The All New Weather Outlook 24/25

A snowHead

@Polo great to have a bit of your commentary back

Well, the person's real but it's just a made up name, see?

Well for the moment I am stuck at desk / sofa all day, and it's hard work to get back up.....so I might as well post stuff.

How can anyone be confident about next week?

....well the 2 week ensembles picked this up well in advance as posted here a few pages back, so it's a pattern that has been consistently on the mid range radar, then the 3 mean anomaly charts (ECM, GFS, GEM) began to form consensus about 10days out, which we've seen many times before. But even the average of 100+ ensembles can change a lot that far out, while at 8 days out if they still agree, then 80% of the time (per an ex M.O. dude) they will get the general shape / location right.

Another good check at this stage is the EC46 weekly model, which for 18-25th Nov has been showing the big euro low anomaly for about week now. It's only really good for week 2 and week 3 at best, beyond that (weeks 4 -6) I wouldn't give any weight.

That still doesn't help with detail like snowline and ppn at resort level, slight shifts in the 500hpa pattern will shift the all important air source for any given area, ie shift from NW air to SW air can change the snowline by 1000-2000m the wrong way. And you still have the 20% possibility of the means being significantly wrong.....a shift east of the azores high just a few hundred miles and most of the alps would miss out.

Finally after watching the Op runs (the high resolution main run, or the control), across several models and see how consistent they are run to run and versus each other, especially as you get to 5-6 days out, which is more or less now. Then you can start to make a useful forecast.

So that's how we got here, normally you'd say 80% chance of good snow now for the alps.....but an even more positive stance is warranted with this set up because of the greenland high / atlantic block, the size of the euro low, and the chance of reloads.

It's all about blocking the normal west-east atlantic flow (jet stream). A small ridge of high pressure in the east atlantic might only last a day or 2 to allow NW flow into alps, so one chance and you're out. While a mid atlantic block like we have now that extends up to greenland is much more robust, causing the jet stream to wave break or buckle, diverting airflow to a more northerly direction into europe. And crucially holding the block in place for up to a week or more, allowing the cold pool over europe to deepen as pressure drops south.

So the greenland high gives more confidence than a typical NW-SE snow event. Because of how far north the block goes though, there is the added risk of low pressure joining the euro low from the W/SW. This is typically how great set ups get spoiled as we saw several times last year. And it's going to have some impact again next week.....but if enough cold air has already descended then this could lead to very heavy snow storms, and a wild snowline.

I'll get some pictures and another coffee

You need to Login to know who's really who.

Weather network says different for val disere from sunday .looks like an awesome dump coming .these forexaats are pointless though ,u know where the snow will be the same places it always comes first

Anyway, snowHeads is much more fun if you do.

You'll need to Register first of course.

Looks like the models are converging on some cold air masses dropping with that Greenland high, to 20ish Nov but further out....I know I know.....looks like the pattern for France and below will be for a westerly pattern bringing in milder air for the Azores with ensembles raising the 2m/850hPa temps from about the 22nd? UK Scandi more dominated by the colder airmasses. Looks like one of those classic cases of the marginal shift will make a big difference to the outcome

Then you can post your own questions or snow reports...

I'm no expert at looking at models (other than googling photos of Gisele Bündchen) but looking at several forecasts, they have consistently been showing a decent amount of snow in mid-west Switzerland (Engelberg, Zermatt, Saas-Fee) between Sunday and Friday next week.
Weather forecast is like politics is 2024: facts are irrelevant, what matters is what you choose to believe; and I choose to believe these forecasts are right.

After all it is free

Yes awesome dump is coming....high resorts are going to do very well, but more exciting / risky looking for snow to low levels....which also means better snow quality higher up. And the UK is right in the firing line, so this is not a typical autumn / mid nov event.

For week 18-25th, here's how EC46 has changed from roughly 13days out (9th to 22nd) on the left, to now 8 days out, on average. Can see the how the low has broadened and tilted more to the west / atlantic. But both are very good for snow from the NW, and that's a strong 7day long trough signal. But also note the mid atlantic block is a lot skinnier now. One other good thing about greenland highs is they can interfere with the strat PV, disrupting it's normal build up in speed into Dec/Jan, so the longer we maintain high lat blocking, the better the odds of a weaker or delayed vortex (less westerly / mild signal up to xmas).

