Model Output Discussion - Deeper into Autumn

[tight isobar]

22 minutes ago, Bristle Si said:

Doesnt that US-based 'severe cold' scenario usually 'fire up the jet' (so to speak), with the UK normally on the 'receiving end' - NOT with cold and snow, but LP systems barrelling thru the UK and copious amounts of rain?

.. NO .the Cmc highlights this thought!. And as the quote, the large scale assumptions of those out of the know is, as unreal @ any USA weather drivers will ultimately be as ours in near future- As we are a mobile attraction for Atlantic drivers!. It’s mythical! - the raw driving units- away from madden julien ocsc- And Nina forms...need to be taken more seriously this season!.. it’s complete etit jigsaw alignment against the clock .. and usually the clock ticks 1 way... it’s definitely NOT at this point!!!- And more notable is the minor / large scale pot holing up the top @ even @500 geo scale... Jet unreliable - And deep basin is about as set- as it gets!!

Edited November 15, 2022 by tight isobar

[damianslaw]

14 minutes ago, Allseasons-si said:

I do think that the first bite of the cold cherry won't come along the first time from this block to our E/NE,the la nina inprint should favour a block more to our NW than NE

as it stands the mjo is currently coming out of the COD then into phase 6-7 as we go into Dec,the models won't show this amplification yet until another few days or so,so sit tight and take a wee break,...i know i won't ha ha as it's in my nature and is of many on here

that said,..the latest gfs run does show some marked WAA going through the UK that could be a precurser to that change in the pattern to more of a la nina style

G'night all.

 The la nina imprint seems to be interfered with at present and we have a el nino effect, hence an atlantic trough rather than ridge.. and and amplified flow. 

Back to the models, not much change overall, big block to the NE, atlantic trough nestled over the UK, negative aligned troughs and southerly jet. End result lots of rain and temps around average, a little below in northern parts with some patchy frost and possible wintry potential higher ground.

GFS very progressive today, suspect it will be much less so tomorrow. 

[Rain All Night]

Our resident trapped vortex chunk brings us my least favourite weather type, so I am displeased that the GEFS suggest it may still be there even by day 15, with the other contenders not convincingly refuting this (IMO).

Later edit: Added the 18z GEFS, and having done so will concede that perhaps there is a signal here for the trough to end up further west eventually.

Edited November 16, 2022 by RainAllNight

[MP-R]

Purely La La Land here (tbh the CFS almost deserves a thread of its own) but this particular run shows how a potentially very snowy outcome can result from an otherwise Atlantic-dominated setup but with southerly tracking lows:

  

Definitely a higher success rate in January than in December though I would think from a snowfall point of view.

[Kirkcaldy Weather]

More hints from the GEFS 18z 

 

 

And worthy to add this 

 

[Kasim Awan]

With a mean like this, personally i cant see anything significant verifying before the end of the month. 

[KTtom]

5 hours ago, Kasim Awan said:

With a mean like this, personally i cant see anything significant verifying before the end of the month. 

Agreed, looking at the overnight runs we are looking 10 days minimum before the static Atlantic trough fills. Until that happens we are on the wrong side of the boundary between Atlantic and continental air.

Just in support of johncam after being shot down for stating fact last night, here is the Mets further outlook for mid month issued late October...no mention of high ground and the second week of November is 7th to 14th.

Quote

quote] Sunday 6 Nov - Sunday 20 Nov

Unsettled conditions are expected to continue at first, with further heavy rain possible, particularly in the south. An increasing chance of settled weather remains during the second week of November, bringing a potential for colder, drier weather especially for the north and west. This will likely bring a risk of chilly nights with mist, frost and fog in places, with some snow expected to fall in any showers in northern and western areas.

Updated: 16:00 (UTC+1) on Sat 22 Oct 2022
 

 

Edited November 16, 2022 by KTtom
Added met forecast

[northwestsnow]

4 hours ago, Kasim Awan said:

With a mean like this, personally i cant see anything significant verifying before the end of the month. 

