Model output discussion - is the beast awakening?

[SqueakheartLW]

After the coldest so far GFS run for the up coming cold spell with a new low cold peak average of -10.4 at 850hpa the 06z had a lot to live up to. Did it deliver or did it perform a backtrack or U turn of sorts?

Here are the average ensemble charts at the peak of the cold spell, on the 06z this was at 150 hours away

Good news is that the average easterly is still showing. The bad news and not really that unexpected after such a cold 00z run was the backtrack on the 850hpa temperature from -10.4 back to -9.0 which is a 1.4 in the direction of less cold. This is still a decent -6.4 below the long term mean and the anomaly chart does still have us under quite deep blues. It was probably a bit much to expect the average to stay below -10 after all. However the area of average -10 isotherm or lower covers a greater area of the UK compared with the 00z, just a bit further north than on the 00z meaning my average from Scunthorpe went back less cold compared to the 00z so based on this we are probably still basically on track still on average.

Mildest 3 charts from the GFS 06z at 150 hours away

3rd     Member 26     850hpa temp -4.0

2nd     Member 9     850hpa temp -3.3

1st     Member 30     850hpa temp 2.8

Coldest 3 charts from the GFS 06z at 150 hours away

3rd     Member 29     850hpa temp -12.4

2nd     Member 6     850hpa temp -13.8

1st     Member 23     850hpa temp -13.9

6 Closest to the average mean of -9.0 charts (Range -8.4 to -9.9)

Member 14     850hpa temp -8.4

Member 28     850hpa temp -8.5

Member 7     850hpa temp -8.6

Member 10     850hpa temp -9.6

Member 12     850hpa temp -9.9

Member 19     850hpa temp -9.9

Mildest doom and gloom charts from the GFS 06z

Two charts share the shame here of joint mildest charts in the GFS 06z, not what I wanted to see

Member 8     +246 hours     850hpa temp 8.3

Member 17     +330 hours     850hpa temp 8.3

Coldest fantasy chart from the GFS 06z

Member 23     +150 hours     850hpa temp -13.9

Edited February 1, 2021 by SqueakheartLW

[goosey007]

15 minutes ago, Man Without Beard said:

Time to remember how the GFS often works.

D6-D10: Stick resolutely to a solution, while other models fluster

D6: Other models start to move a little to the GFS and firm up

D5: GFS jumps ship

D3: GFS returns 50% of the way back. We now have the final solution.

this kind of makes a little bit of sense ....as they are programmed (for want of a better word) differently and day 5-6 is still generally FI espcially with these set ups 

[bluearmy]

i'm seeing mean snowfall precip on gefs charts widely across the  uk by end sunday 

this is my general snow indicator of likelihood

[northwestsnow]

4 minutes ago, bluearmy said:

i'm seeing mean snowfall precip on gefs charts widely across the  uk by end sunday 

this is my general snow indicator of likelihood

The potential is there for a decent snow event across your patch Blue...

[Bradley in Kent]

Afternoon all,

A quick, slightly off topic, side note from me:

I spotted off the US East Coast how a plunge of seriously cold air is due to slide off the continent this weekend.

GFS is giving uppers of -20c out at sea level with Washington DC and water temps of 20c, a MASSIVE 40c difference! 

Firstly, if that actually happens you can only imagine the convection! But also, for us in the UK this'll surely end any Easterly regime as it livens up the Atlantic. 

Unlike western Europe cold in North America is easier to model and way more likely to verify, in fact I'd say when it is modeled, it definitely will happen!

[bluearmy]

6 minutes ago, northwestsnow said:

The potential is there for a decent snow event across your patch Blue...

Right up the eastern side and in my experience of the flow is strong enough can get right over to the west 

let’s try and get across the hurdles that still lie ahead ...

[bluearmy]

1 minute ago, Bradley in Kent said:

Afternoon all,

A quick, slightly off topic, side note from me:

I spotted off the US East Coast how a plunge of seriously cold air is due to slide off the continent this weekend.

GFS is giving uppers of -20c out at sea level with Washington DC and water temps of 20c, a MASSIVE 40c difference! 

Firstly, if that actually happens you can only imagine the convection! But also, for us in the UK this'll surely end any Easterly regime as it livens up the Atlantic. 

