Model Output Discussion - Into Winter

[FetchCB]

33 minutes ago, Nick F said:

00z and now 06z GEFS H500 mean by day 10 quite bullish to push Atlantic troughing east across NW Europe

00z EPS H500 mean at day 10 more blocked - with a ridge just to our west .

Be interesting to see if GFS backtracks on its keenness to bring back the default unsettled Atlantic zonal train or whether EC is wrong.

More closer in time, now Thursday's low looks off the menu, there looks to be a brief window for wintry showers, perhaps falling as snow inland, to affect eastern areas Thursday night / Friday morning in the strong NEly wind, before winds back northerly later on Friday and into the weekend, with most places becoming dry away from coasts. ARPEGE below Friday morning:

No widespread snow event on the horizon, far north and east likely the best place to be to catch a flake, drier and sunnier in the west.

Looks like a Wash Streamer? 

[summer blizzard]

Euro still does not get a sub 1000mb low past southern Greenland until day 8 (a day slower than yesterday) and then actually kills it. Euro ensemble mean is as weak through day 10.

[TSNWK]

6 minutes ago, summer blizzard said:

Euro still does not get a sub 1000mb low past southern Greenland until day 8 (a day slower than yesterday) and then actually kills it. Euro ensemble mean is as weak through day 10.

is this good or bad for longivity? 

[Mcconnor8]

12 minutes ago, TSNWK said:

is this good or bad for longivity? 

Good, means block is stronger.

 

Icon 12z is another upgrade with amplification into Greenland on the 06z due to the low going further South and moving through quicker yet again.

I expect the rest of the model suites will follow it and we should have an extension of the cold with the stronger block in place.

Day 6 looks MUCH better!

Edited November 27, 2023 by Mcconnor8

[alexisj9]

18 minutes ago, Lord Grogon said:

Dumb question from an ignorant fool.

Why do models trend low pressure systems south? 

Is it simply some sort of empirical bias? i.e. they don't always all trend south, some go the other way. But it tends to pop up in the higher profile situations where more people are watching.

Other point is that is if they do go south, why don't the people who program the models adjust for it over time? Afer all a model is just a big computer program that should use ever increasing levels of historical data to improve it's accuracy. 

 

In this case, underestimating the strength of the cold to our ne, which has pushed the systems south.

[TSNWK]

atlantic much closer on this ICON compared with 00z - however the rewards if the little low goes under could be better

[northwestsnow]

ICON looks interesting at 144h...

[Mcconnor8]

7 minutes ago, TSNWK said:

atlantic much closer on this ICON compared with 00z - however the rewards if the little low goes under could be better

 

It looks much much better here, way stronger block and that low will slide under the UK, fantastic.

Arpege follows with a stronger block as well at day 3, this is looking very good for an extended cold spell now.

 

 

Edited November 27, 2023 by Mcconnor8

[Battleground Snow]

3 minutes ago, Mcconnor8 said:

It looks much much better here, way stronger block and that low will slide under the UK, fantastic.

I think the Atlantic ridge may join up with greenland by 180, hence why it's important we keep stronger heights on Greenland earlier on in the run

Edited November 27, 2023 by Battleground Snow

[Allseasons-Si]

Huge upgrade on the 12z ICON...so far!!!

12z v's 00z.

and to end at 180,...beautiful

 

Edited November 27, 2023 by Allseasons-si
typo

[pages]

Just now, Mcconnor8 said:

It looks much much better here, way stronger block and that low will slide under the UK, fantastic.

Icon at 150 The low about coming in is slightly to far north which at this far out is excellent as we know from experience it will more than likely trend further and further south.  

 

 

[Severe Siberian icy blast]

38 minutes ago, Kasim Awan said:

Hard to believe that most of the UK only has a slight chance of barely scrape a dusting by the weekend from these synoptics but that looks to be the case as it stands.

But this is the thing, as it stands, do you remember how dry December 2010 was meant to be!

We only have a short window but Thursday night and more so Friday i wouldn't be surprised to see little features get picked up later today or throughout tomorrow to bring abit more instability. 

If not then its onwards and upwards look north north/east for a shift east of the high pressure towards scandi maybe

 

Edit: wedges over scandi and with Euro troughing shows my thoughts 

Edited November 27, 2023 by Severe Siberian icy blast

[Lukesluckybunch]

Lovely stuff from the ICON at 180 we end up with what we will have Friday this week..the wrap around of those northeasterly winds!

[BartyHater]

12 ICON simply a variation of the generally cold theme....milder air gives a pretty wet day next Sunday across much of England and Wales on this run, but the precise track of the offending Low is clearly subject to change at this range. 

[Duane S.]

I've just spent a quick spare 10 minutes looking at the overnight runs and fancy the ECM has the next 10 days nearest the mark. 'Nearest', not necissariliy 'near' of course

I don't see super deep (and thus potentially more north tracking) low pressures later this week, more of a slacker, thus southerly affair. But certainly better for cold retention.

Thereafter, it ought to more difficult for northerly blocking to gain much of a foothold through early - mid December. Again, I think the ECM reflects this quite well.

