?) to get two genuine cold spells this year. 
Hell most years I’d take a frost and no red rain warnings thank you very much!

[alexisj9]

45 minutes ago, 38.7°C said:

Looking at some of the current charts i really dont see why people are getting excited over cold rain /sleet on xmas day. The 850s dont look low enough to deliver snow.  Still theres time for things to get colder (or warmer). 

All the se needs is negative 850s and dry air from the continent, which bring negative dew points. Looks fine for SE England too me. However I'm not so sure about further north. Far to far to be looking, the trigger low is still changing what it does every run. I wonder what it will do tomorrow.

Edited December 15, 2020 by alexisj9

[Mike Poole]

Right, that is 2 runs I’ve ballsed up tonight, being wrong footed by the ECM after T216, and missing the support for the high on the pub run (Abbot ale likely responsible for the latter)

But what strikes me is there isn’t just one potential route to cold, there are many...future runs will no doubt confound, confuse and eventually elucidate...we will see, enjoyable evenings model watch, goodnight folks.

 

[Scott Ingham]

2 minutes ago, Uncertainy said:

I think you’re both right here. The dream scenario this winter always was the blocked December predicted by the seasonals verifying then we get the big mid Jan SSW with correct split location etc and a Feb91/10/18 redux. The fact this scenario remains possible is wonderful in itself. In my view if we don’t get the SSW we get VI which means zonal winds get flushed down followed by zonal winds getting flushed down. So a Feb2020 redux. No thanks.

I’d take a short period of zonal flushing (?!?) to get two genuine cold spells this year. 
Hell most years I’d take a frost and no red rain warnings thank you very much!

Yeah so would i! 

I never expected this first spell to evolve for the better. The atmosphere has been far more sensitive to tropical forcing than I could imagine in a moderate to strong la nina! So we could in theory get two excellent periods of cold and if were really lucky both periods overlapping each other and a cracking winter. Btw the control is more how i saw things evolving with the Greenland High in play sooner 

[Cheshire Freeze]

On the ensembles graph, the 18z GEFS 850s mean will flatline at around -4/-5 between days 8 and 11

[feb1991blizzard]

The GEFS and EPS are both a stonker in FI, how come BBC are going mild?

Edited December 15, 2020 by feb1991blizzard

[Zak M]

Looks like the GFS control is out of control..

That Atlantic ridge just stalls there which gives the UK a northerly, and another reload after! It’s a very good run. We drag in the -8c uppers too.

Right, off to bed. Great posts guys - this was an enjoyable evening!

[northwestsnow]

3 minutes ago, feb1991blizzard said:

The GEFS and EPS are both a stonker in FI, how come BBC are going mild?

They are going for a brief cold snap via a collapsing high...

[Mike Poole]

3 minutes ago, feb1991blizzard said:

The GEFS and EPS are both a stonker in FI, how come BBC are going mild?

On that graph, they’ve gone with the GFS op!

[alexisj9]

18 minutes ago, CreweCold said:

Control at D10!

They've both done this lol, fantastic.

[tight isobar]

6 minutes ago, feb1991blizzard said:

The GEFS and EPS are both a stonker in FI, how come BBC are going mild?

@cautious pessimism..

[MATTWOLVES 3]

Pretty solid ens out to day 11...take ya pick there's plenty to mull over.

[Daniel*]

25 minutes ago, Scott Ingham said:

Yeah so would i! 

I never expected this first spell to evolve for the better. The atmosphere has been far more sensitive to tropical forcing than I could imagine in a moderate to strong la nina! So we could in theory get two excellent periods of cold and if were really lucky both periods overlapping each other and a cracking winter. Btw the control is more how i saw things evolving with the Greenland High in play sooner 

The La Niña isn’t remotely strong. The only region which is in moderate threshold right now is 3.4 in fact right now you could argue it’s weak to moderate La Niña.

