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Effects of Climate Change on the Pacific Northwest Ski Industry
Alan F. Hamlet
Philip W. Mote
Amy K. Snover Dennis P. Lettenmaier
JISAO CSES Climate Impacts Group
Department of Civil and Environmental Engineering
University of Washington
Results
Methodology
Snow Model and Driving Data
Sample of Daily Snow Simulation for Snoqualmie
An hourly time step, energy balance snow model incorporated in the Variable Infiltration Capacity (VIC)
hydrologic model is used in this study to simulate snowpack (snow water equivalent) at different locations. A
schematic of the snow model is shown below.
3000
1973-1974
Snow Water Equivalent (mm)
2500
Daily minimum and maximum temperature, total precipitation, and wind data have been interpolated from
station data for each of 6300 1/8 degree grid cells in the Columbia River basin and coastal areas for use with
the VIC snow model. Monthly long-term means for precipitation are scaled to PRISM (see Daly et al., 1994)
means for the period from 1960-1990, to account for topographic variations. These data are available from
January 1, 1949-December 31, 1999 at daily time step. A typical diurnal cycle for temperature is used to
produce hourly temperature data, and precipitation is assumed to be distributed uniformly over the 24 hours.
To represent each ski area, the nearest grid cell location to each ski area at comparable elevation is selected to
provide driving data for each location, and 15 separate elevation bands are simulated separately for each cell
as shown below. The driving data may not closely match local conditions if available stations are not nearby,
but are sufficiently representative of daily time step climate variability at each location for the purposes at hand.
Temperature is lapsed according to elevation at each of the elevation bands in the cell (~6.1 C per 1000m of
elevation). Daily precipitation is assumed to be equally distributed amongst the 24 hours of the day, and is
assumed to be constant over all elevation bands.
2000
1972-1973
1500
1000
500
0
10
11
12
1
2
3
4
5
schweitzer
bogus_basin
magic_mountain
sun_valley
anthony_lakes
mt_ashland
mt_bachelor
mt_hood_meadows
willamette_pass
stevens
snoqualmie
mission
badger_mtn
bluewood
crystal_mtn
mt_baker
mt_spokane
paradise
silver_star
hidden_lakes
big_white
50 m
Introduction
Temperature
Decreases
with Altitude
(6.1 C per 1000m)
50 m
50 m
Location and Description of Ski Areas
The locations of the ski areas were chosen primarily to represent a range of locations both
east and west of the cascades as well as a range of elevations. Most of the sites are
managed ski areas with lifts, but sites 18, 19, and 20 below represent back country areas.
The elevations listed are for the base of the lifts (or for the lowest range of elevations typically
used for winter recreation in the case of back-country areas) and the highest elevations used
for skiing at each site.
Base Elevation of Ski Area
New Snow
5
Base
(m)
Top
(m)
1
Snow simulation at Stevens for 1974
Climate Change Scenarios and Effects to Snowpack in the PNW
The figure below shows an ensemble of four global climate model scenarios of changing precipitation and
temperature over the PNW produced using the “delta” downscaling method. Simulations of April 1 snowpack
using the VIC hydrologic model show that despite moderate increases in winter precipitation regional
snowpack declines overall, and moderate elevation areas that are close to freezing in mid winter for the
current climate are most sensitive to warming. Four scenarios shown below (HadCM2 and ECHAM4 for the
2020s and 2040s) are used in this study to examine the sensitivity of a number of ski areas to a range of
changes in temperature and precipitation.
Climate Change Scenarios 2020s
Climate Change Scenarios 2040s
De lta T
D elta T
4
5
3
4
Degrees C
Degrees C
Name
13
3
14
5
15
7
16
9
12
1
97
10
9
73
85
61
37
49
0
13
3
14
5
15
7
16
9
10
hadCM3
PCM3
1
ECHAM4
hadCM2
hadCM3
3
PCM3
2
ECHAM4
mean
1
0
O-M precip
(mm)
J
F
M
A
M
J
J
