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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: Crewe, Cheshire
  • Weather Preferences: Snow, storms and other extremes
  • Location: Crewe, Cheshire
Just now, s4lancia said:

8 days for astronomical winter. March this year shows why that should be used for ‘winter’, not the meteorological winter version. Far more cold Marches than Decembers.

March temperatures can get into the 20s. It's a spring month. Day length is on par with late September too.

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Posted
  • Location: STEVENAGE, HERTS (100M ASL)
  • Location: STEVENAGE, HERTS (100M ASL)
33 minutes ago, MattStoke said:

Can’t understand why people keep claiming that the cold was previously forecast for before and then around Christmas when the strat warming was always forecast to occur just after Christmas. Doubt we we’re going to see the effects of strat warming before it had occurred....

To be fair there were several NW members forecasting cold before or during Christmas and this is, in all likelihood,  what has stuck in some people’s minds - regardless of the SSW 

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

I said yesterday - the best way to describe current conditions is 'a state of flux', and fully expect wild swings from model run to run, and lots of divergence. Today has proven this point, we have had significant variance between GFS and ECM, the former wanting to bring in a raging zonal jet, only for it to back away quickly from this idea (how often does this happen - all the time!), whereas ECM is now showing an increasingly colder outlook as we move into the New Year, with high pressure holding firm and building further north - embedded surface cold air, and light winds will spell freezing temps. We saw on christmas eve how with high pressure ridging just a bit north enabled low temps with frost lingering all day - you don't need very cold uppers at this time of year to produce ice days... 

Will ECM swing back to an atlantic onslaught - I doubt it, it was right in mid Dec compared to GFS which had to retreat from its quick atlantic onslaught - delaying it at least 48 hours..

ECM is showing major amplified flow, with significant warm air advection through mid atlantic - no wonder the high pressure is set to pump into a major one with core 1040 heights - the atlantic will struggle to push it aside. 

All eyes on the azores high - it has been a spoiler in recent weeks, there are signs it may be forced westwards, this would be the trigger to sending low pressure further southwards opening up the door to a wedge of robust heights in the Iceland region.

 

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)
30 minutes ago, bluearmy said:

If you want to see the correction in the Atlantic being pushed back, check out the charts from the normally consistent eps mean anomoly for the last three 12z runs for current day 10 left to right oldest to newest 

 

818445CB-EBA0-4C12-8CA9-2787555FD2BA.thumb.jpeg.d40a20d59ee9e6573f090219531eeb1d.jpeg B85E3450-B8F5-4292-9410-4696BE55EE35.thumb.jpeg.5069a3f3cb26cfdee5e5379984d16904.jpeg25D081EF-AA3F-4BBF-9CAB-E36FA0396CEA.thumb.jpeg.b6b72d47228b30d657e0368c4e334b08.jpeg

Shows the extratropical response to the tropical cycle being picked up on more and more; GWO phase 5 supports the latest D10 anomaly. Remains to be seen whether it can withstand the MJO being more amplified in P6 than this model is going with at the mo; odds are it will be given SSW interaction with tropical convection.

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Posted
  • Location: Solihull, WestMidlands, 121m asl -20 :-)
  • Weather Preferences: Cold and Snow -20 would be nice :)
  • Location: Solihull, WestMidlands, 121m asl -20 :-)
9 minutes ago, FiftyShadesofSnow said:

Your interpretation of March being part of Winter. 

I can sort of see where your coming from but back in 2013 in my backyard I had 20+cm and daytime temps didn’t get above -1...you don’t  see that in September.

Edited by Dancerwithwings
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Posted
  • Location: Kirklees, West Yorks
  • Weather Preferences: Winter
  • Location: Kirklees, West Yorks

What date does the ssw officially start? Just to add look at how uncertain the models were last winter with the ssw. I think things will start unearthing soon. I believe we are in uncharted territory and the models are struggling to get grips on it. The models are flipping from zonal to blocked scenarios. Thats quite a difference in patterns for the northern hemisphere on a wide scale, so that just says it all. Things are likely to change

Edited by Snowjokes92
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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset
2 minutes ago, Snowjokes92 said:

What date does the ssw officially start? Just to add look at how uncertain the models were last winter with the ssw. I think things will start unearthing soon. I believe we are in uncharted territory and the models are struggling to get grips on it. The models are flipping from zonal to blocked scenarios. Thats quite a difference in patterns for the northern hemisphere on a wide scale, so that just says it all. Things are likely to change

Currently January 1st, give or take a day.

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Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset
3 minutes ago, s4lancia said:

March tends to have more lowland wintery episodes than December.

... but also takes something that bit more exceptional to deliver. I can count many more December wintry episodes in my lifetime than March. That's living in the south though...

