The All New Weather Outlook 24/25

A snowHead

https://www.wetter3.de/ [GFS 0.5] very often forecasts big dumps ….. this time it’s The Grampians, 85cm new snow due to fall this coming weekend.

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all looks like good potential?

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Paging @polo…

Is that (the 1005 on @Ackie68’s first chart) a Genoa low..? Un Retour d’Est?

If not, why not…?

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@IanTr, not an expert on all the micro events, more of a macro waffler myself.....maybe others here with more local knowledge or understanding of the necessary conditions better placed to discuss

But from what I've read, you need a strong easterly wind over a few days, so a genoa low that is a bit deeper and maybe not as titled to the SE. Ideally you'd also have cold air in place across the Po valley and maybe even higher pressure just to the north of the western alps to hold the med low in place and veer the winds easterly.

While above chart is 6 days away so a lot of time left before any such details would be possible. Several ingredients are in there, with cold air in place for several days and general low pressure over the med tilting NE-SW for up to a week, and highs building to the north. So it could become a feature but very few genoa lows go on to become retour d'est from my limited time watching.

Wepowder 6 day snow chart now includes sunday's amounts, can see the focus on eastern Swiss / western Austria, but good enough in most areas too. Surely a powder alert is being typed up.

Quite a low snowline last night in the pre alps around lac leman, and the Jura has turned a little white again. Maybe 5cm at 1600m, 10cm at 1800m and a dusting lower down? but hard to tell as most cameras either off line or hazy.

Interesting chart for 12th on ECM 00z Op....goes for iceland-norway high and a euro undercut. Very cold chart, but wouldn't be my preferred route to the next stage.

Looking at the 3 mean anomaly charts for 12th, can see ECM first is very different to the other 2, shutting off any N/NW flow. While GFS and GEM keep enough of a gap across the north sea to reload this coming Sunday pattern again from next Thursday on. They will converge over the next few days no doubt.

06z rolling out shifts the Sun-Mon pattern further east, and with the subsequent tilt to the NE trailing lows could end up over northern spain

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Are we entering days of modest yet steady snowfall for parts of The Alps, which in aggregate will be very helpful? A welcome alternative to the always hoped for big dump.

MeteoFrance and MeteoSuisse showing exactly that from Friday onwards for plenty of ski villages.

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I'm seeing some sort of no particular anomalies setting up from 14-16th onwards perhaps a bit more precip that week then normal temps and precip in the extended forecasts. Seems like...as usual....snow is getting moderated for the weekend where I'm looking at for parts of french Alps, with the FL remaining stubbornly relatively high ......But who knows. Overall for me it is better than what it looked like 2 weeks ago.

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looking like an incresasingly positive picture emerging for the weekend...after initial high snow line temps drop to near on baltic and snow rolls in

for my personal preference of snow around VDI ready for next Thursday its looking like 40-60cm which should improve the situation no end.......further out to sat/sun 19-20 looks like further snow...but a long way off and much can change as we know

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Very positive outlook for the northern and western Alps, perhaps particularly for areas near the Alpine edge (e.g. resorts around Geneva, Grenoble, plus the Jura etc.). Unlike some recent falls, the spell of heavy snowfall to increasingly low levels on Saturday into Sunday should be followed by a fairly extended cold spell, so the fresh snow should stick around. And snowmaking should be possible!

Wepowder's latests forecast brings gifts to all areas:

https://wepowder.com/en/weblog/2024/12/04/wintry-with-snow-and-lingering-cold-next-week

You know it makes sense.

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

@Snow&skifan, a very wet blizzard perhaps !!

A snowHead

Looks like the Rain/Snow level has moved up at bit Friday/Sat morning in the North West Alps back up to 1800m plus till the real action starts Sat afternoon .

A snowHead

@Le Grand Renard, yep FL could hit 2400m or +5c at 1500m, as has been shown on the ensembles for a good while now for Friday, but you are right that Sat noon is still warm and taking a little longer into the afternoon before dropping fast. Seeing more modest accumulations programmed for the valleys.

