trends in spatial and temporal variability of snowfall totals and events in wisconsin, 1974 - 2010

Trends in Spatial and Temporal Variability of

Snowfall Totals and Events in Wisconsin, 1974 - 2010

Presented by: Daryn HardwickGraduate, Geography Department, Saint Cloud State University

Faculty Advisors: Dr. Keith Rice, UWSP Geography Department Eugene Martin, UWSP Geography Department

Introduction

Purposeo To better understand winter climatology for the state of

Wisconsin

Hypothesiso 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.

Introduction Economic Benefits

o Winter Tourism - $7.9 billion annuallyo Cold Water Fishing - $2.3 billion/year industryo Snowpack Water Storage saves between $2.3 - 348

billion/year

Economic Costso Snow Removal - $2 billion/yearo Road Closures - $2.5 billion/year

• Lost retail trade, wages, and tax revenueo Damage to Utilities

• $2 billion lost in 1994 snow storm in Mississippio Flooding

• $4.7 billion lost in 1997 Red River flooding in ND and MN

Introduction

The Impact of Snow/Winter Events on Humans:o 23.4 deaths per year causedo 161.7 injuries per year causedo $484 million in damage caused annually

Groundwater Rechargeo Urie (1966) determined about 2/3 of yearly groundwater

recharge contributed by winter precipitation

Literature Review Decline in snow cover extent and duration

o Choi et al. 2010, Davies 1994, Dêry and Brown 2007

Great Lakes studieso Burnett et al. (2003) - increase in snowfall and both the

lee and windward sideso Norton and Bolsenga (2007) – increase in lake-effect

snowfall

Wisconsin snowfallo Kunkel et al. (2009) – slight increase in snowfall

Methodology 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

Analyseso Station Homogenyo Season Averages and Event Totalso Snowfall/Precipitation Ratioo Regression lines (trends)

Analysis & Results Station Homogeny – having <10% missing data

over the study period (Kunkel et al. 2009)

o 137/152 (90%) determined homogenous for precipitationo 120/152 (79%) determined homogenous for snowfallo 78/152 (51%) determined homogenous for snow deptho Only stations suitable in both precipitation and snowfall

were used in final analysis, 117 stations (77%)

2008-2010 Seasons

Homogenous Stations

Results - Precipitation

Season Average Number of Events

48.73 - 51.5

51.51 - 54.28

54.29 - 57.05

57.06 - 59.83

59.84 - 62.6

62.61 - 65.38

65.39 - 68.16

68.17 - 70.93

70.94 - 73.71

4.935 - 5.319

5.32 - 5.704

5.705 - 6.088

6.089 - 6.472

6.473 - 6.856

6.857 - 7.241

7.242 - 7.625

7.626 - 8.009

8.01 - 8.393 Avg. = 60.1371 days/seasonAvg. = 6.31167 (0.01 in./recorded day)

Results – Precipitation Trends

Avg. Precipitation 1974-2010

Avg. Precipitation 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

> 0.0125 State Trend = - 0.00112 (0.01 in./recorded day/year)State Trend = 0.01063 (0.01 in./recorded day/year)

Results – Precipitation Trends

Precipitation Events 1974-2010

Precipitation Events 1974-2007

> -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

> 0.15 Avg. = - 0.02615 days/season/yearAvg. = 0.05314 days/season/year

Results - Snowfall

Season Average Number of Events

1.417 - 1.963

1.964 - 2.508

2.509 - 3.053

3.054 - 3.599

3.6 - 4.144

4.145 - 4.689

4.69 - 5.235

5.236 - 5.78

5.781 - 6.325

17.5 - 21.32

21.33 - 25.13

25.14 - 28.95

28.96 - 32.77

32.78 - 36.59

36.6 - 40.4

40.41 - 44.22

44.23 - 48.04

48.05 - 51.86 Avg. = 26.8694 days/seasonAvg. = 2.30673 (0.1 in./recorded day)

Results – Snowfall Trends

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

> 0.0125 Avg. = - 0.0046 (0.1 in./recorded day/year)Avg. = 0.00151 (0.1 in./recorded day/year)

Results – Snowfall Trends

Snowfall Events 1974-2010

Snowfall Events 1974-2007

> -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

> 0.15 Avg. = - 0.12792 days/season/yearAvg. = - 0.03975 days/season/year

Snowfall/Precipitation Ratio

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

Snowfall/Precipitation Ratio

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

> 0.0175 Avg. = - 0.00774 (0.1 in./recorded day/year)Avg. = - 0.00529 (0.1 in./recorded day/year)

Precipitation by Latitude

41 42 43 44 45 46 47 48

-1.5

-1

-0.5

0

0.5

1

Precipitation as Rain Event Trend, 1975-2010

Latitude (degrees)

Tre

nd (

days/s

eason/y

ear)

41 42 43 44 45 46 47 48-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0.1

Precipitation as Rain Trend, 1975-2010

Latitude (degrees)

Tre

nd (

0.0

1 in./

record

ed d

ay/y

ear)

