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Model output discussion - here comes the beast!


Message added by Paul

Please only post model discussion in this thread 

For more general chat and banter, or moans and ramps loosely around the models, please head to the banter thread:
https://www.netweather.tv/forum/topic/86721-model-moans-ramps-and-banter/

For general weather chat including about the snow/cold chances around the country, please go to the regional threads:
https://www.netweather.tv/forum/forum/142-regional-discussions/

We also have a special post SSW cold spell discussion open here:
https://www.netweather.tv/forum/topic/89358-ssw-related-cold-spell-will-it-wont-it/

Thank you!

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1 minute ago, blizzard81 said:

I bet they didn't mention the snow threat for the north for next Tuesday? 

The "south" event also seems to hit large parts of the north. Not sure why, for example, the 18z was posted as showing heavy snow in the south when it's all of England and Wales before moving up into S Scotland.

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Early guidance forewarning of next weeks weather was issued earlier on, and this has been further enhanced with extended outlooks in bulletins. AFAIK (comms not being my area) public agencies and majo

Come on those looking for the breadown before the major cold and snow has begun You will be very lucky if that is the correct word to see this in ANY winter in the rest of your lives I would sugg

Microscale detail absorbing an awful lot of attention on here, when in reality it is a waste of emotion. The macroscale pattern is now fixed - it will not change significantly now for the start of nex

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4 minutes ago, easton888 said:

Will the uppers be cold enough to keep any snow that falls from the 27th on the ground till the potential blizzard on March 1st? Asking for a friend.

Need low dew points, and they would be very low in a continental flow.

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2 minutes ago, Robbie Garrett said:

I am trying to re-collect a similar situation in April 2012. The low that came up from France and dumped 48 hours rainfall on the South.  I think that was it?

I don't remember that one but in a cold set-up, different considerations apply especially given a strong block to our NE

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7 minutes ago, blizzard81 said:

I bet they didn't mention the snow threat for the north for next Tuesday? 

They showed a historic event on the charts though. Snow covering 70% of the county I also believe it's the ECM output it goes off so a good signal as to what that is showing.

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As always, I would be inclined to take a half way house between the ECM and GFS for the system at the end of next week. It is far too far ahead to have any confidence in though.

Edited by MattStoke
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To my eye there are still a couple of GFS 18z ensembles which quickly take the high pressure to greenland and rapidly cut off the easterly flow from the deep cold pool. I think related to @bluearmy's shortwave point earlier. So, hopefully from a coldie perspective that cluster goes from 10% to 0% tomorrow. They are still cold though.

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Looking at the 18z OP, I calculated the CET estimate for the first 10 days of March and it came to an amazing -1.3C :rofl: and thats with the milder weather at the end! Some crazy minimums over the snow fields.

Anyhow just had a look at the ensembles and most of them show a battle with milder air from the Azores low trying to make its way through. However the majority support the OP in keeping us in the cold air under a slack regime.... so maybe that CET estimate for the first 10 days of March may not be too unrealistic....

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Just now, Quicksilver1989 said:

Looking at the 18z OP, I calculated the CET estimate for the first 10 days of March and it came to an amazing -1.3C :rofl: and thats with the milder weather at the end! Some crazy minimums over the snow fields.

Anyhow just had a look at the ensembles and most of them show a battle with milder air from the Azores low trying to make its way through. However the majority support the OP in keeping us in the cold air under a slack regime.... so maybe that CET estimate for the first 10 days of March may not be too unrealistic....

What do you think of the couple of ensembles which drag high pressure quickly to Greenland? Noise? Or still potentially a signal to be aware of?

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3 minutes ago, jethro said:

An ode....

The charts they have shown from long, long away

That the SSW would hold immense sway

Some urged caution, some said doubt

They said 'la la la, we're not listening, our faith is devout'.

Their ideas they have shown with chart after chart

Their belief, their knowledge, it came from the heart

I always reckon, credit where credit's due

So take it from me, an enormous 'thank you'

I can't read the charts, they're blob after blob

I rely on you all doing a fantastic job

So the beasterly's coming, inching closer each day

The temperature's dropping, the rain's gone away

What wonders await? Well no one can say

But I do know one thing, I'm polishing my sleigh

Pondering starts, what can it be

Surely it means '91, maybe '63?

With charts such as these, manna from heaven

Sure can mean just one thing, another'47

The cold, it's a coming, we all know that

Wrap up warm folks and remember your hat

Will we get an inversion or plenty of snow?

Or that mythical beast, a channel low?

Our dreams they've been busted many times in the past

The cold came and it went, it just didn't last

This time it is different, our boffins of gold

Foresaw and predicted and then we were told

Look up to the sky, high over the cloud

Stratosphere it said 'yes' and it said it loud

So when it comes, go out to play

Sure check the charts but then step away

Synoptics like these, well we know that they're rare

Ski, skate, slip and slide, sledge without care

Dear Mods I may be a tad off topic

But charts such as these, by god, they're epic

Please forgive me I beg, the rule, I don't mock it

But such weather porn made this lass poetic

Epic poetry to an epic development.........

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16 minutes ago, NickR said:

The "south" event also seems to hit large parts of the north. Not sure why, for example, the 18z was posted as showing heavy snow in the south when it's all of England and Wales before moving up into S Scotland.

Only organised snow event that looks like it's firming up ATM is the trough moving from NE to SW on Tuesday. Later on in the week, pin a tail on the donkey. But a very large tail.

Mind you, Eastern areas have an all week snow event anyway!

