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Model Output Discussion - Snow for some, but what else is in store?


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Posted
  • Location: Bury St Edmunds, Suffolk
  • Weather Preferences: Cold, frost and snow
  • Location: Bury St Edmunds, Suffolk
6 minutes ago, Tim Bland said:

As others have said : GFS & GFSp both starting to give a slightly consistent signal for a slider with a chance of snow late next weekend. One to watch for sure...

4D64D2CD-4B79-444F-85A6-0CC3E347A52C.png

86BE53D8-E163-4C44-B90B-ACCA5E75070D.png

9CDE1F7F-917B-4F44-92F4-DE138408B396.png

We all know that'll be in the Chanel/northern France by then

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Posted
  • Location: King’s Lynn, Norfolk.
  • Weather Preferences: Hot and Thundery, Cold and Snowy
  • Location: King’s Lynn, Norfolk.
23 minutes ago, General Cluster said:

So, here we are at Day 7, and it's welcome back to The Water Margin:

h500slp.png    h850t850eu.png

Always, when I see charts like these, I wonder just how marginal things would be, were we able to superimpose these exact synoptics onto the Northern Hemisphere's (average sea-ice, SSTs and snow-cover...) basal conditions, as they were in say 1980?

 

Sorry if slightly off topic. I do wonder myself! It must play some part. Seems like we could see some decent ice  returns by March if the serious cold keeps setting up shop over the Barents. If we see more mid latitude outbreaks of cold and snow going into February and March, it would be a start at least of increasing albedo effect and reducing more damage to the arctic and hopefully a slower melt season than last. 

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Posted
  • Location: Bury St Edmunds, Suffolk
  • Weather Preferences: Cold, frost and snow
  • Location: Bury St Edmunds, Suffolk
3 minutes ago, General Cluster said:

At least it'll have an expensive aroma?

Can't beat the smell of snow!

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Posted
  • Location: Broxbourne, Herts
  • Weather Preferences: Snow snow and snow
  • Location: Broxbourne, Herts
4 minutes ago, Snow Queen one said:

Tim Bland those charts you posted are Wednesdays charts.  Can you post updated ones plz

Are they?   My French must be terrible!

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Posted
  • Location: Orpington Kent.
  • Location: Orpington Kent.
12 minutes ago, NewEra21 said:

We all know that'll be in the Chanel/northern France by then

I hope.. personally living in Kent I'm perfectly content with southward shunts bringing us all into a colder airmass at macro level.. get me there and I'll take my chances on what might pop up at micro level.. and say this quietly I'm sensing we are moving south at macro these past 24 hours of modelling

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Posted
  • Location: Oxford
  • Location: Oxford
4 minutes ago, Nick F said:

Morning, trends still good from the 06z.

Agree with not taking operational charts beyond day 6 too literally, particularly with added uncertainty with how the models deal with the imprint of the recent SSW and its displacement and, today, the brief split of the SPV. Though the ramifications of the split and further weakening of the already weakened SPV may not be seen until later this month.

ecmwf10f48.thumb.png.bfd99e0b6a5a2446f93b97bb2894c901.png

The 06z op's positive signal for coldies is it delays phasing of Atlantic troughing with the NE Europe trough, which gives chance to get the arctic cold in. Get the arctic cold air in and, should the southern arm of the jet undercutting the Greenland block be weak enough, then weaker lows moving over the Atlantic under the block will have do a 'slider' as they encounter cold air over NW Europe. If the jet under the block get too strong, then we end up more like 00z EC and the Atlantic troughing gradually phases with the NE Europe trough.

We see 00z/06Z GFS op diverge from the 00z EC det past day 6 with troughing over Europe, GFS digs a deep trough, while EC is much flatter. We need the deeper trough, as this diffluent nature of such a deep trough, i.e. strong jet on the western side of the trough, will better advect arctic cold south across the UK than the EC's flatter trough.

Day 8 - Sat 23 Jan 00z

GFS 00z + 06z

GFSOPEU00_192_1.thumb.png.5a5e514366e611aaeed85419259d4cfd.pngGFSOPEU06_186_1.thumb.png.2586e6bb51b971f124a3436da97d0892.png

EC 00z

ECMOPEU00_192_1.thumb.png.a5303b278de759f8d486eefaa02a6261.png

We can see from the EC spreads the uncertainty of 500 hPa heights over the Atlantic but also with the heights over Europe, which suggests there could be improvements with regards to higher heights between NE European trough and troughing over NW Atlantic plus deeper troughing over Europe as per GFS. Also note spread over western Greenland, maybe EC det retrograding the block too much?