Looking at the jet steam, right now on the left, it's a long way north (going over the atlantic to UK high pressure block), but as the block shifts NW by next wedneday, the jet becomes more meridonal (bingo card lingo checkbox for those playing long), and slams into the alps instead of Norway.

Now for the short wave drama.....something that keeps cropping up, and is notoriously hard to model. A short wave is a small area of low pressure that attachs itself (phases) with a much bigger trough. It will cause big swings in forecasts because both the path it takes and the amount of energy it absorbs are so volatile.

Here's the latest GFS 06z run showing the little buggr as it starts to form on Sunday (kinked isobars), and then by Tues morning it's sucked in and crossing the english channel. This is going to cause a decent spike in the snowline for the alps as it moves across with a strong SW flow. And it may cause blizzards for middle England on the northern flank if the air is already cold enough.....but as stressed, the path and intensity will keep changing....while consenus among the pro's is that they tend to be modelled further south as reality approaches, so maybe Paris / UK south coast get the brunt.

Right... stretch break

Woo hooo!! Very Happy

At last! From Wepowder.com today:

*Ski* the Net with snowHeads

This https://www.severe-weather.eu/global-weather/first-winter-weather-pattern-shift-cold-anomaly-united-states-canada-fa/ is along the same lines as the posts above but also suggesting early December might be good too.

snowHeads are a friendly bunch.

Excellent posts. Let's hope for a stong start to the season.

snow reports

@Ackie68, yes that's possible and does keep cropping up in the 2 week window, much like the current change was well modelled in advance.....but apart from the usual caveats of it being too far away to worry about, next week is going to flip 'normality', so I would wait until the low actually sinks into europe and the high reaches greenland on mon/tues, so once those patterns are in the starting data, the models may reevaluate. Probably clutching at straws, but either way let's get the snow in first.

Last 4 GFS snow depth charts to Sat 23rd.....slight weakening on the latest 06z run (last graph). Not easy to read, but dark blue is 50+cm, Balkans seem to be gaining.

ECM 00z ensembles.....as usual a few degrees warmer than GFS, but I think it's gonna be right that the cold won't hit the alps until after this short wave has passed, so Wed 20th.
Some earlier runs, and still one or two models do not make as big a deal out of this small trough and have lower temps 17-19th, but it's beginning to look like a warm sector initially overall, would guess near 2000m snowline. Then the big drop 20-23 nov, mean is -5c at 1500m on several models. Worryingly the cold has been pushed back a few days for the alps, but the risk was always there with the broadening of the trough too far west and picking up a short wave, or other SW low.

Looking at some more snow charts.....just for very loose numbers like above GFS charts

ICON and WRF out to Tuessay, UK and high altitude alps 'at risk'

And then the even more random snow depth charts by Sat 23rd, GFS and ECM....still looking 'fairly widespread'

You know it makes sense.

It is now possible to tour from Val Thorens thanks to a hard 5cm layer of man made up to the glaciers. However Meteo France describes the current snow conditions below 2900 meters as "pitoyable". We'll see if next week's snow is enough to get the party started. It will start as rain on Monday at resort level, turning to snow later on Tuesday and continuing through the week as snow with a return to sun at the weekend (23rd November)

Otherwise you'll just go on seeing the one name:

So for a newby whonis taking 18 non skiers to val on the 14th dec will the dump expected this week still be there by then
Even with the change after how dramatic can changes be

Fascinated by your knowledge

A snowHead

Looking great, but as I'm due to be in Cervinia (and therefore skiing over in Zermatt a lot) next week on a ski course, I fear we may face blizzard, wind and lift closures..

A snowHead

Well, the person's real but it's just a made up name, see?

@picnmix1974 I would be extremely surprised if it was warm enough above 2000 meters to destroy a base once it has been established. Of all the French resorts, Val is one of the best positioned in terms of altitude and snow making to withstand period of non favorable weather.

If the base forms next week they'll definitely be something to ski on the week of 14th.

You need to Login to know who's really who.

