Model output discussion - the beast arrives

[SLEETY]

2 minutes ago, Alderc said:

Exactly, whether a cold or hot block either can be punted out in a flash. In continental areas yes it’s more difficult to move the seasonal areas of high pressure but not in the uk. Wouldn’t be surprised to see the breakdown accelerated into Thursday and push even further north and west as that is clearly the trend.

But the trend could be all wrong,I m still convinced it will all be pushed back S maybe in 48hrs the model will resolve the mess they are in,currently,

[Richard Waugh]

5 minutes ago, Alderc said:

Exactly, whether a cold or hot block either can be punted out in a flash. In continental areas yes it’s more difficult to move the seasonal areas of high pressure but not in the uk. Wouldn’t be surprised to see the breakdown accelerated into Thursday and push even further north and west as that is clearly the trend.

Errr no that is very clearly not the trend at all have you actually looked at anything other than a few GFS runs? 

[Banbury]

19 minutes ago, Alderc said:

Exactly, whether a cold or hot block either can be punted out in a flash. In continental areas yes it’s more difficult to move the seasonal areas of high pressure but not in the uk. Wouldn’t be surprised to see the breakdown accelerated into Thursday and push even further north and west as that is clearly the trend.

Have you looked at the mean

[jayb1989]

27 minutes ago, frosty ground said:

If you think the GFS has it naild okay.... but most reasonable people don't think this is a done deal either way. That's probably the most reasonable positon this morning 

 It’s clear over the last two days the models have trended to push the low further north and mild air gets into the south. This is something shown in pretty much all outputs not just the GFS.

Edited February 26, 2018 by Polar Maritime
To move discussion on..

[MattStoke]

People predicting what happens at the end of the week solely on the GFS output. The model that always performs worst in these situations. Doesn't necessarily mean it will be wrong this time but to base a forecast soley on it is bizarre, and to state that the Met Office will re-word their forecasts based on the GFS output alone is a ridiculous thing to say.

Edited February 26, 2018 by MattStoke

[Mr Frost]

Morning all!

We have made it! This is the week the Beast from the East finally arrives after what seems like the longest build up in history! 

Loving the UKMO (charts below from 48 hours to 144) this morning - heavy snow showers will be moving in today through places such as Norwich and Newcastle Upon Tyne then spreading through large parts of the East from North to South! We will see the first significant accumulations settling later on today. 

The frequent and heavy snow showers just keep going tomorow - more widespread with the Lothian and Borders in for a hammering in Scotland, Sheffield and Peterborough to name a very few! 

Wednesday more of Scotland, England, Northern Ireland, Wales and Ireland join in the snow fun with a special mention for Edinburgh and Aberdeen as they will be taking a proper pasting! 

Thursday and Friday look big days for even more significant prolonged snowfall to occur - London, Cardiff, Exeter or Birmingham with a big chance of this but a special mention for Dublin and Belfast as they could be in for a big blizzard lasting hours!  

The cold air keeps going in the North - Scotland in the Freezer until the end of this run! 

What a week this is going to for loads of us! It truly is incredible - wonderful time to be a lover of wintry weather! Live every moment of it! 

Enjoy everyone! 

Edited February 26, 2018 by Mr Frost

[Troubleatmill]

28 minutes ago, Alderc said:

Exactly, whether a cold or hot block either can be punted out in a flash. In continental areas yes it’s more difficult to move the seasonal areas of high pressure but not in the uk. Wouldn’t be surprised to see the breakdown accelerated into Thursday and push even further north and west as that is clearly the trend.

Not in a flash though, hence why uppers are shown to be less cold but all snow event for most. To coin phrase, think of cold air as treacle, run warm water over it and it doesnt just wash off instantly

[Tim Bland]

GEM is pick of the bunch for me this morning, not far off the UKMO outcome. Low on Fri elongates and spills east loosing intensity. Still plenty of heavy snow and more snow chances through the weekend. 

 

[Sky Full]

5 hours ago, Tracy Flick said:

TLDR of my take:  AI uses purely historic weather observations, whereas traditional NWP uses purely Newton's Laws of physics, with approximations. 

I'm sure someone at the MetO is playing with AI but they surely aren't using it yet.

 

Far and away the best explanation I have ever read on the way our favourite weather models calculate the predictions which leave us elated or deflated depending on the outcomes.  Very interesting reading especially the issues surrounding the cost of extra computing power v the value of improved equations.  Thank you.

[bluearmy]

The gfs is a fine model. One of the top three out there. But it isn’t known as the ‘goofus’ amongst the pros for nothing! 

None of the ops should be used for any detail past day 6/7. That when ens come in . It’s no surprise that the model which runs to day 6 is considered the most stable on here. And ecm op is judged to jump around a bit because we only see one frame every 24 hours. 

we’ve been doing this for more than a decade now ...... can we remember so many occasions when gfs has been so much better than ec (and ukmo) within day 6.  

Yes there has been but really not many considering the sample size.

Neither model has the end of the week tied down just yet. Should be there by tomorrow morning.

[Ali1977]

9 minutes ago, Tim Bland said:

GEM is pick of the bunch for me this morning, not far off the UKMO outcome. Low on Fri elongates and spills east loosing intensity. Still plenty of heavy snow and more snow chances through the weekend. 

