Model output discussion - Jan 3rd onwards

[Anthony Burden]

30 minutes ago, Nick F said:

Agree, it does appear the models are struggling with the fast flow out of the Pacific into N America - which is characterised by short-wave lengths over USA with numerous shortwaves moving east in split southern and northern streams which merge off the east coast. How these shortwaves interact when they arrive towards the Atlantic against a big block maybe causing some model uncertainty over the NW Atlantic sector. Add to this what appears to be too much volatility over the arctic between models and run-to-run of each model, hard to call any model correct past days 5-6.

Yes Nick totaly agree 144 hrs looks correct.

 

[Doctor96]

when do UKMo and ECM  come out with there next  model forecast 

sorry to ask this question 

[bluearmy]

Just now, Doctor96 said:

when do UKMo and ECM  come out with there next  model forecast 

sorry to ask this question 

Ukmo 4pm 

ecm between 6 and 7 (approx 6:20 is T120 and 6:30 is T144) 

[TSNWK]

Just now, Doctor96 said:

when do UKMo and ECM  come out with there next  model forecast 

sorry to ask this question 

Morning 16:00 and 04:00 for UK

ECM rolls out between 6:15 7:00 am & PM

[SLEETY]

That's two runs from gfs which are consistent, also it latest run has the newest data 6 hours ahead of the latest Ecm, UKMO runs, which means it has a better chance of being correct, especially as it hasn't moved to the other models solutions, despite the newer data. 

Fingers crossed anyway! 

Edited January 3, 2021 by SLEETY

[Methuselah]

Oh, looky here... a potential snow fest , on or around Day 10! Well, blow me down with a feather, if Day 10 hasn't been 'nailed' ever since 2003!

    

But, do I suspect that the SSW will deliver? Well, yes I do... But it'll do it when it's good and ready!

Edited January 3, 2021 by General Cluster

[Uncertainty]

Regardless of the short term conundrum the improvement in the day 10-15 EPS is significant as @mulzyhas highlighted. The long fetch SW feed runs are now in the minority and there is a bit more blocking showing up to our NW and to an extent N.

Here’s last night’s clusters at day 15 with 40% going for a long fetch SWer

The 0z for the same timestamp 

The signal for NW heights now stronger.

Cluster 2 looks most like cluster one from the 12z but it’s further south with the low anomaly and the GH heights look more influential. Cluster 3 looks excellent with w/ a Euro low / Gricelandic high similar to recently and the 1st cluster shows a general area of heights to the N but probably non-descript weather for us at the surface.

I continue to see a short milder spell day 8-9 to day 12-14 but evidence is building that it looks brief. No need to berate the models if this shows up as the signal has been there for about a week. If however we end up with a UK high in the holding pattern then it could well feel cold at the surface throughout...

GFS on its own in the mid term unfortunately but we’ll give it till tonight to make the call. If it was the one going flatter on its own we’d be discounting it. Hard to bet against the Euros here unfortunately

Would love to be wrong!

Edited January 3, 2021 by Uncertainy

[Vikos]

 

 

 

Edited January 3, 2021 by Vikos

[Tim Bland]

A colder set of ensembles. This time yesterday the mean (white line) was just above the average (white line) so they are heading in the right direction to avoid a milder spell mid month... 

[Speedbird]

1 minute ago, Tim Bland said:

A colder set of ensembles. This time yesterday the mean (white line) was just above the average (white line) so they are heading in the right direction to avoid a milder spell mid month... 

Isn't the red line average ?

[Snowy L]

GFS has acknowledged the fact a reversal of zonal winds has happened and the ECM + UKMO haven't

[Cassivellaunus]

I think the models are currently beginning to take in to account the effects of the SSW event and it's clear we are getting massive swings between runs.

I like to imagine a pendulum on an old clock, it's currently just at its highest swinging point due to the crazy effects of the SSW and it will continue to flip from extremes over the next few days and will hone it's way down to a solution in between, becoming less extreme as it goes.

We will then start to see more consistency and agreement in the models in around a week to two weeks. I would suggest no one knows the answer at the moment to if it will go to the epic charts of GFS-p last night or the more mild option shown by UKMO this morning.

At an educated guess I would suggest that neither extreme options are likely and there is more chance of favouring an overall colder theme with some more benign milder intrusions.

This is based on the fact that SSW's usually increase our chances of cold but does not guarantee it, the overall lack of amplification in the jet on our side of the globe and the blocking over the Atlantic. I believe we will remain on the boundary of any colder weather coming from the north and east and the more milder high pressure over the Atlantic. This would give us cold chances that remain marginal at times and at other times more favourable like we are about the witness this week.

I've seen nothing to suggest a return to westerly Atlantic driven lows we all dread but as the UKMO chart has shown we could end up with the blocking high sitting to far over us as it drops further east and south a bit which would introduce slightly milder but nice and calm weather.

I do feel we can all get caught up in seeing individual charts either mild or extreme cold and convince our selves this will be the outcome.

I would like to point out I am not experienced like some people on the site but having a go at providing a balanced view on the current situation, feel free to point out if I have got anything wrong.

