Model output discussion - Closing in on Christmas

[Mapantz]

Looking at the GEFS for my location over the past few days, around the 29th, the OP for MSLP has either been an outlier, or the bottom of the pack. Something is going to give soon! Either that low pressure will be modelled weaker, or it will correct East.

[Battleground Snow]

The lack of energy over  North East Canada is a positive..  like @CreweCold says, if we do get unlucky with the trough not clearing enough south east of the UK, then we should be 3rd time lucky on the next wave of amplification. 

Edited December 19, 2020 by Battleground Snow

[Kentspur]

The highest snow risk % yet for London on Xmas eve  GFS 18z ensembles

[Allseasons-Si]

The gefs mean at 192.

 

[Uncertainty]

8 minutes ago, Bullseye said:

With regard to potential strat warming that GFS has been consistently running over last few days. Now that it's approaching some degree of warming around day 10 - is this backed up to some extent by ECM or JMA now it's coming into their range?

Feel free to move into strat if not suitable for here. 

Coming into view on the JMA now. Some level of warming is now highly likely as the precursor patterns have already occurred. Answers to a)how strong b)what type of SSW c)long term permutations in the troposphere... are presently unknown...

[tight isobar]

5 minutes ago, Kentspur said:

The highest snow risk % yet for London on Xmas eve  GFS 18z ensembles

Yes.. that mean and member sync.  Are belly diving..... it’s as good an-ens plot ya could possibly wish for... on we roll!@Xmas period..

Edited December 19, 2020 by tight isobar

[damianslaw]

36 minutes ago, blizzard81 said:

The gfs is like a dog with a bone. Nobody has banged on about the gfs superiority over ecm with regards to north western atlantic blocking than me over the years. The ecm has been all over the shop these last 48hrs. The gfs has been as cool as a cucumber. No more to be said. 

Don't often blow the trumpet of GFS against ECM, but I do when it comes  blocking to the NW, from my watching of models for a long time, it outperforms ECM in this respect. ECM tends to outperform GFS when it comes to blocking to our NE and E, that's my observation anyway.

[damianslaw]

1 hour ago, Djdazzle said:

Great charts though - may as well hope to be snowed in as most of us won’t be going anywhere anyway!

Mmm you wonder if government new Christmas rules took account of weather forecast, I suspect may well have had some influence, people unable to travel back and being stuck somewhere else, emergency services, I would not at all be surprise and being serious. 

[blizzard81]

3 minutes ago, damianslaw said:

Don't often blow the trumpet of GFS against ECM, but I do when it comes  blocking to the NW, from my watching of models for a long time, it outperforms ECM in this respect. ECM tends to outperform GFS when it comes to blocking to our NE and E, that's my observation anyway.

The winter achilles heel of the ecm. The north west atlantic amplification conundrum. 

[NeilN]

Just now, damianslaw said:

Mmm you wonder if government new Christmas rules took account of weather forecast, I suspect may well have had some influence, people unable to travel back and being stuck somewhere else, emergency services, I would not at all be surprise and being serious. 

This is what I had in mind. It does make you wonder, they've had an advance warning in regards to the weather but we'll have to see what happens!

[tight isobar]

Aww gwan then we’ll take em .  Eps/gefs .. obviously with diversity.. but on the same page @ultimately!!   The polar/block formats . The troughing and scales a little different.. but overall singing the same hymn!! .. bias or not unfolding sequence.. as I have.. the Gefs are by way of evolution.. the more supportive/supposed... quote something tbh

The west based/east bast oscillating are again imo favoured via gefs.. to polar/and momentum reasons!.. yet with a more pronounced ghp.. as we near.. and fold.

Edited December 20, 2020 by tight isobar

[damianslaw]

1 minute ago, NeilN said:

This is what I had in mind. It does make you wonder, they've had an advance warning in regards to the weather but we'll have to see what happens!

Perhaps the weather might finally make some headlines over the virus!..

Back to GFS 18z that is a locked in cold pattern. No easy way out of it. Just one run, but significant consistency from GFS about 8 runs now, prior we had major fluctuations from one run to the next. I do sit up when GFS is so consistent and bullish, more so when we have blocking sign to the NW.

[Paul_1978]

1 hour ago, northwestsnow said:

GFS moving towards Euro ...

Try hold off posting too early mate, plenty of the run still to go when to you posted that and it didn’t turn out too bad in the end did it?!

[northwestsnow]

31 minutes ago, Paul_1978 said:

Try hold off posting too early mate, plenty of the run still to go when to you posted that and it didn’t turn out too bad in the end did it?!

Haha... well it did to be fair,and then did a Houdini....

Let's hope for the same come morning !!

[tight isobar]

1 hour ago, Vikos said:

Ok, last one, but this does remind me of something

 

Me old mukka-mr singh wants ya number pal @new editions just in!!!

Edited December 20, 2020 by tight isobar

[Pixel]

56 minutes ago, damianslaw said:

Perhaps the weather might finally make some headlines over the virus!..

Back to GFS 18z that is a locked in cold pattern. No easy way out of it. Just one run, but significant consistency from GFS about 8 runs now, prior we had major fluctuations from one run to the next. I do sit up when GFS is so consistent and bullish, more so when we have blocking sign to the NW.

