 Poster: A snowHead
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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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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Damn, should have booked 
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You need to Login to know who's really who.
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@BobinCH, Siberia is coming to Europe
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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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You'll need to Register first of course.
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@Oleski, Uk will get first cold blast Sun-Mon, then hopefully a much bigger incursion for the whole of europe from Thurs 25th on. Has all the makings of a potential prolonged cold spell into month end too.
ECM 00z mean temp at 1500m for 25th
Ex MetOffice poster John Holmes did a write up over on netweather about forecasting snow on the ground in UK
https://www.netweather.tv/forum/topic/23729-will-it-snow/
You need between -5 and -8c temps at 850hpa, and ideally 522 DAM to snow at sea level. Think northern areas have a good chance of seeing the -8c isotherm.
Bit more marginal at 1500m for the alps as things stand, need a few more corrections east in the modelling before I put on the new winter tyres.
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Get the sledge out for the Grandson in Camphill!
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24 hours later I'd say that's an upgrade.
These are 10 day GFS Op cummulative snow charts. On their own they are not that reliable, but there is near complete cross model support for the general pattern.
I did chuckle at last nights ECM (via YR.NO) showing -21C in Les Gets at 1200m on the 26th....now updated to -5C.
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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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@polo, well as usual SE England gets a miss 
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@Oleski, you need an easterly ideally, which I wouldn't rule out in early Dec as often these large atlantic blocks eventually topple over the UK.
In any case, it's too small a target to worry about more than a few days out
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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I'll probably just do a few more updates and then give it a rest, plently of others capable of posting outlooks I'm sure...each year I tend to lose enthusiasm anyway once there is a base down locally and I've selfishly filled my boots with fresh snow.
This whole late November snow forecast was visible about 2 weeks ago, based on -AO signal and corresponding mid range anomaly charts for euro trough. However as time drew nearer there have been several false starts, ie 22-25th fantasy island Op charts never materialised. In most cases the modelling underestimated the extent of high pressure and crucially its eastward position, ie low pressure systems also end up further east, or south west under the high (spain), and also in a weakened state.....as less energy gets over / around the more bloated atlantic ridge.
So while the current outlook (euro low) remains solid into month end, there is still considerable variation in the timing and detail. Even within the semi reliable timeframe of days 5-7 there are enough differences to warrant caution on temps and where the snow will land. Northern Spain, Norway, Scotland and most of the alps should get a decent covering though.
A dusting is likey on 22nd as the first low curves back to northern Spain, followed by main incoming northerly systems from 26th nov on.
By the 29th models end up with the atlantic high starting to sink and the whole pattern moving east, bringing more N/NW flow (as opposed to NE/SW) to the alps as the low centre crosses.
Latest GFS chart out to month end.
Any low lying snow on that chart is suspect of course until within very short timeframes. Even large deep areas will continue to change for a few more days too. I wouldn't be surprised if GFS is underestimating the snowfall, given the forecasted pressure drop. When low pressure comes in that far south and sits over the alps for a few days it can produce long spells of moderate snowfall to low altitude.
Temp anomaly out to the 28th. I expect deeper and broader lows (blues) to show up in the coming days as the pattern moves east and the current mild temps get replaced with colder ones into month end.
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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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Thanks for the update polo
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@polo, this thread isn't going to be the same without you. Thank you for your efforts!
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You know it makes sense.
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Thanks for the update @polo,
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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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@polo, this may sound like smoke being blown up your a*se but genuinely your posts are the highlight of this forum right now. Please keep them coming.
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Poster: A snowHead
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thanks, let's not get carried away though  , I just have less threads to read these days.....I'll still be around spending way too much time staring at charts.
The 06z run just out didn't help at all....more change, colder but again pushing the main low back another day from reaching alps, frustrating, but it has to come down eventually....still wide open for snow to build up slowly under slack air before the main low arrives. Southern areas, from Spain to Croatia are best placed to get some big numbers initially.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Here's an example from the 12z of the uncertainty at just t+144, next Friday
Met Office - slack, but snowing
GFS, same at ICON, atlantic high getting flattended into anvil shape, low pressure delayed / deflected, milder air getting mixed in
GEM - best of both worlds, though the low is probably heading too far west initially
They all end up with the low swinging across the alps....so it'a choice of early but lighter snow, or slightly later and heavier snow.....either way, winters on next week
edit ECM 12z has the ideal track / evolution.....26th snow, 27th snow, 28th snow, 29th a lot of snow.
30th snow.
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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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You need to Login to know who's really who.
You need to Login to know who's really who.
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GFS now looking more accurate.
10 day chart caveats, but fri-mon will be heavy going and very cold,-5 to -8c in the NW alps, hopefully get a few breaks in the weather. Possibly turning 'milder' next week (early dec) as flow becomes more westerly...but even then the mean temps at 850 hpa / 1500m don't stray far from 0c.
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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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Thanks polo. Watching this with interest as we head to alpe-dhuez over Christmas. Do you class ADH as Southern or western alps during your write ups.? Thanks
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Thanks Polo.
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@Boarderfarce, western, as on the west side of the main ridge....probably call it NW if you had to choose a broad section
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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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@Weathercam, it does look like you have been unlucky so far.....but wouldn't get hung up on the numbers, as long as it's cold and under low pressure for 4-5 days there should be widespread snow. No valleys will be left behind.
