Model output discussion - Winter approaches

[Chesil View]

Well the morning forecast modelling has gone a bit further towards a la Nina pattern. It's hardly Nov/Dec 2010 buts it's a start and more importantly a step in the right direction.

[Methuselah]

1 hour ago, mushymanrob said:

Any northerly will only be transient according to these charts, as we retain a moderately strong westerly mean upper flow. This looks unsettled, average, wettest and cloudiest in the north .

Sorry but that ECM chart isnt the start of a new trend/pattern/whatever.

 

Over all, I'd agree with that, Mushy; I think History is most definitely on your side... But, do 5-Day anomalies ever pick up on a pattern-change, faster than the 'normal' models can? Can 5-Day 'averaged' anomaly charts ever be first to spot an upcoming change?

Edit: Though I never take a pattern-change seriously until it's showing in the anoms, I never look to the anoms, for the first indications of said change... Does that make sense?

Edited November 13, 2020 by General Cluster

[johnholmes]

10 minutes ago, General Cluster said:

Over all, I'd agree with that, Mushy; I think History is most definitely on your side... But, do 5-Day anomalies ever pick up on a pattern-change, faster than the 'normal' models can? Can 5-Day 'averaged' anomaly charts ever be first to spot an upcoming change?

Almost always, that from using them for 10-12 years. I would say in that time no more than single figure instances in that time

[BLAST FROM THE PAST]

1 hour ago, General Cluster said:

Och well, the GFS 06Z ends on a slightly more optimistic look...  But is that HP about to build back in again? A cold and snowy winter? Who the heck knows!

    

However, I do hope we don't end up with a 'Classic' 20th Century winter... like 1975!

You ARE old Pete

 

BFTP

[BLAST FROM THE PAST]

1 hour ago, mushymanrob said:

Any northerly will only be transient according to these charts, as we retain a moderately strong westerly mean upper flow. This looks unsettled, average, wettest and cloudiest in the north .

Sorry but that ECM chart isnt the start of a new trend/pattern/whatever.

 

A cooler and times cold pM NW’ly theme would be more seasonal and a ‘shift’.  What’s being shown in the models is not an unreasonable shift , but does need still need to verify

 

BFTP

[blizzard81]

I like the look of the week 4 cfs pressure anomaly chart. 

[DavidS]

2 minutes ago, blizzard81 said:

I like the look of the week 4 cfs pressure anomaly chart. 

Yes, lots to like, including lower heights over Iberia.

[BlueHedgehog074]

1 hour ago, northwestsnow said:

Anyway, some interest for the 12z runs today... Paul, if we get some tasty charts over the next few weeks prepare the server! With lockdown ongoing you might get deluged with snow hungry coldies on here !!

We’re also placing a large order for a stack of naughty chairs ready to put mischief makers from here into. So to all the snow hungry cold fans in here, if you don’t behave, you know what will happen to you. And did we mention that if you behave while on the naughty seat, we may be kind enough to plug in the Xbox Series X and allow you to rock around the UK in Forza Horizons 4

[Methuselah]

28 minutes ago, BLAST FROM THE PAST said:

You ARE old Pete

 

BFTP

Indeed Fred... I'm sold old, I still have dreams of joining Starfleet!

[Frosty.]

Oh my, what have I missed?..the chance of snaw.. anyhoo the 6z continues that chance of snow / snaw...fingers crossed gang!!!! ..such a hot topic !

 

Edited November 13, 2020 by Jon Snow

[mushymanrob]

2 hours ago, northwestsnow said:

However, we may see enough energy digging into Europe which will be potentially helpful down the line...

 Yep, thats possible..
 