Unlike western Europe cold in North America is easier to model and way more likely to verify, in fact I'd say when it is modeled, it definitely will happen!

Yes - the Atlantic looks like awakening through week 2 but if we get deep cold established in nw Europe then you’d be surprised what’s possible with a slack zonal flow through the atmosphere 

[northwestsnow]

1 minute ago, bluearmy said:

Right up the eastern side and in my experience of the flow is strong enough can get right over to the west 

let’s try and get across the hurdles that still lie ahead ...

Oh absolutely...

I can assure you E ,ENE,or NE winds nearly without fail deliver to my location...

Fingers crossed we get that cyclonic easterly...

[Battleground Snow]

MJO update.

When I first seen this I was disappointed it's not really making much progress into phase 7, but then I thought maybe with it stuck around 6/7 for a long period, it will give us a more sustained period of blocking  in February with multiple reloads of cold from the north or the east and battlegrounds as the Atlantic tries to push in

In 2018 it raced through phases 6 and 7 at high amplitude which delivered exceptional cold but  it came through quite fast and pushed west of Ireland into the Atlantic.

FWIW the ECM 06z at 72 has the low a little ESE of the GFS 06z, maybe 60-70 miles, could have big knock on effect later though

[Cold Winter Night]

As the dust settles on the first two runs of the day, I put in my two pennies.

At the 120h "fairly reliable/FI" break point, EC 0z, UKMO 0z and GFS 0z (114h) have reached a decent amount of agreement, especially on the placement of Highs and Lows in North America, the Davis Strait and Greenland, which are important for what happens later on. GFS still holds on to a deeper low between the UK and North Africa, mainly over the Iberian peninsula.
The 120h-144h is also the moment where the cold is about to enter our areas. Will it prevail or not?

At 144h, there is already some disagreement. UKMO and EC/GFS handle the ejection of that low from the East America Seaboard (ESB) differently. I think that would certainly influence what happens at UKMO 168h afterwards.
The placement and shape of the Iberian low decides if the cold will get in à la EC, or barely, like GFS 6z.
At this moment I would give the cold an 80% chance of getting in for 2-3 days in the UK (and the low countries, in my case).

Then, into the realm of speculation and Fantasy Island, I noticed how the beautiful Scandi Highs that GFS FI showed last week, and to an extent EPS as well, are pretty much gone. They did not get closer in time and they do not really appear in FI anymore either. Instead we see Euro height rises and an incoming Atlantic.
Now, this being FI, it could turn out differently again (as the Scandi Highs disappeared, so could those Euro heights), but it is a bit of a concern.
My hope is that models are underestimating the blocking as they usually do, since models tend to move cold blocks away too easily and they underestimate the longevity of them. But we'll see.
That "cold February" is not on the charts yet. Certainly not in Europe, nor in the UK South and Southeast. Just a possible cold shot for about 3 days for now.

The block post 216h seems to be modelled too far North and West in Greenland, at least for the UK SE and my country. Again, just like earlier in January.
That can work out just fine, like EC had it this morning, but it is fickle and of a short duration.

@Catacol's post yesterday evening about new injections of angular momentum and opportunities for Northern blocking in our vicinity were encouraging, but I don't think we are seeing its effects in the output just yet. I might be wrong about that though.

[Battleground Snow]

52 minutes ago, Valleyboy said:

That could fire up the Atlantic, which might be bad news for the UK.

Yes true, but it could also fire waa up greenland and enforce a greenland ridge, it's not as simple as USA extreme cold equals a rampant jet towards us.

[jacke]

1 hour ago, offerman said:

Best post of the week. 
The charts are so inconsistent and especially further out where more often than not they downgrade cold potential . 

just focus on the within five days for more reliability even with this the charts can be flippant . 
 

good luck everyone who wants cold snow s as I do. 

Sorry to correct you Offerman, not best post of the week, best post of the Winter!  My goodness my heart goes out to some on here, very overall run exchange of emotion!

[winterof79]

12 minutes ago, bluearmy said:

Yes - the Atlantic looks like awakening through week 2 but if we get deep cold established in nw Europe then you’d be surprised what’s possible with a slack zonal flow through the atmosphere 

Slack zonal with our own cold pool. Thinking 2009 poss with lows filling and meandering 

Edited February 1, 2021 by winterof79

[Purga]

Hope all are keeping calm

A clear majority of the ECM 00z clusters for days 8-10 also show continued cold weather, with the the odd nuance etc. But virtually no signal for milder options so far.
 

