 Poster: A snowHead
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Gulf stream moves significantly over next 7-10 days. Should result is colder artic air being drawn down towards the alps and hopefully a bit more snow. A lot of base on that fell on lower slopes will have been melted off / significantly thinned down by this mild spell
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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@t44tomo, did you mean the jet stream? AIFS showing it here at day 3 and day 10, can see how the flow turns from a southerly direction to more of a northerly one for UK, albeit still kicking back a bit too far west for the alps.
 
Significant disagreement across the models still on how that Biscay low to the SW merges, or doesn't, with the low over scandinavia. If there's no link up then it's a harder and longer route to bringing down colder air far enough south. Maybe the eastern end only.
Here are latest ICON, UKMO and ECM at day 7 all showing the low stuck to the west, no link or phasing to the NE, with a band of high pressure over UK blocking the arctic air.
  
And in the better looking group, we have GFS, GEM and AIFS, isobars closer to hooking up to the NE, lower heights over UK, will likely lead to northerly flow into alps and maybe sub zero at 850hpa.
  
I'd nearly always rate the first group as more accurate, ECM and UKMO tend to handle blocking better, but there is the AI model also in the second group as a wild card, so 50/50 at the moment. It might end up as a blend between the 2 groups, which would hopefully just delay the colder air a few days.....maybe from the 20th. Looking at ensembles mean for NW alps though ECM is still 5 or 6 degrees warmer than GFS by then.
Going back to the first chart that caught the eye last wednesday from the EC weekly model (left), it's showing an improvement 6 days later....both for week 3 (17-24th). Although again it's sloping a little too much NE-SW, so would probably be milder eastern end. But it's a weekly average so I'd expect all areas to see some FL swings.
 
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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12z ICON and UKMO have a moment of clarity and flip back to group 2. ECM is now the only model left standing between us and november blizzards.
GFS further east and south as well.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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@v1cky24, I know, it’s mostly mumbo jumbo 
The bottom line is snow is coming. Others have said the same in one post, but I like to cover all the angles just in case. Many things can go wrong when predicting the future so I’ve adapted to using an abundance of caution. And much jumbo.
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| polo wrote: |
| The bottom line is snow is coming. Others have said the same in one post, but I like to cover all the angles just in case. Many things can go wrong when predicting the future so I’ve adapted to using an abundance of caution. And much jumbo. |
What this thread does best is to provide on ongoing commentary (from people who have some understanding of meteorology) on weather patterns as they emerge. Not so much a detailed forecast (I prefer my local weather guy in the Tarentaise, who does 2 or 3 days forecasts with very good accuracy), but a longer term suggestion of what might happen, with increasing confidence as we get closer to the weather event, where this is warranted by the different meteo models. For that I'm very grateful, and this is one of my go to sources each winter.
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@rob@rar, cheers, I’ve always held you in high regard since we had different views in the past but remained respectful, or at least polite 
Wish people in general would be more tolerant of different perspectives. No matter how much you disagree. For investing as an example, I regularly seek out viewpoints from analysts with opposing positioning to my own as it’s far too easy these days to succumb to confirmation bias, via algos or any media.
Back on thread, it’s a stronger signal now on the ensembles, just the European ECM model is not as cold. Way too far still for detail or high fives but am getting the winter tyres off the shelf.
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You'll get to see more forums and be part of the best ski club on the net.
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I think I’d have been better as a meteorologist in my career. It’s much more interesting than accountancy and uses numbers and assumptions and models.
I love a cloud spot.  I should probably pay more attention to what you’re interpreting
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| polo wrote: |
| @t44tomo, did you mean the jet stream? |
oops yes! Gulf stream is more ocean based!
I think I'd been watching what I still refer to as "the Farming forecast" on Countryfile, so was their interpretation of one / some of the models
Some change is definitely on the way, and is still early doors season-wise.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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Wetterzentrale is looking quite exciting for Chamonix over the next 2 weeks. Accepting all the usual caveats about forecasting, it is at least suggesting a lot of instablity and likely quite cold and precipitating.
I was worried that my trip in 10days time would be snowbare. Now I'm thinking Snowmageddon...
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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Yep, it's going to be drama. Next few days we go from +5c now at 1500m to +15c by thursday and back to +5 by weekend, so expect a 2000m+ snowline initially sunday.
Still some lingering doubts over how far south the cold will get next week. While ECM again improved, other models like UKMO and GEM backtracked a little. Only point here is that most people are watching the GFS output which happens to be showing the coldest solutions right now. As a model it's consistently verifying at 4th or 5th best, but past performance no guarantee etc, so while it has a chance of winning this time, we need to see the better models all join in soon to be sure to be sure.
Ensembles for NW alps. Comparing the red line next week across the main models, it's roughly GFS -2c, AIFS -1c, GEM +2.5, ECM +1 mean temp at 1500m. So it could be a bumpy snowline.
  
Average pressure anomalies for wed 19th show the lows finally merging and moving a little further east. It's not perfect but not bad either....and could see general NW flow establish for a few days after.
  