So perhaps this earlier than expected weakening of La Niña is helping us it already peaked in October the models really got it wrong, I believe the La Niña weakened from moderate to weak through winter 2012-13 as well so interesting parallels. A December that give a big easterly tease but ultimately disappointed but then came a wintry January with SSW and a cold spring.......

Edited December 16, 2020 by Daniel*

[BlueHedgehog074]

8 minutes ago, feb1991blizzard said:

The GEFS and EPS are both a stonker in FI, how come BBC are going mild?

What’s interesting, too, is that both the GFS and ECMWF are like mild outliers between 21st and 24th December for London

[Cheshire Freeze]

Just now, Daniel* said:

The La Niña isn’t remotely strong. The only region which is in moderate threshold right now is 3.4 in fact right now you could argue it’s weak to moderate La Niña.

So perhaps this earlier than expected weakening of La Niña is helping us it already peaked in October the models really got it wrong, I believe the La Niña weakened from moderate to weak through winter 2012-13 as well so interesting parallels. A December that give a big easterly trade but ultimately disappointed but then came a wintry January with SSW and a cold spring.......

Had a feeling the Nina was being overplayed- I said as much back when we were seeing those super Nina charts being pumped out. In truth, we've been ambling fairly close to neutral for a few years now. That's why such a strong Nina seemed outlandish to me.

[Uncertainty]

7 minutes ago, feb1991blizzard said:

The GEFS and EPS are both a stonker in FI, how come BBC are going mild?

Feb I’d wait until the monthly outlook comes out tomorrow, they’ve been hinting at a cold snap in some regard back end of the month for the last few updates. Hopefully they’ll reinforce that tomorrow.

Vis the 18z ensembles... 

Not far off a mean North Easterly there. Good concordance with the EPS at the same timeframe

 

Noaa also ‘on board’ with the blocking signal. 
 

 

We’re 3 for 3!

Gonna need more than a sofa to hide behind in the morning to watch the 0z come out though... there’s more twists to come I’m sure...

[kumquat]

37 minutes ago, CreweCold said:

Had a feeling the Nina was being overplayed- I said as much back when we were seeing those super Nina charts being pumped out. In truth, we've been ambling fairly close to neutral for a few years now. That's why such a strong Nina seemed outlandish to me.

Also overplayed due to a strong background global warming of SSTs (in general)

Edited December 16, 2020 by kumquat

[SLEETY]

Let's hope the models don't downgrade in the morning as they have a tendency to do when the previous runs have been so good,how many times have we seen that happen! 

[Scott Ingham]

1 hour ago, Daniel* said:

The La Niña isn’t remotely strong. The only region which is in moderate threshold right now is 3.4 in fact right now you could argue it’s weak to moderate La Niña.

So perhaps this earlier than expected weakening of La Niña is helping us it already peaked in October the models really got it wrong, I believe the La Niña weakened from moderate to weak through winter 2012-13 as well so interesting parallels. A December that give a big easterly tease but ultimately disappointed but then came a wintry January with SSW and a cold spring.......

Those graphs can be misleading. The value i look at when thinking about our climate is the SOI index.

This is often show to rise as a lag to low nina values.

Currently these values are rising on a daily basis.

As these are consistently above 7 and they are now at 11 these strengthen the trades and make tropical convection via the MJO more difficult. What this means is as the winter progresses we will find it harder and harder to achieve convective episodes to drive amplification (remember that post) and harder to drive waves to create a SSW.

Now what is intetesting is we ARE seeing tropical convection and AAM staying positive.

Now i have tho theories on this.

1) The summer heat over Russia and Asia - This has created higher than normal pressure in this region and has increased the chances via feedbacks of East Asian Mountain Torque Episodes.

2) Almost record sea ice loss especially on the Russian side of the arctic has been shown through recent studies to decrease the trade winds created by La Nina and is said to create a CP Nino atmospheric set up in the tropics.

So we have anonolous feedbacks at play created by a changing/warmer climate against an ever strengthening SOI value created by NINA that seeks to increase the trades and battle against this. The only way to know who wins this battle is to keep an eye on the trade wind charts/AAM charts and progression of MJO.

