2011-12: How Bad Was It?

In a few past discussions I've noted that we have not had an across-the-board bad snow year in North America since 1991-92, fairly impressive since there were 4 of them in the 16 years through that season. 2011-12 does not make the cut on an equal region rated basis either mainly because 2 regions (Pacific Northwest and western Canada) had excellent seasons well above average. 1980-81, 1986-87 and 1991-92 stand out because no regions were above average, similar to 1981-82 and 2010-11 being the only seasons with no regions being below average.

1976-77 is still prominent despite being a huge season in the East because it was so extreme in the West. All 7 western regions were bad and for 5 of them it was the lowest overall season in 40+ years.

Unlike last year 2011-12 comes out differently if you weight by skier visits (I'm using 15 million for the natural snowfall relevant Northeast). The 2 highest regions for visits (the other being Front Range Colorado) are also the 2 with the worst snowfall. So by skier visit weighting 2011-12 comes out similar to 1986-87 and 1991-92 with only 1980-81 and 1976-77 being worse.

Details on the low snow regions:
Northeast
Only 1979-80 was as low for snowfall, and given the March meltdown I think there's a case for 2011-12 being qualitatively the worst ever season for the Northeast.

Northern and Central Colorado
By snowfall 2011-12 is the worst, but there are a lot more areas with complete season data now than in 1976-77 and 1980-81. There's quite of bit of monthly data for those seasons, and comparing those I would say that 2011-12 was about the same as 1980-81 with 1976-77 being not quite as bad. During the latter 2 seasons the early season drought persisted through most of January but March snowfall was actually above average compared to the record low this year.

California
With Sierra volatility there have been 7 lower snow years than 2011-12. But since half the snow came in March qualitatively it was the 3rd worst behind 1976-77 and 1990-91 (more total snow but 3/4 of it in March).

Utah
1976-77 was clearly the worst but 2011-12 is similar to about 6 other seasons next in line. For slowest start through mid-January 2011-12 was probably 3rd worst behind only 1980-81 also.

Southern and Western Colorado
3 seasons were much worse and another 3 similar to 2011-12. The Southwest was the only region with decent December snow in 2011, so qualitatively those areas may have had better overall skiing than the raw numbers would indicate. I include Aspen and Crested Butte in this region but they were much worse than the areas farther south and more comparable to the areas farther east along I-70.

The U.S. Northern Rockies were overall close to average, though most areas were below average offset by a few near the Canadian border that were far above average.

Blue = 120+%

Green = 108-119%

Yellow = 93-107%

Orange = 81-92%

Red = 80% or less

Standard deviations:

California 31%

Pacific Northwest 21%

Interior Western Canada 16%
US Northern Rockies 19%
Utah 21%

Northern & Central Colorado 21%

Southern & Western Colorado 23%

Northeast 17%

Average 8 Regions 14%

In terms of individual ski areas Grand Targhee is almost in a class by itself for consistency.  The environment Canada weather station at Mt. Fidelity near Rogers' Pass is also very consistent. 

Mix & match:  North America average was 77% in 1991-92 and 84% in 2011-12.  The Northeast was 85% in 1991-92 and 65% in 2011-12.  Northeast was 58% in 1979-80 and no other Northeast season is under 75%. 

The Kottke report had US total skier visits at 60.5 million in 2010-11 (tied with 2007-08 for highest in their records) and 2011-12 at 51 million.  The season-over-season decline is matched only by 1980-81.   One would presume that western Canada was very strong in skier visits while eastern Canada was likely down as much as the US Northeast.

The last line of the chart is not a total line, it's 2011-12.  The 24% standard deviation is the deviation among regions within that season.  No surprise it was 4th highest sd with 2 strong regions and 5 bad ones.

To the extent that regions are not closely correlated, standard deviation of the total will be lower than the pieces.  It's the same principle as reduction of investment risk by diversification of asset classes.  As with investments true diversification is not that easy to achieve because most of the western US regions are fairly well correlated with each other.  The Pacific Northwest and western Canada are the western regions that aren't.  

I would remind DanoT of 2001 and 2005, which were pretty bad in the Pacific Northwest and western Canada.  That same Crystal Mt. I skied on July 1 this year was closed for lack of snow cover from mid-January to mid-March of 2005.  As a resident of California it is perhaps no accident I spend ski time in western Canada nearly every year since 1997.  I did feel somewhat foolish being up there in January 2005 skiing thin or rain-saturated snow when my home mountain Mammoth already had a 14-foot base.  

