Model Output Discussion - cold spell to end Autumn

[Man With Beard]

People are saying ECM = snow north of M4 because ... that's what its snow charts show!!

In reality: Marginal for snow between M4 and Birmingham. North of that: plenty plenty.

The ECM op is churning out this same solution run after run (slightly further south this time). In fact, if you check the archives, it is getting closest to the eventual solution consistently ATM, bar a couple of zany runs.

Still 5 days out so room for changes, but after the analysis of sliders I did earlier today, I'm afraid I would rate the chances of a northern correction more highly than a southern one, give this set up.

[Optimus Prime]

5 minutes ago, Winter Hill said:

Pointless having -10 uppers if your DPS are +2 

But without taking into account relative humidity and temperature gradient? 

 

Quite absurd trying to forecast precip type 4-5 days out really. 

Edited December 5, 2017 by Optimus Prime

[ANYWEATHER]

4 minutes ago, igloo said:

yes many people are in denial about next weeks forecast the uppers are simply to high even in my location it would be 50/50 for the first slider and for the second no chance it would be great if we still seen the cold uppers from the 60s and 70s then it would a different story 

Plenty of scope from Friday into Sunday, for snow to fall just about anywhere, and even though Ive not got the dewpoint figures but as long as they are at freezing or below ,despite an air temperature above freezing, snow will fall.

[northwestsnow]

2 minutes ago, feb1991blizzard said:

I'm pretty confident it wont be a washout for us, I think it may correct westwards, which even if it did mean we were to miss out, we would be in with another chance midweek as we are still on the cold side.

I am beginning to think higher parts of Oldham are going to see serious drifting snow by this time next week

certainly think EC is better than the 0z run, the PMm flow is relentless!!

Edited December 5, 2017 by northwestsnow

[Mike Poole]

48 minutes ago, bobbydog said:

i think a major part of the problem is, so many people throwing in the word "zonal" when they dont actually know what it means....

Worse, many people throw in the word "zonality" when it doesn't even exist.

[Djdazzle]

I think the reality going forward is that there just isn’t enough blocking to sustain anything cold for any length of time. The models aren’t showing any clear signals for establishing blocking.

[Daniel*]

Sunday on EC a smattering of snow for the London area the dividing line of infamous M4 corridor in all its might.

[blizzard81]

6 minutes ago, karlos1983 said:

What a dire situation we find ourselves in........

We have seen much worse charts over the last few years. That is true but where does it go from there? The azores high can only go east from that position which means the following charts would not look pretty at all. The intense pv to the north west is looking more ominous with each and every run. 

[bradymk]

Before Sunday, GFS shows a more organised shower/precip band moving down through southern counties from the north west Friday night into Saturday morning. One to watch. 

[MattStoke]

4 minutes ago, Daniel* said:

Sunday on EC a smattering of snow for the London area the dividing line of infamous M4 corridor in all its might.

Have you got the link for those charts, please?

[Daniel*]

Just now, MattStoke said:

Have you got the link for those charts, please?

Here you go  

https://weather.us/model-charts/euro/2017120512/europe/snow-depth-in/20171210-1200z.html

[karlos1983]

1 minute ago, blizzard81 said:

We have seen much worse charts over the last few years. That is true but where does it go from there? The azores high can only go east from that position which means the following charts would not look pretty at all. The intense pv to the north west is looking more ominous with each and every run. 

I disagree with that, you could equally have said the same at 144. Why worry about a chart that we can’t even see yet anyway.  

 

 

[Frosty.]

A good thing about the Ecm 12z is that it's generally on the cold side after thursday with some very cold air on fri / sat and some less cold uppers to follow but never mild and another surge of cold heading south later in the run so I will say, enjoy this upcoming arctic blast and good luck with the snow, some will do really well out of this, especially those further north and higher up..could be a lot worse!!

Edited December 5, 2017 by Frosty.

[weirpig]

2 minutes ago, MattStoke said:

Have you got the link for those charts, please?

https://weather.us/model-charts/euro/2017120512/europe/snow-depth-in/20171210-1200z.html

like I said midlands north especially you in the north of the region . 

[ACCOUNT DELETED]

3 minutes ago, Man With Beard said:

People are saying ECM = snow north of M4 because ... that's what its snow charts show!!

In reality: Marginal for snow between M4 and Birmingham. North of that: plenty plenty.

