ECM is again the pick of the crop with cold weather out to at least 01 December from Sunday. GFS a bit wobbly.
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
Let's praise the ECMWF then.
As I remembered correctly, last year it was ECMWF who was a party breaker. When GFS had epic snowmageddons in his charts (always T+7 days ahead), the sneaky EMCWF had mild and dry conditions for the same period and she was always right.
So let's end this very good month with a bang and hope that the rest of the winter months will also deliver.
Last edited by Obviously A snowHead isn't a real person on Tue 21-11-17 15:33; edited 2 times in total
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?
The last few days illustrate the continued volatility in short range model output. For this example, I've used the best model (ECM), and taken the average pressure anomaly of all ensembles. These are single best charts available at that timeframe. Clearly if I had used just the Op run, or anything from GFS, the differences would be far greater.
In any case, you can see on the left image below how 4 days ago the smartest computer runs in the world averaged out to high pressure over Europe for Mon 27th Nov, with a very atlantic driven (zonal) mild flow, which at the time was also forecast to run to end of the month and even beyond.
On the right, we have the latest output, for the same day Mon 27th Nov. Almost landing a full 360 backflip, low pressure is now over Europe, with highs mid atlantic, and northerly cold airflow for alps. This is also now forecast to run to the end of the month on several models.
Looks like the 06z GFS today is coming into line with ECM for cold from next weekend. In situations where the main 2 models differ it's worth checking the UKMO out to t+144, and to a lesser degree GEM.
@langball, That is interesting, especially as an average. Were any of the ensembles predicting this backflip?
Also, cold and snowy or cold and clear?
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
@leggyblonde, ECM has 51 ensemble members I think, vs 20 for GFS. There are some websites that group the ECM members into clusters of ensembles (that show groups of HP/LP areas). I haven't gone back to look, there probably were a few that got it right, but the above is the average, so clearly the vast majority were completely wrong.
As for snow beyond the weekend, both models think so. You'll see snowforecast light up soon, and YR.no looking good for northern alps, hopefully across the full spectrum, but too early for detail quantities / freeze levels.....
Last edited by Anyway, snowHeads is much more fun if you do. on Tue 21-11-17 11:36; edited 1 time in total
@langball, very interesting thanks. Also credit to @nozawaonsen for spotting the building high pressure over Greenland a few days back and the effect that might have on the cold air flow, contrary to model output at the time.
Then you can post your own questions or snow reports...
Then you can post your own questions or snow reports...
leggyblonde wrote:
Were any of the ensembles predicting this backflip?
A limited number of GFS ensembles were yes but the significant majority were predicting mild weather continuing through the weekend. As far as GFS is concerned it's been quite a turnaround.
hd on Sunday wrote:
Checking the ensembles the warm up until Friday is nailed on but some disparity is evident for the weekend with a reasonable number dipping back down to seasonal average temperatures.
After all it is free
After all it is free
I only look at GFS for Zermatt and I have to say that it has been consistent (over more than a week) in showing a cold and snowy period from the weekend onwards. Latest GFS ensemble for Zermatt is here:
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@mitcva, on the previous page lots of mentions of GFS looking mild and dry, extending into FI / end of month, with caveats of course. Also Wepowders latest vid from last Friday warns of mild and dry conditions being forecast for the whole of europe until the end of the month.
GFS ensemble output covers 16 days, anything in the second half of that is fantasy, and will always show a wider range of scatter as you go further out. Sometimes FI becomes reality, several examples on this thread already of forecasts verifying 7-8 days out, but it's the exception. I think <20% chance of a forecast being right at that range. The ensemble average is a better guide in that low res timeframe, and even then the overall picture can change dramatically in 4-5 days like we just saw.
Ski the Net with snowHeads
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Here in Morzine, it will be a cold winter, definitely, according to the locals. 1) Plagues of wasps over the summer, and 2) souris are/were everywhere in plague proportions. Overbreeding in anticipation!
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
@noggy, is that actual farmers almanac knowledge?
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.
@noggy, love that kind of stuff!
So if you're just off somewhere snowy come back and post a snow report of your own and we'll all love you very much
So if you're just off somewhere snowy come back and post a snow report of your own and we'll all love you very much
matejp wrote:
As I remembered correctly, last year it was ECMWF who was a party breaker. When GFS had epic snowmageddons in his charts (always T+7 days ahead), the sneaky EMCWF had mild and dry conditions for the same period and he was always right.
He? Interesting!
I've got this image of GFS as an opinionated male voicing his views, only to be brought into line by his smarter wife (ECM). After a few days of grumpily sticking to his guns, he has to begrudingly admit his wife was right all along..
You know it makes sense.
You know it makes sense.
@Handy Turnip, I corrected my sentence ...
Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
@matejp, haha!!
