Model output discussion - January cold spell ending, what next?

[Day_9]

Friday to Sunday and look at that change.  A much better handle on the “mild” interlude and then a crash.   Great views and trend is the friend here.  And he’s a coldie!!  The cold is being firmly sniffed out now.  More on board for a longer term and much less scatter.

[bluearmy]

The 00z ecm mean has a max in Luton of 4C for Saturday.  The 06z has 1C

[Cold Winter Night]

1 hour ago, IDO said:

These have a 30-day sampling so have few issues in the context of a fair representation. 

Heights are a good choice as they pertain to amplification deviance and I have looked into when the ecm performs badly in the individual daily drops and they mostly relate to overdoing heights.

It is not the average over the 30-days per se, as you say relatively small differences, it is in the dips in verification which drags the average down from gfsP>gfs at d5, to gfs>gfsP at d10 (also ecm). Look for the dips and extrapolate that to the actual charts and generally the causal link is excessive height estimation by ecm (and I suspect gfsP).

eg 15 Dec d10 chart verified at 0.26 compared to the 30-day mean of 0.561 (ecm

The d10 forecast and the actual day:

The forecast was for two plumes of heights, the reality was more trough dominated. Going from a UK HP to UK LP! Those two ridges much less amplified than the 10-day charts suggested.

Ah yes, well I was responding to you, and also a bit to some who were quick to conclude that the new GFS (GFSp) would be worse than the current GFS, just based on this past month's 500hPa height verification being a little lower. I know 500 hPa heights give a good indication, but they're just one parameter in a huge and complex model that covers NH and SH, Trop and Strat.

Plus, these verification stats came up in response to the likelihood of the very cold GFSp verifying, but we won't know the verification of that output until after it happened. This run might become one of those dips, end up in the middle of the pack, or it might become GFSp's heyday. We simply don't know in advance.

For all we know, this specific run might verify brilliantly, just not in our area, so we end up in mild SWlies, OR it has terrible verification, but we still end up in deep cold. Both are possible, because those stats apply to the entire Northern Hemisphere outside of the tropics.

Edited January 10, 2021 by Cold Winter Night

[Tim Bland]

15 minutes ago, bluearmy said:

The 00z ecm mean has a max in Luton of 4C for Saturday.  The 06z has 1C

Assume this front is a bit further west as well then

[MATTWOLVES 3]

1 hour ago, Jon Snow said:

1979 will mean diddly squat to most new members on here..what happened in 1979??.hmmm..on second thoughts, don’t bother..

What happened!! The Winter of discontent...the coal minor strikes, The Sounds of the Disco music era..I can safely say the world was a far happier place back then,and I so do wish for some of our younger members to be able to experience these great times sometime in the future again...while I'm at it get your laughing gear around this...that should do for a starter..

[sheikhy]

20 minutes ago, bluearmy said:

The 00z ecm mean has a max in Luton of 4C for Saturday.  The 06z has 1C

Interesting!!!!any further push west on the 12z and it could be a frikkin ice day blue!!!!!

[Frosty.]

For sure, the last third of Jan has wintry stamped all over it according too the GEFS 6z MEAN..it’s STUNNING..what a switch compared to the mild filth of the 0z mean!!!!!!...with all this talk of ssw, I can’t stand the thought of a mild last third of Jan..or the possibility of high pressure sat on top of the u k sucking the life out of the height of winter!!..fingers crossed for wintry nirvana!!!..there’s potential for some excitement on the way in the next few weeks..or else, what’s the point of bothering????!!!!!!

 

 

Edited January 10, 2021 by Jon Snow

[IDO]

12 minutes ago, Cold Winter Night said:

 

For all we know, this specific run might verify brilliantly, just not in our area, so we end up in mild SWlies, OR it has terrible verification, but we still end up in deep cold. Both are possible, because those stats apply to the entire Northern Hemisphere outside of the tropics.

I do not disagree! We should learn a lot.

As for it applying to the entire NH, that is correct, but my research tended to indicate that the main spread is in the Atlantic sector so the verification stats can be taken literally for our region. In fact without the more stable Pacific/Asia/Russian regions the verification for the Atlantic arena would be even worse.

eg: the spread on the current ecm op:

[Scott Ingham]

3 hours ago, Met4Cast said:

As some have already pointed out, the GEFS 06z show a huge shift towards a colder outlook compared with previous runs. Not sure when the last time such a dramatic shift occurred, but 2010 stands out in my mind.

GFS Op is a clear outlier now. I would also put more weight in the GFS(P) simply because it has more vertical layers so should resolve any SSW downwelling more accurately. 

After a tricky few days, things are steadily improving towards a colder outlook for the UK. EPS means/clusters are strengthening the signal with each model run. 

We're reaching the "tipping point" where we start to see increasingly cold and blocked runs appearing in the mid-extended. Buckle up!

You beat me to it! If you look at the verification stats. When we last had an arctic high modelled the gfsp beat both gfs and ecm in verification.

So could be a case its a better model in instances like this with a ssw filtering through

Its fact it has a better handle in the north pole due to nearly twice the layers of the current gfs.

The one thing to take into accoun though is greater layers mean when its wrong its wrong in a big way

The period 27th to the 1st had polar heights and the gfsp was king of verifìcation through this week.