The ECM op is churning out this same solution run after run (slightly further south this time). In fact, if you check the archives, it is getting closest to the eventual solution consistently ATM, bar a couple of zany runs.

Still 5 days out so room for changes, but after the analysis of sliders I did earlier today, I'm afraid I would rate the chances of a northern correction more highly than a southern one, give this set up.

So many on here are saying the best chance of snow will be anywhere north of the M4. Luckily for me, I live 1 mile north of the M4 in South Wales but for those that live a couple of miles south of the M4, take a stroll over the footbridges and come join us in our magical winter wonderland when it arrives! 

 

[blizzard81]

2 minutes ago, karlos1983 said:

I disagree with that, you could equally have said the same at 144. Why worry about a chart that we can’t even see yet anyway.  

 

 

The azores high is tilting away from us at 144 whereas it is tilting towards western Europe on the 240 chart. 

[Optimus Prime]

10 minutes ago, ANYWEATHER said:

Plenty of scope from Friday into Sunday, for snow to fall just about anywhere, and even though Ive not got the dewpoint figures but as long as they are at freezing or below ,despite an air temperature above freezing, snow will fall.

Lest not we forget wet bulb temperature? Probably more important than dew points. 

[mulzy]

In the near term, moderate differences still exist in the depth of the uppers that cover the country at day 3.  Does GFS have a cold bias when it comes to uppers in a northerly outbreak?

GFS

ECMWF

[jvenge]

8 minutes ago, Optimus Prime said:

But without taking into account relative humidity and temperature gradient? 

 

Quite absurd trying to forecast precip type 4-5 days out really. 

Well. Agree with trying to pick apart precipitation forecasts and thinking they wont change 5 days out, but at the same time, every model comes with a precipitation forecast and a breakdown of the type, quantity and location.

Therefore, I dont really understand this netweather weirdness of denying snow when it is shown or claiming snow when its not. We slip into forecast territory then, rather than actual output.

 

[MattStoke]

3 minutes ago, weirpig said:

https://weather.us/model-charts/euro/2017120512/europe/snow-depth-in/20171210-1200z.html

like I said midlands north especially you in the north of the region . 

I think it may be touch and go here. A slight southward and westward correct would be nice, from a totally selfish point of view! Hoping to catch the Cheshire Gap streamer on Friday, anyway.

[LRD]

4 minutes ago, blizzard81 said:

The azores high is tilting away from us at 144 whereas it is tilting towards western Europe on the 240 chart. 

Equally you could say it's ridging to Greenland... despite the purple over northern Canada. 

[Daniel*]

7 minutes ago, mulzy said:

In the near term, moderate differences still exist in the depth of the uppers that cover the country at day 3.  Does GFS have a cold bias when it comes to uppers in a northerly outbreak?

GFS

ECMWF

I must say I’ve never noticed so I don’t think so, the forecast mentioned any PPN inland falling as snow based on EC values you would not be seeing that, more likely a middle house between the two. 

Edited December 5, 2017 by Daniel*

[Man With Beard]

9 minutes ago, weirpig said:

https://weather.us/model-charts/euro/2017120512/europe/snow-depth-in/20171210-1200z.html

like I said midlands north especially you in the north of the region . 

Those snow charts need a public health warning though!! They often invent snow where there is none!!

I find the better ECM guide on weather.us is the "significant weather" charts

[swfc]

Well its seems we have a "slider gate" scenario hitting the headlines on here and a bout of rutting!!! Not sure if its that worth getting to stressed over ladies to be honest. These things are so difficult to pin down by the meto ete even up to 24 hrs.just enjoy the crisp cold weekend and you may catch a bit of snow or a shower or two.relax 

[Geordiesnow]

5 minutes ago, mulzy said:

In the near term, moderate differences still exist in the depth of the uppers that cover the country at day 3.  Does GFS have a cold bias when it comes to uppers in a northerly outbreak?

GFS

ECMWF

I think it does have a cold bias in general as the UKMO run is fairly similar in terms of uppers but to counteract that slightly, does the GFS have a higher resolution which means it can be more precise in terms of details on the upper air temp charts? Take Siberia for example, ECM shows a pool of -28 hpa yet on the GFS for the same timeframe it shows a pool of -32 uppers. The annoying answer is we will never know for certain which is right but basing on the last Northerly for this area and looking at the temps/dew points that was recorded during that time, I will say the ECM is probably the more accurate unfortunately.