1.  
Presented by: Daryn Hardwick
Graduate, Geography Department, Saint Cloud State University
Faculty Advisors: Dr. Keith Rice, UWSP Geography Department
Eugene Martin, UWSP Geography Department

2.  Purpose
o To better understand winter climatology for the state of
Wisconsin
 Hypothesis
o Ha = There has been a decrease in both the amount of snowfall
and individual snowfall events in the state of Wisconsin between
1974 and 2010.
o Ho = There has been no change in the amount of snowfall or
individual snowfall events in the state of Wisconsin between
1974 and 2010.

3.  Economic Benefits
o Winter Tourism - $7.9 billion annually
o Cold Water Fishing - $2.3 billion/year industry
o Snowpack Water Storage saves between $2.3 - 348 billion/year
 Economic Costs
o Snow Removal - $2 billion/year
o Road Closures - $2.5 billion/year
• Lost retail trade, wages, and tax revenue
o Damage to Utilities
• $2 billion lost in 1994 snow storm in Mississippi
o Flooding
• $4.7 billion lost in 1997 Red River flooding in ND and MN

4.  The Impact of Snow/Winter Events on Humans:
o 23.4 deaths per year caused
o 161.7 injuries per year caused
o $484 million in damage caused annually
 Groundwater Recharge
o Urie (1966) determined about 2/3 of yearly groundwater
recharge contributed by winter precipitation

5.  Decline in snow cover extent and duration
o Choi et al. 2010, Davies 1994, Dêry and Brown 2007
 Great Lakes studies
o Burnett et al. (2003) - increase in snowfall and both the lee and
windward sides
o Norton and Bolsenga (2007) – increase in lake-effect snowfall
 Wisconsin snowfall
o Kunkel et al. (2009) – slight increase in snowfall

6.  Data
o National Weather Service Cooperative Observer Program
• Precipitation, Snowfall, and Snow Depth
• October – April
• 1974/75 – 2009/10 seasons
• 152 weather stations, 11 out-of-state
 Analyses
o Station Homogeny
o Season Averages and Event Totals
o Snowfall/Precipitation Ratio
o Regression lines (trends)

7.  Station Homogeny – having <10% missing data over the
study period (Kunkel et al. 2009)
o 137/152 (90%) determined homogenous for precipitation
o 120/152 (79%) determined homogenous for snowfall
o 78/152 (51%) determined homogenous for snow depth
o Only stations suitable in both precipitation and snowfall were
used in final analysis, 117 stations (77%)
 2008-2010 Seasons

9. Season Average Number of Events
4.935 - 5.319 48.73 - 51.5
5.32 - 5.704 51.51 - 54.28
5.705 - 6.088 54.29 - 57.05
6.089 - 6.472 57.06 - 59.83
6.473 - 6.856 59.84 - 62.6
6.857 - 7.241 62.61 - 65.38
7.242 - 7.625 65.39 - 68.16
7.626 - 8.009 68.17 - 70.93
8.01 - 8.393 Avg. = 6.31167 (0.01 in./recorded day) 70.94 - 73.71 Avg. = 60.1371 days/season

10. Avg. Precipitation 1974- Avg. Precipitation 1974-
2010 2007
< -0.0175
-0.0175 - -0.0125
-0.0125 - -0.0075
-0.0075 - -0.0025
-0.0025 - 0.0025
0.0025 - 0.0075
0.0075 - 0.01
0.01 - 0.0125
State Trend = 0.01063 (0.01 in./recorded day/year) > 0.0125 State Trend = - 0.00112 (0.01 in./recorded day/year)

11. Precipitation Events 1974- Precipitation Events 1974-
2010 2007
> -0.3
-0.3 - -0.2
-0.2 - -0.1
-0.1 - -0.005
-0.005 - 0.005
0.005 - 0.05
0.05 - 0.1
0.1 - 0.15
Avg. = 0.05314 days/season/year > 0.15 Avg. = - 0.02615 days/season/year

12. Season Average Number of Events
1.417 - 1.963 17.5 - 21.32
1.964 - 2.508 21.33 - 25.13
2.509 - 3.053 25.14 - 28.95
3.054 - 3.599 28.96 - 32.77
3.6 - 4.144 32.78 - 36.59
4.145 - 4.689 36.6 - 40.4
4.69 - 5.235 40.41 - 44.22
5.236 - 5.78 44.23 - 48.04
5.781 - 6.325 Avg. = 2.30673 (0.1 in./recorded day) 48.05 - 51.86 Avg. = 26.8694 days/season