Edited January 3, 2021 by Cassivellaunus

[wellington boot]

16 minutes ago, Tim Bland said:

Comparing to the total precip chart it looks like it’s picking out the downs and chilterns  so perhaps mainly sleet or rain below 150m? Could fall lower if intensity increases (evap coming)...up until Tuesday morning at least. Tuesday looks the best bet for the south / east as uppers / DPs should be low enough for lowland snow 

I'm at 150m! Which way will it go?!?!

I've backed this being snowier than generally forecast for a while, at least inland and over higher parts of the undulating SE - been here before and we have had significant snow in similar supposedly marginal situations here. On the other hand, a marginal ENE'rly in early January is unusual, and a quick rise in temps and spitting rain during yesterday's warm sector made me nervous. Was also concerned last night how much rain the short termers were showing, even if I stand by my forecast...

Is it possible to rank the short term models by resolution and by verification? Have a sense of some biases built up loosely over years, but don't really know how they compare in this regard.

[Vikos]

Just now, Snowy L said:

GFS has acknowledged the fact a reversal of zonal winds has happened and the ECM + UKMO haven't

Sorry, but that is nonsense. ECM has better strat. resolution than all other models.

[feb1991blizzard]

59 minutes ago, davehsug said:

That's strange, because Nick Sussex used to regularly post discussions from US weather pros, which mostly consisted of ignoring the GFS and going with either ECM UKMO or a blend of the 2.

Indeed, and the once they even admitted that if they had just ignored the GFS from the start and used the ECM, their forecasting re a hurricane would have given a better indication of track, makes sense given the GFS propensity to over deepen lows, there is just one thing to cling to this time, its the GFS with the more amplified scenario, so i would give it credence if ECM op was outlier against its suite, but the fact that the eps are rock solid on a warm up means even at a push, i cant really, that said, i fully expect the SSW to start making an impact on both suites with some frigid runs at the end showing, within the next week or so - warm up lasting one week i think.

Edited January 3, 2021 by feb1991blizzard

[wellington boot]

24 minutes ago, bluearmy said:

Just to correct a myth that seems to have been created this morning without correction - the pre Xmas drop of the trough was not mis modelled by Ukmo. By the time we got to day 6 all the models were on the same page. 
 

ecm didn’t agree with gfs between days 8/10 on many runs. I recall below day 8 it was fully on board .....

Agree with this. I actually thought the UKMO nailed it a couple of times and got little credit, after being written off when it wasn't showing what people wanted.

[Snowy L]

3 minutes ago, Vikos said:

Sorry, but that is nonsense. ECM has better strat. resolution than all other models.

Let me know when it starts acting like it instead of flattening and going AO+

[Dancerwithwings]

6 minutes ago, Speedbird said:

Isn't the red line average ?

Red is the 1981 to 2010 mean, white is the mean with all 30 members on this particular run

[Battleground Snow]

2 minutes ago, wellington boot said:

Agree with this. I actually thought the UKMO nailed it a couple of times and got little credit, after being written off when it wasn't showing what people wanted.

Agree - they both did drop the trough at day 6, but I think what people remember is the more pronounced ridging on the GFS into Greenland led to a slightly colder outcome when it actually happened. The fine margins around Greenland at 96 coming up will drastically affect the downstream in the later frames. The 12z should give more clarity in that area, or at least we hope!

[bluearmy]

11 minutes ago, Vikos said:

Sorry, but that is nonsense. ECM has better strat. resolution than all other models.

Indeed but that’s also true in the trop and it’s not always right down here

8 minutes ago, Snowy L said:

Let me know when it starts acting like it instead of flattening and going AO+

It’s still solidly negative .......... gfs more negative 

Edited January 3, 2021 by bluearmy

[Vikos]

5 minutes ago, Snowy L said:

Let me know when it starts acting like it instead of flattening and going AO+

Well what to say... wait and see... by now it looks like a minor scratch, not a flesh wound.

[bluearmy]

1 minute ago, Vikos said:

Well what to say... wait and see... by now it looks like a minor scratch, not a flesh wound.

Reverse flow levels out before dropping again - as per all the forecasts over the past week .....

[Frosty.]

Just too prove how much I love cold, honestly guys, you will never, in your wildest dreams know how much I love cold..believe me..I’m the original FROSTY for gawd sake!!!!!..anyhoo, the GEFS 6z has some wintry potential at the 10 day range..unlike some other, frankly crap output today!

Edited January 3, 2021 by Jon Snow

[SnowSalah]

If you think UKMO/ECM leads the way, “like” this...

if you think GFS leads the way, “thanks” this...

Somewhere in between the two? “Happy new year” this...

 

im not sure polls are allowed so apologies if they’re not!!! But it would nice to see people’s thoughts on going forward with out the usual sniping and tearing down at others suggestion..

 

In my opinion the models have not got a clue what’s going on and the volatility is only like to increase!! before it decreases!! around T120+   all part of the fun tho isn’t it?? Oh and happy new year!! 

[Updated_Weather]

Just to try and calm some nerves.

a MetO senior operational meteorologist has said weather models WILL struggle with SSW over the next few weeks.

People taking what happens 10+ or in FI in this case 5+ days if that! 

Take it with a pinch of salt.