Everybody’s heard of tornado alley, the region of the U.S that has a high frequency of tornadoes in proportion to the other states. But not everybody knows where tornado alley is or why this phenomenon occurs.
What States Are in Tornado Alley?
At the center of tornado alley:
- Eastern Colorado
- South Dakota
Less intense areas of the tornado alley (Some are said to be in Dixie Alley):
There is some dispute as to what states are considered a part of tornado alley, the less intense areas are sometimes taken out because they are on the fringe. Some classify another area of America as “Dixie Alley” which Is in the southeast and shares states with “Tornado Alley” However, the heart of Tornado Alley lies in the most intense areas listed above.
A Look at Tornado Alley States
The term “tornado alley” was first used in 1952 when meteorologists named a title of their study about the extreme weather in areas of Texas and Oklahoma. Texas has the most tornadoes out of all the states (about 132 annually), some parts of Texas even require strict building codes to cut down on loss of life and property damage.
Being in the most intense area of “tornado alley” Texas has recorded the highest number of tornadoes out of all the states, their highest ever was in 1967 when Texans reported 232 tornadoes.
Oklahoma statistically has the most dangerous storms; these consist of F4 and F5 storms and are most likely to happen in April. On average Oklahoma has 22 tornadoes in May, usually forming in the mid-afternoon to the early evening.
Tornadoes formation patterns can be erratic and unpredictable, one day Oklahoma had 5 tornadoes touch down within 24 hours of each other. The distance tornadoes can take objects is incredible, one motel in Oklahoma was destroyed by a tornado and its sign was found in Arkansas
Kansas is in a central part of “tornado alley” and ranked third in the country for its number of annual tornadoes. Edwards county is the deepest into tornado alley and is always at the highest risk.
The conditions for tornadoes in Kansas are so favorable that they have had a tornado in every month, they also recorded the most F5 tornadoes out of all the states.
Nebraska right inside tornado alley, on average they have 50 tornadoes per year. However, throughout the years of 1987 and 2003, no one died from the effects of a tornado.
Conditions for tornadoes are very favorable year-round, every month has had a tornado in Nebraska except for February. A majority of tornadoes will occur between 4 and 8 p.m. and in May and June.
The east side of Colorado is a part of tornado alley while the other parts are just outside of it. June has had the largest number of tornadoes, seeing 714 in that period. The most tornado active counties are Weld County and Adams County.
The widest tornado ever was 1,760 yards, spotted on May 22, 2008, this tornado was also the most destructive causing $147 million in damage.
Tornadoes in South Dakota have done $300 million in damage, injured 465 people and killed 18 since 1950. Cold drafts in South Dakota’s vicinity tend to produce tornadoes, and snow in Nebraska since they share borders.
The strongest tornado in South Dakota’s history was in 1955. This tornado was a mile-wide F-5 that wreaked havoc for thirty minutes and went thirty miles in that time. No one was killed except for one lamb on a farm.
A majority of Louisiana’s tornadoes will happen between 3-4 PM. Hurricanes usually create the summer tornadoes because hurricanes conditions are very similar to tornadoes.
The southern parts of Louisiana will have much more tornadoes than the north. November is Louisiana’s month with most tornado occurrences. About 75% of their tornadoes will have a path of roughly 4 miles but will be less than 300 feet wide this is thinner and less distance than most tornadoes.
They see an average of 41 tornadoes per year. 1,884 tornadoes were reported between the years of 1950-2013. There is a lot of variation between tornado frequency in Mississippi, for example, 2008 saw 109 tornadoes, while 2014 only saw 27. The deadliest tornado year in Mississippi was 1971 which caused 128 deaths and the injuries of 1494 people.
The term “tornado alley” was made in 1952 and Iowa was the location of the research project done by Major Ernest J. Fawbush and Captain C. Miller.
Most tornadoes have occurred between 4 and 7 PM in Iowa, and the months with the most tornadoes reported are in the spring and summer months.
Being on the fringes of tornado alley, most tornadoes since 2010 have been categorized as F0/F1. The annual average frequency of tornadoes in Iowa is 47 tornadoes, which is quite high except that most are not very dangerous
Some say Tennessee isn’t a part of tornado alley, but that it’s a part of the other area known as “Dixie Alley” in the southeastern United States.
Dixie Alley has more deaths and destruction because it has higher populations that live in smaller areas creating high density, there are also more mobile homes in this area.
