Dr. Theodore Fujita
Dr. Tetsuya Theodore (Ted) Fujita (1920-1998) was one of the most famous meteorologists to ever study tornadoes. He was popularly known as the Tornado Man or Mr. Tornado. His depth of knowledge and dedication to the study of tornadoes lead to many significant advances in tornado climatology.
The Fujita Scale
The Fujita Scale was developed by Dr. Theodore Fujita. Fujita's hope was to create estimates of tornado intensity based on damage patterns. Early in his career, Fujita studied typhoons and other storms in Japan. He would later write to professor Horace Byers at the University of Chicago about his predictions on downward spikes of airflow. Byers would later invite Fujita to Chicago to complete more research.
Along with his wife, Sumiko, Fujita introduced the F-scale in a February 1971 paper - Proposed Characterization of Tornadoes and Hurricanes by Area and Intensity. The original Fujita scale contained 6 categories of storms ranging from F0 to F5.
The Enhanced Fujita Scale
The Enhanced Fujita Scale, or EF-scale, was developed based on the original Fujita Scale. After some devastating storms in the 1990s, scientists and emergency management officials began to think the original wind estimates in the Fujita scale were too high. According to a National Climatic Data Center article, the FEMA document #342: "Building Performance Assessment Team Report, Midwest Tornadoes of May 3, 1999" focused on some of the weaknesses of the original Fujita scale.
On February 1, 2007, the Enhanced Fujita scale replaced the original Fujita scale. The wind estimates are based on damages to 28 structures and not recorded wind speeds. Each link below is given by structure number, abbreviation, and description. A full graph of the levels of damage are indicated for each structure. Meteorologists use the damages to these 28 structures to estimate wind speeds and assign an EF-scale rating.
Tornado Season
Tornado season varies by location across the United States. Most tornadoes are associated with spring and summer, but winter tornadoes do occur. Any time there is a severe thunderstorm event predicted for an area, there is the potential for the formation of a tornado. There is no real tornado season similar to hurricane season. Instead, there is a greater probability of a tornado at certain points in the year.
The intensity of a tornado usually corresponds to the intensity of a severe thunderstorm. Since thunderstorms are convective storms, there is a dependence on solar heating. For that reason, tornadoes are most common in the late afternoon and evening. The sun heats the surface creating latent heat to supply fuel for massive thunderstorms. However, tornadoes can occur at any time of the day or night.
All 50 states have experienced tornadoes of differing severity. Typically, tornadoes will migrate in a more northward direction as spring progresses. In other words, more southern states experience tornadoes sooner than more northern states. The peak month for all states for the years 2003-2005 was May with June as a close second.
Tornado Frequency
Tornado frequency can be described based on statistics. The National Climatic Data Center describes the average number of tornadoes by state based on the years 1953 through 2004.
How Tornadoes Form
What causes tornadoes?
How do tornadoes form?
Why do some storms produce tornadoes and other do not?
These are common questions asked by weather watchers of all ages about tornadogenesis. With millions of dollars spent on weather research, these questions are still not easily answered.
In tornado alley, air masses to the west are typically continental air masses meaning there is little moisture in the air. This warm, dry air meets the warm, moist air in the Central Plains creating a dryline. It is a well-known fact that tornadoes and severe thunderstorms often form along drylines.
Most tornadoes form during supercell thunderstorms from an intensely rotating updraft. It is believed that differences in vertical wind shear are contributors to the rotation of a tornado. The larger scale rotation inside the severe thunderstorm is known as a mesocyclone and a tornado is one extension of that mesocyclone. An excellent flash animation of tornado formation is available from USA Today.
Dorothy and Tornadoes
Was Dorothy from the movie Twister a real machine for studying tornadoes? Actually, the answer is Yes...sort of.
The Dorothy and DOT machines featured in the popular 1996 disaster movie Twister were based on a real project by the National Severe Storm Laboratory (NSSL). In the movie, Dorothy is placed in the path of a tornado as tiny sensors swirl up into the intense winds and take data from inside a tornado.
In real life, this would be nearly impossible.
The Totable Tornado Observatory, or TOTO for short, was a project created by the NSSL and used for several years with little success. The TOTO was large, bulky, and hard to place in the path of a tornado. Inside the TOTO were sensors that measured wind speed, dew point temperature, and other atmospheric conditions. The difference was the sensors did not fly up inside the tornado.
Newer projects were developed by the NSSL that were a big improvement on the TOTO platform. In the mid-1990's, VORTEX-1 was designed to deploy "turtles" to study tornadoes. First used in 1986, a turtle was like a flipped-over stainless steel salad bowl filled with tornado sensors. More on the turtles is available from the Tornado Project.