Edited by Man With Beard
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7 minutes ago, oasis said:

What do you think of the couple of ensembles which drag high pressure quickly to Greenland? Noise? Or still potentially a signal to be aware of?

I think its just noise, I can only count 3 runs that pursue a scenario where pressure is higher to a significant extent in the north, the cold pool over Scandi still hits the UK albeit more the south.

There is always going to be a bit of noise, in fact 19 ensemble members show the Scandi cold pool having a clean hit on the UK so an unusually low level of noise.

Many GFS runs develop a small low and send it to Greenland but it gets gobbled up by the high pressure anyway :)

Edited by Quicksilver1989
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@jethro that was great you’re like a tight isobar albeit more refined ;-) 

Model output consensus growing that this cold will establish, and acceleration of significant snow potential if anything next week the first of March itself looks epically cold and snowy. Spring? Pft dead like sidney. :shok:

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2 minutes ago, Quicksilver1989 said:

I think its just noise, I can only count 3 runs that pursue a scenario where pressure is higher to a significant extent in the north, the cold pool over Scandi still hits the UK albeit more the south.

There is always going to be a bit of noise, in fact 19 ensemble members show the Scandi cold pool having a clean hit on the UK so an unusually low level of noise.

Some GFS runs develop a small low and send it to Greenland but that will get gobbled up by the high pressure anyway :)

Thanks. Yeah, I guess with ECM and UKMO on board as well you'd expect the overwhelming majority to be correct. In a more zonal situation 19/22 would normally prevail.. And as you point out, even on those runs where a northerly sets up you still get some of an easterly in the south. 

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15 minutes ago, oasis said:

To my eye there are still a couple of GFS 18z ensembles which quickly take the high pressure to greenland and rapidly cut off the easterly flow from the deep cold pool. I think related to @bluearmy's shortwave point earlier. So, hopefully from a coldie perspective that cluster goes from 10% to 0% tomorrow. They are still cold though.

I’ve just made this point on TWO. Yes I count 4 of the GEFS which show high pressure for much of Northern Britain midday Tuesday with relatively disappointing cold air advection away from the far south east. P17 is the worst. 

In my view if there is a sudden last minute backtrack then it will be something akin to this scenario, but low risk in my view, given all the other output and the vast majority of the GEFS. 

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Just now, CloudyBay said:

I find it very interesting that the TV weather forecasts still seem to be gently suggesting that it will be "turning a bit chillier" with "the risk of some wintry showers" and so on.

Based on the model outputs we are seeing, and the dwindling chance that the weather won't be highly disruptive next week, I'm puzzled as to why this is the case.  

Could anyone shed some light on the decision making processes used to interpret these models into mainstream forecasts?  At what sort of threshold of probability would much starker weather warnings be issued in circumstances such as these?  

I would be making the assumption when the charts show it at T24 ot T48 , when its pretty much a dead cert. Last thing you want is panic and the emptying of supermarkets

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We are still removing posts.A lot are just general chit chit about the BBC forecasts,past snow events and one liners,none of which belong here.

It's late and the team have been working overtime-voluntary i may add-to keep some semblance of order in the thread.

Please keep to model discussions in here and use the cold spell or ramp thread for general chat.

Thanks all.

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3 minutes ago, sorepaw1 said:

My job consists of driving urgent life saving medical supplies for the NHS. 

Ive had no warning of snow from any authority .

I've been looking at the models including the 18z. I have my own interpretation on what I see

l live in North East Yorkshire .

If I'm honest I maybe doing the BBC some mis justice but I'm disappointed about the lack of warning.

If it wasn't for you guys for your exceptional service and forecasts and model analysis. 

I'd be one of millions of motorists to get caught out. 

As I  say this isn't a moan about the weather or the models it' a valid model topic discussion that potentially hundreds of people will read and have the same opinion and a valid concern. 

Thanks guys for all your hard work and good model discussion. 

As much as I am enjoying the excitement of watching the models remain so consistent as D-day approaches, and as much as I feel smugly prepared (new waterproof trousers and new sledges for playing/carrying shopping), I am worried too that so many people are not prepared enough for worst case scenarios. I hope you and you colleagues continue to do your work safely wherever possible - be safe folks!

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18 minutes ago, Catacol said:

Nick is right - but I'm not sure we have "normal" conditions here. I have a feeling the low maybe pulled north into the easterly flow more readily than might be the case at other times. But we shall see. All conjecture and guesswork at 7 days' range, and we dont have a picture of frontal systems attached yet. Model consistency is remarkable though.

Agree, it’s an unusual setup from the west to east norm, 18z low moving up across France and then even NW into UK later next week is related to the movement and position of the 500mb low (in blue on chart below) moving SW across the UK. The surface low will tend to follow the 500mb contour, so when the upper low positions SW of UK the surface low on eastern flank is drawn N then NW.

753AF0E6-9971-4D13-8330-0D084BBB8915.thumb.gif.9100afd4cf0dde33cdfc244f8a15635a.gif

As the 12z GEFS stamps show, quite a lot of scatter to where the upper low ends up by start of next Friday. 

6F55EDB3-CE10-469D-8797-50C74176B50A.thumb.png.8318cdf1c87a17b51aca4a028af9691f.png

12z EC moves the upper low (blue) SW further south over near continent and so surface lows can’t track as far north toward UK

6C0D879A-CC14-41A1-8DA8-DCBF65D25563.thumb.png.f329a7874c63a8c1a13e04f2df96bb36.png

 

 

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