Which month  

Lots of wind and rain over the coming weeks according to GFS at least.

[Mark Smithy]

As expected the so-called Scandinavian High is getting pushed away eastwards on the latest runs. The ECM and UKMO were right about this, against the GFS which keeps trying to build height rises. So the anomaly forecasts were inaccurate: let's not beat around the bush.

Basically, the weather has reverted to type: an ongoing blast from the Atlantic with rainfall totals steadily accumulating. When the weather in Britain is like this it's possibly better not to pay too much attention to medium and long term modelling. The jetstream remains very strong and relatively flat. It will abate because it always does, but there's a way to go yet. Could easily be mid-December before this lot blows itself out and we come under the spell of genuine blocking.

That's okay though. I'd rather have autumnal conditions in autumn anyway. And we did need the rain.

Edited November 16, 2022 by Mark Smithy

[Kasim Awan]

3 minutes ago, northwestsnow said:

Which month  

Lots of wind and rain over the coming weeks according to GFS at least.

Seems plausable IMO given the combination of signals for both a strong jet aswell as a stubborn high over central / NE Europe. Produces a deep low as the block forces it to stall and deepen. Conditons wise, can get windy and very wet with fronts stalling against the block. Rather mild, too much jet energy to allow for more optimal troughing to our southeast. This is a classic pattern seen when opposing signals are at play. Think January 2014.

Just now, Mark Smithy said:

As expected the so-called Scandinavian High is getting pushed away eastwards on the latest runs. The ECM and UKMO were right about this, against the GFS which keeps trying to build height rises.

So the anomaly forecasts were complete rubbish: let's not beat around the bush.

Basically, the weather has reverted to type: an ongoing blast from the Atlantic with rainfall totals steadily accumulating. When the weather in Britain is like this it's possibly better not to pay too much attention to medium and long term modelling. The jetstream remains very strong and relatively flat It will abate because it always does, but there's a way to go yet. Could easily be mid-December before this lot blows itself out and we come under the spell of genuine blocking.

That's okay though. I'd rather have autumnal conditions in autumn anyway. And we did need the rain.

Anomaly charts are often extremely misleading. Especially the pressure anomalies.

[northwestsnow]

EC is Atlantic dominated too..

I suspect any potential  settling down is going to be delayed again.

[mb018538]

7 minutes ago, northwestsnow said:

EC is Atlantic dominated too..

I suspect any potential  settling down is going to be delayed again.

Very tedious isn't it @northwestsnow. Just can't shake this troughed pattern off. Nothing in the forecasts suggests this is going to change in the next couple of weeks, so we're likely to see out most of (if not all) of November with more of the same. Think I might just come back in a couple of days and see if anything has changed. Either wet, very wet or in some spots that see 100-200mm of rain in the next 10 days, flooding likely.

[Sceptical]

Atlantic domination well into December.

[sheikhy]

Im still thinking its looking interesting up to 144 hours!!aint given up yet lol!!ecm and ukmo once again different to gfs as early as 72 hours!!somethings gota give this evening!!watch thiis space!!if anything at least it wil feel colder than the rubbish we have endured so far!

[SLEETY]

8 minutes ago, Sceptical said:

Atlantic domination well into December.

Not exactly, looks like the jet stream is heading further South looking at the Ecm, so maybe something Wintry for some places, eventually, like the Met mention in their outlook, perhaps eventually the block will take full - control, as long as it doesn't start to sink South, or its back to square one! 

Edited November 16, 2022 by SLEETY

[IDO]

The current spell is not synonymous with the dreaded zonal flow of bygone days, instead just the transient results of the draining of some of the tPV lower-heights to our NW. The mean suggests this will pass, and although in FI, that will relax after D8:

Due to the inconvenient block to our east, never seems to be more than a hindrance to the UK, the process of filling that trough does mean November is more wet than cold.

The London ens for 2m temps sums it up, average at worse and heavy spells of rain with showers in the mix:

Still too much scatter for any confidence post D10, but heights building somewhere in the Atlantic to W Europe landscape seems likely.