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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.
10 minutes ago, FiftyShadesofSnow said:

Your interpretation of March being part of Winter. 

It isn't an interpretation. It's a fact. Winter is defined in different ways. https://en.m.wikipedia.org/wiki/Winter#Astronomical_and_other_calendar-based_reckoning

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Posted
  • Location: Kirklees, West Yorks
  • Weather Preferences: Winter
  • Location: Kirklees, West Yorks

Can anyone remember for comparison how the models handled the output a few days before the SSW last winter? So we can compare similarities to the output now and get am idea on how it may affect model output

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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset
Just now, FiftyShadesofSnow said:

No I agree it maybe a thing, it's just not the thing shared by most. Forget cold Marchs it's Spring, they tend to lead into fine sunny weather, quickly. Marchs have more lowland wintry episodes than December maybe, but December is leading into Xmas, Winter, were buzzing....March leads as a Spring month into April showers. Il take Dec over March all day long.

It is definitely a thing.

Fair enough, at this point we will go around in circles. I prefer to call winter from the winter solstice to the spring equinox, you prefer to go by the meteorological timescale. Both equally viable today.

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Posted
  • Location: Drayton, Portsmouth
  • Location: Drayton, Portsmouth

ECM ensembles 12th Jan - similar story to 9th: 20 members with uppers -5C or below in many parts, and out of the remaining 31 members, not an awful lot with positive uppers. 

 

Edited by Man With Beard
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Posted
  • Location: Burton-on-Trent (90m), Larnaka most Augusts
  • Location: Burton-on-Trent (90m), Larnaka most Augusts
18 minutes ago, Snowjokes92 said:

Can anyone remember for comparison how the models handled the output a few days before the SSW last winter? So we can compare similarities to the output now and get am idea on how it may affect model output

I haven't been comparing to last year but I have been comparing to 2013 as that SSW happened almost the same date as this one. They are very similar so far with high pressure to our south in the days proceeding the wind reversal. Then shortly after the 2013 SSW low pressure to our North suddenly weakened allowing high pressure to migrate North and a scandi block to set up. We are now beginning to see signs of thks, especially in the ECM. It is why I have maintained for a while now to wait until the SSW is close to happening before waiting to see what the models show. The ECM is showing that weakening of lows to our North and signs that we might get a push North with our high.

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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
43 minutes ago, Man With Beard said:

ECM ensembles 12th Jan - similar story to 9th: 20 members with uppers -5C or below in many parts, and out of the remaining 31 members, not an awful lot with positive uppers. 

 

Whats the composition of the upper cold clustering, ie - mainly Northerly, mainly Easterly or combination of both?

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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl

No comment on GFS 18z - not surprised it shows the high sinking very quickly south, despite it shown to ridge north and north east - it seems to split the trough to the east of it - all rather odd.. creating shortwave activity to ride over it, whilst also building heights to the NW out from the Pole. In my view its an odd evolution.

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire

See the upgrades? Compare and contrast. There are so many examples I could use today. Trying my best to get the message across for all you cold lovers

gfsnh-0-192.png

gfsnh-0-168.png

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Posted
  • Location: Derry 106m asl
  • Location: Derry 106m asl
4 minutes ago, Team Jo said:

There aren’t mods on here 24/7.. believe it or not we have lives too. Also, it’s Friday night. 

If anyone is in any doubt, It is a lot easier if you can report the post(s) you are concerned about rather than posting that you are concerned about posts. This sends us a notification but also allows us to look at the specific post and then sort them out, rather than deal with the problem posts and all the posts saying that there is a problem post.

Scrolling through, I saw a comment about Moderating consistency. Sorry it’s not to expectation, small thing called Christmas holidays happening and unfortunately my three year old requires far more moderating than you lot do.....

Just a lurker in here, but have utmost respect for the amateurs, the experts and the mods, especially when the models don't have a clue and we have to figure it out TOGETHER..but hate it when it's a cat fight....I also have a three year old to moderate and explaining the lag time between a SSW and a tropospheric response into snow that he can touch is a triffle difficult ... I suspect I will have about two weeks of "are we there yet" coming 

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Posted
  • Location: Heckmondwike, West Yorkshire
  • Location: Heckmondwike, West Yorkshire
9 minutes ago, damianslaw said:

No comment on GFS 18z - not surprised it shows the high sinking very quickly south, despite it shown to ridge north and north east - it seems to split the trough to the east of it - all rather odd.. creating shortwave activity to ride over it, whilst also building heights to the NW out from the Pole. In my view its an odd evolution.

It is an upgrade in the 4 to 6 day timeframe and that's all that counts. The GFS 18z doesn't have a clue post day 7 at the best of times and believe me, these are not the best of times for weather models

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