Ski tips #5: Weather forecasting, and how to get more powder days

When I started this blog, I gave you some of my background regarding my skiing. For this post, it kinda helps to know my background in another area: weather forecasting.

I am (or was) a glider pilot, and flew for ~20 years before I eventually gave it up. I got particularly interested in weather as a result of this, and worked my way up to become the weatherman for the annual Alberta summer soaring camp for about 5 years, plus acted as the assistant weatherman for the 1982 Canadian National Soaring Championships hosted by Calgary. In both of these roles, I spent a LOT of time working with Environment Canada forecasters. For a few years, I taught the weather section of the ground school for student pilots held in Calgary, and my teaching partner was Steve Rothfells, who not only plays a weatherman on TV, but is actually a meteorologist.

A lot of people, the owner of this blog included, like to look at weather prediction data for ski areas. The challenge with forecasting weather for ski areas is simple: they are in the mountains, and mountain weather forecasting is a challenge.

Environment Canada generates about 90% of their forecasts using computer models. As one EnviroCan forecaster said to me a number of years ago, “the computers haven’t figured out the mountains are there” (they’re better now, but not much). Of particular issue are airmasses that move in from the north west associated with low pressure centers (read: storms). These are more common in the summer than the winter due to jet stream positioning, but they are a good illustration of the computer problem. While air should drag behind them, and the models model it that way, the mountains cause the air mass to bend in front and around them. The associated weather is not as predicted.

In addition, mountains make their own weather. Most people understand the concept of orographic precipitation — precip caused when an airmass hits a mountain and has to rise up and over it. But mountains are full of microclimates. Nakiska doesn’t get much snow. Fortress, just down the road, gets more than double the precipitation as Nakiska. Sunshine sits on the divide and gets 30% more snow than Louise, and 50% more than Norquay. Fernie sits in the confluence of 3 valleys and frequently gets hammered with snow.

Put a little solar heating on some exposed rock in the mountains and you can develop thermal heating in the dead of winter, which results in swirling winds on an otherwise calm day. Cold air is heavy and dense and it sinks, filling valleys with chill when it’s warm up top (one day last year I was at Sunshine it was -28° in the parking lot and +2 ° and sunny at the top).

And EnviroCan models none of this, because generally they don’t care. That’s not crass, nor a slight against EnviroCan, it’s just not their mandate. EnviroCan tries to model population centers, and people don’t live at the tops of mountains. What does live up there is airplanes, and EnviroCan cares a lot about them. So EnviroCan actually does an awesome job of forecasting winds aloft and high level cloud. Bet you didn’t know this, but EnviroCan’s weather radar show precipitation that planes could run into, NOT precip that will hit the ground. In the summer (and winter, to a lesser extent) you’ll often see areas of virga painted on the radar. Virga is the name of precip that doesn’t ever hit the ground (due to evaporation, or rising air that sucks it back up). There’s a group that comes in during the summer in Alberta and targets their radar on precip hitting the ground. They’re called Weather Modification Inc, and they’re paid by insurance companies to seed clouds to reduce hail damage. Comparing the WeatherMod radar and the EnviroCan radar during the summer is quite interesting. Here’s a post where I do just that.

So message #1: EnviroCan isn’t trying to forecast the weather for ski areas. In the shoulder seasons, they’ll report freezing level (data of high quality, because pilots care about that). But generally, they’re not that useful if you want the answer to the question “What’s it going to be like at Big White today”? If the radar image shows precip, because EnviroCan is looking up (for airplanes) and mountains are up, it’s pretty good data. Because pilots care, the radar is excellent at identifying rain vs snow. I should mention that EnviroCan has a commercial section that will do custom forecasts for anyone who pays them, and that’s usually good data, because the guys who work there are good.  However, I’m not aware of any ski resort who currently pays EnviroCan for custom forecasts. Some (like Sunshine) used to.

So if EnviroCan doesn’t make the forecasts, who does? Well, don’t say The Weather Network. All they do is put EnviroCan’s forecasts into a stand alone TV show (and a cheezy one at that). Avoid.

There are a few worth noting: www.Snow-Forecast.com, Sunshine’s automated sites, Alberta Environment and Parks, Washington State University, Avalanche.ca, SpotWX and SnowCasts.ca’s weather pages.