 

Now what happened in 2010? 

 

Who remembers the historic heat wave in Russia in 2010? 

 

Russian sea ice loss wasnt as bad as this year but it was bad compared to the average.

 

 

 

[Daniel*]

15 minutes ago, Scott Ingham said:

Those graphs can be misleading. The value i look at when thinking about our climate is the SOI index.

This is often show to rise as a lag to low nina values.

Currently these values are rising on a daily basis.

As these are consistently above 7 and they are now at 11 these strengthen the trades and make tropical convection via the MJO more difficult. What this means is as the winter progresses we will find it harder and harder to achieve convective episodes to drive amplification (remember that post) and harder to drive waves to create a SSW.

I don’t really follow this surely stronger trade winds means cooler SSTs. Even that SOI index which has been on the way up for weeks now accounting for lag where’s evidence yet? It’s the cooler waters which kill the convection/MJO? Maybe this suggests a disconnect but I’m just speculating. 

[Scott Ingham]

13 minutes ago, Daniel* said:

I don’t really follow this surely stronger trade winds means cooler SSTs. Even that SOI index which has been on the way up for weeks now accounting for lag where’s evidence yet? It’s the cooler waters which kill the convection/MJO? Maybe this suggests a disconnect but I’m just speculating. 

Your just telling me what ive told you 

Stronger Trade winds should mean this kills the impact of the Convection and MJO. So it SHOULD mean down the line convection should slow down deeper into winter and its still a possibility. As the SOI rises the stronger these trade winds become and the more convection wanes.

BUT these winds are being countered and i believe its down to the Russian heat wave and low sea ice extent in the arctic.

There are papers showing in 2010 this created an atmosphere that is similar to a CP NINO. 

So what wins out later? The unusual state of the atmosphere or the rising SOI value

Have a read do some research on the Russian heatwave in 2010 and the state of the ice and the effects this had on tropical temperatures and winds.

Clearly something is stopping the NINA imprint and its the phases of the MJO and the EAMT events.

Dont forget we also had a NINA on 2010 and had that epic 2010 

Edited December 16, 2020 by Scott Ingham

[Geordiesnow]

1 hour ago, SLEETY said:

Let's hope the models don't downgrade in the morning as they have a tendency to do when the previous runs have been so good,how many times have we seen that happen! 

All depends how much ridging there is in the Atlantic, if the pattern is flatter then it's more likely the charts will downgrade, if it does not then they probably wont.

I must say, despite the excitement, it's a very mild outlook and the amount of warmth heading into Scandinavia yet again is depressing too see. I do accept we could start seeing the jet buckle in the Atlantic hence a ridge may develop but it's not a strong signal to say it will definitely turn colder near xmas as we seen much flatter model runs also. Certainly no where near the stage where your looking at the runs in the morning with your hands covering your face.

[Daniel*]

13 minutes ago, Geordiesnow said:

All depends how much ridging there is in the Atlantic, if the pattern is flatter then it's more likely the charts will downgrade, if it does not then they probably wont.

I must say, despite the excitement, it's a very mild outlook and the amount of warmth heading into Scandinavia yet again is depressing too see. I do accept we could start seeing the jet buckle in the Atlantic hence a ridge may develop but it's not a strong signal to say it will definitely turn colder near xmas as we seen much flatter model runs also. Certainly no where near the stage where your looking at the runs in the morning with your hands covering your face.

Sorry but you’re totally out of touch with reality you can’t get a much stronger colder signal given range the ens have been remarkably persistent. A cold snap looks likely around Christmas there will be amplification in Atlantic we know there will be now the extent of which is up for grabs, a cold spell like GFS 18z showed well let’s be real no one is really expecting that to happen. 

 

[tight isobar]

RGfs ooz running .. and backtracking from its 18z suite....     Edit; considerably!!!   Where we are@00z top.      Where we were 18z. @bottom   But with given time outs.. there’s plenty still to be resolved... via formats etc..

Edited December 16, 2020 by tight isobar