In terms of reliability it's the intersection of high average and low standard deviation that matters.  The standard deviation tends to be consistent within geographic region (may be smaller than my divisions).   Targhee's 21% standard deviation is low but not exceptional.  Big Sky's is 19%.  But when Targhee's average is 472 inches and Big Sky's only 257, Big Sky is unquestionably less reliable.  Other factors also enter into Targhee's unsurpassed early season record, mainly its more intermediate terrain that is fully covered by a 4-foot base.  Alta's standard deviation is 20% but it has some steep sectors that need more coverage than Targhee so we all remember a handful of seasons where those sectors weren't skiable until after the holidays.  At places like Jackson and Snowbird  with predominantly steep terrain early season can be speculative despite snow statistics that are excellent.

From a weather geography standpoint there are at least 3 distinct subregions here.  The areas in the region from the Okanagan to Roger's Pass are the most consistent, with sd's in the 16-19% range.  However Sun Peaks and the Okanagan areas average under 300 inches.  Mt. Fidelity and the snowcat/heli areas in the Selkirks/Monashees are 400+ inches with excellent consistency.   The Kootenay areas closer to the US. border get 300+ but sd's are in the 22-25% range.   The Alberta areas are mostly under 250 inches with sd's in the 22-25% range, but they are higher, colder and rarely get rain like some of the B.C. areas near the border or west of Rogers' Pass.   To the extent that the 3 subregions get different weather patterns the combination of the 3 (16% sd) has a distinctly lower sd than individual areas do, on the same principle as the total having lower sd than any of the 8 regions.

U.S. Northern Rockies areas other than Targhee and Big Sky are in the 22-25% sd range.  This region is also spread out so its collective 19% sd is lower than most of the areas.

Utah by contrast to the above 2 regions is compact, except for Brian Head (sd = 27%).  Individual Wasatch sd's are 20-23% and the collective sd is 21%.

In Northern and Central  Colorado  individual area sd's are 20-26% and the collective is 21%.

In Southern and Central  Colorado  individual area sd's are 22-28% and the collective is 23%. 

FYI Taos sd is 29%, only a bit more volatile than southern Colorado.

At Pacific Northwest ski elevations, Alyeska and Whistler/Blackcomb have sd's 23-25%,  Washington State and Mt. Hood 27-29% and Mt. Bachelor 32%.  But remember all of these places get 350+ inches.  Subregions are spread out, so collective sd is 21%.  Reliability issues relate more to low altitude rain than drought (mid-season 2005 being the outlier exception).

North Tahoe areas on the Sierra Crest have sd's 29-32%.  East of the Sierra Crest and south of Tahoe sd's range from 34-39%.  Arizona's sd is 39% and Southern California's is 50%.  Collective sd is 31%.

For those of you considering skiing in South America, Las Lenas sd is 46% and Portillo's is 56%.   Since average in both cases is only a bit over 250 inches, that's why I recommend not committing $ until snow is on the ground.

In the Northeast Vermont sd's are 19-23% while New Hampshire and Maine's are 28-34%.  Collective sd is 17%.  Northeast reliability is more related to temperature/rain than drought.

Getting past the numbers, there being 3 subregions up there enhances reliability.  If DanoT in Sun Peaks can get to Kootenay areas like Red/Whitewater or to Banff/Lake Louise, there will be relatively few seasons that all of those will be bad.  Of course driving times among those subregions can be comparable to Utah skiers driving into Colorado or the Northern Rockies.

For the more typical avid skier in a metro area distant from prime ski destiantions, the only possible lesson here is to consider planning multiple ski trips into different regions, specifically one more northern and one more southern.   But the best strategy, as recommended on Epic by me and many others, is to hold off committing $ until the season starts and you know who has early snow and thus will at least have reasonable coverage.

In terms of ski area snowfall there is no climate trend in my ski area snowfall data.  The data starts in the 1970's and nearly everyone agrees that temperatures warmed in the 1980's and 1990's  and have generally maintained a plateau since then at a higher level than the 1970's.    As noted in the original post the 4 worst seasons were all before 1993 and the best season was 2010-11 (with 2007-08 being among the next 3 best), so there is no case that snowfall in North American ski areas is in decline.   If you're concerned about temperatures look to altitude, as the lowest altitude places get occasional rain now and more of the precipitation might flip from snow to rain if temperatures resume rising.   So regions like Colorado and Alberta that get essentially zero winter rain look safest to me if warming is your concern. Or choose the highest altitude places in other regions (Alta/Snowbird/Mammoth/Bachelor/Big Sky/Targhee).