I for one (having just come out of hibernation) am loving the pin the 'tail on the donkey' NetWeather seasonal banter this year, Cold is coming and the will it wont it gfs /ukmo/ arpege et' al certainly excites.

It's not like we're going anywhere for a while yet - so very enjoyable 

[kumquat]

1 hour ago, Pixel said:

I for one (having just come out of hibernation) am loving the pin the 'tail on the donkey' NetWeather seasonal banter this year, Cold is coming and the will it wont it gfs /ukmo/ arpege et' al certainly excites.

It's not like we're going anywhere for a while yet - so very enjoyable 

Well said! Beautiful retrogression in the almost near 

In winters' past we'd take this big time.

[Kasim Awan]

Slightly more positive (flatter) tilt to the gfs - coming in line with other output's more zonal cold blast theme

 

Edit: by more zonal I mean more of a nw-se jet than a ne-sw jet as shown on the gfs. I thought zonal was an adjective, describing zonality as a magnitude / index than a definitive westerly is how I think.

Edited December 20, 2020 by Kasim Awan

[Kasim Awan]

The ec, gem and icon all have a significantly more zonal / westerly component to the cold injection. The GFS has made some considerable progress towards producing this outcome by more realistically dealing with shortwave activity during the ridge pivoting.

This is a classic scenario, imho, where the gfs is playing catchup with other output. Hopefully I'm wrong. The "other output" is just as fugitive for cold / snow risk; more a continued nw-se train with temporary colder sectors, than a complete east circulation / deep cold shown on the gfs.

Look at the ec clusters and you will see this

Edited December 20, 2020 by Kasim Awan

[Scott Ingham]

19 minutes ago, Kasim Awan said:

It may be funny to you, but the ec, gem and icon all have a significantly more zonal / westerly component to the cold injection. The GFS has made some considerable progress towards producing this outcome by more realistically dealing with shortwave activity during the ridge pivoting.

This is a classic scenario, imho, where the gfs is playing catchup with other output. Hopefully I'm wrong. The "other output" is just as fugitive for cold / snow risk; more a continued nw-se train with temporary colder sectors, than a complete east circulation / deep cold shown on the gfs.

Look at the ec clusters and you will see this

The gfs is another good run with the same ideas. The ecm will move to the GFS as expected. The cold spell is still there and will continue to be there. 

To use the word zonal in any of the output is misleading.

No model is showing zonal weather 

Edited December 20, 2020 by Scott Ingham

[Kasim Awan]

Just now, Scott Ingham said:

The gfs is another good run with the same ideas. The ecm will move to the GFS as expected. The cold spell is still there and will continue to be there no matter how much you spin.

The more easterly low track has been favoured by the majority of output for 2 runs now. I favour a gem+ecm combo more than the gfs, I don't disregard the gfs completely, it's idea of a huge cut otf low which develops into a NErly seems a little "optimistic".

Instead, a more zonal component as faboured would do the following: a more easterly low track will drive in colder uppers. This seen very nicely on the GEM. It also means showers would be plentiful. As the ridge is pushed eastwards, the northerly is initiated. This also hinted at on the ECM. This would be better for many than the GFS..

[Scott Ingham]

1 minute ago, Kasim Awan said:

The more easterly low track has been favoured by the majority of output for 2 runs now. I favour a gem+ecm combo more than the gfs, I don't disregard the gfs completely, it's idea of a huge cut otf low which develops into a NErly seems a little "optimistic".

Instead, a more zonal component as faboured would do the following: a more easterly low track will drive in colder uppers. This seen very nicely on the GEM. It also means showers would be plentiful. As the ridge is pushed eastwards, the northerly is initiated. This also hinted at on the ECM. This would be better for many than the GFS..

Both outputs are coming together.

Ecm isnt even out yet.

Just because the ridge thrown up is a little less robust after one run doesnt automatically mean a climb down.

Stay on the fence and watch them converge your over reacting

[Kasim Awan]

2 minutes ago, Scott Ingham said:

Both outputs are coming together.

Ecm isnt even out yet.

Just because the ridge thrown up is a little less robust after one run doesnt automatically mean a climb down.

Stay on the fence and watch them converge your over reacting

There is a difference between a zonal component and complete zonality - the former when associated with a cold spell produces more of toppler type characteristics / progression, rather than a complete cut off from the polar yet, like ecm 12z yesterday. This progression at the day 7-9 timeframe, which is imo favoured, does not guarantee a sudden break down either.

I can't see a gfs carbon copy verifying given the more credible output is more sensible in the evolution. 

[Scott Ingham]

10 minutes ago, Kasim Awan said:

There is a difference between a zonal component and complete zonality - the former when associated with a cold spell produces more of toppler type characteristics / progression, rather than a complete cut off from the polar yet, like ecm 12z yesterday. This progression at the day 7-9 timeframe, which is imo favoured, does not guarantee a sudden break down either.

I can't see a gfs carbon copy verifying given the more credible output is more sensible in the evolution. 

There is no west to east unhindered jet so there is no zonality at all. Full stop. I guess well wait and see. The full outcome will be nearer GFS than ECM

[Kasim Awan]

Polar zonality on a nw-se with Arctic injections seems most credible then...