Model output discussion - here comes the beast!

[Paul_1978]

Notice the low pressure system well developed by T+207 (9pm next Thurs) which moves south over the UK resulting in the second image by T+234 (midnight Fri into Sat).

SURELY that's a significant snowmaker?

[karyo]

1 minute ago, danm said:

No one is becoming enemy number 1, but you are posting inaccurate information. The first pulse of cold air is still modelled on the GFS6z to come in on Monday as previously forecast, it is not delayed to Wednesday. What the 6z is showing is a second pulse of very cold air coming in again on Wednesday. So where is the delay to Wednesday?

No inaccurate info is posted. Yesterday the deep cold (sub -10) was coming Sunday and continuing uninterrupted for days. Now it is shown to come on Monday  briefly before it gets moderated by the shortwave (so less last -10) and then the next pulse is coming Wednesday. So there is a delay and a discontinuity in the deep cold which is still many days away.

[markw2680]

10 minutes ago, Neilsouth said:

Exactly what I've been saying but it either gets deleted or pushed aside!

Deep cold uppers were due Saturday, then Sunday, then Monday, next Tuesday now Wednesday! In fact I'll add it to my signature

Tbh I thought the same and have done for a week or so as every day there is yet another delay but as I’m just an amateur I find it better to just keep quite lol, sure it’s getting cold we no that but the really deep stuff is constantly getting a slight delay I don’t care if some don’t agree but I can see it for myself. Anyway let’s get it here and see where it goes

[seb]

2 minutes ago, karyo said:

No inaccurate info is posted. Yesterday the deep cold (sub -10) was coming Sunday and continuing uninterrupted for days. Now it is shown to come on Monday  briefly before it gets moderated by the shortwave (so less last -10) and then the next pulse is coming Wednesday. So there is a delay and a discontinuity in the deep cold which is still many days away.

It wasn't ever shown across the board to come on Sunday. Overall consensus was always Sunday into Monday.

As for the shortwave - that's perfect as it means snow rather than just cold.

[Frosty.]

The Gfs 6z shows probably the best cold spell since 2010..all coldies should be thrilled with the latest output which continues to produce dream runs galore..Epic spell on the way!

[bluearmy]

Just now, weirpig said:

Can anyone tell me when the clusters for the ecm come out please?.  or if they already have  Ta

They are out and show six clusters in the period to day 7. All below 23% so analysing them pretty pointless and adds to the uncertainly about just how the cold will come in and how cold/convective/unstable it will actually be

At day 8, the op cluster becomes the largest at 40%. The other two clusters are closer to what we have been seeing over the past few days. 

The upshot of this is we have no strong guidance on the easterly and the trend on  the transition to greeny ridge (omega block as ed posted earlier so succinctly) looks a bit 50/50 on whether it stays all snowy cold or we get a less cold day or so. 

[danm]

5 minutes ago, karyo said:

No inaccurate info is posted. Yesterday the deep cold (sub -10) was coming Sunday and continuing uninterrupted for days. Now it is shown to come on Monday  briefly before it gets moderated by the shortwave (so less last -10) and then the next pulse is coming Wednesday. So there is a delay and a discontinuity in the deep cold which is still many days away.

No, over countless runs, the first pulse of sub -10c uppers has been forecast to arrive between Sunday and Monday. Different runs have played around with the arrival of this air, some showing Sunday, others Monday. The 6z still shows Monday. So there is no delay. Certainly not until Wednesday. Yes on the 6z the uppers moderate temporarily on Tuesday before an even colder wave of 850's come in, but even in that "less cold" interlude on Tuesday, it will still be cold enough for snow. So what is the problem?

Edited February 21, 2018 by danm

[Rocheydub]

5 minutes ago, karyo said:

No inaccurate info is posted. Yesterday the deep cold (sub -10) was coming Sunday and continuing uninterrupted for days. Now it is shown to come on Monday  briefly before it gets moderated by the shortwave (so less last -10) and then the next pulse is coming Wednesday. So there is a delay and a discontinuity in the deep cold which is still many days away.

Have to agree with this. It’s not moaning, it’s factual! If anything, it’s impatience I feel, but I can’t speak for Karyo either. It’s not moaning, it’s a comment on what the models have shown. It niggles at my mind too.

that said, it’s the most fascinating NWP I can remember since 2010, and it’s wholly likely it will be as memorable an event! 

