Model output discussion - cold spell approaching?

[PDM]

9 minutes ago, daz_4 said:

Does it though? Maybe I'm reading the chart wrong but I see most of the Europe average or slightly above and cold locked away in Scandinavia.

I read this as UK going below average temps

[MATTWOLVES 3]

10 minutes ago, daz_4 said:

Does it though? Maybe I'm reading the chart wrong but I see most of the Europe average or slightly above and cold locked away in Scandinavia.

Its one chart that I think as improved since the previous one. Let's not forget major snowfalls tend to come when the Temps are just the right side of marginal,we could easily get deep cold and bone dry..I know which outcome I would prefer.

Edited January 11, 2021 by MATTWOLVES

[stewfox]

2 hours ago, Severe Siberian icy blast said:

I don't understand why everyone's posting charts over t200 with BOOM, its got as much change of verifying as me loosing a stone in 1 wk. Just not gonna happen. 

 

Do you have a sponsorship form ?

T200 looks messy

[pyrotech]

1 hour ago, johnholmes said:

That's what i'm seeing too. Unless the dashes don't imply air mass direction.

 

See my comment above, no hey do not.

 

 

Hi John, i have followed your advice for years and aware of your background.

May i ask that you share your 500mb guidance so others can learn as they are by far the best use for longer term forecasting. Your knowledge and experience is very welcome here and sharing that knowledge again with new members can only make this a better place. Glad your still here and hope your well. pyro 

[MattStoke]

1 hour ago, Jamie M said:

Tweet from Mike Ventrice with ECMWF weeklies that peaks some interest.

Temperature anomaly of +/- 0.5’C doesn’t bring much excitement to me.

[Bricriu]

1 hour ago, mushymanrob said:

 

 

 

Hi guys

The red/blue dotted lines are pressure anomalies, not flow lines , the green lines are the mean upper wind direction from West (left) to East (right).

Being the mean over that period allows surface winds from other directions, but the further away from the mean, the shorter their duration. So we could have a Northeasterly, but it wont be sustained, and to balance out the mean, for every Northeasterly there needs to be a westerly.

Im msure my mentour @johnholmes will correct me if this is inaccurate.

So if i understand you correctly, it all looks to be unfolding as per recent UK Met Office Long Range guidance; a brief potent cold spell, but it's unlikely to be a sustained one. So it could well be an ebbing  and flowing between milder and colder air, with some part of England as the boundary. That could mean ecstasy for some and heartache for others further south and west.

Edited January 11, 2021 by Bricriu

[mulzy]

2 minutes ago, MattStoke said:

Temperature anomaly of +/- 0.5’C doesn’t bring much excitement to me.

It is a week three anomaly - will probably change. One thing for sure is that Scandinavia has locked in brutal cold.

[MattStoke]

8 minutes ago, mulzy said:

It is a week three anomaly - will probably change. One thing for sure is that Scandinavia has locked in brutal cold.

But the excitement some U.K. cold weather lovers are showing over that tweet/chart, as if it’s showing severe cold here, is ridiculous. It doesn’t show that at all. It shows average temperatures. I couldn’t give a stuff if there’s plenty of cold air to our east unless we are going to ‘tap into’ it.

Edited January 11, 2021 by MattStoke

[danm]

Bit perplexed with some of the posts suggesting central/northern areas are primed and the south missing out. At this range, the overall synoptic pattern looks great but the micro details and specific placement of any battleground scenarios are nowhere near being resolved, let alone guaranteed. A few hundred miles either way on the macro, NH scale is miniscule. 

[SLEETY]

you need brutal cold over scandinavia,if you want to see it over here,as thats the direction we get our coldest weather from,so good sign.

Need a cold set of afternoon runs now..

[johnholmes]

22 minutes ago, pyrotech said:

Hi John, i have followed your advice for years and aware of your background.

May i ask that you share your 500mb guidance so others can learn as they are by far the best use for longer term forecasting. Your knowledge and experience is very welcome here and sharing that knowledge again with new members can only make this a better place. Glad your still here and hope your well. pyro 

Will try and post a link to simple explanations and will pm you.