Today, the NSSL is working to deploy the VORTEX-2(Verification of the Origins of Rotation in Tornadoes Experiment-2, or V2) from May 10 - June 15 of 2009 and 2010. The V2 will target severe storms in the central plains with instruments including radars, mobile vehicles equipped with instruments, weather balloons, and unmanned aerial vehicles.
According to the NSSL, the project will focus on gaining new insight about how, when, and why tornadoes form, why some thunderstorms produce tornadoes and others do not, and the structure of tornadoes. Answers to these questions will help improve forecasts and provide better warning systems for potential tornado outbreaks.
Famous tornadoes are hard to describe. Does the death toll make a tornado famous? What about wind speed? Or the target of a tornado? Each and every natural disaster that occurs is infamous for a variety of reasons.
Tornadoes of the more distant past are hard to verify. Records of tornadoes exist, but the accuracy of those records remains a bit shaky. Part of the problem is that the existence of a tornado needed to be verified by sight in the past.
One of the oldest tornado photos was taken in South Dakota in 1884. Now imagine if no one was around to photograph the tornado. The unpredictability of tornadoes means they do not necessarily land where anyone will see them.
Tornado safety is vital to understand. There are key safety points to follow before, during, and after a severe thunderstorm threatens your area.
Families need to practice a tornado safety drill.
Each family member needs to know exactly what to do in the event of a tornado.
Pay attention to all watches and warnings issued by the National Weather Service. Never, ever assume that the tornado is not in your area. A warning issued by the NWS means a tornado is either happening or very likely to happen in a short period of time.
If you are outside, you should seek shelter in a flat, low-lying area. Bridges and overpasses are not safe. Do the best you can to protect yourself from debris. A strong tornado can pick up cars, trucks, and even houses.
If you are in a car, never try to outrun the tornado. A car is no match for a strong tornado.
Not only is the wind speed in a tornado intense, the forward progression of a tornado can be extremely fast as well. Several of these videos of tornadoes show ways cars and tornadoes do not mix.
Dr. Tetsuya Theodore (Ted) Fujita (1920-1998) was one of the most famous meteorologists to ever study tornadoes. He was popularly known as the Tornado Man or Mr. Tornado. His depth of knowledge and dedication to the study of tornadoes lead to many significant advances in tornado climatology.
Significant Accomplishments
- Fujita is most famous for his development of a tornado intensity scale known as the Fujita Scale or Fujita-Pearson scale.
- Fujita theorized the existence of microbursts after studying the crash of Eastern Airlines Flight 66 as it attempted to land at New York's JFK International Airport in June 1975. By May 29, 1978, he and his colleagues had gotten the very first microburst image via Doppler radar.
- Fujita also pioneered the study of mesoscale meteorology by concentrating on specific tornado events.
- Fujita introduced the idea of tornado families or multiple vortex tornadoes which are individual weather events within one larger scale storm.
- He helped to develop one of the first tornado sensors similar to the 'Dorothy' apparatus in the movie Twister.
- Fujita is credited with coining the terms 'microburst' and 'downburst' which revolutionized the study of severe thunderstorms. This also contributed to the understanding of airline crashes.
- Dr. Fujita was the director of the University of Chicago Wind Research Laboratory. Fujita also made the first color movie of planet Earth in 1967 using colored satellite pictures taken at 30-minute intervals.
- He also recognized the existence of 'bow echoes' in severe weather events. These bow echoes have been used to predict the formation of tornadoes.
- He was an early pioneer in the use of photogrammetry — the science of making maps and calculations from photographs. This was one key way he discovered microbursts.
- He painstakingly mapped a 70-yr period of tornadoes from 1916–1985.
The Fujita Scale
The Fujita Scale was developed by Dr. Theodore Fujita. Fujita's hope was to create estimates of tornado intensity based on damage patterns. Early in his career, Fujita studied typhoons and other storms in Japan. He would later write to professor Horace Byers at the University of Chicago about his predictions on downward spikes of airflow. Byers would later invite Fujita to Chicago to complete more research.
Along with his wife, Sumiko, Fujita introduced the F-scale in a February 1971 paper - Proposed Characterization of Tornadoes and Hurricanes by Area and Intensity. The original Fujita scale contained 6 categories of storms ranging from F0 to F5.
F0 Tornado
- Wind Speeds of 40-72 mph.
- Mild damages to trees, homes, and signs.
- Also known as a gale tornado.
F1 Tornado
- Wind Speeds of 73-112 mph.
- Stronger structures show damage. Mobile homes are pushed off their foundations. Vehicles can get pushed off the road.
