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Hunt For Cold: Model Discussion - Heading Into Christmas


Paul
Message added by Paul

If you're hunting for cold potential in the model output, this thread is for you. But if you'd like to look more widely at the models, please head over to the general model discussion thread.

This is a model related thread, so a general, frequent theme of the model output is a given, but it will not be strictly enforced:

  • Some topic drift, humorous responses etc are fine
  • Posts likely to lead the thread off on an entirely off topic tangent are not ok. For example (but not solely limited to): Posts entirely or mainly about Met Office, BBC or media forecasts with little or no model context, and posts solely asking for a weather forecast in a specific location.
  • Posts which start with something like 'I know this is off topic but ...' are not ok.
  • Posts which break the forum guidelines are not ok (eg trolling, troll-hunting, weather guilt tripping, overly defensive/aggressive, abusive, disrespectful to others)

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Posted
  • Location: Carryduff, County Down 420ft ASL
  • Location: Carryduff, County Down 420ft ASL
7 minutes ago, frosty ground said:

icon-9-180.png?19-00icon-9-168.png?19-12

Much milder run from the ICON... Block shunted east

To be fair, that only shows out to the 26th. The SSW not due to impact until mid January into February.

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
13 minutes ago, Daniel Smith said:

We saw a mid-month cold spell.. blocking did materialise, in fact it was such a strong block the high was showing up on Stratospheric charts, rather rare for a block to that extent to develop across Scandinavia. 

It wasn't as long lasting/cold as perhaps expected but the general pattern was pretty spot on as was the timing.

I think that's fair enough. 

7 minutes ago, Tim Bland said:

Most places hardly had a frost and almost no one had snow, so for December I wouldn’t call last week a cold spell

I'm not really sure what you're saying... we should stop hoping that a SSW will produce a cold spell for the UK.. ?

Once this Warming event takes hold, we will start to see some eye candy popping up, whether it materialises or not god knows! But the chances of a cold spell are increasing significantly as we head into 2019.. there's really no argument against that? is there? 

Edited by karlos1983
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Posted
  • Location: Nr Malton, North Yorkshire 53m
  • Weather Preferences: Snow/Thunderstorms
  • Location: Nr Malton, North Yorkshire 53m

Id like to order the latest CFS month forecast please.

Rumour has it this model is highly accurate and ahead of the EC in regards to performance.

http://www.meteociel.fr/modeles/cfse_cartes.php?ech=894&mode=2&carte=0&run=10

In all seriousness though it shows what could potentially happen if the SSW effects in the trop are favourable, mid latitude block gradually migrating northwards.

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Posted
  • Location: Stoke Gifford, nr Bristol, SGlos
  • Location: Stoke Gifford, nr Bristol, SGlos
8 minutes ago, Daniel Smith said:

You wouldn't call a week of below average temperatures and uppers of -10c a "cold spell"? Just because you personally may not have seen snow, many people in the North did along with quite a freezing rain event for some areas, too. 

The lack of widespread snowfall doesn't mean it wasn't a cold spell, when it quite categorically was. 

It was a cold "snap".

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Posted
  • Location: North East Hampshire
  • Location: North East Hampshire
19 minutes ago, Tim Bland said:

Most places hardly had a frost and almost no one had snow, so for December I wouldn’t call last week a cold spell

I got down to -7c in Farnborough (suburban southern England).

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Posted
  • Location: Warsaw, Poland. Formerly London.
  • Weather Preferences: Four true seasons. Hot summers and cold winters.
  • Location: Warsaw, Poland. Formerly London.
5 minutes ago, Bristle boy said:

It was a cold "snap".

Is there an official definition of spell vs snap? 

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Posted
  • Location: Live in NW Kent by the Thames & work in SE London
  • Weather Preferences: Snowy November to March and Sunny and warm April to October
  • Location: Live in NW Kent by the Thames & work in SE London
8 minutes ago, Seasonality said:

Is there an official definition of spell vs snap? 

I always think of a snap to be 3 to 6 days and a spell 7days+ not sure officially however 

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

12s rolling.  What am I looking for, well first, I'm not that concerned about Christmas, the form horse looks to be an anticyclone reasonably close, temperatures dependent on wind direction and cloud, and largely dry.

Taking 25th as SSW day, we can expect extreme variations in model output in FI, while interesting to watch, the uncertainty here is massive, so nothing here can be nailed down.

Beyond that is watching the nature of the SSW and what follows in the stratosphere, in particular firming up on whether we get a split and if so where the bits of the dismembered vortex go.  

There is a lot to be interested in. 