[Bricriu]

9 minutes ago, danm said:

Bit perplexed with some of the posts suggesting central/northern areas are primed and the south missing out. At this range, the overall synoptic pattern looks great but the micro details and specific placement of any battleground scenarios are nowhere near being resolved, let alone guaranteed. A few hundred miles either way on the macro, NH scale is miniscule. 

I  think initially almost everywhere will do quite well, but if we go by the UK Met Office long range and some of the runs, the cold could retreat further north and east. Of course many area could still do well in that scenario, depending where the boundary is, but Ireland  and  parts of England and Wales could be the places that  come under a milder influence while others areas are buried in snow.

Edited January 11, 2021 by Bricriu

[KTtom]

6 minutes ago, MattStoke said:

But the excitement some U.K. cold weather lovers are showing over that tweet/chart is ridiculous. It’s rubbish.

I think its a clever way of using dramatic colours to fool people, look at the key and you see its no where near as dramatic as it looks. Good post above regarding the battleground scenario's,  absolutely no point anyone getting excited yet as in these cases the heavy snow band is usually fairly narrow, a hundred miles too far north east and youll be dry, 100 miles south west, your wet...IF it happens we'll still be debating sweet spots 48 hours before the event. 

[Chesil View]

14 minutes ago, Bricriu said:

So if i understand you correctly, it all looks to be unfolding as per recent UK Met Office Long Range guidance; a brief potent cold spell, but it's unlikely to be a sustained one. So it could well be an ebbing  and flowing between milder and colder air, with some part of England as the boundary. That could mean ecstasy for some and heartache for others further south and west.

Or of course the boundary could be further south and  west than envisaged or further north and east

[Daniel*]

2 hours ago, Scott Ingham said:

Looking at them temperatures, check precipitation (many spikes)

Check manchester or Sheffield. (A lot colder?) Precipitation spikes?

If the answer to all them questions is yes i would suggest they are maybe latching on to @feb1991blizzard previous posts of a potentially very snowy (for the midlands and me in yorkshire) pattern of west based nao and battleground.

Would be cruel down south and x rated for snow up north 

Its a strong possibility. I thought wed have a cut off greenland high moving to west based -NAO in discussions with Steve

Bit colder but not cold. Most of precip is signalled later this week.

[danm]

4 minutes ago, Bricriu said:

I  think initially almost everywhere will do quite well, but if we go by the UK Met Office long range and some of the runs, the cold could retreat further north and east. Of course many area could still do well in that scenario, depending where the boundary is, but Ireland  and  parts of England and Wales could be the places that  come under a milder influence while others areas are buried in snow.

Ofcourse, and I think that's true with most cold spells. Milder air always encroaches from the south or west, so it is almost always the north that hangs onto the colder air longest. Before that point, assuming the cold reaches all of us, any details on which areas will get buried and which areas miss out is impossible to determine. 

If we all remember the BFTE, it was assumed that mainly eastern areas would see the heaviest snowfall. In fact, the battleground that set up at the end of that week dropped huge amounts of snowfall to the far south of the Republic of Ireland. 

[frosty ground]

8 minutes ago, KTtom said:

I think its a clever way of using dramatic colours to fool people, look at the key and you see its no where near as dramatic as it looks. Good post above regarding the battleground scenario's,  absolutely no point anyone getting excited yet as in these cases the heavy snow band is usually fairly narrow, a hundred miles too far north east and youll be dry, 100 miles south west, your wet...IF it happens we'll still be debating sweet spots 48 hours before the event. 

Indeed but there could be several of these opportunities for heavy snow fall almost anywhere across the country. 

Long cold spell may not happen and the ensembles clearly show cold coming and going 

[Tim Bland]

1 minute ago, frosty ground said:

Indeed but there could be several of these opportunities for heavy snow fall almost anywhere across the country. 

Long cold spell may not happen and the ensembles clearly show cold coming and going 

Couldn’t agree more. I know these ensembles are as fickle as the op runs but they don’t scream long deep freeze. There is a clear signal for a slight warm up on 19th before going colder again. It’s worth remembering though that in mid- late Jan we don’t need temps to far below normal for snow. I’d also rather roll the dice with Atlantic systems pushing up against the cold block as that is where proper snow falls can come from. It seems the meto are on this page as well. So no deep cold but plenty of scope for deep snow. Where and when is up for debate and I would say it’s not necessarily the north that is favored for snow, it could be that the north is cold and dry whilst the central belt is seeing the rain / snow boundary ..all to play for if it’s snow you are after ️

[Bricriu]

17 minutes ago, danm said:

Ofcourse, and I think that's true with most cold spells. Milder air always encroaches from the south or west, so it is almost always the north that hangs onto the colder air longest. Before that point, assuming the cold reaches all of us, any details on which areas will get buried and which areas miss out is impossible to determine. 