2 hours ago, bluearmy said:

Indeed rob, looking at these charts below from nov 2010 shows that even at two weeks, the ens means can be in v good agreement over a week period to show some defined upper patterns 

8/14 day from 13th nov which is a bit undefined but still a long way from where we are with lowish anoms over Europe and high ones to our north

but a few days later and things have really become solid on the outlook with that mid Atlantic upper ridge and high greeny anom 

 

I would still urge caution in all directions s 2010 was one of those strange periods where the nwp seemed to get onto the same page into the distance 

 Absolutely, i was of course referring to the timeframe the noaa charts currently pertain to, in this case i used the 8-14 day chart as it is at the moment and that covers the t240 ECM chart timeframe.  Will the ECM "win" over the NOAA's?.. possibly but unlikely imho.

1 hour ago, General Cluster said:

Over all, I'd agree with that, Mushy; I think History is most definitely on your side... But, do 5-Day anomalies ever pick up on a pattern-change, faster than the 'normal' models can? Can 5-Day 'averaged' anomaly charts ever be first to spot an upcoming change?

Edit: Though I never take a pattern-change seriously until it's showing in the anoms, I never look to the anoms, for the first indications of said change... Does that make sense?

From my pov, the ops especially the GFS which goes out further then the ECM , come up with many different permitations over a few days. They will pick up a new development sometimes before the anomalies do, But you dont always know if its a realistic development/pattern change as many others arent. The Anomaly charts are hardly ever far out and certainly not as far out as many of the ops more fanciful predictions can be.

Thats why i view the anomalies first, because of their accuracy in predicting the mean synoptic pattern, i then "match" the nearest ECM/GFS run to what i think the Anomalies are suggesting - and that can become tricky to get right - to get a better idea of the detail. This prevents (at least in theory) being lead up the garden patch be it looking for cold/snow in winter, or heat/sun in summer.

So for me, its not so much about being the first to spot a change, but its about them being the first to spot a change accurately. And at 6-14 days, thats far enough in advance to be creditable imho.

[mushymanrob]

1 hour ago, blizzard81 said:

I like the look of the week 4 cfs pressure anomaly chart. 

Very similar to an MJO phase 3 December composite chart ... MJO phase 3 into December looks viable to me.. just the strength is to be determined which currently isnt good.

[Frosty.]

Oh my goodness!..could winter be coming sooner than expected?..shock horror!..you know what?, looking at the GEFS 6z..it may just be!  

Edited November 13, 2020 by Jon Snow

[bluearmy]

2 hours ago, blizzard81 said:

I like the look of the week 4 cfs pressure anomaly chart. 

yes its fairly  likeable  apart from its title ………….which is pretty crucial ......

 

[TSNWK]

1 minute ago, bluearmy said:

yes its fairly  likeable  apart from its title ………….which is pretty crucial ......

 

Week 4 blue?

[Tim Bland]

Many places seeing their first taste of winter at the end of next week!...

[Met4Cast]

An absolute beauty of a slider low on the 12z GFS.

Cold air on it's northern flank would likely bring snowfall to many areas in the north. Support for a northerly incursion from the UKMO 12z too. Whether it transpires like this remains to be seen but at least there's something of interest to watch.

[swfc]

12z gfs brings a flatter Atlantic and big jump in the synoptics ie to nnw. All subject to change but possibly ties in with John's comments earlier in regard to the 500mb set up ie West to east flow past transient northerly 

Edited November 13, 2020 by swfc

[Methuselah]

Yee Ha! Snowy Beccles might see a sleet blob... or two!

    

Edited November 13, 2020 by General Cluster

[northwestsnow]

UKMO further east than GFS...

Not to say either model is correct of course !

EC will be interesting...

Edited November 13, 2020 by northwestsnow

[bluearmy]

1 hour ago, mushymanrob said:

 Yep, thats possible..
 

 Absolutely, i was of course referring to the timeframe the noaa charts currently pertain to, in this case i used the 8-14 day chart as it is at the moment and that covers the t240 ECM chart timeframe.  Will the ECM "win" over the NOAA's?.. possibly but unlikely imho.

From my pov, the ops especially the GFS which goes out further then the ECM , come up with many different permitations over a few days. They will pick up a new development sometimes before the anomalies do, But you dont always know if its a realistic development/pattern change as many others arent. The Anomaly charts are hardly ever far out and certainly not as far out as many of the ops more fanciful predictions can be.