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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset
6 minutes ago, Kentspur said:

I always think of a snap to be 3 to 6 days and a spell 7days+ not sure officially however 

In that case it was a cold ‘day’ here lol. Only Friday failed to get above 5C and was the only day that started below freezing. I suppose by this December’s standards though we could stretch as far as to call it a cold snap.

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Posted
  • Location: Bath, Oxford
  • Weather Preferences: Cold and snowy winters, hot and sunny summers with thunderstorms!
  • Location: Bath, Oxford
19 minutes ago, Seasonality said:

Is there an official definition of spell vs snap? 

I'd say snap is when it's just a few days like last week and a spell is much more prolonged and extreme like BFTE in March or December 2010.

I don't think last week counted as a cold snap apart from the freezing rain event, it was really just hill snow in Scotland.

Edited by Leon1
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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
9 minutes ago, Johnp said:

Nice UKMO - am improvement from this morning.

UE144-21_zkt0.GIF

Yes take that now over storms and rain, wouldn't be particularly cold unless clear skies over night, T850s:

image.thumb.jpg.0be341f058596323d3bbdb4a6b8ed2c7.jpg

OK for those who need to travel.  Actually, personally, there is nothing special about Christmas Day regards snow, any day will do, and you can't get a snow day if the  office is closed anyway!  My interest is on January.

Edited by Mike Poole
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Posted
  • Location: Bournemouth
  • Weather Preferences: Dry mild or snow winter. Hot and humid summer.
  • Location: Bournemouth

Nice. Stronger ridge. Ukmo has improved also

9BBA5C93-DB37-4521-978A-6DE467AB8D47.png

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Posted
  • Location: leicester
  • Location: leicester
44 minutes ago, frosty ground said:

icon-9-180.png?19-00icon-9-168.png?19-12

Much milder run from the ICON... Block shunted east

And then out comes the gfs and high is further west and north!!!more frost hopefully!!

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Posted
  • Location: Purley, Surrey - 246 Ft ASL
  • Weather Preferences: January 1987 / July 2006
  • Location: Purley, Surrey - 246 Ft ASL
38 minutes ago, Daniel Smith said:

You wouldn't call a week of below average temperatures and uppers of -10c a "cold spell"? Just because you personally may not have seen snow, many people in the North did along with quite a freezing rain event for some areas, too. 

The lack of widespread snowfall doesn't mean it wasn't a cold spell, when it quite categorically was. 

We never had uppers of -10c - they bottomed out at -8 near East Anglia.

It was certainly chilly for a few days, but not what I look forward to chasing in winter put it that way.

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Posted
  • Location: Morden, Surrey.
  • Location: Morden, Surrey.

With the touted SSW around christmas is it reasonable to think about a sudden swift response filtered into the output. Or are we always looking at a 2 week min lag time for what is going on high up to filter down? 

I remember a few years back a dreaded outlook but sudden change and run with it type which materialised (Not to sure if it was strat related though). 

 

Could we we we’ll see this happen post Christmas? 

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Posted
  • Location: Lytchett Matravers - 301 ft ASL
  • Weather Preferences: Snowy Winters, Torrential Storm Summers
  • Location: Lytchett Matravers - 301 ft ASL
4 minutes ago, london-snow said:

With the touted SSW around christmas is it reasonable to think about a sudden swift response filtered into the output. Or are we always looking at a 2 week min lag time for what is going on high up to filter down? 

I remember a few years back a dreaded outlook but sudden change and run with it type which materialised (Not to sure if it was strat related though). 

 

Could we we we’ll see this happen post Christmas? 

Depends on if we see a split PV or displaced. Split PV will give a quicker Trop response than a displaced PV

Pre-Christmas no way.

Edited by karlos1983
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Posted
  • Location: Wantage, Oxon
  • Weather Preferences: Hot, cold!
  • Location: Wantage, Oxon
1 minute ago, london-snow said:

With the touted SSW around christmas is it reasonable to think about a sudden swift response filtered into the output. Or are we always looking at a 2 week min lag time for what is going on high up to filter down? 

I remember a few years back a dreaded outlook but sudden change and run with it type which materialised (Not to sure if it was strat related though). 

 

Could we we we’ll see this happen post Christmas? 

Well it will happen post Christmas!

My money on 10th January for shift to cold, provided the dice fall right for us after the SSW.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.

Much better orientated ridging into Greenland on the GFS 12z as opposed to the 6z.

 

It might just hold the Atlantic back that bit better to get a cold plunge into Europe.

Edited by feb1991blizzard
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Posted
  • Location: Stoke Gifford, nr Bristol, SGlos
  • Location: Stoke Gifford, nr Bristol, SGlos
33 minutes ago, Seasonality said:

Is there an official definition of spell vs snap? 

Officially, my definition is 2-3 days = "Snap";

4-5 days plus anymore is a "spell".

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