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@polo loving your work. So a reasonable chance by this time next week we'll be gawping at winter wonderland pics of snow deep into the valleys across most of the Alps? 
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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@hd, more than reasonable.....even allowing for a few more wobbles and the bias to drift the pattern east. It's only a matter of who gets the bragging rights...
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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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@weathercam thanks for the forecast. Fingers crossed that you get some snow this week.
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You know it makes sense.
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@polo, do you have a view as to the English and Scottish ski slopes getting any snow this week?
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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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@kitenski, no more than the various charts and apps are showing. Am more familiar with what's needed in the alps, but with the -4c to -8c 850hpa isotherms coming down by the weekend the odds are good. Saw some tweets about snow in northern parts already.
From Jo Farrow / netweather:
Later this week it does look more wintry. There will be the risk of snow showers (from the north), more frost and also ice. With the high pressure further west, south of Greenland, low pressure swings down from the north. One mid-week slides away to Denmark but the one of interest to the UK heads down from Iceland by Friday.
This looks to take its time moving southwards (an unusual direction for us) and will bring strong winds, heavy rain and some sleet and hill snow. For Scotland, there could be gales, even severe gales to end the working week so anyone travelling, particularly for the Islands this looks worth keeping an eye on.
Significant lying snow looks set to be restricted to high ground, mainly in the north, but many northern parts are likely to see sleet and snow falling at some stage.
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Poster: A snowHead
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| polo wrote: |
| So you might notice YR / Bergex looks a lot better than other sites. |
Thank you for your posts. What is YR?
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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@südtirolistdeutsch, www.yr.no is a Norwegian-based weather forecasting service. Forget which model they use (@polo mentions this up thread somewhere so you can check).
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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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YR.NO and Bergex sites use the ECM model, other sites mostly use GFS. While ECM is slightly more accurate over the long term the other models are essential viewing too, notably UKMO, GFS (US), GEM (canada), ICON (german) and even the JMA from Japan. I like to use a forecast based on average model output to predict the most likely outcomes, but the 3-4 main ones are usually enough.
For most people looking at apps, it can be useful to know if a GFS Operational run for example is an outlier, or whether it's supported by its ensembles / and other models. The point above was showing that to me a few days ago it looked like GFS was underestimating snow, especially for northern alps, as its projected pressure charts were slighlty less well aligned than other models were showing. But that kind of obsessive detail probably isn't for everyone
They all converge together at the end of course regarding the pattern at T zero...but there will still be slight close range differences in temps, and especially precipitation estimates.
Here's a quick recap of where we are, and about to go....
EC average pressure anomaly this week shows the jet stream running down to Spain and back up thru med / alps. It's a cold pattern because air flow is sourced from the NE...Scandinavia / Russia. It can bring warmer air from the med to SE europe, but that gets quickly swept away as systems move east and more cold is pulled down.
Looking at next week (29th nov - 6th dec) below, you can see how the low pressure anomaly tilts back to a NW-SE track (follow the black lines). So the air source is milder as the cold air gets moderated crossing the relatively warm atlantic.
If this pattern was coming after a euro high / mild and dry background then it would likely have quite a high snowline for the NW alps (say 1600m).....but so far it looks like there will be enough cold air over europe already to keep the freeze level low, maybe peaking at 1400m around wed 1st and heading back down to sub 1000m by the 3rd. The other big difference with the flow switching to the NW is that precipitation will be heavier.
Mean GFS pressure chart for 2nd dec...the reload
All of that combined leads to this incredible 10 day snow chart, out to the 4th Dec.
Signs of a creep towards average temps after that, +AO/NAO forecast, so maybe high pressure getting into the west.....nothing to worry about, enjoy the next 10 days first.
Last edited by Well, the person's real but it's just a made up name, see? on Wed 24-11-21 15:00; edited 1 time in total
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You need to Login to know who's really who.
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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You'll need to Register first of course.
You'll need to Register first of course.
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| Quote: |
| The other big difference with the flow switching to the NW is that precipitation will be heavier. |
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Ive seen in the forecasts low temps and snowy days are ahead..(29th onwards). am visiting cervinia at about 5th of december, Any idea when the weather gets a bit clearer by the graphs?(ive seen that also 5th onwards is still snowy and afraid to reach all the way and get shut down)
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| Quote: |
| afraid to reach all the way and get shut down) |
Unlike the inch of snow required to close schools, roads and workplaces in England  snowfall has to be beyond extreme to shut down an alpine town or resort.
I was in Austria during the monster snow of January 2019 and everything just operated normally. And athough I have been in Tignes when movement between Val Claret and Le Lac was forbidden on a night due to avalanche risk, the skiing was still operational.
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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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My daughter and husband have been in Cervinia 2018:I think and the authorities had everyone staying in hotels due to the avalanche risk off building roofs! This was one day only, till it was cleared, but no skiing for 3 days as everything including lifts had to be dug out. It is very unlikely to happen though. As they say in the Sopranos, ‘whatya gonna do?’
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FAQ
Fingers crossed for some sledging and snowman making in a local park 