Thats why i view the anomalies first, because of their accuracy in predicting the mean synoptic pattern, i then "match" the nearest ECM/GFS run to what i think the Anomalies are suggesting - and that can become tricky to get right - to get a better idea of the detail. This prevents (at least in theory) being lead up the garden patch be it looking for cold/snow in winter, or heat/sun in summer.

So for me, its not so much about being the first to spot a change, but its about them being the first to spot a change accurately. And at 6-14 days, thats far enough in advance to be creditable imho.

 

i have just been reading the cpc discussion and it seems that the chart for the 8/14 day was made up as follows 

The official 8-14 day 500-hPa height blend consists of: 25% of Today's 0z GFS Ensemble Mean centered on Day 11, 50% of Today's 0z European Ensemble Mean centered on Day 11, and 25% of Today's 0z Canadian Ensemble Mean centered on Day 11

so the chart is taken from one days merged ens output and not from a week  - the geps looked very flat across the atlantic day 11 yesterday and the gefs were more trough than ridge - be interesting to see todays given that the eps and geps were more ridgy around Greenland - however the gefs isn't so a blend could well still look fairly flat. unless cpc are going to ditch a model that conflicts then until all three ens are on the same page its a struggle to get cpc to show a marked upper feature 

[nick sussex]

Hi all . I’m back from my summer hibernation . A warm welcome to all the new members .

It’s hard to believe we’re back again chasing those hard to come by good winter charts . It’s true the older you get the quicker the years seem to flash by!

Anyway in terms of the latest models. Certainly some interest has developed over the last few days in terms of some colder weather , snow wise not the depth of cold at this stage unless you’re higher up .

The GFS does have a shortwave feature running east/se with some colder air tucking south .

In mid winter this would be leading to pandemonium in here but currently not quite cold enough for more widespread interest.

I think the thing to keep an eye on is how the models deal with pressure rising to the nw and also what happens to the PV . If you don’t get a chunk splitting off and taking up shop over sw Greenland then the energy supply for low pressure moving east is going to be reduced so more shallower features could disrupt se under any high pressure .

Day 6 into 7 looks key where you need sufficient upstream trough disruption to support that lobe of high pressure to the nw .

Edited November 13, 2020 by nick sussex

[Methuselah]

Just now, nick sussex said:

Hi all . I’m back from my summer hibernation . A warm welcome to all the new members .

It’s hard to believe we’re back again chasing those hard to come by good winter charts . It’s true the older you get the quicker the years seem to flash by!

Anyway in terms of the latest models. Certainly some interest has developed over the last few days in terms of some colder weather , snow wise not the depth of cold at this stage unless you’re higher up .

The GFS does have a shortwave feature running east/se with some colder air tucking south .

In mid winter this would be leading to pandemonium in here but currently not quite cold enough for more widespread interest.

I think the thing to keep an eye on is how the models deal with pressure rising to the nw and also what happens to the PV . If you don’t get a chunk splitting off and taking up shop over sw Greenland then the energy supply for low pressure moving east is going to be reduced so more shallower features could disrupt se under any high pressure .

Day 6 into 7 looks key where you need sufficient trough disruption to support that love of high pressure to the nw .

Good to see you back, Nick... May the shortwaves be with you!

[StretfordEnd1996]

GFS perhaps a little less bullish out up to D10 but still some chilly looking charts for a time - 

 

We're not even in Winter yet so for me any little bit of cold weather no matter how short or small it is is more than welcome and good to see, and I shall not be getting disappointed or disgruntled at failed cold incursions at this stage. 

It'd be a freezing start for many a week tomorrow perhaps ... Brrrrr

Flatter by D10 (which is a little interesting considering in the 6z GEFS suit there was a vast majority of runs that were showing much colder uppers around D10 close to or at the -5 isotherm), perhaps the 12z operational is out on its own a little - we shall see

[ICE COLD]

Welcome back @nick sussex . Here’s a chart to welcome you back from the GFS 12z . Pretty cold that