 Poster: A snowHead
|
|
well im sure we are in for a very interesteing 10 tays if all this is true, please can the guys in the know keep us updated, cheers. let it snow, let it snow, let it snow!!!
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
|
18z seems to have ramped up the snowfall a bit for Friday in the Eastern Alps.
|
|
|
|
|
|
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 12z (the latest I have seen) for St Johann has quite a few of the precipitation and temperature lines overlapping once you get beyond 17th 
And yes, I know that is too far away to be useful, and they are all over the place.
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
Ricklovesthepowder,
brian and carled must not be nagged: being pearls of great price, they should be treated with the utmost sensitivity. 
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
Ricklovesthepowder, I'll venture a further explanation, but I'm no expert.
On that chart, the surface pressure isobars (white lines) tell you what's happening on the ground i.e High pressure=dry & clear; Low Pressure=wet & cloudy; Wind direction follows the lines.
The colours are telling you what's happening in the upper air at around 5,500m/18,000ft, from this activity inferences can be drawn about which way the surface weather patterns are being driven.
I think the excitement is about a high pressure forming over Greenland blocking the mild Atlantic weather, allowing dry, frigid continental air to spill out of Scandinavia/Russia into parts further west including the Alps and Britain, the hope is that some moisture will find it's way in and provide some of that stuff you love. 
If I am interpreting correctly, the latest 18z charts show a nasty low pressure system ploughing into eastern Britain next Thursday bringing a potential snowfall event, due to the low temps that will accompany it.  
But it could all change again tomorrow!
|
|
|
|
|
|
|
|
|
Back to a real muddle from 17 December on 00z GFS. A whole 20C difference between the Kontroll and Hauptlauf...
Last edited by Then you can post your own questions or snow reports... on Thu 10-12-09 10:40; edited 1 time in total
|
|
|
|
|
|
|
|
Ricklovesthepowder. Be aware, too, that if you ask them now whether they think you'll have snow in Avoriaz in the middle of January you might risk getting a flea in your ear. When they have something worthwhile to tell us, they will tell us. Just don't ask.
|
|
|
|
|
|
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.
|
|
|
|
|
|
|
|
|
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
|
|
I've just looked at the wigglies for my bit of the UK (long lat 052) and a white Xmas looks possible but the wigglies are the usual 850hPa which is a bit misleading being so high. Are there any wigglies showing ground temps? I can get the pretty coloured pictures but not wigglies.
|
|
|
|
|
|
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.
|
| nozawaonsen wrote: |
| Back to a real muddle from 17 December on 00z. A whole 20C difference between the Kontroll and Hauptlauf... |
I assume you're talking about an Alpine location, as they both agree on ongoing cold for Britain (0,52N) from 13th-23rd December, with a potential snow event around the 19th.
|
|
|
|
|
|
|
|
|
luigi Western Austria, West of Ischgl, http://91.121.93.17/pics/MS_1047_ens.png
Last edited by 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  on Thu 10-12-09 11:09; edited 3 times in total
|
|
|
|
|
|
brian
brian
Guest
|
|
|
|
brian
brian
Guest
|
Ricklovesthepowder, listen very carefully, I shall say this only once ....
2 types of charts. First one:
White lines are sea level pressure. As explained by luigi the wind flows roughly parallel to these, actually clockwise round High Pressure but slightly flowing out from the centre and anti-clockwise round Low Pressure slightly flowing in towards the centre. The closer the lines are together the stronger the wind.
Unless you're really interested ignore the colours on this chart. For the more interested reader, the colours are the altitude (in decametres, ie. 550 = 5500 metres) where the pressure is 500 hPa (ie. roughly half sea level pressure). You can infer a measure of temperature of the mass of air, as pressure and temperature are proportional, from the difference in the 500 hPa height and (notional) 1000 hPa height. This is referred to as "thickness". The rule of thumb is that precip at less than 520 dam will almost certainly be snow, greater than 530 dam almost certainly rain, in between marginal.
Still with me? Ok, 2nd chart:
White lines are the height where the pressure is 850 hPa, eg. 152 = 1520 metres. Colours are temperature where the pressure is 850hPa and you already know the height that is, yes? However, remember when applying this to ski stations that this is a forecast of free air temperature, it doesn't take into account the effects of having a huge lump of mass (the ground!) right next to it, so be careful (because snow-forecast aren't  ).
Clear as mud, right?
|
|
|
|
|
|
Poster: A snowHead
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
brian, brilliant explanation, I think I understand it a lot better now, particularly the 500hPa geopot colours and their predictor of precip as snow.
So, does a value of under 520 dam indicate precip as snow right down to sea-level? And why the thick black line at 552dam?
How does snow-forecast get it so wrong with regard to free air temps? Is it because a cold ground mass tends lower the temp of the air above it allowing precip to fall as snow even if the free air temp was indicating rain?
I think I'm turning into a weather geek!
|
|
|
|
|
|
brian
brian
Guest
|
luigi, yes, I should have said, that rule of thumb was for sea level. Obviously altitude improves things, the 546 dam line is a reasonable rain/snow safety line for 2000m (actually probably a bit lower, but let's be on the safe side).
Note however that the colours do not show the thickness (specifically we're talking about 1000-500 thickness here) directly. You calculate it by:
thickness = (500hpa height in dm) + 0.9 * (1000 - sea level pressure)
So at the point where SLP is 1000hPa, you have the thickness value by colour, everywhere else you have to adjust it.