EEM1-192.thumb.gif.72d5a5439119486dde4c5f8fef218653.gifEEM1-216.thumb.gif.8ac85682a309d20390cfb866bceb77ae.gif

So my advice, if you are going to looks beyond 6 days, look for consistency / trends and match this with spread charts like above. The NE Europe trough looks stable bet, but Atlantic, W and S Europe there's more uncertainty.

Hi Nick,

superb analysis totaly agree.

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Posted
  • Location: Pontypool, 132m ASL
  • Weather Preferences: Extremes
  • Location: Pontypool, 132m ASL
2 minutes ago, Battleground Snow said:

Indeed, the mean is also somewhat better at 204.

Nice downward trend in graph form with not too much scatter at that range

gensnh-31-1-204 (3).png

gfs-london-gb-515n-0e (18).jpeg

Yes loving this set for a week's time:

gfs-pontypool-gb-515n-3w.thumb.png.df9bf76bc6fdcc202108c4370b3f59c7.png

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Posted
  • Location: Banbury
  • Weather Preferences: Deep Deep Snow causing chaos
  • Location: Banbury

image.thumb.png.d1256e166e31ec300b35b1e0cfa5b851.png

Looks like a slider coming on the Control as well , hopefully this could get interesting 

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Posted
  • Location: Banbury
  • Weather Preferences: Deep Deep Snow causing chaos
  • Location: Banbury

Slider at 228h from the Control

image.thumb.png.028afd47db74dc36ac4183a68031a792.png

Takes the snow to the South of the UK at 240 - but the slider scenarios are a good trend I think 

image.thumb.png.7afbb8ba012aa5ae81de67d390d4cd3c.png

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Posted
  • Location: Beccles, Suffolk.
  • Weather Preferences: Thunder, snow, heat, sunshine...
  • Location: Beccles, Suffolk.

An interesting end to the GFS 06Z, IMO...

I'm not attempting pin-the-tail-on-the-donkey here, but merely musing at the projected extents of the various air masses. But, as has happened quite a lot, these past three-years, the early build-up of +10 to > +15C Uppers, away to our south (in conjunction with the typical springtime random bits of shattered tPV) could mean that a volatile (more volatile than is usual perhaps?) spring might ensue...?

h500slp.png    h850t850eu.png

PS: Late winter into spring has always been my favourite time of year!

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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon

HARMONIE 6z take on Saturdays snow risk, seems to tie in well with the MO warning, could be heavy for some for a while.

anim_sxm6.gif

 

 

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Posted
  • Location: Arendal, Norway
  • Weather Preferences: Snow, snow and more snow!
  • Location: Arendal, Norway

If you look one by one the ensembles there is no possibility of severe Siberian cold penetrating into Europe. The reason is low pressure in Scandinavia, quite the opposite of what we all hoped. 

Moreover, Atlantic seems more and more active after 240hr..

So probably La nina force winning the battle against SSW?

Also, a lot of the ensembles show the same high pressure in western Russia that was too stubborn  during December, coming back. Rinse and repeat?

Edited by topo
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Posted
  • Location: Liphook
  • Location: Liphook

Looks like the set-up is getting increasingly active in terms of LP developing in the Atlantic and heading broadly in our direction.

Exactly where they end up makes a huge difference in the actual weather clearly.

The key thing which may scupper alot of potenial is if we can't get a cold enough drag of air into the region in the first place and we end up with several wet LPs racing across the UK increasing the flooding risk.

As long as we can get a surface flow somewhere from the S-SE direction ahead of any low, we stand a chance of snow even if the uppers on the face of it really aren't all that good. However obviously the colder we can go, the more margin for error we have, especially for the south which is always more at risk at milder intrusions, especially in a situation that really is very borderline like we are seeing set-up again.

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Posted
  • Location: Midlands
  • Weather Preferences: Very Cold, Very Snowy
  • Location: Midlands
5 minutes ago, kold weather said:

Looks like the set-up is getting increasingly active in terms of LP developing in the Atlantic and heading broadly in our direction.

