Model output discussion 02/02/20

[stodge]

10 minutes ago, SLEETY said:

and i tajke it the ecm is not very good for cold as no comments on it?

The ECM 12Z OP is remarkably unsurprising in content. Plenty of PM air especially for northern parts but milder incursions further south. Continuing unsettled with more rain to come for most as we end February.

The GFS 12Z OP and to an extent Control show, for the first time, a possible way out of the Atlantic rut as we head into March. The key is stopping the Azores HP ridging into Europe which keeps the trough aligned positively (as it is now). As the jet edges south and the LP systems head more ESE into Europe once across the British Isles, the HP is forced to ridge further west and north-west in the Atlantic and eventually (in FI so just eye candy for now) one such HP cell ridges far enough north for an undercutting NE and E'ly flow to impact the south.

850s drop to -12 in far FI so that might be good enough for wintry precipitation to both higher and lower ground if other factors work.

It's always good to see OP and Control heading in the same direction and there are plenty of colder options in the GEFS.

The key remains whether we can get some form of vortex displacement in March but it's all very early days and tiny steps.

 

[Cheshire Freeze]

2 hours ago, Steve Murr said:

This wave would almost secure a cold first half of March

I wonder if March could be the coldest month of all 4 !

Would it surprise you Steve??

Seems to have been a slight trend for unseasonably late wintry weather over the past decade or so.

[feb1991blizzard]

2 minutes ago, CreweCold said:

Would it surprise you Steve??

Seems to have been a slight trend for unseasonably late wintry weather over the past decade or so.

It wouldn't be a massive surprise - as there really isn't much to beat out of the 3 winter months.

[snowray]

ECM 12z ens, the cold snap early next week looks like our best bet. The north and higher ground might do best.

 

 

 

Edited February 21, 2020 by snowray

[Mike Poole]

22 hours ago, nick sussex said:

You’re right to be very dubious. One thing notable from this winter is any bit of amplification shown at the longer range has failed to materialize.

Its even been a struggle at day 6 to see that survive . In this instance a lot depends on that storm forecast for the eastern USA , where exactly that tracks and whether it develops any secondary features has a large impact on any ridging ahead of it .

 

I strongly agree with the bold bit, since mid-December when that fateful trop and strat vortex coupling thingy took place, model bias as you highlight is clearly obvious, any significant amplification has failed to verify, and that is true for all models, not just the ones that people usually tend to castigate.  

Biases in models are present all the time, of course, but in a normal winter, the weather itself would be varying from mild to cold to stormy etc. so the model biases would be harder to see. 

I reiterate what I said in a previous post, some here wrote off winter in October, I didn't, but from mid- December it was practically a winter write off - but two things

• Have we been 'lucky' in that the current wave train of Atlantic huge storms didn't start in mid Dec, but at about the turn of this month?
• what will the endgame be?  How long will this horrid period of weather last, and what will follow it - and the latter may depend on the strat evolution. 

[Zak M]

Lets hope the GFS or any other model shows something more wintry as time passes. Some arctic cold air drifting towards the British Isles along with some snow could be possible on the 29th, but once again, it's just way too far out, and is unlikely to verify. And it is rightly so, as @nick sussex says in the post above.

Edited February 21, 2020 by Zak M

[PiscesStar]

1 hour ago, CreweCold said:

Would it surprise you Steve??

Seems to have been a slight trend for unseasonably late wintry weather over the past decade or so.

Spot on. Yes it does and that's a fact! 

[MATTWOLVES 3]

Good god the GFS 12z really does throw the cat among the pigeons... Even manages to throw up a NE wind and a potential snow maker come the 8th March.. I said when Winter started, the GFS may overplay colder snaps in FI, especially as this new FV3 model still seems to overplay uppers especially from the W/NW quadrant!! And low and behold this holds true... Parctice what you preach matt... Don't be suckered in by tempting snow charts beyond a week.... Thing is when there is nothing showing at day 5 for weeks on end.... We have to find something to satisfy the urge! Maybe, just maybe one of these days, the good old GFS will nail one of these sypnotics at day 10,and then count them down!! Anyway it's nearly spring, so it's sods law the conditions may become colder. 

[PiscesStar]

29 minutes ago, Mattwolves said:

Good god the GFS 12z really does throw the cat among the pigeons... Even manages to throw up a NE wind and a potential snow maker come the 8th March.. I said when Winter started, the GFS may overplay colder snaps in FI, especially as this new FV3 model still seems to overplay uppers especially from the W/NW quadrant!! And low and behold this holds true... Parctice what you preach matt... Don't be suckered in by tempting snow charts beyond a week.... Thing is when there is nothing showing at day 5 for weeks on end.... We have to find something to satisfy the urge! Maybe, just maybe one of these days, the good old GFS will nail one of these sypnotics at day 10,and then count them down!! Anyway it's nearly spring, so it's sods law the conditions may become colder. 