Edited February 21, 2018 by Rocheydub

[captaincroc]

2 minutes ago, karyo said:

No inaccurate info is posted. Yesterday the deep cold (sub -10) was coming Sunday and continuing uninterrupted for days. Now it is shown to come on Monday  briefly before it gets moderated by the shortwave (so less last -10) and then the next pulse is coming Wednesday. So there is a delay and a discontinuity in the deep cold which is still many days away.

I think we all may have been tarred by the -18c uppers that some models have predicted.  Yes both are you are right in your arguments but the 'warming' up of the air is minimal in the sense it will still snow and still be sub zero. I personally would rather unstable air and a slight rise in upper temps and get bands of snow instead.

[DIS1970]

Five days is bad enough, but anything after ten days really is complete fantasy. It's just another translation of the info.

[TEITS]

11 minutes ago, Neilsouth said:

Exactly what I've been saying but it either gets deleted or pushed aside!

Deep cold uppers were due Saturday, then Sunday, then Monday, next Tuesday now Wednesday! In fact I'll add it to my signature

Sorry but posts like this are getting on my nerves.

I said about 3 or 4 days ago that Mon-Tues was the likely days the cold air will arrive. Unless my eyes are decieving me then the 06Z is showing between -11 to -13C on Monday for the E.

We are bound to see slight variations i.e some runs being 1 to 3 C colder, cold air arriving 24hrs earlier or later. However I have hardly seen any runs that bring the cold air in on Saturday?

I cannot believe some of the negative comments in this thread recently. Synoptically this in my opinion is a once in 10 yr event. Maybe even 1 in 20yr event if you look at how rare E,lys have been since the 1980s.

[frosty ground]

3 minutes ago, karyo said:

No inaccurate info is posted. Yesterday the deep cold (sub -10) was coming Sunday and continuing uninterrupted for days. Now it is shown to come on Monday  briefly before it gets moderated by the shortwave (so less last -10) and then the next pulse is coming Wednesday. So there is a delay and a discontinuity in the deep cold which is still many days away.

Max temps Sunday


I think the cold is here.

You are hung up on 850's, you are also forgetting the GFS was at one point the quickest solution and that the cold air was always arriving Sunday/Monday as a cross model mean. 

The Temps fluctuating between runs are down to features being picked up, features that also bring moisture.   

[ICE COLD]

So let's just run through this on the GFS 6z. 

The cold is starting to hit the east Sunday night/mon morning -

BY mon afternoon it's well and truly in . IT WILL BE FREEZING ?. 

And this is what we have from Tuesday until at least Sunday -

That is a very cold and snowy 7 day cold spell . If people think it ant then give up chasing cold spells . Because it's hard to get a better one than this ??

[Weathizard]

Why does anyone who has a different opinion or worries get shot down as a moaner or have patronising posts directed at them?  

 

To give my point some credence, for example we had this on predicted Sunday at day 7... here's what's actually predicted now for the same day

Edited February 21, 2018 by Weathizard

[captaincroc]

1 minute ago, TEITS said:

Sorry but posts like this are getting on my nerves.

I said about 3 or 4 days ago that Mon-Tues was the likely days the cold air will arrive. Unless my eyes are decieving me then the 06Z is showing between -11 to -13C on Monday for the E.

We are bound to see slight variations i.e some runs being 1 to 3 C colder, cold air arriving 24hrs earlier or later. However I have hardly seen any runs that bring the cold air in on Saturday?

I cannot believe some of the negative comments in this thread recently. Synoptically this in my opinion is a once in 10 yr event. Maybe even 1 in 20yr event if you look at how rare E,lys have been since the 1980s.

You're right TEITS. It has NEVER been modelled to come in Saturday AND the super cold was never meant to come in till a few days later. Yeah there have been shifts forward and backwards slightly in time but nothing to write home about. Like I said previously we have been spoilt by the off-the-wall charts of some days previous. If we had been given even the worse of today's charts a few weeks ago we would be like giddy kids.

 

[nick sussex]

Right my final post until later.

Even if the 850 temps moderate for a time the flow is still coming off the continent.

This means dew points will remain well below freezing . Of course the increase in solar energy will effect snow melt but snow remains if it’s deep or in the shade .

For example if your air temp is + 2 with a dew point of 0 you will lose more snow than say if your air temp is +4 with a dew point of say -4.

Its amazing how long snow can last with low dew points.