Snow-Forecast.Com

Snow Forecast is generated out of the UK. They have a sister site called Mountain Forecast that is tied to hiking which I also reference, and another called Surf Forecast which I look at when I go to Maui. All of their forecasts are purely computer modeled, though with a detailed terrain model built in (which EnviroCan does not use). However, what sets them apart is that their forecasts (1) are for ski areas, (2) are tuned to mountain areas. I have followed them for years. While I keep a lot of stats on my skiing, I have not kept stats to see how accurate their forecasts are, but I can tell you what I have generally come to believe.

Message #2: Snow-Forecast.com is good but far from perfect

  • I think Snow Forecast has very reliable predictions of temperatures, freezing levels and winds. I choose how warm to dress using this data each day. Every morning I check the temps on Sunshine’s webcams. Snow Forecast is rarely more than 2° off.
  • Their cloud cover forecasts are not bad; call it 60%. I pick sunglasses based on it, but always carry backups.
  • Their forecasts of precipitation are 75% or better. If Snow Forecast says it will snow, it’s a good bet it will snow. However, there’s a lot of time where they predict no snow and it dumps.
  • Their forecasts of precipitation accumulation are rotten. They’ll predict 10 cm, we’ll get 2. Or 20. They’ll predict 1 cm, we’ll get 25. I put no faith in them whatsoever (though I do get excited if their prediction numbers get big).
Snow-Forecast breaks the day down into forecasts for 2 and 8 hour increments, and the 8 hr forecast is free (4 AM – noon, noon- 8 PM, 8 PM to 4 AM). They re-run their models 3 times a day, so they changes their forecasts a lot. This week, for instance, they predicted snow at Sunshine for Wednesday overnight (8 PM to 4 AM Thursday) from a high of 17 cm to a low of 3 cm, and a lot of points in between. Makes comparing actuals to predictions difficult. Take a look at the Forecast History section of this page from Wx.ca where that comparison is made for temperature prediction for Calgary to see how tough it would be.
So because I could, I actually did break down how actuals compare to the various forecasts, live, for one week when a storm was forecast. It makes for an interesting (if long) read. See it here.
There are a few more resources that are requirements for weather data and forecasts.
MountainWeather.ca

This is your access to Sunshine’s automated weather stations (and some for Fernie, Kicking Horse and others, too). You want “real time, what’s happening on the mountain right now” data? This is your site.

Sunshine has 2 stations (used to be 3) that are now automated and for which you can see data basically 24/7.

  • Stonehenge is the main station just off the base of the Wawa Chair (on the Corral Cutoff run), where snow depth is measured (and the snow web cam is). You can get temperature data, too. HN24 is the new snow in the last 24 hrs, since they last cleaned off the sensor, usually at 7 AM. HST is the snow associated with a storm; they’ll clean it off and reset it to zero every few days. Always worth a check to see if that 15 cm fell overnight, meaning fresh AM tracks, or in the morning the previous day, meaning it’s going to be harder to find freshies.
  • Goat’s Eye, who’s sensors are in two places. Wind data comes from the tower at the top of the Cleavage rocks, and temperature comes from the weather station at the base of Mother In Law.

I say you can get the data 24/7, but I find they often aren’t accessible at 11 PM when I go to look at stuff before I go to bed. Don’t know why, and I’ve asked. You may notice that Mountainweather.ca also has automated data from Fernie, Kicking Horse and a couple of other ski areas I’ve never heard of (do such things exist?). I don’t look at Fernie’s or KHMR’s data, and I don’t ski there, so can’t say anything about them.

Also now linked on Sunshine’s Mountainweather.ca page are the Parks Canada weather sites, which you can get through Avalanche.ca as well.

Parks Canada keeps changing how they offer their weather data. These days, you can find it on their avalanche site here. “Lookout” is the name of the station at the top of Divide. It has temperature and wind data that is useful. “Sunshine” is the Park’s station behind the old warden cabin just above the base of Strawberry. It has temperature and snow data, both fully automated. It’s always interesting to compare the Parks snowfall data with the Stonehenge data from Mountainweather.ca. Park’s data, too, seems to be unavailable from 10 PM to 6 AM, and is often delayed 2 hrs.

