The Effects Temperature Has on the Frequency, Intensity and Average
Snowfall Amounts from Blizzards within Southeastern Wisconsin Between
1980-2010
By
Allie Coleman
An Undergraduate Thesis
Bachelor of Arts
in
Geography and Earth Science
Carthage College
Kenosha, WI
May, 2011
1
Table Of Contents
Abstract…………………………………………………………………2
Introduction…………………………………………….……………….3
Methods………………………………………………..……………..…12
Results………………………………………………..…………………13
Discussion…………………………………………...…………………..19
Conclusion………………………………………..……………………..20
Acknowledgments………………………………………………………21
References………………………………………………………………22
2
Abstract
Winter in southeast Wisconsin is generally pleasurable, but sometimes the winter
conditions can become dangerous. Winter storms can quickly sweep through the state,
bringing high winds, large amounts of precipitation, hazardous conditions, and extremely
cold temperatures. Within the past thirty years, severe winter storms are continuing to get
more extreme and frequent. This kind of weather is consistent with climate change
research and increasing higher annual snowfall from blizzards, more intense blizzards,
and the overall frequency of blizzards. Specific recoding stations within the state of
Wisconsin obtained data that record the air temperature, wind speeds, and the amount of
snowfall from1895 to 2010. The data was used to look at the change, over a period of
thirty years, of blizzard frequency, intensity, and average snowfall accumulations of
blizzards within southeast Wisconsin. The data supports my hypothesis that the number
of blizzards per decade has increased. It cannot be decided with confidence that my
hypothesis, that the intensity of blizzards and the average snowfall amounts for blizzards
in Southeast Wisconsin, are direct result of warmer winter temperature and climate
change or that there is a correlation between temperature and intensity of blizzards.
2
Introduction
Winter in southeast Wisconsin is generally pleasurable, but sometimes the winter
conditions can become dangerous. Winter storms can quickly sweep through the state,
bringing high winds, large amounts of precipitation, hazardous conditions, and extremely
cold temperatures. The state of Wisconsin has seen its fair share of winter snowstorms
and blizzards in the past (Moran and Hopkins 2002). Within the past thirty years, severe
winter storms are continuing to get more extreme and frequent (United States Global
Change Research Program 1990). This kind of weather is consistent with climate change
research and increasing higher annual snowfall from blizzards, more intense blizzards,
and the overall frequency of blizzards.
Astronomical winter begins at the winter solstice, on or about December 21st, in
the Northern Hemisphere. Meteorologists consider winter to be the three coldest months;
December, January, and February (National Oceanic and Atmospheric Administration
2009). It continues until the spring equinox, on or about March 21 (Moran and Hopkins
2002). In mid-latitude locations, such as Wisconsin, episodes of summer-like weather can
occur before the summer solstice, and winter-like weather can set in after the winter
solstice (Bryson and Lahey 1958). It is possible to get summer-like conditions in January
and winter-like conditions in April because in Wisconsin’s climate, the annual
temperature cycle lags behind the annual solar radiation cycle by about a month (Moran
and Hopkins 2002).
Snow is precipitation in the form of ice crystals or a combination of ice crystals.
The size, shape, and concentration of snowflakes depend on the temperature at which
3
they form in the atmosphere. Snow forms in clouds where the temperature is below
freezing, 32 degrees Fahrenheit, or 0 degrees Celsius. The ice crystals form around bits of
dirt that have been carried up into the atmosphere by atmospheric winds. As snow
crystals grow, they become heavy and begin to fall towards the Earth producing snow
(Lutgens & Tarbuck 2010).
The difference between a blizzard and a winter storm lies in the presence and
strength of winds. A winter storm is a precipitation event that only occurs at cold
temperatures ranging from -10 degrees Celsius or 14 degrees Fahrenheit to 0 degrees
Celsius or 32 degrees Fahrenheit (National Oceanic and Atmospheric Administration
2009). They are characterized by snowfall, rain, sleet, and / or ice. Winter storms can
produce snow, sleet, or a rainstorm where ground temperatures are cold enough to allow
ice to form. Blizzards are massive snowstorms with very strong winds ranging from 35
mph or greater (Wisconsin Department of Natural Resources 2010). In Canada and the
northern United States blizzards come from a warm air mass, filled with moisture from
the Gulf of Mexico and the Atlantic Ocean. It then moves northward and meets cold
Arctic air mass under a strong jet stream (Burnett 2003).
