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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: Nuneaton,Warks. 128m asl
  • Weather Preferences: Snow then clear and frosty.
  • Location: Nuneaton,Warks. 128m asl
1 minute ago, bluearmy said:

Agree Phil - the higher sharper ridge is certainly an option and wouldn’t be surprised to see the op jump there later ......from that point at day 10, could get interesting sooner ......

Yes i am starting to think that way. A short spell of nw/n winds then heights building north. 

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Posted
  • Location: Wincanton,Somerset
  • Weather Preferences: Channel low = Heavy snow
  • Location: Wincanton,Somerset

With December being quite mild or very mild for some... The model output really needs to behave to get a below average winter you would think...I dont think even the Met predicted December to be so poor by predicting a below average as a reasonable possibility 

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Looking on the positive side if one can under the cloud of doom 

There are possibly the good chances that down the line we won't see any real set in stone changes till the end of the week with just hints of changes in the coming days ,then we will see through the current smoke screen for the better

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Posted
  • Location: Hernia Bay
  • Weather Preferences: Heavy Snow
  • Location: Hernia Bay
26 minutes ago, Eastnorthwest said:

Looking on the positive side if one can under the cloud of doom 

There are possibly the good chances that down the line we won't see any real set in stone changes till the end of the week with just hints of changes in the coming days ,then we will see through the current smoke screen for the better

Totally agree. The gfs in particular isn't factoring in changes that have begun in the trop let alone the strat!! I Still think the runs will progressively Become more impressive from Hereon in and the impact of which should be felt around 15th as progged.... That's my take on it. 

Edited by snowfish1
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Posted
  • Location: Wath upon Dearne, Rotherham
  • Weather Preferences: Snow, severe frost, freezing fog and summer sunshine
  • Location: Wath upon Dearne, Rotherham
32 minutes ago, Dave Kightley said:

With December being quite mild or very mild for some... The model output really needs to behave to get a below average winter you would think...I dont think even the Met predicted December to be so poor by predicting a below average as a reasonable possibility 

As long as we get one or two cold snowy periods of a decent length I would take that. Not overly bothered if winter is above or below average. A below average month would do (preferably well below average). Hopefully models are beginning to pick up on a change...

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Posted
  • Location: Slovenia (Maribor)
  • Location: Slovenia (Maribor)

If we look at the GFS  (ensemble) scenarios it doesnt look that bad. 12/20 of them on GFS06Z are seeing the rise of height with the Azores high pressure system that pushes towards the north in the area around Greenland.

GFSP04EU06_234_1.thumb.png.090695f2261798673153bb88043b90c0.pngGFSP17EU06_234_1.thumb.png.47595bac36cead486f5919ff20c80f26.pngGFSP16EU06_234_1.thumb.png.afd386e7e2f9686606da0b708f448af4.pngGFSP12EU06_234_1.thumb.png.a6a708498cc8f83acda70f64fc547cf5.pngGFSP07EU06_234_1.thumb.png.552033df0a70c39109ab985ef97212ac.pngGFSP04EU06_234_1.thumb.png.9f5e2d5e531ac46f5e09726af3762072.pngGFSP05EU06_234_1.thumb.png.0d26386a494bbe460aa1d1e183a7c43b.png

With this SSW event already in progress we really dont know what will happen, the PNA index looks to stay positive, thats good news. AO index is currently slightly positive, but will probably go to neutral to negative state in the next few days. NAO index is now negative, but is predicted to go to into positive state in 7-10 days time. But that isnt done and dusted yet. I think interesting days, weeks are ahead of us.

This forum is quite amazing, I already learnt a lot of new things from you guys here. And I respect that.

Cheers.

Edited by Redbull165
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Posted
  • Location: Windermere 120m asl
  • Location: Windermere 120m asl
40 minutes ago, Dave Kightley said:

With December being quite mild or very mild for some... The model output really needs to behave to get a below average winter you would think...I dont think even the Met predicted December to be so poor by predicting a below average as a reasonable possibility 

December could have turned quite a bit colder, had the current high sat over us, since the 23rd managed to drift a bit further north, alas it sank south and we have been plagued with cloud instead of clear skies - a notably frosty last week or so would have ensued, just as we saw on christmas eve. Subtle differences in position of core heights make the world of difference at this time of year - as is about to happen again tomorrow, when the high inflates north and pulls down some cold surface air, temps will be pegged back notably to low single digit figures and frost returning - we could have a week of that.. oh well..

