The Climatology of Tornadoes in the State of Wisconsin (1950-2000)
Nichole A. Moller
Supervisor: Dr. Hildebrandt
Department of Geography, Southern Illinois University, Edwardsville, Illinois 62026-1459 USA
Email: [email protected]
Results and Discussion
Introduction on Tornadoes
Frequency of Tornadoes by Year
Frequency
250
25
20
15
10
200
150
100
50
2000
1998
1996
1994
1992
1990
1988
1986
1984
1982
1980
1978
1976
1974
1972
1970
1968
1966
1964
1962
1960
1958
0
1956
Fujita Scale
1954
Figure 2
1952
Frequency
300
45
40
35
30
5
0
Figure 1
Frequency of Tornadoes by Decade
50
1950
•A tornado is a rotating column of air coming from a cumuliform cloud
•Most of the world’ s tornadoes occur in North America, primarily the USA
• 25% of USA tornadoes occur in ‘ Tornado Alley’
•Tornado Alley is located in the central Great Plains (Figure 1)
•Tornado Alley is most prone to tornadoes because continental pol ar air
masses from Canada collide with maritime tropical air masses fro m the
Gulf of Mexico in the region
•Tornadoes are ranked on the Fujita Scale, according to the amount of
destruction that the tornado causes (Figure 2)
Annual Statistics
•From 1950 to 2000, there was at least one tornado that occurred every year (varying magnitudes)
•The year with the highest activity was 1980 with 47 tornadoes; the fewest (1) were observed in 1952
•The 1980s was the worst decade with 268 tornadoes
•NOTE: The 2000 decade only accounts for 1 year of data
1950
1960
1970
Typical Damage
F0
40-72 mph
Tree branches broken
F1
73-112 mph
Mobile homes pushed off foundation
F2
113-157 mph
Considerable damage, mobile homes demolished, trees uprooted
F3
158-205 mph
Roofs and walls blown down, cars thrown
F4
206-260 mph
Well-constructed buildings leveled
F5
261-318 mph
Massive destruction, autos thrown as far as 100 meters
Figure 3
Frequency
Introduction on Wisconsin
Frequency of injuries per Month
Frequency of Tornadoes Per Month
http://www.weeklyreader.com/featurezone/tornadoes/index.asp
•Wisconsin is not located in Tornado Alley, however there have been
numerous tornadoes ranging from F0 to F5 that have occurred within the
state
•Upper Midwest location, due north of Illinois; 72 Counties (Figure 3)
•Due to its close proximity, WI may show temporal and spatial pat terns
as those states in ‘ Tornado Alley’
1990
2000
Monthly Statistics
•Tornadoes occurred in every month except February
•June had the highest activity of tornadoes with 251 recorded (about 25%)
•June also had the highest frequency for injuries (473) and death s (44)
500
50
250
400
40
200
150
100
300
200
100
30
20
10
50
0
0
1
2
3
4
5
6
7
8
9
10
11
0
1
12
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
Month
Month
6
7
8
9
10
11
12
Months
http://emergencymanagement.wi.gov/
Daily / Hourly Statistics
•Tornadoes in Wisconsin generally occur between early afternoon and early h ours of the morning
•This spike in activity could be explained by daytime heating of the Earth and atmos
atmosphere
•The probability of a fatality in Wisconsin is low at 0.09 (9%)
•On June 7 th, 1984, an F5 tornado struck Iowa county killing 9 people and injuring
juring 200
This tornado touched down at 11:41 pm, a time when people were l ikely asleep
leep
•Sunday has been hit with more tornadoes than any other part of t he week with a total of 199 tornadoes
Frequency of Tornadoes by Hour
Frequency by Day of Week
140
250
200
100
Frequency
Frequency
120
80
60
40
150
100
50
20
0
Monday
22
00
20
00
18
00
16
00
14
00
12
00
10
00
08
00
06
00
04
00
02
00
0
00
00
http://www.wisducks.org/projectsites/
Tuesday
Wednesday Thursday
Friday
Saturday
Sunday
Weekday
Hour
Methodology
Magnitude Statistics
•On average, the intensity of a tornado in Wisconsin is an F1 with winds
nds o f 73-112 mph
•Most of the injuries occurred with tornadoes ranging from F1 to F5. F0 and the unclassified did not
have many injuries recorded over the period of time
•Most of the deaths occurred with the intensity of an F4 tornado
Frequency of Tornadoes by Magnitude
Frequency of Injuries by Magnitude
Frequecy of Deaths By Magnitude
350
35
400
350
300
30
250
25
300
250
200
150
100
Frequency
450
Frequency
Frequency
•Data Source: National Climatic Data Center (NOAA)
•Data converted into a data matrix in Microsoft Excel
•13 data columns to organize and manipulate data for statistical purposes
The columns created were: the county, month, day, year, weekday, time
(military time), hour, Fujita Scale magnitude, the number of deaths,
injuries, the amount in dollars of property damage, and crop damage for
each of the 1000 tornado events during 1950-2000 study period
•Some data errors existed; un-ranked tornadoes are called ‘ unclassified’
•Statistical tests conducted using Microsoft Excel and SPSS
•Research on Wisconsin and Wisconsin's climatology using the World
Wide Web and SIUE library
•Knowing what to do and where to go in the event of a severe stor m is
critical for the safety of the people of Wisconsin
•April 21 -25 is Wisconsin’ s Tornado and Severe Weather Awareness
Week; this event aims to remind people of the dangers associated with
severe weather as well as protective safety measures
•The Office of the Commissioner of Insurance (OCI) encourages
consumers to take this week as an opportunity to check that they are
properly insured for damage that may result from severe weather
•Wisconsin conducts state wide tornado drills
•WEM distributes tornado and severe weather information to school s
•Put together a Disaster Supply Kit
Freuency of Deaths per Month
300
Frequency
Wind Speed
Frequency
Scale
1980
Year
Year
Wisconsin’s
Weather Management
200
150
100
50
50
0
0
1
2
3
Magnitude
4
5
Unclassified
20
15
10
5
0
0
0
1
2
3
Magnitude
4
5
Unclassified
Summary
•Tornadoes have been declining in recent years (not including data after
2000)
•The state averages 19.6 tornadoes a year, but some years have up to 47
tornadoes
•Tornadoes are likely to happen between March and September in
Wisconsin. This is a time of year when warm, moist tropical air from the
Gulf of Mexico reaches the state. Similar circumstances of tornadoes in
Tornado Alley
•Peak activity for tornadoes is June. Similar to northern states in
Tornado Alley such as Illinois and Iowa
•Wisconsin tornadoes are likely to occur in the early afternoon t hrough
the evening hours to around midnight
•Weak tornadoes are most frequent, with F1s being the most common,
followed by F2
•Not all of the 2000 decade have been recorded yet, we are not sure
what the outcome will be
•Even though Wisconsin is not in tornado alley, the state needs to make
sure they are keeping up with new technology and re-inform their
residents about the precautions they must take if a tornado was to
happen
0
1
2
3
Magnitude
4
5
Unclassified
Acknowledgements and References
furnished upon request