 

 

 

[ptow]

15 minutes ago, terrier said:

If anyone can complain at that gfs06z then they really need a new hobby. Cold to very cold conditions with snowfall for many. Great run 

Yes, today it is cold to very cold, yesterday it was holy grail and being compared with 1991/87/96 by many experienced members. Now it is not. Hence the dissappointment. It not rocket science

[Southender]

3 minutes ago, bluearmy said:

They are out and show six clusters in the period to day 7. All below 23% so analysing them pretty pointless and adds to the uncertainly about just how the cold will come in and how cold/convective/unstable it will actually be

At day 8, the op cluster becomes the largest at 40%. The other two clusters are closer to what we have been seeing over the past few days. 

The upshot of this is we have no strong guidance on the easterly and the trend on  the transition to greeny ridge (omega block as ed posted earlier so succinctly) looks a bit 50/50 on whether it stays all snowy cold or we get a less cold day or so. 

Bolded the important bit. For those stressing, read that last sentence over and over. Worst case we get a brief window of less cold air, before going back in the freezer. Enough time to dig out and re-stock with supplies? 

[Derecho]

1 minute ago, TEITS said:

Sorry but posts like this are getting on my nerves.

I said about 3 or 4 days ago that Mon-Tues was the likely days the cold air will arrive. Unless my eyes are decieving me then the 06Z is showing between -11 to -13C on Monday for the E.

We are bound to see slight variations i.e some runs being 1 to 3 C colder, cold air arriving 24hrs earlier or later. However I have hardly seen any runs that bring the cold air in on Saturday?

I cannot believe some of the negative comments in this thread recently. Synoptically this in my opinion is a once in 10 yr event. Maybe even 1 in 20yr event if you look at how rare E,lys have been since the 1980s.

Spot on, the only difference today is that the easterly flow is slacker, meaning the really cold air is delayed till Monday morning. The high is further north so that promotes instability, the less cold uppers on Tuesday itself may be a catalyst for extra instability.

Then on wednesday we get the really bitter cold air building up over Scandi and a very potent polar low forming. We would get so much snow from that. The slower nature of the easterly flow means that the cold airmass is likely to stay over us for longer or even get stuck.

So waiting an extra 12 hours for the inevitable for some extra rewards later on? Sounds good to me.

ECM is a little concerning but hopefully its gone off on one. I find no reason to moan about the 06z though. Yes it would be good to get the cold uppers in a bit earlier but it's still looking fantastic.

[Rocheydub]

2 minutes ago, Weathizard said:

Why does anyone who has a different option or worries get shot down as a moaner or have patronising posts directed at them?  

 

To give my point some credence, for example we had this on predicted Sunday at day 7... here's what's actually predicted now for the same day

Exhibit A m’lawd!

Theres the proof it has been delayed. Again, I’m not moaning, just fact!

[seb]

2 minutes ago, Weathizard said:

Why does anyone who has a different option or worries get shot down as a moaner or have patronising posts directed at them?  

 

To give my point some credence, for example we had this on predicted Sunday at day 7... here's what's actually predicted now for the same day

And other models on the 18th showed what the GFS is showing now, whereas they have no sped up the arrival of the very cold air.

On balance there is no delay.

[frosty ground]

3 minutes ago, Weathizard said:

Why does anyone who has a different opinion or worries get shot down as a moaner or have patronising posts directed at them?  

 

To give my point some credence, for example we had this on predicted Sunday at day 7... here's what's actually predicted now for the same day

And where did that run at day 7 sit within the ensembles and within the other model suites?

[karyo]

3 minutes ago, Weathizard said:

Why does anyone who has a different opinion or worries get shot down as a moaner or have patronising posts directed at them?  

 

To give my point some credence, for example we had this on predicted Sunday at day 7... here's what's actually predicted now for the same day

Thank you for providing the evidence! 

[frosty ground]

4 minutes ago, frosty ground said:

And where did that run at day 7 sit within the ensembles and within the other model suites?

What about the 06z run

 
or the 12z run?

or the 18z run.


or the 0z ECM



Saying its been delayed over and over again like some religious mantra and providing once Operation run as proof does not cut the mustard I am afraid.

It leads me to believe that some experienced members still do not understand the basics of model watching! 

Edited February 21, 2018 by frosty ground

[bluearmy]

1 minute ago, Southender said:

Bolded the important bit. For those stressing, read that last sentence over and over. Worst case we get a brief window of less cold air, before going back in the freezer. Enough time to dig out and re-stock with supplies? 

Indeed but bear in mind that the second round is probably less deeply cold continental air and therefore potentially less likely to be no issue with melt. As I have said all along, I cannot stress enough how important I think it is to get decent snowcover from the first round in order to sustain the surface cold such that the second round is less knife edge with what falls from the sky settling and avoiding a slushfest!