The number of tornadoes that occurs in the spring is much more combined than the amount that occur in Tennessee’s winter, fall and summer months. November has the highest number of formed tornadoes after the spring months, while July, September, and December see the least tornado development.
Kentucky’s tornadoes are mostly EF0-EF1 sized tornadoes, and a majority of their tornadoes are formed in April. Kentucky is ranked 27th for tornado frequency and 15 for deaths related to tornados.
One particularly nasty tornado, “The Brandenburg tornado” caused $110 million in damages In 1974, and made that section of the state declared a disaster area.
Since 1844 there have been 1537 documented tornadoes which have caused 511 direct deaths and 3056 injuries that were directly related. 2005 has been Wisconsin’s biggest year for tornadoes, seeing 62 all year, while only seeing one in 1952.
One of the most severe tornadoes in the history of Wisconsin was in 1996, an F5 tornado hit Oakfield in June of that year injuring 12 and causing $40.4 million damage
Minnesota lies along the top edge of “tornado alley” and has seen tornadoes in all months between March and November. The best time for tornadoes to occur in Minnesota is in late spring to early summer between the times of 2:00 PM and 9:00 PM.
In June of 1979 16 tornadoes touched down within the same day moving from the northwest to the southeast for 6 and a half hours.
Why Tornado Alley Exists
The conditions in this part of America are simply favorable to tornado formation. During summer time these middle parts of America get extremely hot which causes updrafts, leading to thunderstorms. Tornadoes form during these many thunderstorms when unstable hot air rises and comes into contact with cool air in the thunder clouds. Tornadoes are able to form at any time of year but the most likely time is when the plains get very hot between the months of March and August.
The F Scale:
This scale was a revolutionary way to categorize tornadoes, before then people used to just base them off records. In 1971 Tetsuya Fujita created the f scale that used length of path, wind speed, and damage to categorize them by classes. Nowadays we have the Enhanced Fujita scale which has 28 factors, replacing the old Fujita scale.
Here’s how EF (enhanced Fujita) storms break down:
EF-0: 65-85 mph winds:
- shallow trees knocked over
- breaks branches
- causes chimney damage
EF-1 86-100 mph:
- surface damage done to roofs
- mobile homes are pushed off their foundations
- vehicles in motion are shoved off the road
EF-2: 111-135 mph winds:
- Roofs torn off of frame houses;
- complete destruction of mobile homes
- train boxcars knocked over
- snapping of trees or uprooted
- small debris become flying projectiles
EF-3: 135-165 mph winds:
- Roofs are entirely ripped off of the most well constructed buildings, walls are ripped as well
- Most trees are uprooted from the ground.
- Entire trains are overturned.
- Vehicles are taken off the ground
EF-4 166-200 mph winds:
- The most well-constructed homes are destroyed completely
- Structures that have weak foundations will blow away.
- Vehicles will be thrown around
- Large debris becomes missiles.
EF-5 200+ winds:
- Most buildings will be severely damaged if not utterly destroyed
- Vehicles will become flying missiles
Other Tornado Facts
- Though tornadoes are more frequent in tornado alley they still can occur anywhere in America
- Tornadoes known as supercells are more likely to form during 3:00-9:00 in the evening.
- Tornado warnings have an average lead of 13-minutes and the false alarm rate is about 70%.
- Some tornadoes may destroy houses but leave light objects like paper plates, and lamps unmoved on top of tables.
- There are cases of tornadoes that have plucked the feathers off of chickens.
- A particular violent tornado in 1896 St Louis sent a piece of wood through the Eads Bridge, which is made of iron.
- Tornadoes occur on every single continent except Antarctica, there is also no evidence to suggest Antarctica has ever had one.
- The United States has about 1,000 tornadoes every year that touch the ground.
- Tornadoes can carry very heavy objects like cars up to a mile away, some lighter objects like clothing and books have gone 20 miles. Extremely light objects like paper have been found 200 miles away from its starting location.
- The lifespan of a tornado can a few seconds to upward of an hour. Nobody knows what the longest life of a tornado is because many tornadoes before the mid 1900’s are now believed to be a chain of tornadoes.
- On average tornadoes will last a less than 10 minutes, the longest-lived tornado on record is the Tri State Tornado that was on the ground for three and a half hours.
- The longest lived tornado is also the deadliest one, it is said to have been invisible. It had a mile-wide path as it trekked across Missouri, Illinois, and Indiana for 220 miles at 60-70 MPH. That is roughly twice the speed of the average tornado. While its looks didn’t match the standard tornado, it injured 2,000 people, killed 700 and caused $16 million in damages.