Latest AIFS Op also showing a decent pattern with good snow accumulations possible at altitude even by wednesday. Scandinavia more widepsread, and Scotland not too shabby.
 
And the last 3 GFS runs to 19th, gone from 90cm peaks to 40cm peaks, but normal to see big changes that far out.... just want to see better consensus on a good NW pattern building and the numbers will be fine.
  
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| polo wrote: |
| @rob@rar, cheers, I’ve always held you in high regard ... |
Thank you, that’s very kind.
Good to see the potential for more snow coming in to focus. Second half of November is when I start to get excited or anxious about snow conditions, any earlier is probably too soon to have a definitive impact on the season opening conditions.
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You know it makes sense.
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Well the GFS is certainly persistent....06z going baltic, sea level for midlands? and widely 400m fl central europe setting in for several days.
I don't usually get carried away with run to run noise, but the first sign of a proper winter spell usually tips me over the edge of reason.
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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Looks like your Atlantic temperature indicator may be coming up trumps this season @davidof. Since, October has been snowy & relatively cold in Europe, so much so that places like Verbier are opening a month early.... so let the good times roll!! 
https://www.snow-forecast.com/resorts/Verbier/12day/mid
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Poster: A snowHead
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The thing with teleconnections is you never know which one is driving / forcing the pressure patterns. There are probably up to 10 seasonal factors that have correlations with certain outcomes like the NAO state so it's always a question of probabilities rather than direct cause effect.
Regarding the SST's, still looking pretty warm to the north west and south of europe. The cold blob near eastern US seaboard and south of greenland is developing into a favourable 'tri-pole' pattern of warm-cold-warm vertically. Something gavsweather channel talks about....quite rare and well correlated I believe to -NAO.
In terms of SST's vs last year, it has been looking colder overall this year since April but recently seems to be at the same level now and back above long term mean.
https://climatereanalyzer.org/clim/sst_daily/?dm_id=natlsp
For the upcoming cold spell I'd say it's more likely strat driven, or at least -AO. The strat polar vortex is very weak for the time of year and getting weaker into month end, as is the trop vortex (-AO), both here:
https://charts.ecmwf.int/products/extended-zonal-mean-zonal-wind?area=nh&base_time=202511110000
https://www.cpc.ncep.noaa.gov/products/precip/CWlink/daily_ao_index/ao.gefs.sprd2.png
Looking at NH pressure charts for next thurday, strong blocking over Greenland (similar to strat warming over Canada area) leads to -AO.....and the blue vortex lobes are segregated into 3 or 4 different mid latitudes rather than a tightly formed single mass of cold over say greenland (which would be the default mild +NAO).
Following the isobars from UK back up to the Arctic shows where the cold is sourced.
Anyway, still some wobbles in the output. It became one of those trickier set ups once a deep low formed so far west and how that eventually crosses europe....with high pressure never far away. Some recent runs would see eastern end get most of the snow early in the week, but then a second shot for the west from wed-thursday. Gotta say AIFS and GFS have been the most consistent at least, so fingers crossed they are still on the right track, thursday currently looks the best bet, but will probably change again.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Thanks @polo
Don’t know why but feeling pretty relaxed about the season ahead less anxiety than I normally have despite the mild spell
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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@Le Grand Renard, that comes with age , midday shorts and t-shirts this week to go with your slippers.
Forgot to say....apparently there is a huge solar flare (coronal mass ejections) going on right now. Northern lights and a severe geomagnetic storm. One more thing that has been studied and linked to westerly resugerence, so can blame the sun as well if the whole pattern collapses.
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You need to Login to know who's really who.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Felt like the first day of winter this morning, very crisp, bright blue skies, ice on the car windows, the council & DB had gritted the streets / train platforms. All we need now is some snow (small amounts due next week). Warmed up this afternoon though.
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ECM is the best of the physics models, and close to no.1 or 2 overall including AI models, but this period has not been one of it's finest. A lot more chopping around and milder than the others, slowly backtracking. It's still milder than the others for Monday-Tues in the NW with a mean of +3 versus GEM +2, AIFS -1, GFS -3. So quite a big spread for day 4 and 5. It could still be right of course, but I'm leaning towards the colder ones as they have been more consistent. Reckon Monday will start warm but end up close to zero by evening.
GFS is probably over-doing the cold and also back tracking a bit now....compare wed morning FL to previous pic above
Ironically there's almost better consensus further out around thurs-fri with the means around -4c. So it's definitely a colder spell, but not a huge amount of snow showing up. Sun-Tues looks mainly higher altitude in the west, with snow to lower levels in the east. I'd guess 10-30cm range. But if some of those thurs-fri charts come off it would a significant dump, despite some modest numbers currently showing on the apps.
In the ovenight 0z example, we really want ECM to be right again. Gotta say some models are still bringing high pressure in a bit too close for comfort into france (again), and another one or two models are still aiming the second wave towards Spain, so too far west, while ECM splits it all down the middle with a direct hit.
Here the run from wed night to sat morning. Does not get much better for widespread deep cold snow over 3 days.
  