Re-visiting the mean anom's for 12/13th, ECM GFS GEM. They have converged but not in an ideal fashion....there is still a gap to the north, but also more blocking, while the euro low is centered over Spain, which will bring up some milder air. Alps still largely under cold air, but don't want the Iberian low hanging around for long.

On to the 15th, still have the slight NE-SW tilt on ECM and GFS, while GEM (last) has lower pressure focused over Iceland-Scandinavia. So looking good for another interesting spell, but 10 days out.
Nice to see the large mid Atlantic block still there, but with the jet running so far SW it could get messy.....been there before with the real cold held up to the north and interference from south atlantic lows into alps. Too far for detail though.

Looking at some of the best and worst Operational runs around the 15th....JMA very good, while KMA shows the SW low concern and ECM AI very flat and zonal.....so no clues there.

That's the problem with single Op runs at that range, can get 3 completely different patterns and they can have big swings run to run.
Btw I read that the ECM model now has all of it's ensemble runs at the same high level of resolution as the old Operational run. Presume other models heading the same way. So it re-emphasizes the value of using mean charts at all time frames. The only difference in the Op run, vs an ensemble member, is that the Op has not had any of it's starting data adjusted. Would still rather judge the trend by the average of it's 50 slightly adjusted ensemble members than just the raw Op run on its own.

EC46 still shows a decent Northern Hemisphere set up for the all important week 16-23....trop vortex fragment lobes in NE Canada, Siberia and Scandinavia, -AO (arctic high) with W-NW flow into europe.

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@Polo - is the ECM AI that you report the one based on Google DeepMind?

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@philhitch, don't think so, description says "AIFS machine learning available in Open-data"

Charts here
https://www.meteociel.fr/modeles/ecmwf_aifs.php

Here are latest ECMWF stats on a few AI models.....

And the old school example below......hard to compare based on these graphs but I've read the ECM AI one is close overall to the top physics models

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https://www.skipass.com/news/meteo-du-jeudi-5-decembre-neige.html

Meteo Alps forecast worth pushing through translate .

Expecting Pyrenees to get whacked also good for Massif Central and Jura . Looking for good falls around Grenoble but not so bullish for the inner ranges although still useful numbers .

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There was a new AI model released yesterday by google. More accurate than physics models apparently.

https://deepmind.google/discover/blog/gencast-predicts-weather-and-the-risks-of-extreme-conditions-with-sota-accuracy/

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Above 1,500m, 70cm snow by Sunday?
https://www.meteoblue.com/en/weather/week/les-gets_france_3000902

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@Snow&skifan, not from now when I clicked the link? 20-30cm showing

Very high rain snow level last night I understand much higher than forecast once again the warm air so much warmer than anticipated. As suggested on yesterday forecast I posted above that most of the action this weekend will take place away from the inner alps

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@davidof, suggesting your area is going to see plenty this Sat and Sun.

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Moutiers 5C just now. Snowing above 1,000m in La Tarentaise?

@Snow&skifan, Nope not on my terrace at 1550m according to my webcam , suggestions is there may be a few flakes late morning but nothing on the ground , you’ll have to wait for tomorrow afternoon for snow .

You know it makes sense.

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

this terrace was wet and brown at 10:30am UK time, now showing a light dusting at 2000m. Bouc Blanc at the top of the La Tania bubble.

A snowHead

Chamonix Meteo calling for 40-50cm @1,200m over next two days. Snow-Forecast.com calling for 5cm. Somebody’s got to be right!

A snowHead

I believe Chamonix meteo involves real actual people. Fingers crossed......

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

@Origen, it does, I hope they're right. Meteoblue reasonably optimistic too ...

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This is the most comprehensive forecast for the French Alps issued this evening by Meteo Alps , I think Chamonix Meteo in disguise .