13. Avg. Snowfall 1974-2010 Avg. Snowfall 1974-2007
< -0.0175
-0.0175 - -0.0125
-0.0125 - -0.0075
-0.0075 - -0.0025
-0.0025 - 0.0025
0.0025 - 0.0075
0.0075 - 0.01
0.01 - 0.0125
Avg. = 0.00151 (0.1 in./recorded day/year) > 0.0125 Avg. = - 0.0046 (0.1 in./recorded day/year)

14. Snowfall Events 1974- Snowfall Events 1974-
2010 2007
> -0.3
-0.3 - -0.2
-0.2 - -0.1
-0.1 - -0.005
-0.005 - 0.005
0.005 - 0.05
0.05 - 0.1
0.1 - 0.15
Avg. = - 0.03975 days/season/year > 0.15 Avg. = - 0.12792 days/season/year

15. Season Average
1.775 - 2.525
2.526 - 3.275
3.276 - 4.025
4.026 - 4.775
4.776 - 5.526
5.527 - 6.276
6.277 - 7.026
7.027 - 7.776
7.777 - 8.527 Avg. = 3.77435

16. 1974-2010 Trend 1974-2007 Trend
< -0.0175
-0.0175 - -0.0125
-0.0125 - -0.0075
-0.0075 - -0.0025
-0.0025 - 0.0025
0.0025 - 0.0075
0.0075 - 0.0125
0.0125 - 0.0175
Avg. = - 0.00529 (0.1 in./recorded day/year) > 0.0175 Avg. = - 0.00774 (0.1 in./recorded day/year)

17. Precipitation as Rain Precipitation as Rain Event
Trend, 1975-2010 Trend, 1975-2010
0.1 1
0.8
0.08
0.6
Trend (0.01 in./recorded day/year)
0.06
0.4
Trend (days/season/year)
0.04 0.2
0
0.02
-0.2
0 -0.4
-0.6
-0.02
-0.8
-0.04
-1
-0.06 -1.2
41 42 43 44 45 46 47 48 41 42 43 44 45 46 47 48
Latitude (degrees) Latitude (degrees)

18. Snowfall Trend , 1975-2010 Snowfall Events
0.08 Trend, 1975-2010
0.6
0.06
0.4
Trend (0.1 in./recorded day/year)
0.04 0.2
Trend (days/season/year)
0
0.02
-0.2
0 -0.4
-0.6
-0.02
-0.8
-0.04
-1
-0.06 -1.2
41 42 43 44 45 46 47 48 41 42 43 44 45 46 47 48
Latitude (degrees) Latitude (degrees)

19. Precipitation/Snowfall Ratio Trend, 1975-2010
0.06
0.04
Trend (0.1 in./recorded day/year)
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.1
-0.12
-0.14
41 42 43 44 45 46 47 48
Latitude (degrees)

20.  Increase in Winter Precipitation
o Significant at the ≥ 95% confidence level (p = 0.0001)
 Increase in Winter Snowfall
o Not significant at the ≥ 95% confidence level (p = 0.3624)
 Decrease in Snowfall-to-Precipitation Ratio
o Not significant at the ≥ 95% confidence level (p = 0.0526)
 Increase in Days with Precipitation
o Significant at the ≥ 95% confidence level (p = 0.0365)
 Decrease in Days with Snowfall
o Significant at the ≥ 95% confidence level (p = 0.0271)
 2008-2010 Seasons
o Anomaly or new trend?

21.  Self Critiques
o Climate data inherently unreliable?
o Number of Events in a given season
o Are t-test’s suitable for climatic data?
o Is 36 years enough for a climate study?
 Future Research
o Investigate above critiques
o Do El Niño or La Niña have an effect?
o Spatial and temporal trends in temperature
o Trends in Snow Cover and Snow Depth
o Snowfall-to-Precipitation Ratio

22. Adams, R., L. Houston, and R. Weiher, 2004: The Value of Snow and Snow Information NOAA NCDC Climate-Radar Data Inventory, Cooperative Observer Program climate
Services.Report prepared for NOAA's National Operational data, Data used: 1974-2010.
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NOAA NWS Office of Climate, Water, and Weather Services, Natural Hazard
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Michigan, 1851-1993, as determined from regional lake-ice records.
Limnol. Oceanogr., 40(1), 165-176. NOAA NWS, Summary of Natural Hazard Statistics for 2000 in the United States, 2000, [3
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Braham, R. R., and M. J. Dungey, 1984. Quantitative Estimates of the Effect of Lake
Michigan on Snowfall. J. Climate and Applied NOAA NWS, Summary of Natural Hazard Statistics for 2001 in the United States, 2001, [3
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23.  
Contact: hada1102@stcloudstate.edu