Alberta Environment and Parks

Sunshine Snow Pillow 15-4-26Alberta Environment & Parks maintains a snow pillow on Goat’s Eye near the top of Wildfire (just off Eagle Creek, at the base of the Goat’s Head Soup run). This is a fully automated station that provides input to water supply forecasting. The charts they produce are good to compare to other hills in BC, and to previous years, and to the standard deviation to the normal snowfalls. They just changed the link to it; now you can find it here.

University of Washington

Then there’s the University of Washington’s School of Meteorology. Regular Powderwatch.com reader (and all around good guy) Ginger passed it on to me and it’s worth sharing. They post a stand alone 72 hr snow forecast model run, and you can see it here. I find it better than the Snow Forecast snow prediction model, and the displays are better, too (though it SUCKS on a mobile device).

Avalanche.ca

Avalanche.ca has several weather pages with tons of very technical info. This one is simplified for us humans. I look occasionally but get everything I need from the other sites above.

SnowCast.ca

“New” in the game is SnowCast.ca. I’m not huge fan, but it’s worth of note. It’s an experimental snow forecasting site focused on the Bow Valley area, from the folks at the University of Saskatchewan. The UofS does a LOT of water supply forecasting, and their main man Dr. John Pomeroy just opened a lab in Canmore. It’s beyond the scope of this blog to talk about Pomeroy’s research, but bookmark that site and keep an eye on it.

Snow-Reports.ca

In 2013, a few smart guys in Calgary who liked weather modelling put together for fun Snow-Reports.ca. They quit updating the verbage on their site in 2014 but their forecast models are still available. Pretty sure no one’s updating anything other than the forecasting models, which I believe are automated.

SpotWX

The way weather forecasts work these days is via models (Snow-Reports, Snow-Forecast, EnviroCan, Pomeroy and all the others use models). The BEST WAY to figure out what’s going to happen (according to my brother, the statistician) is to look at a LOT of models, and decide for yourself. SpotWX.com lets you do that. Drop a pin anywhere on the planet (say, Sunshine Village) and you can see the raw modelling forecasts for that point. There are between 8 and 20 forecasts available, depending on where you are, of varying resolution. There are short term and long term models from Canada and the US.

In Conclusion

Here’s about the only three things I can guarantee about forecasting mountain weather here:

  • If there’s a huge fat high pressure system sitting over central BC, it will be sunny at Sunshine.
  • If it’s chinooking in Calgary (and EnviroCan is good at predicting those), it will be probably be precipitating and windy, at least at Sunshine and probably Castle and Fernie, too. Louise, Kicking Horse and Panorama tend not to get that much Chinook associated precip.
  • If EnviroCan is talking about an “upslope flow”, the wind is from the east, and it will snow like crazy at Nakiska (that orographic thing).
Here are some other key messages for powderhounds seeking fresh tracks:
  • Snow that fell more than 2 days ago is basically irrelevant. This video from Lake Louise Lowdown shows one reason why. Stuff gets skied out. Winds blow it away. The sun crusts it in the spring. I know where you can still find it at Sunshine, and so getting to know the area well helps, but still you gotta work to find powder more than 48 hrs old.
  • The last 7 day snowfall number is meaningless. Rob’s “what fell this week” data is only about building the base, and then only interesting in the early season when your favorite hill is opening. One caveat: it’s meaningless if it last snowed 7 days ago. It’s meaningful if it snowed every day for the last 7.
  • Total year to date snowfall is meaningless. Panorama particularly likes to talk this number up. Again, that’s only about building base. Sunshine set a record for most snowfall EVER in 2014, and while it’s great fun to talk it up and show people on the banner, in fact, so what? There are sections of the mountain that are still exposed rock. We had less snow last year, but the coverage was better (I blame the January wind). However, if you know where it blew to (like Barner’s Bowl) you can find VERY deep snow — IF having a 15′ base makes your skiing better.
So I can tell you how to have more powder days, no matter where you ride:
SKI MORE OFTEN
Chasing a weather forecast is folly. They’re all mostly wrong anyway. Back when I skied 9-20 days per year, there was an incredible amount of randomness about getting powder days. My lowest year had 13% of my days as powder days, my best 56%. Every year since I broke 30 days per year, I’ve had a consistent 40% of my days as powder days. The more you ski, the more likely you are to get the days they don’t predict. The more you ski, the more likely you’ll get the snow. It’s that simple.