AIFS snow to next weekend, the purples are back with 1m+ at altitude. Usual caveats, the chase is nearly over, the fat lady is doing her yodelling scales.
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@polo, how well did AIFS do at forecasting the snow at the end of October? Better than the other models, worse?
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You'll get to see more forums and be part of the best ski club on the net.
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@rob@rar, pretty well, think they were reports of 1m by the end. All of of these snow charts are wild guesses, especially when they are 6-10 days away.
The main takeaway is that it's verifying as one of the best models and so far has been more right than wrong with both the Oct and Nov evolutions.
Weird bit for me is that ECM pressure charts suggest more snow that it's showing, while I would think AIFS pressure charts are the opposite.
Still a few days to go before seeing realistic numbers and broad consensus.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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| polo wrote: |
| The main takeaway is that it's verifying as one of the best models and so far has been more right than wrong with both the Oct and Nov evolutions. |
That's good to know. Which meterological organisation is responsible for developing and running that model?
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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ECMWF
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@munich_irish, good article....as always those guys explain these events in great detail, with some cool graphs, eg don't often see that 3d image of the whole vortex.
My view is we are already in a good a position for december with a very weak strat vortex. It's one of the most important background drivers, no doubt helped by the fact we have negative QBO this year, which is the roughly 2 year cycle of strat winds over the equator. No idea why this happens, but every 18 months or so they switch from westerly to easterly and vice versa. So this year they are easterly over the equator which has a natural disruptive part to play in slowing the westerly circulation over the pole.
Latest ECM forecast is for those 10hpa (strat) winds to almost reach zero by the 25th, so another big slowdown over the last 5 days when it was previously looking more like bottoming near 10 m/s. If it happens to go negative that's a technical SSW, although I think it might need 3 days in a row or something officially....either way it's a dramatic and very early disruption to the strat vortex.
Always a lottery thereafter for how long that disruption takes to downwell to the troposphere, and even if that happens, where will the cold spill out....mid atlantic is no good to us. Those guys are saying it looks like a QTR this time....quick trop response, which you can tell by monitoring the wind speeds at different levels in the atmosphere, eg starts at 10hpa, then 30, 50, and finally 500hpa (the trop). You'd have to wait and see though from late Nov how it's progressing. Can take anything from 5 days to 5 weeks or more.
One other point I read by an experienced strat guy is that it's generally better for europe if we are in a +AO phase when the SSW happens. If we are already -AO like now, then the SSW can mess things up so much that we end up back in westerly mild flow. But if we are in a mild westerly phase by late Nov then the SSW has a better chance of turning that around back to -AO, which leads to set ups like next week.
Right now it looks ideal, we are in a -AO phase (the trop vortex is already disrupted), then the strat weakens further next 2 weeks just are we are returning to default westerlies late Nov, meaning we should be back in -AO by mid Dec at the latest.
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You know it makes sense.
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@polo, fingers crossed for Snowmeggedon for Christmas 
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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@munich_irish, ducks are lined up nicely....I'd be happy with anything close to last year though
12z rolling out now....all good so far......goldilocks
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Poster: A snowHead
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@polo, always love your posts sharing how the forecast swings around, I'm out 11th Dec to Tignes so I do declare a vested interest in a dump!!
I think we need a polo scale of confidence, based on a % of the mint, so 100% a full circle, 50% a half polo etc
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Thank you @polo. Love your latest interpretation of what may pan out and chat about the source models (super computers?).
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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I still don’t know what it means. But if it can snow plenty in Val D’Isère before 20th December and then have bright blue skies over Xmas week please
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I am assuming it is way too early for any of this to mean anything for the end of January?
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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Thx…..it’s just a hobby, I genuinely love the twists in the charts as you can tell…..all thx to sH / noza really. Though I suppose it was inevitable once I moved to the alps. Wasn’t really into skiing or certainly the weather pre 2014 approx.
100% on proper cold and widespread snow to low levels. Half mint still on whether it’s a really significant one, probably not considering it’s still relatively early…...AIFS purples are not on the 12z, so maybe looking at 50cm peaks. ECM also toned down the 3 epic charts. Whatever…the computers aren’t great at snow quantities, or even where it might fall…..slight shifts could favour the south in the end etc. Am happy though that this is the second time now we’ll get some decent cold and snow despite a less than ideal initial pattern…..the ‘missed opportunity’ right now today of a deep low heading too far SW and ensuing warm spell. Kind of ended up in the best possible way out of that, fingernail stuff at times….makes the chase all the better.
High pressure moving in again from next weekend it seems, all pretty normal. But….with the Strat knocked off its perch, reasons to be optimistic into Dec.
I’ll take a break from daily updates now unless something shocking pops up….as usual. May we all get the snow we deserve
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@polo,
Where is Noza ? - have you two ever been seen together ?? !!!
I’m suspicious!!!!!
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Luvin it Polo, thanks for sharing these amazing insights into the weather & hence the likelihood of us 'getting the snow we deserve'! 
Much appreciated!!
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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Hi, Sorry for the stupid question - when looking at the Wetterzentrale 'graph' the line that shows temperature - how can i tell what altitude this is based on please?
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FAQ