Snowfall by Latitude

41 42 43 44 45 46 47 48-1.2

-1

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

Snowfall Events Trend, 1975-2010

Latitude (degrees)

Tre

nd (

days/s

eason/y

ear)

41 42 43 44 45 46 47 48-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

Snowfall Trend , 1975-2010

Latitude (degrees)

Tre

nd (

0.1

in./

record

ed d

ay/y

ear)

Precipitation/Snowfall by Latitude

41 42 43 44 45 46 47 48-0.14

-0.12

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

Precipitation/Snowfall Ratio Trend, 1975-2010

Latitude (degrees)

Tre

nd (

0.1

in./

record

ed d

ay/y

ear)

Conclusions

Increase in Winter Precipitationo Significant at the ≥ 95% confidence level (p = 0.0001)

Increase in Winter Snowfallo Not significant at the ≥ 95% confidence level (p = 0.3624)

Decrease in Snowfall-to-Precipitation Ratioo Not significant at the ≥ 95% confidence level (p = 0.0526)

Increase in Days with Precipitationo Significant at the ≥ 95% confidence level (p = 0.0365)

Decrease in Days with Snowfallo Significant at the ≥ 95% confidence level (p = 0.0271)

2008-2010 Seasonso Anomaly or new trend?

Conclusions Self Critiques

o Climate data inherently unreliable?o Number of Events in a given seasono Are t-test’s suitable for climatic data?o Is 36 years enough for a climate study?

Future Researcho Investigate above critiqueso Do El Niño or La Niña have an effect?o Spatial and temporal trends in temperatureo Trends in Snow Cover and Snow Deptho Snowfall-to-Precipitation Ratio

References CitedAdams, R., L. Houston, and R. Weiher, 2004: The Value of Snow and Snow Information Services.Report prepared for NOAA's National Operational Hydrological Remote Sensing Center.

Assel, R. A., and D. M. Robertson, 1995: Changes in winter air temperatures near Lake Michigan, 1851-1993, as determined from regional lake-ice records. Limnol. Oceanogr., 40(1), 165-176.

Braham, R. R., and M. J. Dungey, 1984. Quantitative Estimates of the Effect of Lake Michigan on Snowfall. J. Climate and Applied Meteorology, 23, 940- 949.

Burnett A. W., M. E. Kirby, H. T. Mullins, and W. P. Patterson, 2003: Increasing Great Lake- Effect Snowfall during the Twentieth Century: A Regional Response to Global Warming? J. Climate 16,3535-3541.

Choi, G., D.A. Robinson and S. Kang, 2010: Changing Northern Hemisphere snow seasons. Journal of Climate, 23, 5305-5310.

Davies, T. D., 1994. Snow Cover-atmosphere interactions. Intl. Association of Hydrological Sciences, Publ. No. 223, 3-13.

Déry, S. J., and R. D. Brown, 2007. Recent Northern Hemisphere snow cover extent trends and implications for the snow-albedo feedback. Geophys. Research Letters, 34, 1-6.

Kunkel, K.E., M. Palecki, L. Ensor, K.G. Hubbard, D. Robinson, K. Redmond, and D. Easterling, 2009: Trends in 20th Century U.S. snowfall using a quality-controlled data set. J. Atmos. Ocean. Tech., 26, 33-44.

Kunkel, K. E., M. Palecki, K.G. Hubbard, D.Robinson, K. Redmond, and D. Easterling, 2007: Trend identification in 20th Century U.S. snowfall: The Challenges. J. Atmos. Oceanic Technol., 24, 64-73.

Leathers, D. J., and D. A. Robinson, 1993. The Association between Extremes in North American Snow Cover Extent and United States Temperatures. J. of Climate, 6, 1345-1355.

McCabe G. J., Clark M. P., and Serreze M. C., 2001: Trends in Northern Hemisphere surface cyclone frequency and intensity. J. Climate 14, 2763–2768.

NOAA NCDC Climate-Radar Data Inventory, Cooperative Observer Program climate data, Data used: 1974-2010.

NOAA NWS Office of Climate, Water, and Weather Services, Natural Hazard Statistics, 1940- 2009.

NOAA NWS, Summary of Natural Hazard Statistics for 2000 in the United States, 2000, [3 pp.]










Norton, D. C., and S. J. Bolsenga, 1993. Spatiotemporal Trends in Lake Effect and Continental Snowfall in the Laurentian Great Lakes, 1951-1980. J. of Climate, 6, 1943-1956.

NWS Weather Forecast Office, Cooperative Observer Program, 2009.

Urie, D. H., 1966. Influence of Forest Cover on Snowpack and Ground-Water Recharge. Ground Water, Vol. 4, Issue 1, 5-9.

Wisconsin State Cartographer’s Office, Wisconsin Seasons, 2010.

Wisconsin State Cartographer’s Office, Wisconsin Statistics, 2009.

Daryn HardwickContact: [email protected]

trends in spatial and temporal variability of snowfall totals and events in wisconsin, 1974 - 2010

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