You can read in full here https://www.meteoalpes.fr/bulletin/alpes-du-nord/

Saturday, December 7, 2024:

Becoming disturbed. Yet the beginning of the day is calm, with even a sun that dominates among some scattered clouds. This good weather continues until the end of the morning in the southeast of the region. At the same time, the activated disturbance flows over the west of the region and is generalized by midday with fairly marked precipitation (snow around 1800/1900 meters). The rain-snow limit lowers to 1200/1400 meters in the afternoon then 900/1100 meters in the evening and even 700 meters in the night, under precipitation weakening significantly everywhere in the second part of the night from Saturday to Sunday.
Accumulation of snow by Sunday morning:
- around 1100 meters: 5 to 10 cm in Est-Maurienne/Haute-Maurienne, Oisans/Sud-Vercors, generally 10 to 15 cm elsewhere
- around 1700 meters: 10 to 15 cm in Haute-Maurienne and Oisans, generally 15 to 25 cm elsewhere.
- above 2100 meters: 15 to 25 cm from Haute-Maurienne to Maurienne, 30 to 40 cm elsewhere or even 45 cm in Nord-Belledonne/Lauzière/Beaufortain.

Minimum temperatures between +1 and +4 degrees.
Maximum temperatures between +9 and +12 degrees.
Isothermal 0° towards 2400 then 1000 meters.
Moderate wind from Southwest then Northwest, becoming noticeable in high mountains in the evening.

Sunday, December 8, 2024:

Winter. At the beginning of the day, low to moderate snowfalls continue from 500/700 meters in the Pre-Alps but also on most of the northern slopes of the massifs in the cloud layers. We only talk about a few flaky drizzle in the afternoon in the mountains (under a clogged sky) except on the massifs near Grenoble where more regular snowfall (although weak) is maintained. Weather becoming dry in the plains from the end of the morning and then everywhere throughout the evening.
Additional snow accumulation:
- around 1000 meters: 1 to 3 cm, 2 to 5 cm in the Pre-Alps, 5 to 10 cm on the massifs near Grenoble or even 10 to 15 cm in Chartreuse/Nord-Vercors.
- above 1800 meters: 2 to 5 cm, 5 to 10 cm in the Pre-Alps/Belleville Valley, 10 to 15 cm on the massifs near Grenoble or even 20 cm in the heart of Chartreuse.

Minimum temperatures between +2 and +4 degrees.
Maximum temperatures between +5 and +8 degrees.
Isothermal 0° around 900 meters.
Moderate north

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So area around Grenoble and the Chartreuse to benefit the most , the inner Alps areas including Mt Blanc area will get useful snowfall but more in the area of 25cm at 1500m rather than the 50/60cm talked about a couple of days ago .

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Interesting temperature variations as this front arrives, presumably due to temperature inversions following a dry night. Currently reporting -2C in Chamonix but +4C in Morzine, both at similar altitudes and only a few valleys away. +3C in Avoriaz, 800m higher.

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@denfinella, are those temp measurements all live? and where are the sensors Very Happy

Anyway, already been snowing at 1600m in the bowl (grains d'or camera), while more exposed chavannes 1600m was rain, now sleet at 1400m.....hopefully it won't matter in a few hours

EC46 still looking good week 16-23, maybe a shade too far west, but this being a 6 week model it's not high resolution. Consistent signal so far though.

ECM/GFS/GEM all showing a warmer trend into 13th from Iberian low. Then the day 10 means (17-18th) show better chance from the NW again. Still have that lingering low around Spain though.

ECM and GFS in particular are too far west the -NAO, not great, while GEM is again much better....but a consensus of the 3 would still be a little too far west, milder for alps, maybe good for pyrenees.
There is a risk of a flatter zonal pattern too....so really need EC46 and GEM to be right here, maintaining a decent mid atlantic ridge

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@polo, I use the map section of https://www.weatherandradar.co.uk for live temperatures. I don't know their source, but based on observations when I'm travelling around the UK, they seem fairly accurate, and update every 5 / 15 / 30 mins (it seems to vary, not sure why).

Morzine and Chamonix are holding steady, Avoriaz has dropped to 1C, so the temperature inversion is weakening.

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Straight to snow at 1500m in Haute Tarentaise , my Terrace already white

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The All New Weather Outlook 24/25

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