@Gustavo the Gaper, yes we are doing a Warren Smith course. We did one there in 2016 (our honeymoon) but stayed in Zermatt and joined the group daily. Thankfully the weather was kind. Next week, we may be on the right side of the mountain, but the weather forecast looks pretty wild.

Anyway, snowHeads is much more fun if you do.

ECMWF is still very positive for winter sports hopefuls, at 1,900m. Median value forecasted temperatures from Monday 18th to Thursday 28th in a range -17c to +3c.

https://charts.ecmwf.int/products/opencharts_meteogram?base_time=202411140000&epsgram=classical_15d&lat=46.7833&lon=9.66667&station_name=Arosa

Certainly no 'bad news' as it stands now.

You'll need to Register first of course.

Then you can post your own questions or snow reports...

After all it is free

All having lessons :-)my 50th and im treating them to something i hope they will learn to love .

Has your son got the u universities beer tokens
Asking for me and my two 18 year old nieces and nephews

*Ski* the Net with snowHeads

snowHeads are a friendly bunch.

picnmix......that sounds exceptionally generous.....good on you

hope they all enjoy

also in VDI 12-15th Dec

snow reports

Wow, that's absolutely amazing @picnmix1974! Very Happy

Here's hoping they all love it as much as all of us on here! Do let us know how it all goes.

Thank you very kind of you both
Its a one off but id hate for them to never see what ive been lucy enough to see many times .chalet chardon repeat gues when it was so cheap because their was no guarantee of snow first week of dec i got spoilt .if we come back still talking to each other and without broken bones it will be a result

You know it makes sense.

Otherwise you'll just go on seeing the one name:

@picnmix1974, “ if we come back still talking to each other and without broken bones it will be a result”

Ha ha great attitude - hope you have an excellent time no matter the weather Happy

A snowHead

A snowHead

[quote="picnmix1974"]

Well, the person's real but it's just a made up name, see?

@picnmix1974, This is the’ weather outlook thread ‘ can we keep to the subject please .

You need to Login to know who's really who.

Yes i realised but wasnt sure how to delete sorry

Anyway, snowHeads is much more fun if you do.

Good start to the season so far for the US / Canada Rockies and PNW.

Austria doing good.

Bad start for Northeast US / Canada.

Worst start to the season this century for the French resorts.

You'll need to Register first of course.

^ it's going to get worse before it gets better, and then it will probably get worse again, and then lifts will open about a month later.

The ECM 12z (mon-tues) takes the short wave quite far north into UK and exits in the north sea, so mild in the western alps as expected initially....but then it does this and spins around for a few days.

Then you can post your own questions or snow reports...

Weathertoski.co.uk is currently very optimistic Very Happy

The American Global Forecasting System is currently predicting a very favourable set up for heavy snow to low altitudes across a wide swathe of the Alps next week, particularly in the north-west.

The first of these fronts will bring light to moderate snowfalls to the north-western Alps on Sunday evening but will open the floodgates to a series of much more potent storms next week. By Monday morning, around 10-15cm of snow should have fallen above 1800m in the north-western Alps (e.g. Val d’Isère, Avoriaz, Verbier, Mürren, Engelberg, St Anton) with a rain/snow limit initially around 1800-2000m but dropping to between 1000-1500m on Monday.

After a slight reprieve late on Monday and into the first part of Tuesday, the next, bigger, storm is expected to arrive on Tuesday afternoon and continue into Wednesday. This potent storm is expected to deliver very significant quantities of snow to much of the Alps (especially in the north-west) with snow falling to low altitudes. Yet another potent storm is then expected on Thursday, again bringing heavy snow to much of the Alps.

At this stage we can only speculate as to how much snow will fall in the Alps and when - as it is still too far out to pin down the exact details – but, at this stage, we can be certain that many Alpine regions will see significant snow next week and that there is the potential for some really big falls, especially in the north-west.

After all it is free

VT have today confirmed they are opening on the 23rd as they have been making snow and they are confident of next weeks dump! Fingers Crossed!

Webcams from Oberlech are positive. Looks like a ski slope.

*Ski* the Net with snowHeads

Help!!

The All New Weather Outlook 24/25

snowHeads Forum Index >>> Snow Reports - weather - snow conditions