Blizzards are classified by winds at least 35 miles per hour, a great amount of
falling or drifting snow that reduces visibility to a quarter mile or less (Wisconsin
Department of Natural Resources 2010). There is also no specific defined temperature to
have a blizzard.
Normally, any winter snowstorm, blizzards included, can occur if temperatures
are between -10 degrees Celsius or 14 degrees Fahrenheit and 0 degrees Celsius or 32
4
degrees Fahrenheit (National Severe Storm Laboratory 2006). Global warming and
climate change decreases the likeliness of snowstorm conditions in the warmer, southern
regions like Tennessee or Kentucky (United States Environmental Protection Agency
2009). For northern regions, such temperatures are often too cold for heavy snow. This
can bring better snowstorm conditions to an area, like southeast Wisconsin because the
average winter temperature is 22.5 degrees Fahrenheit (United States Environmental
Protection Agency 2009). Snowfall records around the Great Lakes region indicated a
significant increase in snowfall since the 1930s but there is no such increase in non-Great
Lakes areas (Burnett 2003).
To have a blizzard, cold, below freezing air in the cloud and at ground level is
needed (Lutgens and Tarbuck 2010). If the air near the ground is too warm, the snow will
melt on its way down, creating rain or freezing rain. Water vapor or moisture is also
needed. Air blowing across a body of water, such as a Lake Michigan, is an excellent
source of water vapor. As wind moves air over the water, some water evaporates from the
surface, putting vapor into the air. This is how “lake effect snowstorms” pick up so much
moisture. However, the cold air is not able to hold much water vapor. This is why very
cold air does not make very much snow, which increases the chances that southeastern
Wisconsin can get so much. Lastly, blizzards need warm air that rise over cold air. There
are two ways that this can happen. Winds can either pull cold air toward the equator from
the poles or bring warm air toward the poles from the equator (Lutgens and Tarbuck
2010). When the warm and cold air is brought together, a front is formed and
precipitation, most likely, occurs. The warm air can also rise to form clouds and snow as
it flows up a mountainside. Since blizzards need three things to “survive”; cold air,
5
moisture, and air lift, areas such as southeast Wisconsin, will produce more severe winter
snow storms and blizzards (Olson 2006). Increasing snowfall totals are likely connected
with global warming processes, climate change, and increasingly warmer temperatures
(Burnett 2003). Increasing temperature trends are due mostly to the increase in winter
precipitation, which generally falls as snow as well as to an increase in winter
precipitation during the fall months (Schawartz and Schmidlin 2000).
In contrast, Lawson (2002) concluded from his research that blizzards have
become a less common occurrence during the past 45 years. This is due to blizzards
having a very powerful outbreak of cold arctic air, which in turn, warms the climate,
especially in throughout altitudes like Southeast Wisconsin. This is a contributing factor
in the observed decrease of blizzards and evidence of climate change impact (Lawson
2002).
There is considerable concern about future climate change and the potential
impacts it could have on blizzards, as well as any severe storm, within the United States.
Any increase in greenhouse gas concentration could significantly warm the planet and
create an environment more favorable for severe storms over mid-latitude continental
areas (Balling and Cerveny 2002). It also offers insight into possible continuing warming
and the effects it could have on the Earth. Also, recent increases in the water temperature
of the Great Lakes are consistent with global warming and climate change. These
increases widen the gap between water temperature and air temperature, which is the
ideal condition for snowfall (Burnett 2003). However, most scientists would agree that
the present-day climate models should be used with caution because of their spatial
resolution and quality of input data (Balling and Cerveny 2002).
6
Many scientists have identified an increase in heavy precipitation (Balling and
Cerveny 2002). Over the last three decades, winter precipitation has been above average
(United States Global Change Research Program). This observed pattern of temperature
and precipitation changes are projected to continue (United States Global Change
Research Program). This could lead to more frequent spring flooding, increasing
infrastructure damage and impacts on human health.