But lets get this into perspective, I am seeing this as two major drivers at force (E-QBO and the ENSO state) to ensure low amplitude Pacific / -AAM periods are producing a much higher 'low base' for us (if that makes sense!?) in terms of waiting for the next window of opportunity, which ought to emerge as we head towards Xmas.

IMO, a pre-dispostion of a southerly tracking jet (with diving systems SEwards later on?) off a displaced and relatively very mobile Azore high (with accompanying  -NAO signature) hopefully will continue to be a theme for the winter. A stagnant Euro high / long-lasting flabby bulging hadley cell situations should be largely surpressed as a result I'd imagine.

A classic winter indeed this could be...

[Mcconnor8]

7 minutes ago, BartyHater said:

12 ICON simply a variation of the generally cold theme....milder air gives a pretty wet day next Sunday across much of England and Wales on this run, but the precise track of the offending Low is clearly subject to change at this range. 

That low brings back another round of amplification behind it into Greenland so actually is a positive thing for cold extending further into next week once it clears through.

GFS 12z is already an upgrade at 6 hours compared to the 06z lol!

Icon also has this for Thursday!

Edited November 27, 2023 by Mcconnor8

[Kasim Awan]

2 minutes ago, Severe Siberian icy blast said:

But this is the thing, as it stands, do you remember how dry December 2010 was meant to be!

We only have a short window but Thursday night and more so Friday i wouldn't be surprised to see little features get picked up later today or throughout tomorrow to bring abit more instability. 

If not then its onwards and upwards look north north/east for a shift east of the high pressure towards scandi maybe

It's definitely possible for some last minute increases in the flow structure however as it stands the flow looks very weak given the strength of the blocking to our north west. It's a result of the low weakening to our South. 

[MATTWOLVES 3]

32 minutes ago, Kasim Awan said:

As it stands there has been a significant reduction in the modelled strength of the convective flow which now looks fairly weak. I'd say snow showers mostly restricted to coastal counties with 1-4cm here, with the odd feature bringing a dusting inland locally.

It was only the other day when you said it was all going wrong as everything was to far North! Well it's going that far South we end up with nothing

Well I say nothing..we get an extension of the colder air...we get to keep it in place for longer.

And what does in place for longer mean? Denser air becoming more stubborn that could provide more entertainment during the next push from the West.

In the shorter term expect the unexpected and you won't be far wrong.

[CoventryWeather]

Here we go again, upgrades on the new runs. 

I think models may move towards the icon this evening/ this mornings UKMO - very similar in the track of the weekend low. Positive runs, as it means the extension of the cold is likely. 

Cold pools do tend to be stubborn to move once in place. 

[TSNWK]

2 minutes ago, Mcconnor8 said:

That low brings back another round of amplification behind it into Greenland so actually is a positive thing for cold extending further into next week once it clears through.

but can I be super greedy please ICON and have the weekend low 100 miles south, did not like the green encroachment for southern half.... 

I

[Mike Poole]

14 minutes ago, Allseasons-si said:

Huge upgrade on the 12z ICON...so far!!!

12z v's 00z.

and to end at 180,...beautiful

 

Much cleaner evolution and considerable upgrade on the earlier run, maintains a clear ridge into Greenland, want to see this replicated on the other models now…

Edit, GFS early doors looks improvement in terms of heights towards Greenland.

Edited November 27, 2023 by Mike Poole

[winterof79]

13 minutes ago, Allseasons-si said:

Huge upgrade on the 12z ICON...so far!!!

12z v's 00z.

and to end at 180,...beautiful

 

The feature for Sunday in to monday shown on UKMO too is gathering traction.

[Mcconnor8]

4 minutes ago, Mike Poole said:

Much cleaner evolution and considerable upgrade on the earlier run, maintains a clear ridge into Greenland, want to see this replicated on the other models now..

The difference stems from the movement of the Azores low VERY early on in the run so it should be. 

GFS is following it closely it looks like.

Look at the difference in the positioning of the low just above Spain from yesterdays 12z to todays 12z on GFS, exactly what I was saying about it being completely wrong with it compared to ECM/UKMO, has shunted it quite a bit East today which results in it being further South as it doesn't interact with the Ireland low. Then look at how much greater amplification goes into Greenland as a result of this!

Edited November 27, 2023 by Mcconnor8

[summer blizzard]

31 minutes ago, TSNWK said:

is this good or bad for longivity? 

Good.

There are basically three ways to kill the cold spell. 

1) Local spoiler similar to last year, blow up a secondary low somewhere over or west of us and unfortunately it will suck up some warm air most likely. At least enough to displace the cool air.

2) High pressure can topple. This is unfortunately what often happens when we end up with a snowless breakdown because the high sucks in warm upper air and the cool surface air moderates.

3) Atlantic front, low pressure moves in and washes away the cold spell.

If an Atlantic Low can't pass southern Greenland at strength then you pretty much rule out option three.

[Battleground Snow]

You can see how much better the run would be later on if the arpege ran on to 180 like the icon, huge difference at 114

Edited November 27, 2023 by Battleground Snow