Ski Areas Favored by La Nina

On my El Nino page I introduced the  Multivariate ENSO Index , which is considered by many meteorologists to be the best overall measure of the strength of El Nino/La Nina.  The graph of MEI since 1950 is repeated here for convenience.

 

 

The last posted value of MEI as of 11/21/2007 is -1.117 for SEP/OCT 2007, and we have quite strong confidence that observed La Nina condition will be in effect through the end of 2007, and some confidence that it will persist for the entire 2007-08 ski season. 

 

I have correlated the monthly MEI table with all of the monthly snowfall data I have collected through 2007. The list of ski areas favored by La Nina, along with their monthly and season correlations to the MEI index, is shown below:

Area	Monthly	Seasonal	Seasons
Strongly favored by La Nina
Big Mountain, Mont.   6,700	-26.3%
Sunshine Village, Alb.  7,028	-23.8%	-55.9%	37
Mt. Baker, Wash.   4,300	-21.0%	-53.2%	17
Schweitzer, Idaho   4,700	-22.3%
Fernie Snow Valley, B. C.  5,400	-13.4%	-49.1%	19
Silver Star, B. C.  5,200	-19.9%	-48.9%	18
Whistler Base, B. C.   2,200	-24.4%	-48.5%	37
Mt. Fidelity (Selkirks), B. C.  6,150	-21.9%	-48.5%	38
Mt. Hood Meadows, Ore.   5,400	-6.0%	-47.8%	18
Jackson Hole , Wyo.   8,250	-15.8%	-47.4%	40
Mt. Rainier Paradise, Wash. 5,420	-24.7%	-46.9%	41
Lake Louise, Alb.  6,700	-18.3%	-38.2%	38
Bridger Bowl, Mont.   7,100	-17.9%
Snoqualmie Pass, Wash.   3,000	-14.7%
Teton Pass, Wyo.   8,000	-8.5%
Mildly favored by La Nina
Big White, B. C.  6,200	-15.9%	-36.4%	22
Mt. Norquay, Alb.  5,350	-21.9%	-32.7%	20
Jay Peak, Vt.  3,000	-16.5%	-32.6%	26
Stevens Pass, Wash.   4,061	-14.8%
Loon, N. H.   2,000	-14.5%
Steamboat, Colo.   9,200	-10.5%	-29.6%	24
Crater Lake (Mt. Bailey), Ore.   6,800	-12.2%	-29.4%	41
Mt. St. Anne, Que.  2,000	-12.7%
Whitewater, B. C.  5,500	-12.1%
Stowe, Vt.  3,950	-10.4%	-28.6%	41
Mt. Bachelor , Ore.   6,350	-11.1%	-27.0%	34
Spencer's Creek, Australia   5,903		-25.8%	53
Smuggler's Notch, Vt.   1,600	-8.2%	-24.6%	15
Cannon Mt., N. H. 1,800	-9.3%	-24.2%	31

 

Recall from before that these correlations fit with observed experience that in big El Nino or La Nina years the expected effects occur from time to time but not consistently. So I considered the seasonal correlations to be the main criteria in classifying areas, and it is important to remember that season correlations based upon 15-40 data points have some uncertainty.

 

La Nina strongly favors Washington State and inland areas ranging as far north as Revelstoke/Banff in Canada and as far south as Jackson Hole. Oregon and Colorado's farthest north area Steamboat are mildly favored, and there are scattered areas in the Northern Rockies of both U.S. and Canada that are only mildly or minimally affected. I was somewhat surprised that the snowiest Vermont areas (Jay, Smuggler's Notch, Stowe) are mildly favored by La Nina, while most other eastern areas are minimally affected.

 

The other surprise is that coastal British Columbia is not that sensitive. I believe the Whistler base numbers are misleading because it had so much snow during the big La Nina years of the early 1970's. It has not done so well during more recent La Ninas due to global warming effects of more rain at its low 2,000 foot elevation. Whistler shows minimal La Nina sensitivity up at 5,000 or 6,000 feet, and the same is true for Mt. Washington on Vancouver Island at 4,000. Note in the previous blog that the Valdez/Thompson Pass area of Alaska slightly favors El Nino.

 

Australia/New Zealand have been reputed to be favored by La Nina, but in 2006 I acquired data for 3 South Island New Zealand areas that show little El Nino/La Nina impact. Spencer's Creek (near Thredbo and Perisher Blue ski areas) snowpack data does show that Australia is mildly favored by La Nina.

 

In La Nina years the favored Northwest and Northern Rockies resorts are generally more likely to be covered by Christmas as well as getting extra snow through the season.  November 2007 has not been as strong as other La Nina early seasons, but we still have some confidence that these areas will end up above average for the 2007-08 season as a whole. 

 

In El Nino years my general advice to avoid advance bookings until sufficient snow is on the ground should be taken more seriously at these areas, particularly where average snowfall is modest and there is less margin for error.  High snow areas like Jackson, Fernie and Steamboat are probably still just fine during their normally prime months of January and February.

 

I have constructed graphs to illustrate the variability of the snowfall correlations to El Nino/La Nina.  The one below is for selected areas favorable to La Nina.

 

 

The horizontal axis lists the past 41 ski seasons in order of strong El Nino at left to strong La Nina at right.  The vertical axis is percent deviation from normal snowfall.  The blue line is the sum of MEI indicies from OCT/NOV to APR/MAY, scaled to fit the graph.

 

For Washington and Oregon I selected the Mt. Rainier (purple line) and Crater Lake (yellow line) National Park data because it was complete for all 41 years.  Mt. Rainier is close to Crystal Mt. ski area, and Crater Lake is close to Mt. Bailey snowcat skiing and a couple of hours drive from Mt. Bachelor ski area.  Jackson Hole (orange line) and Sunshine Village (light blue line) are good representative ski areas for the Northern Rockies of the U.S. and Canada respectively.

 

Results are quite consistent for these 4 areas in the strong La Nina seasons.  All 4 areas are at least average in the top 7 La Nina years except for Sunshine at 94% in 1974-75.  In the 2 highest years 1973-74 and 1970-71, 3 of the 4 selected areas were over 130% of normal snowfall.  And in the 5th highest 1998-99, 3 of the 4 areas were over 140%.

 

At Mt. Rainier, Jackson and Sunshine the top 6 El Nino seasons are all below average. Average snowfall at all 3 areas over these 6 years is about 85% of normal, and the worst case was Jackson at 63% in 1986-87.

 

Crater Lake deviated from the expected pattern, with 131% and 113% snowfall in the 2 biggest El Nino years of 1982-83 and 1997-98.  Crater Lake was also 130% in the 6th and 7th highest El Ninos of 1992-93 and 1994-95.  We should remember that Crater Lake and Mt. Bachelor are in the middle of Oregon, and that Mt. Hood is next to Washington State and favored by La Nina as much as Mt. Rainier.

 

But the mixed results from Crater Lake should remind us that the "mildly favored" areas listed above will have less consistent El Nino/La Nina impact than the "strongly favored" areas like Mt. Rainier, Jackson and Sunshine.

 

 

Ski Areas Favored by El Nino

Ski Areas Indifferent to El Nino/La Nina