We were not far off an end to December like we saw in 1992. I think we have been delivered a poor blow currently, given how weak the PV is and westerlies.

Looking forward, as I've said over recent posts, don't expect the models to show any definate trend to colder conditions within the reliable for sometime yet - if the effects of the SSW play ball and lead us to this scenario, the reliable timeframe for such change won't be for another week or so (around 8/9th).. a long time to go.. 

If we do see a change to a colder period with high lattitude blocking - the path towards this will I suspect come from mid atlantic ridge, warm air advection over west greenland and a northerly first, with the jet then crashing south and heights to our west quickly merging with heights over the Pole - to get this point a shortlived more mobile westerly flow would be expected, but not especially mild, and some snow for the hills in the north at least, possibly low levels.

In the meantime - its been quite tedious model watching over the whole christmas period - one of the worst really for anything of interest - with the high pressure going nowhere fast, but its indicative of the fact we have a very weak zonal flow this winter, and the atlantic is really struggling to get its act together, which is a major positive for increasing likelihood of something colder from between north and east - eventually. 

I'd like to refrain from model watching for 7 days or so, in light of the current state of affair, but know I won't..

 

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Posted
  • Location: South Essex
  • Location: South Essex
2 minutes ago, danm said:

Sorry in advance MODS, but it’s comments like these that make brilliant posters like @Tamara stop commenting on here, and this forum is a poorer place for it. 

It sounds like you have a bit of an entitlement complex. We don’t have a god given right to have cold, snowy weather. We know how difficult it is for everything to fall into place for us to get that kind of weather on our small island. 

However, as we all know, those “background signals” don’t guarantee cold but make it much more likely. So we should always have that in the back of our minds, and if things don’t fall into place for us then so be it. 

We have some exceptionally knowledgeable people on this forum who dedicate their time and impart their wisdom to help all of us in our quest for snow. We should be thankful for that, and not moan if things don’t fall into place. 

As it happens, we are still in with a great chance for a cold, snowy outbreak during the second half of winter. Writing anything off now is madness. 

Just seems to me that there should be more respect all round. There are those who just post negative things for the sake of it, but they are in the minority. Equally there are a few on here (again a minority) who will keep posting about the next upcoming easterly despite it manifestly having no support in reality and then claiming victory when the charts subsequently correct at day 5 by 20 miles!! Then there are those that are just on a massive ego trip. Some will fall into more than one camp.

Whatever people post, enjoy the ones that are worthwhile, ignore the ones that aren't, be mindful of peoples agendas and use the ignore button if someone is beyond the pale.

FWIW (and probably not much) I'm holding to my line of slow sink south, zonal / mobile (which I think will be brief i.e. less than a week and doesn't preclude a short sharp northerly). I know Blue said his thinking was along lines of 06 GFS. I actually think the same, but post that I think we may go UK / Mid Lat Euro heights rather than northern blocking. 

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Posted
  • Location: Tullynessle/Westhill
  • Weather Preferences: Cold and snowy or warm and dry
  • Location: Tullynessle/Westhill

Only 2 more runs of the GFS to go for 2018, and one each for the other major models. 

Given what has been said about the GFS ensembles, could we please see one of the Ops hit the cold rather than the mild side of the spread. We need some model fireworks to see in the new year. 

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Posted
  • Location: Weymouth, Dorset
  • Location: Weymouth, Dorset

Still a big difference in today’s MJO plots. Albeit, slightly closer now.

F9D3ED24-0646-41B6-8A62-73A5079FF0A9.thumb.jpeg.49b406dcd0ca1356fdbde533e1502509.jpegC277AEBE-CF7C-4B53-B882-D0D0B379C737.thumb.jpeg.cf32b47dd76d814c68ddf5189a26d8af.jpeg

JMA been fairly solid in the middle though

72CAE8A2-6677-4450-9B67-053E0107929C.thumb.jpeg.77431cf78a04ffde144495fd9b026aaf.jpeg

Edited by s4lancia
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Posted
  • Location: Manchester Deansgate.
  • Weather Preferences: Heavy disruptive snowfall.
  • Location: Manchester Deansgate.
1 hour ago, Paul_1978 said:

What, at T+ 384 hours? 

Just saying, the very top of the strat is hinting at trying to return the vortex to the pole lately, so we cannot afford a flat pattern in the trop, not for any length of time, we need to make the most of it, i still think we will get cold at some point this winter, i would love to have seen it around 10th Jan and would have been buzzing on two counts, it would have been the coldest time of the year, and my analogues i did suggested this timeframe so for a relative novice that would have made for a pretty decent effort towards a seasonal forecast, just think its been pushed back a tad, hopefully not too long - jusry currently out on the rest of winter.