Poster: A snowHead
Poster: A snowHead
GFS 12Z appears to be increasing its forecasted precipitation amounts for Saturday and my resort of choice has just announced a full area opening for the weekend for the first time this season. This should give access to oodles of not yet tracked snow from the recent dumps. Excellent
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
@noggy, we don't actually want a particularly cold winter, as then it often doesn't snow. We want a snowy winter.
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?
hd wrote:
GFS 12Z appears to be increasing its forecasted precipitation amounts for Saturday and my resort of choice has just announced a full area opening for the weekend for the first time this season. This should give access to oodles of not yet tracked snow from the recent dumps. Excellent
@langball, I’m a bit wary of the average or mean. I’m not convinced that it is a very good indicator in itself. Not least as it will inevitably start to display “reversion to the mean” at range.
Anyway whilst we are considering retrospectives, looking back a week...
“GFS and ECM currently have a milder spell from 22-24 November.”
GFS did continue this mild weather but it was an outlier.
“At least a spell of these conditions now look likely from middle of next week. Whether it extends we’ll have to wait and see.”
So that was eight days before the mild weather forecast for tomorrow. Not bad.
The tricky bit was whether this warmer spell would last for a while or not.
By Wednesday 15...
“Out at +240 ECM hints at a way out, but that’s a way off.”
“12z and 18z GFS more in line with earlier ECM with cold and snow sweeping down from around 25 November.”
And that was 10 days out.
Thursday 16 November
Starts off with...
“Any mild weather currently looks restricted to mid week before colder weather arrives again the following weekend with further snowfall. That said the GFS op run is a bit of an outlier.”
By Friday 17 November looks a bit less clear.
“warming up with high pressure and milder temperatures as we head towards end of November (which will melt lower lying snow).”
Though that would need to be seen against the context of the earlier output.
“There have been a few colder alternatives thrown in by some op runs but the ensembles do seem to be trending towards dry and mild for now.”
And indeed by that evening.
“12z GFS continues to have warmer dry weather next week, but by the following week replaces that with cold and fresh snow.”
By Saturday 18 it did look like
“Any serious breakdown in the coming high pressure looks like being towards the end of the month.”
But the complicating factor was how the following weekend played out.
“Next weekend‘s weather being driven by position of this low.
06z GFS sees it digging further south which produces more cold and snow. Other runs have it further north with high pressure in charge.”
By Sunday 19 ECM was back on track with where it had been on the previous Wednesday.
“ECM has next band of cold weather coming in Sunday week. GFS not till the end of the month. Take your pic”
And later...
“Milder temperatures (10c max) will be short lived (from Wednesday till Saturday) and it seems that from 25.11. there will be much colder again with new snow showers.”
“...a return to cold weather after a warm spell has been fairly consistent.”
And later still...
“Boom! ECMWF 12Z goes again for cold+snow.”
By yesterday...
“00z GFS and ECM both now see cold and snowy weather arriving in the Alps this weekend after what looks like being a relatively short mild spell in the coming week.”
So a few thoughts:
- the mild spell was picked up 8 days out.
- a possible return to cold started being flagged 10 days out.
- the timing of this shifted a little, some runs pushing it to the end of the month some sticking with next weekend.
- but after a couple of days of uncertainty (late Friday and Saturday) and some unhelpful trolling we are back to a consistent pattern.
Last edited by You need to Login to know who's really who. on Tue 21-11-17 20:46; edited 4 times in total
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
Right where are the ensembles?
Here!
Cold and snow incoming for the Alps and much colder conditions for Scotland and Pyrenees too!
@staffsan, I've heard that from 2 different locals in the past 2 weeks. So, they believe it, maybe!
Then you can post your own questions or snow reports...
Then you can post your own questions or snow reports...
under a new name wrote:
@noggy, we don't actually want a particularly cold winter, as then it often doesn't snow. We want a snowy winter.
Is Gasteinertal the Bad Gastein area?
After all it is free
After all it is free
FrediKanoute wrote:
under a new name wrote:
@noggy, we don't actually want a particularly cold winter, as then it often doesn't snow. We want a snowy winter.
Is Gasteinertal the Bad Gastein area?
Yes. Sportgastein now opening early on this Friday.
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@nozawaonsen, of course people have different styles....
Agree the averages are less meaningful beyond 6-10 days as you said due to mean reversion, but then again in my view the Ops aren't any better at that range but are of course much more volatile.
Referring again to Morris at wepowder, his rule of thumb for model output is:
12 hours in the future: 80-90% of all the cases are correct
48 hours in the future: 70-85% is correct
Up to 120 hours in the future: 50-75% is correct
Up to 144 hours and further in the future: 45-55% of all the cases are correct
The ensemble mean is always going to be better at a longer range, beyond say 5-7 days. You use the op or control run at shorter ranges. Ensemble means are great at capturing synoptic trends, and poor at telling you what exactly is going to happen at your location, and just terrible at capturing mesoscale systems.