Absolutely be a yewtiful charts let's hope they do indeed tickety tick and countdown on the clock and become the dreams we desire

Edited February 21, 2020 by Snowfish2

[SMU]

2 hours ago, CreweCold said:

Would it surprise you Steve??

Seems to have been a slight trend for unseasonably late wintry weather over the past decade or so.

Nothing would surprise me but with the PV at record strength it isn't the form horse !

[nick sussex]

Four runs now in a row now that the GFS is amplifying the upstream pattern towards day ten .

If that amplified wave helps to pull the PV towards the nw then that will open up an opportunity to the ne , the orientation of the PV as in the sausage ne/sw is what we’re looking for .

So the amplification works like a clock anti clockwise  on the Canadian side it pulls that sw and the bit to the ne works nw . The gap then opens up to the ne . That’s the plan !

The GFS makes a meal of the shortwave over the UK but if we ended up with the PV elongated like that then that’s normally a decent correlation for pressure rising over Scandi .

Edited February 21, 2020 by nick sussex

[Tim Bland]

Surprising consistency in far FI from the the GFS,  despite getting there via different routes. See below 12z Vs 18z  ....

[nick sussex]

Putting aside the nice ending to the GFS18 hrs run this amplification showing up at day ten is a surprise and the ECM also has more amplification at that stage aswell .

The background signals aren’t great to put it mildly. So it’s questionable as to where the models are finding this from .

Generally I tend to be very suspicious of anything the GFS shows past day ten as we see a drop down in the resolution but all runs today have removed the limpet Euro high and displaced that to the nw.

And the amplified wave starts before that . Because of the state of the PV you’d not even expect that to appear . So although pleased to see this amplification I’d be very wary of that .

The discrepancy over what exactly the MJO is doing could be I suppose one factor here , some measures of that have that in phase 7 and about to edge into phase 8 at lowish amplitude but others have it going nowhere and stuck in the inner circle .

There was also talk of the current signal being obscured and not showing up properly on the RMM index .

 

[Zak M]

The GFS 18z is stillllll showing the cold air over the British Isles on day 8...

...followed by another cold plunge on day 11

And something interesting that caught my eye is that the cold air is so far down south that it looks like it goes off the charts!! Obviously this most likely won't verify (in fact, probably all the charts I have just posted won't verify!)

[Zak M]

The ECMWF also has a few days with plumes of cold air:

The GEM is definitely going for a more cold and possibly wintry start to March, with some snow possible.

Don't be surprised if you wake up to some snow in your garden on the first week of March 

[mbrothers]

Can u have a plume of cold air ? 

[Ǝssex Ǝasterly]

3 hours ago, mbrothers said:

Can u have a plume of cold air ? 

I don't think so, plumes usually go upwards/northwards, we rarely if ever have cold air masses to our south, which is why cold masses are usually defined as troughs 

[feb1991blizzard]

Snowfest 216  ECM

[Weather-history]

What has happened to Euro 4? It was a  pretty decent model to look at  for preciptation prospects but now as regards to snow, its just bonkers

[Weather-history]

23 minutes ago, feb1991blizzard said:

Snowfest 216  ECM

Looks good but preciptation charts are unimpressive

[Gowon]

39 minutes ago, Weather-history said:

Looks good but preciptation charts are unimpressive

Looks impressive for some, especially Wales 

[BLAST FROM THE PAST]

Models now sniffing at a change coming for March.  A cold Spring anticipated so let’s see how this progresses.  No deep cold as in BFTE but certainly the jet digging south and HP beginning to position itself more favourably for colder weather.

interesting chart

Jet digging south

 

BFTP

Edited February 22, 2020 by BLAST FROM THE PAST

[feb1991blizzard]

1 hour ago, Weather-history said:

Looks good but preciptation charts are unimpressive

 

The low does seem to fill between 192 and 216, if it didn't quite as much then PPN would be better although having said that it would probably be more likely to be rain then!

[Climate Man]

7 hours ago, mbrothers said:

Can u have a plume of cold air ? 

I thought that too but looked up definition and it is shape and not direction.

[knocker]

As far as I'm aware the term as used in meteorology originally applied to a specific event such as the 'Spanish Plume' which, put very simplistically, is the movement of a warm (hot) airmass north from Iberia. From this the word plume has been  plucked to refer, more or less, to any advcetion of warm air from the south. To refer to a cold plume merely adds another expression to the NW glossary

Edited February 22, 2020 by knocker