 

Edited January 10, 2021 by Scott Ingham

[offerman]

I'm finding it difficult to get excited yet on the latest set of runs . 
FF 3 days and let's hope they then show clod for the weekend in to next week then that'll be nice as in the semi reliable timeframe as opposed to the Jester zone..

[BlackburnChris]

7 minutes ago, Scott Ingham said:

You beat me to it! If you look at the verification stats. When we last had an arctic high modelled the gfsp beat both gfs and ecm in verification.

So could be a case its a better model in instances like this with a ssw filtering through

Its fact it has a better handle in the north pole due to nearly twice the layers of the current gfs.

The one thing to take into accoun though is greater layers mean when its wrong its wrong in a big way

But that would have been the old GFS (P) which is now the current GFS . You cant really compare stats on old upgrades .. 

[Scott Ingham]

1 minute ago, BlackburnChris said:

But that would have been the old GFS (P) which is now the current GFS . You cant really compare stats on old upgrades .. 

Why would it have been the old GFSP?

The chart posted is from 2 weeks ago Chris

[fromey]

Well that changed

[Scott Ingham]

1 hour ago, Trom said:

I can see the argument that the GFS(P) has more vertical levels and theoretically should be able to model the events in the strat more accurately than the existing GFS.  However, it's worth remembering that even the parallel has marginally fewer levels than the ECM.  So for those hanging their coats on the parallel, I'd be looking for some agreement from the ECM before climbing aboard. 

It has more layers than the ECM

The ecm has 91

The new gfs has 127

Edited January 10, 2021 by Scott Ingham

[Evening thunder]

2 hours ago, Jon Snow said:

Oh man, this place is an insane asylum.. but here is the GEFS 6z mean..bank, just bank already!!!!  

 

 

20 minutes ago, Jon Snow said:

For sure, the last third of Jan has wintry stamped all over it according too the GEFS 6z MEAN..it’s STUNNING..what a switch compared to the mild filth of the 0z mean!!!!!!...with all this talk of ssw, I can’t stand the thought of a mild last third of Jan..or the possibility of high pressure sat on top of the u k sucking the life out of the height of winter!!..fingers crossed for wintry nirvana!!!..there’s potential for some excitement on the way in the next few weeks..or else, what’s the point of bothering????!!!!!!

 

 

Just for clarity you've got ensemble member 21 selected there and not the mean

[BlackburnChris]

8 minutes ago, Scott Ingham said:

Why would it have been the old GFSP?

The chart posted is from 2 weeks ago Chris

Sorry , the chart didnt come up on my laptop , I thought you were talking about last winter .

[Scott Ingham]

Just now, BlackburnChris said:

Sorry , the chart didnt come up on my laptop , I thought you were talking about last winter .

Oh no worries.

All said and done all these extra layers although in theory they should make a difference there are still lots of other variable differences which means we cant black and white say the gfsp has this nailed at this distance

[sheikhy]

Icon further west at 60 hours!!!

[Newberryone]

45 minutes ago, Daniel* said:

The Siberian express is returning the question is will it reach its final destination? (UK). Not to mention Ireland 

 

GEFS are now also aboard something is afoot that is clear. For coldies we have had to wait for 3 years for any shot of proper cold spell, but it seems our patience could be rewarded. 

Stands to reason of course, but you guys in the UK always stand a far better chance anytime there's ever a hint of anything truly cold incoming off the nearby continent. Should this cold spell materialize later on this month Ireland will no doubt be left picking up the scraps as it sits on the periphery of the two main air masses. 

[Djdazzle]

Got a feeling these will be a big set of 12z runs. Hoping ECM jumps on board too.

[Battleground Snow]

Here we go then icon cuts off the low at 135 (just)

If the Ukmo does this a bit later I'll be very happy and confidence can start to rise just a little bit.

 

 

[Trom]

25 minutes ago, Scott Ingham said:

It has more layers than the ECM

The ecm has 91

The new gfs has 127

I was talking about the operational run.

ECM = 137 post June (91 before June 2020)

I believe the ENS run with 91 currently

Edited January 10, 2021 by Trom

[bluearmy]

52 minutes ago, Tim Bland said:

Assume this front is a bit further west as well then

The 06z ec op only goes to T90

25 minutes ago, Scott Ingham said:

It has more layers than the ECM

The ecm has 91

The new gfs has 127

Ec op has 137.    Ec eps each have 91.  

[Scott Ingham]

5 minutes ago, Trom said:

I was talking about the operational run.

ECM = 137 post June (91 before June 2020)

I believe the ENS run with 91 currently

 

3 minutes ago, bluearmy said:

The 06z ec op only goes to T90

Ec op has 137.    Ec eps each have 91.  

Thanks for that i wasnt aware of that.

I always thought it was 91 but your right ive just checked it out 

[sundog]

19 minutes ago, Newberryone said:

Stands to reason of course, but you guys in the UK always stand a far better chance anytime there's ever a hint of anything truly cold incoming off the nearby continent. Should this cold spell materialize later on this month Ireland will no doubt be left picking up the scraps as it sits on the periphery of the two main air masses. 

The thing that concerns me about the potential cold spell later this month is that here in Ireland we have not had a real proper cold spell in the second half of Jan since the 80s. Could we miss out again? Very possibly imo. 

Unless any cold spell gets delayed till early feb.  ..