In Canada and the northern part of the United States, climate does not need to be
at an extreme to have severe environmental and economical impacts (Zhang 1999). While
the public at large may perceive some increase in the frequency and magnitude of severe
weather events, many analyses of severe storm records fail to confirm the public
perception (Balling and Cerveny 2002). Blizzards have a larger geographical influence
across the continent (Balling and Cerveny 2002). In particular, severe winter weather,
including blowing snow, blizzards, and high-wind-chill events, can occur across wide
expanses of the continental regions of the United States (Balling and Cerveny 2002).
Damage from severe weather appears to be on the increase also, but normally,
these upward trends disappear with population growth, population redistribution, and
wealth (Balling and Cerveny 2002). Consequently, any public perception of increased
severe storm activity likely relates to the observation of current American television
viewers. Now a days, it is more likely to see coverage of disasters than a viewer of thirty
years ago. This increased coverage leads the viewer to see an overall increase in severe
storm activity and in the climate system (Ungar 1999).
The state of Wisconsin is about 56,153 square miles and also has over 14,000
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lakes (Wisconsin Department of Natural Resources 2010). The southeast part of
Wisconsin is classified as Dodge, Washington, Jefferson, Waukesha, Milwaukee, Rock,
Walworth, Racine, and Kenosha counties (Wisconsin Department of Natural Resources
2010). See Figure 1 and Figure 2.
8
Figure 1. The state of Wisconsin with the nine southeast counties highlighted.
9
Figure 2. Close up of the nine southeastern Wisconsin counties
10
The state has experienced many blizzards throughout its history. In March of
1939, 20 inches or more of snow came down onto central Wisconsin. In January of 1978,
a blizzard hit the northern part of the state producing 70 mile an hour winds, white outs,
and about a foot of snow. There was also as many as 400,000 people without power.
Another snowstorm hit the southern Midwest on December of 1995. Over 20 inches of
snow accumulated from this, just one, storm. That year alone accumulated an all time
season total of 222 inches of snow (Bohnak 2008).
Overall, temperature within the state of Wisconsin affects the severity and
frequency of blizzards. The annual blizzard snowfall amount has also increased within
the past 30 years due to climate change. It is important to understand most studies and
observations have been done over long periods of time and were looking at things other;
like green house gases and different areas, rather than just how temperature effects the
frequency, intensity, and average snowfall accumulations of blizzards within southeast
Wisconsin.
11
Methods
The National Oceanic and Atmospheric Administration and The National Center
for Atmospheric Research provided the free data acquired for this study. Specific
recoding stations within the state of Wisconsin obtained the data. These stations record
the air temperature, wind speeds, and the amount of snowfall. The data has been collected
since 1895 and is as recent as 2010.
This data was used to look at the change, over a period of thirty years, of blizzard
frequency, intensity, and average snowfall accumulations of blizzards within southeast
Wisconsin. The number of blizzards per decade, the average amount of snowfall and the
average wind speeds were looked at and filtered out from the years 1980-2010.
To calculate if there was a increase in blizzard frequency, intensity, and average snowfall
accumulations of blizzards, within southeast Wisconsin, during the past thirty years, I
have also taken the thirty years and split it up into three decades; 1980-1990, 1991-2000,
and 2001-2010. I have then plotted the trends for each decade; the number of blizzards,
the average amount of snowfall, and the average wind speed per decade. I have then
compared the three decades verses the variables. I have visually depicted the relationship
between the variables by showing each variable per decade, in Microsoft Excel and
presenting this data as graphs. I have then compared the three decades verses the
variables: number of blizzards, average amount of snowfall and average wind speed in
one graph for each decade.
In ArcGIS, I have mapped out the state of Wisconsin and highlighted the nine
counties, which make up the southeast part of the state.
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Results
Number of Blizzards Each Decade
There is an increase in general blizzard frequency over the past thirty years 19802010. There is a fifty percent increase in the number of blizzards during this period (see
Figure 3).
Decades
Number of Blizzard Per
Decade
2000's
Blizzards
1990's
1980's
0
2
4
Number of Blizzards
6
Figure 3
13
Overall Wind Speed per Decade
There is a decrease in the wind speed measured from 1980-2010. Statistically the
average wind speed over this period was 41.8 mph. The range of wind speed went from
43.35 mph in the 1980’s to 39.38 mph in the 2000’s (see Figure 4).
