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Tornado
Tornado strength is measured by the Fujita scale which is
described below. At the higher levels, weather instruments are
destroyed, so wind speeds are only indirectly estimated.
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| Scale |
|
Description |
|
|
| F0 |
Under 73 |
Light damage |
Branches broken off trees; signs damaged |
| F1 |
73 – 112 |
Moderate damage |
Peels surface off roofs; mobilehomes pushed off
foundations |
| F2 |
113 – 157 |
Considerable damage |
Roofs torn off frame houses; mobilehomes
demolished; large trees uprooted |
| F3 |
158 – 206 |
Severe damage |
Roofs and some walls torn off well-constructed
houses; most trees uprooted; cars lifted off the ground |
| F4 |
207 – 260 |
Devastating damage |
Well-constructed houses leveled; structures with weak
foundations blown some distance; cars thrown |
| F5 |
261 – 318 |
Incredible damage |
Strong frame houses swept away; trees debarked |
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Missouri Tornado Facts...
 Missouri averages 26 tornadoes per year, and has recorded 1,646 tornadoes from
1950 – 2003.
Peak tornado season for Missouri runs from mid March through late June, with
the months of April and May producing the most tornadoes.
Tornadoes are most likely to occur between 3PM and 9PM.
Roughly 67% of Missouri tornadoes are weak with wind speeds of 50 to 110
mph. About 30% are rated as strong with wind speeds of 110 to 205 mph.
Luckily, only 3% are violent with wind speeds over 205 mph.
Between 1950 and 2003, there have been a total of 1,646 tornadoes, 542 of them
significant, with an intensity of F2 or greater.
When compared to other States, Missouri ranks:
- 7th for frequency of Tornadoes,
- 12th for number of deaths,
- 15th for injuries and
- 9th for cost of damages
Source: www.disastercenter.com; Missouri Hazard Analysis; NCDC Storm Database.
On May 4, 2003 many tornadoes erupted from the southwest of Missouri. This was a very rare
event for this part of Missouri since many of the tornadoes experienced across this area are
short lived small tornadoes and will probably exceed any tornado events that occurred over
the past 100 years for this part of Missouri. The Missouri Department of Insurance estimated
insurers had paid $500Mn in insured property losses by the end of May, 2003.
Sources: Missouri Hazard Analysis; http://www.bizjournals.com/stlouis/stories/2003/06/16/daily45.html; www.noa.gov
Minnesota Tornado Facts...
The deadliest Minnesota tornado of record was the Saint Cloud-Sauk Rapids
tornado on April 14, 1886, which killed 74 people.
The most damaging tornadoes were those occurring in the northern part of
Minneapolis in the late afternoon of May 6, 1965, causing about $285,000,000
(in 2002 dollars) damage.
Most of Minnesota’s deadly and damaging tornadoes occurred in groups of
outbreaks that often last from 6 to 12 hours. The worst such outbreak in
Minnesota occurred on June 28, 1979, when 16 tornadoes touched down across
the State, from northwest to southeast in a 6 ˝ hour period.
When compared to other States, Minnesota ranks:
- 17th for frequency of Tornadoes,
- 29th for annual tornadoes per 10,000 square miles
- 18th for number of deaths,
- 19th for injuries and
- 6th for cost of damages
Sources: www.disastercenter.com/minn/tornado.html; http://climate.umn.edu/doc/historical/tornadic.htm;
http://climate.umn.edu/text/historical/mn_climate_summary.txt
Minnesota Historic Tornado Events
Recorded Tornado Events from 1950-2002
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