[carinthian]

5 hours ago, carinthian said:

Aye Nick, 5 more days of waiting for true cold to arrive in Blighty. Model exhaustion  comes to mind. I am nervous for you guys just watching from my current mild hood 1000km away . In the shorter term I would have liked to see more resistance of the colder block to the frontal movement NE across the British Isles on Tues/ Wed but looks like all models want to push the milder air through most parts apart from the far north. This extra energy sort of helps form that limpet shortwave you refer to. So its the period 24-72 hours that interests me, if more resistance develops, a whole new spectrum to how quickly the advection cold takes place towards the end of the week could occur. I think there will be more twists to the model watching in the next 24 hours. Should get an update from the team over here later this morning with results from the snow model out parameter readings for UK snow location  for tue/ wed.  Current model watching reminds me of the words from the old Willy Nelson song, " Funny how time slips away " !

C

Next 12 hours will be of interest watching the observations. Already the first attack into the cold is taking place over Northern Ireland. We need to the see the trough movements slowing down or not advancing as far north. Look out for pressure trends ahead of the frontal zone. The low formation shown in some of the models does seem to show a delay or cut off of the Arctic Continental air mass  into much of the British Isles ( apart from Northern Scotland ) We need to see that low sink SE and fairly fast, otherwise  milder uppers will be to close. Lots of uncertainty of how things will pan out. Snow will fall ahead of the fronts in Northern England and Southern Scotland but its rate of progress or speed of change to rain will be critical going forward. Two things we need to see : Resistance over the 24 hours to advancement of the Atlantic troughs / sinking of the pesky shortwave period 72-96 h

C

[Blessed Weather]

56 minutes ago, IDO said:

I said last month after some really poor verification runs that the then time scale for implementation, which was Feb, was unlikely. You cannot have statistical failures that the gfsP was showing and it clearly needs some further programming. 

It is def more accurate in benign conditions due to its improvements in resolution and data. That is taken as given and should not influence when it arrives, it is whether it performs outside standard deviation and how far below it falls? It clearly has issues with modelling heights and hopefully they can resolve these by the end of the year!

I'm not sure where you are getting your information from IDO. Have you any links to sources please?

You are correct that the original timeline for replacement of GFS v15 was Q2 2021 and that has slipped to Q4 2021, but all I can find is a statement from NOAA that during parallel trials in Sept 2020 v16 had operational problems that caused the program to crash when modelling excessive vertical velocities (>300 m/s). Maybe this problem delayed the original timeline?

Original timeline from May 2019:

Crashes Sept 20:

As for v16 performance, it seems to out-perform v15 on many aspects according to NOAA stats. Even Ryan Maue back in July 20 using back-of-a-fag-packet comparisons of 47 runs said "Not a game changer. Marginal improvement, if any."

Ryan Maue tweet:

NOAA comparisons of v16 and v15 performance:

Source: https://ufscommunity.org/wp-content/uploads/2020/10/UFS_Webnair_GFSv16_20201022_FanglinYang.pdf

[IDO]

3 minutes ago, Blessed Weather said:

I'm not sure where you are getting your information from IDO. Have you any links to sources please?

 

Source: https://ufscommunity.org/wp-content/uploads/2020/10/UFS_Webnair_GFSv16_20201022_FanglinYang.pdf

I got this from my own research from verification stats, for instance:

At d10 on 12z verifications the gfsP ranks below the older less upgraded version. That should not happen with a large 31-day sample from a "better" model! If you look at the reason you can see runs that fall out of standard deviation, for example on heights, a 0.3 when the average is 0.6. This occurred too many times for it to be just random, and it is fair to conclude that in certain situations the model misfires. They need to correct this and in January when I mentioned this, other members said it was due to come on line in February! I said that this would not be allowed to happen and it was obvious that there was issues. So I am not surprised that there has been a significant delay.

NB. It seems to perform better earlier, say at d5, which is expected as it is an upgrade!

[sheikhy]

38 minutes ago, Battleground Snow said:

MJO update.