Average Wind Speed (mph)
Average Wind Speed Per Decade
50
40
Average
Wind
Speed
30
20
10
0
1980's
1990's
Decade
2000's
Figure 4
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Average Amount of Winter Precipitation
The average amount of winter precipitation over the time period of 1980-2010
was recorded as declining. The nature of this finding is significant because it supports the
definition of a blizzard as not requiring substantial snowfall (see Figure 5).
Average Snowfall Amount 19802010
Amount in Inches
20
Winter Percipitation
15
10
5
0
1980's
1990's
Decade
2000's
Figure 5
15
Average Temperature during Blizzards 1980-2010
The temperatures recorded between 1980-2010 are not a significant factor in
predicting a blizzard. The average temperature range during the eight blizzards from
1980-2010 was 26.5 degrees Fahrenheit to -3.5 degrees Fahrenheit (see Figure 6).
Average Temperature of Each Blizzard
1980-2010
Temperature (F)
40
30
20
Temperature
10
0
-10
1982
1987
1990
1999
2005 2007 2008 2010
Figure 6
16
Average Temperature Compared to Average Snowfall Amounts
Based on Figure 7, there is a direct correlation between temperature and snowfall
amounts in the years 1980-2010 in Southeast Wisconsin.
Temperature VS. Snowfall 1980-2010
40
35
30
25
20
15
10
5
0
-5
-10
Average Snowfall
(Inches)
Average
Temperature (F)
1980
1987
1990
1999
2005 2007 2008 2010
Figure 7
17
Average Temperature Compared to Average Wind Speed
There is no relationship between the average temperature and the average wind
speed of each blizzard between 1980-2010 (see Figure 8).
Average Temperature VS. Average Wind
Speed 1980-2010
60
50
40
30
Average Wind Speed
(mph)
20
Temperature (F)
10
0
-10
1982 1987 1990 1999 2005 2007 2008 2010
Figure 8
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Discussion
The data collected from the National Oceanic and Atmospheric Administration
and the National Center for Atmospheric Research deals with the frequency of blizzards,
the intensity of blizzards and the average snowfall amounts for blizzards in Southeast
Wisconsin between 1980-2010. The results were gathered from data collection and
graphs.
The data, provided free from the National Oceanic and Atmospheric
Administration and The National Center for Atmospheric Research, supports my
hypothesis that the number of blizzards per decade has increased.
It cannot be decided with confidence that my hypothesis, that the intensity of
blizzards and the average snowfall amounts for blizzards in Southeast Wisconsin, are
direct result of warmer winter temperature and climate change or that there is a
correlation between temperature and intensity of blizzards.
For future studies, the data collected from the National Oceanic and Atmospheric
Administration and The National Center for Atmospheric Research, could be over a
greater period of time such as the years 1900-2010. This could then support the
hypothesis. Another suggestion could be to research a greater area of Wisconsin to help
support the hypothesis.
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Conclusion
There is not enough conclusive evidence to say that the hypothesis, the frequency
and intensity of blizzards in Southeast Wisconsin from 1980-2010, are a direct result of
climate change. This is because blizzards are too small of a weather event to base climate
change alone. The reader should remember that this work is organized, thorough, and
concessive.
From the research, the data is not sufficient enough to conclude that there is a
relationship to climate change. New observations include incorporating a broader
spectrum of time such as data collected from 1895-2010. This would suggest more
support since climate change is a very slow process. New insights into future work
include other factors such as carbon dioxide measurements and global axis shifts.
A broader implication to the present work might be man-made influences, such as
the increase in atmospheric CO2, particulates, and urbanized areas, and the normal
climate events over time. Recommendations are more data collection over a greater area
and period of time. Other actions would include strict government enforcement of
environmental protection, globally, to areas with low to no emissions laws such as China
or South America. Further research would include incorporating other areas of the
country with a similar climate or similar latitude and longitude, such as Utah. This would
help with comparative studies.
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Acknowledgements
This undergraduate thesis would not have been possible without the support of
many people. The author wishes to express her gratitude to her advisor, Prof. Dr. Kurt
Piepenburg who was helpful and offered invaluable support and guidance. Deepest
gratitude is also due to Prof. Dr. Matt Zorn and Prof. Dr. Joy Mast without whose
knowledge and assistance this study would not have been successful.
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