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.
Both GFS and ECM this morning see colder than average weather arriving this weekend and lasting into at least early December. The first snowfall looks like arriving on Saturday (10-30cms looking possible across much of the Alps at altitude) with more to follow the week after though hard to judge how much at this point (though the 00z GFS was suggesting heavy falls in the southern Alps... we’ll see). Fresh snow for Scotland too
As far as the mean goes. Close in it will simply replicate the tightening of the ensembles, but in a rough rather unuseful way (so as @Jellybeans1000 says not much help with detailed - mesoscale - output). Further out it will give you a broad sense of how the ensembles as a whole are shifting (so the big picture -synoptic - trend), but that rather ignores the point that outliers can in fact be correct. By its nature a mean will exclude these and given that at a distance a set of ensembles will have a range of outliers that is going to remove all of these. That can be useful, but can also be misleading. It gives you a sense of travel, but no real idea of the destination...
Not completely unhelpful mind you, just treat with caution and use in conjunction with the op run and indeed other model output.
So if you're just off somewhere snowy come back and post a snow report of your own and we'll all love you very much
So if you're just off somewhere snowy come back and post a snow report of your own and we'll all love you very much
really enjoying this thread, thanks to all the posters. Does anyone know in which part of the Alps Saalbach is situated? Would love to be able to follow the thread more accurately when snow is predicted in different regions at different strengths.
You know it makes sense.
You know it makes sense.
This one is closest to Saalbach:
Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
thanks @tccambs!
Poster: A snowHead
Poster: A snowHead
@nozawaonsen, so the mean is "not completely unhelpful" that's a funny way of describing it.
Also amusing to me that you see colder than average output lasting "into at least early December".
So that would be mid December?
As I said, people do things differently. Netweather must have over 50 regular posters on their site, many of them pros, and so much high quality detailed analysis by non pro's. The variety alone is fascinating, some of them won't look beyond t+96, others prefer the FI rollercoaster.
At the end of day, we're all hunting snow and right now the chase is certainly on into month end.
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
@langball, not sure what you mean about mid December/early December? The ECM data runs out till 02 December. You can see GFS out further, but my point was that both saw it lasting until early December (ie 02 December). Can’t comment much beyond that as ECM data (at least on Meteociel and Wetter) doesn’t run beyond that and in any case output is pretty unreliable beyond that point.
You seem to think I was being critical of you. I wasn’t. Simply pointing out that there are limitations to the mean as a tool. It’s a form of herding as it excludes outliers.
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?
@nozawaonsen, Thank you for your continued input. It is very much appreciated.
@tccambs, Saalbach is SW of Salzburg in the Pinzgau Just on the Salzburgerland side of the border with Tirol. The river Saal starts up in the Kitzbühel Alps then flows down into the Glemmtal valley. Which is a really stunning valley. It’s on the north side of the eastern end of the Alps. It’s a great resort.
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
off 13-20 January for the second time. Was in St Anton Jan 14, Saalbach Jan 16. Both times conditions were pretty terrible, hoping third time lucky! fingers crossed for all of us
@nozawaonsen, yes both models see cold until early December, but your comment was cold weather lasting until at least early December. I understand that to be beyond early December?
There are limitations to all these forecasting tools. The mean does not exclude outliers, it incorporates all of the ensemble members, whether they are outliers or not.
Then you can post your own questions or snow reports...
Then you can post your own questions or snow reports...
langball wrote:
@nozawaonsen, yes both models see cold until early December, but your comment was cold weather lasting until at least early December. I understand that to be beyond early December?
@langball, semantics...at least infers definitely until early December and possibly after that.
nozawaonsen wrote:
You can see GFS out further, but my point was that both saw it lasting until early December (ie 02 December).
So if the cold weather were to finish suddenly on 3 December the use of at least by @nozawaonsen would still be correct.
After all it is free
After all it is free
nozawaonsen wrote:
@tccambs, Saalbach is SW of Salzburg in the Pinzgau Just on the Salzburgerland side of the border with Tirol. The river Saal starts up in the Kitzbühel Alps then flows down into the Glemmtal valley. Which is a really stunning valley. It’s on the north side of the eastern end of the Alps. It’s a great resort.
Yes, I know. I had a great time there chez Tatman.
I'm not quite sure why my posting of the nearest ensemble prompted you to think that I needed further information.
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.
I think the response was to a question by @rrd3718
Ski the Net with snowHeads
Ski the Net with snowHeads
Whoop whoop loving that spike on Saturday. Sunday looking good for the weekend warriors!
High temps another reminder to go high early season folks!
FAQ
Poster: A snowHead
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