Random example:
Look at Hull, 500 height is 552, slp is 1020, so thickness is about 534 dam, probably not cold enough for snow (sorry Hull!)
Thickness values are shown directly from GFS (along with SLP and cloud cover) on these charts, for the other models you have to work them out yourself:
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
Thanks Brian, it's a complex but fascinating business, isn't it?
That last 'thickness' chart looks really useful as a snow predictor.
The green 546dam line predicting precip as snow at 2000m anywhere north of it, interesting to see it splitting the Alps in half on the chart.
Presumably the blue 528dam line is a predictor of precip as snow right down to low altitude. The cloud cover showing the fronts where the precip might occur. Very useful, I'll bookmark it.
But I think it's probably easier to just wait for the expert interpretation on this thread.
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
|
Brian, care to cut n copy into the Beginners guide to GFS sticky???
|
|
|
|
|
|
|
|
| Quote: |
Oh and Hurtle... get a room
|
No point in that if she's all on her own, just looking at the charts. Don'tcha just love it when they talk technical.......
|
|
|
|
|
|
|
|
|
I've just cancelled my holiday next week due to the lack of snow and poor conditions. So it will probably dump 1 meter on Sunday.
|
|
|
|
|
|
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.
|
|
|
|
|
|
|
thanks for the explination and yes i do understand it a lot more. thanks for your time in typing all of that out, really appreciate it, cheers rick.
|
|
|
|
|
|
snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
|
| pam w wrote: |
| Quote: |
Oh and Hurtle... get a room
|
No point in that if she's all on her own, just looking at the charts |
Quite.
|
|
|
|
|
|
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.
|
So am I right in thinking that the forecast has moved away from loads of snow next week? Recent GFS runs seem to think so? 
|
|
|
|
|
|
|
|
bobojim, "The" forecast for where?
Not that you can really tell how much is likely that far away, only whether there will be some or not.
|
|
|
|
|
|
You know it makes sense.
|
brian, I like that last chart, a sort of snowx-ray 
|
|
|
|
|
|
Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
|
I don't think anyone ever said the forecast was for loads of snow. The agreeement was for cold weather, but if you check Brians recent post he said:
| Quote: |
| the details of if/when/how much snow gets to the right places are still pretty much all up for grabs though |
|
|
|
|
|
|
Poster: A snowHead
|
| kitenski wrote: |
Where were you going? I guess there's a cheap family room available |
Only in my house but I had intended a taking an extra week in December to ski but have now moved this to the start of January. We'll see but it is very thin below 1900m both on and off the slopes.
|
|
|
|
|
|
Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
|
| davidof wrote: |
| I've just cancelled my holiday next week due to the lack of snow and poor conditions. So it will probably dump 1 meter on Sunday. |
That's very brave of you. I usually rely on blind optimism and selective forecast readings and just go anyway. 
|
|
|
|
|
|
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?
|
alex_heney, I am looking at the PDS and surrounding areas. I am away next Thursday for a week and dont fancy driving to Chamonix every day!
kitenski, You are correct, I still have my fingers crossed for some snow during the next cold period.
Trying to stay positive!
|
|
|
|
|
|
You need to Login to know who's really who.
You need to Login to know who's really who.
|
Hmmm... not too sure what to make of these wigglies. It seems pretty much all the runs are in agreement upto about the 16th Dec, except the Hauptlauf which has decided to go off by itself. Now is this a case of the Hauptlauf drinking a bit too much mulled wine or does the higher resolution mean its able to pick out trends earlier than its fellow wigglies?
PS Wigglies for Ski Amade area if anyone is interested
|
|
|
|
|
|
Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
|
| Quote: |
dont fancy driving to Chamonix every day
|
Is chamonix that much better? Mostly opening on 19 December - fingers crossed.
|
|
|
|
|
|
You'll need to Register first of course.
You'll need to Register first of course.
|
| Markus wrote: |
| Hmmm... not too sure what to make of these wigglies. It seems pretty much all the runs are in agreement upto about the 16th Dec, except the Hauptlauf which has decided to go off by itself. Now is this a case of the Hauptlauf drinking a bit too much mulled wine or does the higher resolution mean its able to pick out trends earlier than its fellow wigglies? |
I've had the same question on my mind for the past week or so of watching the wigglies. It seems to happen fairly often (or at least it has happened often recently) that the Hauptlauf charges way off in one direction while the other runs are more unified in going somewhere else. I've also seen the Hauptlauf change its extreme direction from one run to the next (say, 00 is very cold but 06 is very warm, then returns to very cold for 12). That alone tells me not to put a lot of faith in those Hauptlaufs when they're all alone. It is fun watching sights like snow-forecast respond drastically to each change, though.
Now why the Hauptlauf does this, I have absolutely no idea.
|
|
|
|
|
|
|
|
For what it's worth, one of the meteo-people on skipass.com reckons there'll be snow next week, but not a lot. 
|
|
|
|
|
|
|
|
|
Oh well. A bit plus artificial crap will have to do.
|
|
|
|
|
|
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.
|
|
It so frustrating one minute you check snow-forecast and its forecasting a good 50cm+ dump then the next minute its gone down to 15cm.
|
|
|
|
|
|
|
|
|
I know, it varies so wildly. At least it seems there'll be SOME snow in La Plagne over the next few days, with Wednesday looking like the best day. You just don't know til you get there.
|
|
|
|
|
|
|
|
FAQ
Ah, the power of words! How sad, though, that my feelings remain unrequited.
)