If we all remember the BFTE, it was assumed that mainly eastern areas would see the heaviest snowfall. In fact, the battleground that set up at the end of that week dropped huge amounts of snowfall to the far south of the Republic of Ireland. 

That 2018 situation was where a west based nao actually worked in our favour to bring about a once in a lifetime snow event, but also ensured the cold spell was brief.

You're right of course we can't say for definite  which areas exactly would get buried, until we see where the boundary occurs- assuming it actually  evolves this way in the first place.

Edited January 11, 2021 by Bricriu

[Had Worse]

19 minutes ago, Daniel* said:

Bit colder but not cold. Most of precip is signalled later this week.

Hi Dan,

If i'm reading right, Manchester, 17 miles away, is averaging 2 -3 inches  plus.

Is that over the period of the chart or per day?

[Scott Ingham]

23 minutes ago, Daniel* said:

Bit colder but not cold. Most of precip is signalled later this week.

Them temp ranges would still back sliders and battleground. Tends to be less cold in this set up and i dunno. 

I count

Days 1 - 5 - 15mm

DAYS 5- 10 - 15MM

Days 11- 16 - 25mm

It smells of battleground to me Dan them EPS

I dont wanna be in this forum if thats west based nao with battleground scenarios. Im well placed in that scenario but the south east contingent are gunna run out of toys to throw!

 

Edited January 11, 2021 by Scott Ingham

[Cold Winter Night]

Another interesting round of 12Z's coming up soon.

This morning I went through this:

1. Quickly going through the runs: Wow! Charts look great, massive upgrade!
2. Looking more closely: Yikes, they are not that good at all. Heights way too far Northwest.
3. Ensembles, esp. EPS + plume De Bilt confirm: downgrade. The De Bilt plume was actually a bit of a cold bucket of water in the face.

It is good for you folks who live in Scotland, the North of England, Northern Ireland perhaps, but not for those in the South or for me in Holland.

Whether it is formally called a West based -NAO or not does not matter much, but we really need heights between Greenland and Norway for deeper and lasting cold.

I was hoping for a stronger Scandi high to develop in the 72-120 timeframe. This is still getting modelled stronger every run and has my interest these 12Z's.
If it gets strong enough, it will sustain itself through CAA and WAA. It would force an undercut, allowing depressions to enter from the West and cold to come in from Siberia. That would be my preferred scenario, some GEFS-members do this to an extent. It would assist in a Greenland High that extends in the GIN area. Retrogressing Scandi Highs are the foundation of much better Greenland Highs.

Based on EC-72 this morning it would look like this:
 

[Daniel*]

2 minutes ago, Had Worse said:

Hi Dan,

If i'm reading right, Manchester, 17 miles away, is averaging 2 -3 inches  plus.

Is that over the period of the chart or per day?

Hi,

Over the period. If you look at bottom easier to figure out shows mean accumulated rainfall over next 15 days. Averages over 3” by end (15 days) accumulated. Forecasting 49mm over the space of this week, so a lot of rain, and well a lot of snow for some.

[Had Worse]

1 minute ago, Daniel* said:

Hi,

Over the period. If you look at bottom easier to figure out shows mean accumulated rainfall over next 15 days. Averages over 3” by end (15 days) accumulated. Forecasting 49mm over the space of this week, so a lot of rain, and well a lot of snow for some.

I partly figured it out before you answered, thanks anyway.

Where I am, its wetter still so Id add another 25 mm on the the Manc total.

[london-snow]

Can we just get to this possible cold outbreak before talking snow chances, duration of the spell itself etc etc..

I feel that it will calm a lot of nerves and toy throwing and doom and booms..

The uk north to south, east to west is a tiny mass of land not even a thousand miles HUNDREDS which equates to needle in a haystack when trying to pin down weather patterns especially when the abnormal occurs such as a ssw.