 

[CoventryWeather]

Looking at the GEFS this morning, there are a few ensembles showing a Greenland high taking control near to days 10 until the end of the run. In my opinion, I'd say this is the pattern that I would expect to be seen over the next few days from the GFS. Probably follows the longer range Met Office as well. 

[iceman1991]

Like I said yesterday with the metoffice wording not going to get me hopes up watch them back track today or tomorrow if it carry’s on where it’s going 

[Mike Poole]

Looks quite a lot of uncertainty still about the behaviour of that low in 7 days time.  Focusing on the clusters for that time, T168:

You can compare the low between the clusters and it ranges from being negatively tilted cluster 1 and 3 in particular to rounder to full on bowling ball in clusters 5 and 6.  Difficult to see beyond resolving that uncertainty. 

But a point to note on the later timeframe T264+ is the opportunity to push a ridge up between lows to connect with and reinforce the block, as illustrated by cluster 3 and somewhat by cluster 2 - and which has been observed on a couple of GFS // runs too.  One to maybe look out for.

[Frosty.]

 

The CFS 0z  has certainly piqued my interest regarding next month! ️  
 

[Scandinavian High.]

57 minutes ago, iceman1991 said:

Like I said yesterday with the metoffice wording not going to get me hopes up watch them back track today or tomorrow if it carry’s on where it’s going 

Why would they back track today or tomorrow ?

[LRD]

2 hours ago, Kasim Awan said:

Seems plausable IMO given the combination of signals for both a strong jet aswell as a stubborn high over central / NE Europe. Produces a deep low as the block forces it to stall and deepen. Conditons wise, can get windy and very wet with fronts stalling against the block. Rather mild, too much jet energy to allow for more optimal troughing to our southeast. This is a classic pattern seen when opposing signals are at play. Think January 2014.

Anomaly charts are often extremely misleading. Especially the pressure anomalies.

Amen. I don't take any notice of pressure anomaly charts anymore. I still think there is value in temp and precipitation anomalies though. 

I believe that clusters take a mean of different ensemble runs so those pressure anomaly charts might be statistically more valuable, I guess. I might be incorrect on that though 

Thing is virtually every winter, pressure anomalies are rolled out and they make things look far, far better than both the present and what turns out to be future reality

Edited November 16, 2022 by LRD

[bluearmy]

The scrussian upper ridge looks to retreat to become Russian - the week 2 ens modelling has been consistently strong on the Atlantic trough depth which forces this. 

beyond that, as some have noted, the upstream tpv relaxes. What Atlantic sector pattern sets up beyond the trough is v llkely going to be down to where the tpv segments fall after the they separate out over the polar field. if we see nothing of any real strength in the e Canadian sector then we are in the game for some blocking to be effective in driving a coldie pattern in nw europe. 

Both 00z gfs and gfsp are illustrations of that 

[phil nw.]

When reading pressure anomaly charts you have to take into account the location of the anomaly features.

For example a weak positive ( pale pink)over Greenland will still indicate low pressure up there as that is the climatic norm.You would need to see a dark red to suggest different.

On the other hand a weak positive over the Azores would confirm a high pressure area as that is the normal setup.

A bit of a generalised summary but just to give an idea.

[bluearmy]

15 minutes ago, phil nw. said:

When reading pressure anomaly charts you have to take into account the location of the anomaly features.

For example a weak positive ( pale pink)over Greenland will still indicate low pressure up there as that is the climatic norm.You would need to see a dark red to suggest different.

On the other hand a weak positive over the Azores would confirm a high pressure area as that is the normal setup.

A bit of a generalised summary but just to give an idea.

This always crops up when people deliver the post mortem on the season ……. Those saying it in the chaos of the lead up tend to be drowned out by the excitement of a positive anomoly 

we aren’t yet into winter proper so wedges probably won’t do - once we get into late dec and Jan then they could well. looking at the way the atmosphere seems pre disposed to amplification yet still fairly mobile, we may be looking at a season of wedges .

Edited November 16, 2022 by bluearmy