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

Some disappointing Op runs this morning but the ensemble suits were much more promising.

Strong hint of Atlantic blocking around day 9/10 which is responsible for the colder mean 850 temps

It would be great to see them firm up on that and the Operational output get on board this evening.

This evening may not give us lift off, but it may start the countdown to cold spell.

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Posted
  • Location: Burton-on-Trent (90m), Larnaka most Augusts
  • Location: Burton-on-Trent (90m), Larnaka most Augusts
10 minutes ago, feb1991blizzard said:

Just saying, the very top of the strat is hinting at trying to return the vortex to the pole lately, so we cannot afford a flat pattern in the trop, not for any length of time, we need to make the most of it, i still think we will get cold at some point this winter, i would love to have seen it around 10th Jan and would have been buzzing on two counts, it would have been the coldest time of the year, and my analogues i did suggested this timeframe so for a relative novice that would have made for a pretty decent effort towards a seasonal forecast, just think its been pushed back a tad, hopefully not too long - jusry currently out on the rest of winter.

A 2 week reversal is far better than average. And even when the vortex does reform, it doesn't matter, the damage has been done. Assuming we get a decent downwelling of the initial reversal we will have a good opportunity in a window of 45-60 days to get negative AO events, regardless of the state of the stratosphere afterwards.

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

A 2 week reversal is far better than average. And even when the vortex does reform, it doesn't matter, the damage has been done. Assuming we get a decent downwelling of the initial reversal we will have a good opportunity in a window of 45-60 days to get negative AO events, regardless of the state of the stratosphere afterwards.

Exactly and pretty much that entire period it will still be possible for snow! Granted I’m sure we’d all prefer the snow in Jan/Feb so  we can maximise the length of time it hangs around. But we may head into March having already had a couple of decent cold spells, with some Bonus early spring snow a distinct possibility! 

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Posted
  • Location: New Forest (Western)
  • Weather Preferences: Fascinated by extreme weather. Despise drizzle.
  • Location: New Forest (Western)

h850t850eu.png h850t850eu.png

Hmm okay. So that trough out to the east has become cut-off on this run with a bit of a ridge over the top. I wonder what that might lead to? A bit of a wildcard if much comes of it; not in line with the mid-Atlantic ridging theme but perhaps GWO phase 5 permits something along the Scandinavian linkup route?

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester

Clearly the adjustments upstream are still being made through the mid term with output quite different in the Atlantic sector.

GFS 12z yesterday/today

gfsnh-0-168.pnggfsnh-0-144.png?12

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Posted
  • Location: Brighton (currently)
  • Location: Brighton (currently)
8 minutes ago, northwestsnow said:

Liking UKMO 144 personally- finally some subtle signs of Atlantic becoming 'ridgy'..

Yes and improvement from the UKMO although it still has problematic shortwaves getting in the way.

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Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

Day 6

GFS/UKMO/GEM

gfs-0-144.png?12   UW144-21.GIF?31-17   gem-0-144.png?12

All three have that shallow trough slowly being absorbed by the upstream ridge pushing north east in the Atlantic, slightly different ideas on how to resolve this. The UKMO seems quite keen to dig a large cold pool south east towards the Azores (This looks a little erroneous to me). 

One thing I will say is I don't think a return to westerlies is the way forward with the high staying close to the UK, just a case of hoping to see a trough dig a long way south across the eastern parts of the US to finally give our high the amplitude required to turn things colder. The GEM attempts this though the high is always too close to the UK.

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Posted
  • Location: Manchester
  • Weather Preferences: Sunny and warm in the Summer, cold and snowy in the winter, simples!
  • Location: Manchester
6 minutes ago, karyo said:

Yes and improvement from the UKMO although it still has problematic shortwaves getting in the way.

 

I'm surprised the UKMO and GFS are so close at day 7 re shortwave trough that travels across the states.

That could be the trigger low that builds the ridge day 7+ or it could just develop into the trough that flattens the pattern as with today's OP output.

Thought we may see improvements there this evening but unfortunately not on this run.

 

Edited by Mucka
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Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

Hopefully, this trend over the pole is maintained moving forward:

gfsnh-12-210.thumb.png.d127ea1a2d91c8278dbb62253abc5a0b.png

Nice to see this develop in the op.

Next sharper Atlantic Ridge, please!

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