 

This looks more in-line with the forecasts from the pros, the whole of the U.K. at rush rather than the SW

[Derecho]

Still no clearer as to Friday's fate this morning but perhaps a hint of more trough disruption on the GFS. A few more colder runs in there so this one clearly isn't over yet. Definitely not enough to say the milder GFS solutions will win out.... Anyway here is an updated graph showing the state of play for Saturday.



Not a bad morning of model output but its all very borderline stuff! If P14 transpired in the GFS ensembles a lot of record low minima would be set for March early next week.

[Summer Sun]

UKMO extended keeps the snow going into Monday

 

[nick sussex]

Still no resolution to the low this morning .

Don’t expect any answers to at least tonight.

In the medium term the ECM has a very slack Atlantic pattern , it looks quite messy but interesting with the PV shredded.

 

[Summer Sun]

The ECM 00z London mean again shows the cold air peaking around Thursday with -15 850's we then see a rapid rise to around -1 in just 24hrs after this the mean stays between -1 and -4

Northern England ens shows a more steady and slower rise not getting above -4

[nick sussex]

The thing to take account of here isn’t so much the 850s but whether you see a change of air mass.

Once the cold is entrenched the rise in 850s won’t translate simply at surface level as long as you maintain the continental flow.

 

[SLEETY]

42 minutes ago, Summer Sun said:

The ECM 00z London mean again shows the cold air peaking around Thursday with -15 850's we then see a rapid rise to around -1 in just 24hrs after this the mean stays between -1 and -4

Northern England ens shows a more steady and slower rise not getting above -4

Hi.thanks for posting that chart.

I find that incredible  rise of temps very hard to believe.Think ECM has it completely wrong for end of week

Next met update be interesting,Think all models are way off with the track of the low pressure system.

 

 

 

[Paul T]

Its less the track of the "original" low as most models have that shooting west of Ireland, its more the development and progression of the shortwave(s) as it nears the UK. 

Look at 144hrs gfs (18z v 00z). They paint a fairly different picture all driven by the treatment of the shortwave across the UK.

The GEM 18z v 00z has changed towards a potentially more snowy and cooler friday/saturday. 

The MO v ECM differences (attached) at 120hrs are down to the treatment of the shortwaves...MO going for channel low development and a further one over the Slovakia area whilst ECM is not to fussed and therefore brings a milder southerly.

Given that shortwave development can change pretty drastically right up to 24 to 48hrs we are someway off consistancy across the models. Although it must be said that even the fairly "mild" GFS 00z solution has significant snow on Friday for many (incl. the south) and temps on sat are hovering around zero from the Midlands North... 

[Sky Full]

Just looking ahead to the extreme limits of the normally 'reliable' timeframe, there are some distinct disagreements between the models as to the position on the 4th March:

                                         500s                                                      850s

ECM                

GFS                 

GEM                

UKMO.          . 

However, they all agree that most of the UK remains on the cold side of the border between the frigid Siberian air and the not-so-cold European / Mediterranean air, with Atlantic depressions forming a queue to get in.  All these solutions could lead to further cold incursions as we head into March though, so as winter goes into extra time a couple of late arctic goals could still be scored.   In the meantime we have some very interesting days ahead as the battle between Siberia and the Atlantic takes place over the southern UK.

[snowstorm27x]

6 minutes ago, Faronstream said:

Many people in here are in denial about the change to milder air in medium range ( around 5-7th march) for big parts of western europé. Let's just hope that the trend with NAO raising will occur.Why would anyone want the winter to continue deep into march and destroy half of the spring just like last years

Don't think anyone is in denial but it's not clear cut as the models don't agree with eachother. Just compare UKMO to GFS both plausible outcomes but an agreement not a chance. The trend is for milder air to push through but it's not a done deal. Why would people want the cold to continue ermmm one word !SNOW!

[jayb1989]

25 minutes ago, SLEETY said:

Hi.thanks for posting that chart.

I find that incredible  rise of temps very hard to believe.Think ECM has it completely wrong for end of week

Next met update be interesting,Think all models are way off with the track of the low pressure system.

 

 

 

What about the consistent support for the same thing throughout the GFS members?

I think it’s set in stone that milder air will creep in across the south, question is how far north will it push and will we be able to reload cold from the north east!?

[SLEETY]

I don’t think gfs is any more clued up TBH I know it always is keen to want to get rid of cold dense in these situation very quickly.

Its a fascinating model watching at the moment and great learning tool

Hope we all see snow before then 

[karyo]

The updated ICON takes the first low across the channel keeping the country cold up to Saturday.

https://www.meteociel.fr/modeles/icone_cartes.php?&ech=120&mode=0&map=0&archive=0

The 0z had the low moving to the west of the UK 

[Yarmy]

Anyone watching the ICON?

You should be: look where the first low is heading.

 

[ALL ABOARD]

Just now, karyo said:

The updated ICON takes the first low across the channel keeping the country cold up to Saturday.

https://www.meteociel.fr/modeles/icone_cartes.php?&ech=120&mode=0&map=0&archive=0

The 0z had the low moving to the west of the UK 

Yes much better blizzards for all in the south.