Exactly where they end up makes a huge difference in the actual weather clearly.

The key thing which may scupper alot of potenial is if we can't get a cold enough drag of air into the region in the first place and we end up with several wet LPs racing across the UK increasing the flooding risk.

As long as we can get a surface flow somewhere from the S-SE direction ahead of any low, we stand a chance of snow even if the uppers on the face of it really aren't all that good. However obviously the colder we can go, the more margin for error we have, especially for the south which is always more at risk at milder intrusions, especially in a situation that really is very borderline like we are seeing set-up again.

Quite incredible how busy the Atlantic is now looking given the warming/s and the time of year. Should just about be thinking about quietening as we move towards the end of January. You are spot on. Potentially very wet in the South and very snowy in the North.  Where will the dividing line be......

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Posted
  • Location: Fleet, Hampshire
  • Location: Fleet, Hampshire
57 minutes ago, NewEra21 said:

We all know that'll be in the Chanel/northern France by then

Well, if it does that will mean that the trough has dug down further and we will be in the colder air - so win win - maybe

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Posted
  • Location: Liphook
  • Location: Liphook
3 minutes ago, Climate Man said:

Quite incredible how busy the Atlantic is now looking given the warming/s and the time of year. Should just about be thinking about quietening as we move towards the end of January. You are spot on. Potentially very wet in the South and very snowy in the North.  Where will the dividing line be......

I wouldn't be surprised if there was a really major snowfall at some point, especially further north where there is just a little bit more leeway due to the cold penetration being stronger.

Also whilst I do think the south will struggle, I'd still expect at the least decent transient events as long as we can keep the airflow coming in from the SE ahead of any LP (that requires none of that bowling ball LP nonsense!)

 

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Posted
  • Location: Bury St Edmunds, Suffolk
  • Weather Preferences: Cold, frost and snow
  • Location: Bury St Edmunds, Suffolk
4 minutes ago, ptow said:

Well, if it does that will mean that the trough has dug down further and we will be in the colder air - so win win - maybe

Very true, overall the further south everything is the better.

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Posted
  • Location: North West of Ireland
  • Location: North West of Ireland
2 hours ago, jules216 said:

If you ask me I find the medium/long range charts pretty underwhelming considering we have a post SSW period coming up, of course models can swing towards better(or worse) but I see a broad westerly pattern generally in Europe, to me this does look like swinging towards 2019 scenario rather then 2018,2013 or 2006. I am kind of lucky to have gotten the 7 day cold spell in central Europe as things are looking average going forward(GEFS,EPS,EC46d) snow mostly confined to Scandinavia or high ground elsewhere(500m+) Of course February can still bring noteable stratospheric responses too, but also we have a strong shift of Nina to west based and also +IOD emerging(SE Europe ridge) The boundary between cold and mild will be hard to predict still,hoping for a change of models to better and trouging to be more to the east(not east Atlantic)

20210115094342-a532b7b48b7b960e29eafc04a3bdaba0d53e3c74.png

I suspect the glosea5 model envisaged the la nina forcing probably overriding the SSW factor in our part of the world. It certainly seems to be unfolding that way. Despite people saying you can't trust models past day six, and hope casting if this feature does this or that we'll be in the freezer, the consistent signal now is for deep cold to be outside the reach of most, if not all of us. The best we can hope  for is that sometimes we are on the right side of the boundary of the colder airmass, although it looks  far more likely to be over parts of northern  England  and Scotland than the rest of us.  From an imby perspective i could get snow later next week, but its looks to be brief. The best case scenario now looks to be brief colder interludes before milder weather returns.

Edited by Bricriu
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Posted
  • Location: Midlands
  • Weather Preferences: Very Cold, Very Snowy
  • Location: Midlands
3 minutes ago, kold weather said:

I wouldn't be surprised if there was a really major snowfall at some point, especially further north where there is just a little bit more leeway due to the cold penetration being stronger.

Also whilst I do think the south will struggle, I'd still expect at the least decent transient events as long as we can keep the airflow coming in from the SE ahead of any LP (that requires none of that bowling ball LP nonsense!)

 

Think you are spot on.

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