A
S
O
N
D
0
-1
J
F
M
A
M
J
J
A
S
O
N
D
1
schweitzer
1220
1951
642
2
bogus_basin*
1768
2316
667
3
magic_mountain
1981
2194
245
4
sun_valley*
1753
2789
309
5
anthony_lakes
2164
2438
570
6
mt_ashland
1935
2286
961
hadCM2
hadCM2
7
mt_bachelor*
1920
2763
896
hadCM3
hadCM3
8
mt_hood_meadows
1379
2225
1205
9
willamette_pass*
1560
2037
1377
10
stevens
1238
1768
1564
11
snoqualmie
914
1646
2209
12
mission
1372
2073
555
13
badger_mtn
914
1158
204
14
bluewood
1385
1728
818
15
crystal_mtn
1341
2137
1340
16
mt_baker
1079
1539
2191
17
mt_spokane
1280
1792
665
18
paradise
1676
3048
2045
19
silver_star
1524
2705
700
20
hidden_lakes
1829
2703
1863
21
big_white
2054
2054
403
Precipitation Fraction
Precipitation Fraction
1.5
Fraction
Fraction
1.5
PCM3
1
ECHAM4
1
PCM3
ECHAM4
mean
mean
0.5
0.5
J
F
M
A
M
J
J
Current Climate
A
S
O
N
D
9
10
11
12
1
2
hcdec2
3
4
5
6
7
Days with Rain
mpdec2
% Probability of Exceeding 240 mm SWE by December 15
hcdec4
mpdec4
90
86
78
78
65
73
73
69
71
63
6
6
6
6
6
27
24
22
22
8
82
90
80
82
73
92
86
84
82
73
88
84
82
84
71
98
90
92
92
67
96
80
82
82
51
100
98
98
98
98
100
88
92
90
67
88
88
82
84
75
4
6
2
4
2
76
63
61
61
35
100
96
98
98
88
100
100
100
100
98
71
51
47
47
24
100
100
100
100
98
96
98
94
98
94
100
100
100
100
100
59
43
25
37
14
base
schweitzer
bogus_basin
magic_mountain
sun_valley
anthony_lakes
mt_ashland
mt_bachelor
mt_hood_meadows
willamette_pass
stevens
snoqualmie
mission
badger_mtn
bluewood
crystal_mtn
mt_baker
mt_spokane
paradise
silver_star
hidden_lakes
big_white
J
F
M
A
M
J
J
A
2020s
S
Average Number of Days Between 10/1 and 3/31 Exceeding 100 mm SWE
VIC
97
10
9
12
1
VIC
73
85
15
hist
61
hist
37
49
20
2
8
hcdec2
mpdec2
Percentage of Days with 240 mm SWE 10/1 and 3/31 with Rain
hcdec4
mpdec4
24
35
18
24
8
27
35
25
27
12
0
0
0
0
0
0
0
0
0
0
18
39
16
22
8
55
57
45
51
20
57
57
43
47
29
75
65
53
57
29
65
37
35
37
18
92
88
82
82
73
86
55
59
63
27
24
39
20
25
12
0
0
0
0
0
25
20
14
14
6
84
82
71
75
57
100
94
96
96
78
12
6
6
6
4
98
96
96
96
90
55
76
51
63
43
100
100
100
100
100
2
4
2
2
0
base
schweitzer
bogus_basin
magic_mountain
sun_valley
anthony_lakes
mt_ashland
mt_bachelor
mt_hood_meadows
willamette_pass
stevens
snoqualmie
mission
badger_mtn
bluewood
crystal_mtn
mt_baker
mt_spokane
paradise
silver_star
hidden_lakes
big_white
hcdec2
mpdec2
hcdec4
mpdec4
21
34
36
37
41
23
34
36
37
39
29
21
30
28
50
22
24
29
29
32
13
22
23
25
28
29
41
41
42
44
27
43
43
45
46
30
48
47
50
51
46
59
59
60
61
31
50
50
52
54
49
61
62
62
61
12
19
19
20
24
9
15
24
18
0
36
47
49
49
52
34
54
54
56
57
37
55
56
58
59
26
37
37
38
42
31
51
50
53
55
6
13
13
14
18
6
17
13
17
19
25
27
29
28
30
Days Open 10/1 to 3/31 with Specified Snow Amounts
13
25
25
mean
ID #
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
30
hadCM2
7
Precip
35
1
13
25
While many uncertainties exist with regard to the potential effects of climate change at the
regional scale, the effects of rising temperatures on mountain snowpack has been identified
as a primary impact to the Pacific Northwest (PNW) associated with global warming (see, for
example, Mote et al., 1999; Hamlet and Lettenmaier, 1999). Temperature related downward
trends in observed spring snow accumulation over the past 75 years have also been noted in
recent studies (see Mote, 2003). For ski areas at moderate elevation where winter
temperatures are frequently close to freezing, relatively small changes in climate may
significantly affect the amount of accumulated snow at the base of the lifts at any given date.
This quantity is expected to affect ski area revenue because a minimum accumulation
determines when the area can open for business and also largely determines the length of
the ski season. In addition, the probability of rain when adequate snow conditions exist may
also affect revenue, because of less desirable conditions for skiing that may reduce
patronage, particularly in spring. In this study we examine the effects of several global
warming scenarios on a number of managed ski areas in the PNW, and a few unmanaged
back-country areas.