When I first seen this I was disappointed it's not really making much progress into phase 7, but then I thought maybe with it stuck around 6/7 for a long period, it will give us a more sustained period of blocking  in February with multiple reloads of cold from the north or the east and battlegrounds as the Atlantic tries to push in

In 2018 it raced through phases 6 and 7 at high amplitude which delivered exceptional cold but  it came through quite fast and pushed west of Ireland into the Atlantic.

FWIW the ECM 06z at 72 has the low a little ESE of the GFS 06z, maybe 60-70 miles, could have big knock on effect later though

Was gona say the exact same thing an hour ago in regards to the 06z ecm at 72 hours!!!!looks less deep and futher east!!!

[Battleground Snow]

1 minute ago, sheikhy said:

Was gona say the exact same thing an hour ago in regards to the 06z ecm at 72 hours!!!!looks less deep and futher east!!!

It's about 2-3 millibars, less deep, I think we are starting to lose the plot with this micro analysis

[PolarWarsaw]

45 minutes ago, Blessed Weather said:

I'm not sure where you are getting your information from IDO. Have you any links to sources please?

You are correct that the original timeline for replacement of GFS v15 was Q2 2021 and that has slipped to Q4 2021, but all I can find is a statement from NOAA that during parallel trials in Sept 2020 v16 had operational problems that caused the program to crash when modelling excessive vertical velocities (>300 m/s). Maybe this problem delayed the original timeline?

Original timeline from May 2019:

Crashes Sept 20:

As for v16 performance, it seems to out-perform v15 on many aspects according to NOAA stats. Even Ryan Maue back in July 20 using back-of-a-fag-packet comparisons of 47 runs said "Not a game changer. Marginal improvement, if any."

Ryan Maue tweet:

NOAA comparisons of v16 and v15 performance:

Source: https://ufscommunity.org/wp-content/uploads/2020/10/UFS_Webnair_GFSv16_20201022_FanglinYang.pdf

In short, @IDO is stubbornly refusing to let go of his beloved (and useless) Day 10-12 GFS means. 

The GFSp is verifying as good, if not marginally better than the GFS. It's turning into the operational and the GFS as we know it, is gone, without fail - it's happened. Get over it.

Even with that said, it still doesn't out-perform the ECM/UKMO statistically so, it will still be looked upon as the weak/fodder model - always will. 

Edited February 1, 2021 by Paul

[Paul]

@Nick F's latest blog is well worth a read:

Potential for a cold easterly to develop this weekend, but model chaos agreeing on it

WWW.NETWEATHER.TV

---

A look at the weather model divergence over recent days over what now looks to be the increasing potential for a cold easterly to develop over the weekend, with a risk of snow for some.

 

[sheikhy]

5 minutes ago, Battleground Snow said:

It's about 2-3 millibars, less deep, I think we are starting to lose the plot with this micro analysis

We defo are mate but i guess every millibar makes a difference!!i think we might about to lose the plot in about 1 hour 30 mins from now as well!!!in a good way or a bad way?!!we find out soon

[IDO]

2 minutes ago, PolarWarsaw said:

In short, @IDO is stubbornly refusing to let go of his beloved Day 10-12 GFS means - normally because they are trash and full of Bartlett's/Zonal resets - The GFSp is verifying as good, if not marginally better than the GFS. It's turning into the operational and the GFS as we know it, is gone, without fail - it's happened. Get over it.

 

The 0z and 12z at d10:

Please can you confirm where the gfsP outperforms the gfs? In fact there is a significant advantage for the old gfs! I know you are my harshest critic but post some tables to prove your point, which I did, to explain my conclusions? Cheers!

[SLEETY]

 

7 minutes ago, IDO said:

The 0z and 12z at d10:

Please can you confirm where the gfsP outperforms the gfs? In fact there is a significant advantage for the old gfs! I know you are my harshest critic but post some tables to prove your point, which I did, to explain my conclusions? Cheers!

looks like it is outperforming gfs ?,anyway think im expecting downgrades now im afraid.Turning colder,but deep cold looking unlikely it appears.

[topo]

Quite impressed by how poor GFS 06 is performing in nowcast..

Just have a look at the predictions for Southern Norway today, and look at the cameras..

So basically 0mm from GFS 06z and showing the snow band at least 150km south (and not at all so intense) and the result is white out with almost 15-20cm at the coast..

Almost all models failed for today, but GFS was the worst. GEM was by far the best