6
Early Season Snow
base
[15 bands]
.....
mpdec2
240mm thresh
% Probability of Exceeding 100 mm SWE by December 15
Uniform Daily Precipitation
over all Elevation Bands
base
O
N
D
2040s
base
schweitzer
bogus_basin
magic_mountain
sun_valley
anthony_lakes
mt_ashland
mt_bachelor
mt_hood_meadows
willamette_pass
stevens
snoqualmie
mission
badger_mtn
bluewood
crystal_mtn
mt_baker
mt_spokane
paradise
silver_star
hidden_lakes
big_white
hcdec2
mpdec2
hcdec4
Average Number of Days Between 10/1 and 3/31 Exceeding 240 mm SWE
mpdec4
129
127
122
124
115
121
122
117
120
110
61
51
37
39
22
79
71
67
66
53
124
130
122
124
118
131
130
124
125
115
130
131
127
127
118
137
133
130
130
114
132
126
121
121
101
145
143
139
139
132
141
130
129
129
107
125
129
122
124
115
37
17
12
12
8
122
112
103
104
83
144
142
139
140
130
151
147
145
144
136
118
103
93
92
70
160
157
151
151
145
138
144
136
139
132
163
164
157
158
152
107
101
96
94
80
base
schweitzer
bogus_basin
magic_mountain
sun_valley
anthony_lakes
mt_ashland
mt_bachelor
mt_hood_meadows
willamette_pass
stevens
snoqualmie
mission
badger_mtn
bluewood
crystal_mtn
mt_baker
mt_spokane
paradise
silver_star
hidden_lakes
big_white
hcdec2
mpdec2
hcdec4
Average Number of Days Between 10/1 and 3/31 Exceeding 500 mm SWE
mpdec4
94
97
88
91
75
89
93
86
87
74
2
3
1
2
0
26
22
14
15
8
86
98
84
88
76
106
105
92
95
76
108
110
100
103
87
119
112
103
106
83
115
98
91
92
67
130
129
124
124
112
127
109
106
105
76
85
95
82
84
69
1
2
1
1
0
87
71
62
62
44
127
126
120
121
107
139
135
132
132
121
81
56
48
45
28
144
143
138
139
131
109
121
106
111
99
148
150
144
145
139
45
42
33
34
20
base
schweitzer
bogus_basin
magic_mountain
sun_valley
anthony_lakes
mt_ashland
mt_bachelor
mt_hood_meadows
willamette_pass
stevens
snoqualmie
mission
badger_mtn
bluewood
crystal_mtn
mt_baker
mt_spokane
paradise
silver_star
hidden_lakes
big_white
hcdec2
mpdec2
hcdec4
mpdec4
31
36
24
25
11
35
40
31
34
22
0
0
0
0
0
0
0
0
0
0
24
34
24
26
15
61
57
39
41
18
63
64
50
52
34
82
73
58
62
36
80
57
47
46
23
102
103
90
92
70
103
72
66
63
41
22
30
21
22
14
0
0
0
0
0
39
29
23
22
8
94
92
80
82
62
120
116
110
111
96
21
9
5
6
3
127
127
118
120
107
47
61
46
51
36
127
136
124
128
118
3
2
2
2
1
Discussion
The results demonstrate that different ski areas in different parts of the region are likely to experience
substantially different responses to regional warming and the changes in precipitation projected by the
scenarios. The most sensitive to warming are the ski areas influenced by the maritime climate west of the
Cascades and at moderate elevations (e.g. Snoqualmie Pass and Stevens Pass). Areas with colder winter
climates (e.g. at higher elevations and/or east of the Cascades) are generally less sensitive to warming.
Precipitation changes affect all areas, but areas with relatively little precipitation are often more severely
impacted. The greatest reductions in length of season and desirable snow conditions are associated with
the ECHAM4 scenarios, which are both warm and dry. It should be noted that some areas with limited
precipitation also have snow making capacity (e.g. Sun Valley), so reductions in precipitation may not be as
serious a problem if there is a reliable water supply in winter for snow making. Further study is needed to
assess the effectiveness of snow making technology to mitigate these potential impacts.
Many other issues affect ski area revenue and patronage. In the early stages of warming, for example, when
snow conditions on the mountain are still relatively good, patronage could potentially increase simply
because there is less snow on the roads at lower elevation leading to the ski areas. Such effects could help
mitigate reductions in revenue due to shortening of the season suggested by the results above. Other
mitigation efforts such as smoothing of terrain to allow the slopes to open with less snow, or alternate lift
loading stations at higher elevations could also be an effective means of lengthening the ski season.
The three back country areas simulated in this study (paradise, silver_star, hidden_lakes) would appear to
be relatively insensitive to all but the ECHAM4 warming scenarios. Back country skiers may also find
themselves more readily adaptable to climatic changes in the sense that they are less dependent on
permanently placed infrastructure (e.g. lifts, lodges, etc.). In some cases, however, reduced snow pack may
expose vegetation or rough terrain, or may reduce the snow covered area of and/or access to land open to
the public for winter recreation. Further study is needed to better assess the potential impacts to these
areas.
*Indicates snowmaking
capability at site
Acknowledgements
Elevation (m)
Simulated April 1 Snow Water Equivalent (mm)
The preliminary study upon which this project is based was proposed and funded in 1999 by Harbor
Properties (owners and operators of Stevens, Mission Ridge, and Schweitzer Mt. ski areas). Many thanks
also to Chester Marler of Harbor Properties for obtaining data and sharing his extensive knowledge of the
PNW ski industry.