- Also known as a moderate tornado.
F2 Tornado
- Wind Speeds of 113-157 mph.
- Significant damages to frame structures. Light objects can become projectiles. Trees can be snapped off or uprooted. Mobile homes are demolished.
- Also known as a significant tornado.
F3 Tornado
- Wind Speeds of 158-206 mph.
- Homes and businesses severely damaged. Roofs and walls torn off a homes. Trains are overturned and trees in a forest are uprooted or broken. Cars can be tossed into the air.
- Also known as a severe tornado.
F4 Tornado
- Wind Speeds of 207-260 mph.
- Most homes are leveled. Large objects can become projectiles and the zone of debris increases.
- Also known as a devastating tornado.
F5 Tornado
- Wind Speeds of 261-318 mph.
- Almost total devastation occurs. Houses can be completely lifted from their foundations. Objects larger than cars can be carried by the funnel and later become dangerous projectiles.
- Also known as an incredible tornado.
The Enhanced Fujita Scale
The Enhanced Fujita Scale, or EF-scale, was developed based on the original Fujita Scale. After some devastating storms in the 1990s, scientists and emergency management officials began to think the original wind estimates in the Fujita scale were too high. According to a National Climatic Data Center article, the FEMA document #342: "Building Performance Assessment Team Report, Midwest Tornadoes of May 3, 1999" focused on some of the weaknesses of the original Fujita scale.
On February 1, 2007, the Enhanced Fujita scale replaced the original Fujita scale. The wind estimates are based on damages to 28 structures and not recorded wind speeds. Each link below is given by structure number, abbreviation, and description. A full graph of the levels of damage are indicated for each structure. Meteorologists use the damages to these 28 structures to estimate wind speeds and assign an EF-scale rating.
28 Structures on the EF-Scale
- SBO Small barns
- FR12 One- and two-family residences
- MHSW Single-wide mobile homes
- MHDW Double-wide mobile homes
- ACT 3 story or less apartments and condos
- M Motels
- MAM Masonry apartments or motels
- SRB Small retail buildings such as fast food stores
- SPB Small professional buildings such as a doctor office or bank
- SM Strip mall
- LSM Large shopping mall
- LIRB Large isolated retail buildings
- ASR Automobile showrooms
- ASB Automotive service buildings
- ES 1-story elementary schools
- JHSH Jr. and Sr. high schools
- LRB Low-rise 1 to 4 story buildings
- MRB Mid-rise 5 to 20 story buildings
- HRB High-rise buildings over 20 stories
- IB Industrial buildings such as hospitals or universities
- MBS Metal building systems
- SSC Service station caopies
- WHB Warehouse buildings
- TLT Transmission line towers
- FST Free standing towers
- FSP Free standing poles such as light poles and flags
- TH Hardwood trees
- TS Softwood trees
Tornado Season
Tornado season varies by location across the United States. Most tornadoes are associated with spring and summer, but winter tornadoes do occur. Any time there is a severe thunderstorm event predicted for an area, there is the potential for the formation of a tornado. There is no real tornado season similar to hurricane season. Instead, there is a greater probability of a tornado at certain points in the year.
The intensity of a tornado usually corresponds to the intensity of a severe thunderstorm. Since thunderstorms are convective storms, there is a dependence on solar heating. For that reason, tornadoes are most common in the late afternoon and evening. The sun heats the surface creating latent heat to supply fuel for massive thunderstorms. However, tornadoes can occur at any time of the day or night.
All 50 states have experienced tornadoes of differing severity. Typically, tornadoes will migrate in a more northward direction as spring progresses. In other words, more southern states experience tornadoes sooner than more northern states. The peak month for all states for the years 2003-2005 was May with June as a close second.
Tornado Frequency
Tornado frequency can be described based on statistics. The National Climatic Data Center describes the average number of tornadoes by state based on the years 1953 through 2004.
Average Annual Number of Tornadoes, 1953-2004
- Alabama...25
- Alaska...0
- Arizona...4
- Arkansas...25
- California...5
- Colorado...22
- Connecticut...1
- Delaware...1
- Florida...55
- Georgia...22
- Hawaii...1
- Idaho...3
- Illinois...35
- Indiana...22
- Iowa...37
- Kansas...55
- Kentucky...12
- Louisiana...27
- Maine...2
- Maryland...6
- Massachusetts...3
- Michigan...17
- Minnesota...25
- Mississippi...27
- Missouri...30
- Montana...7
- Nebraska...45
- Nevada...1
- New Hampshire...2
- New Jersey...3
- New Mexico...9
- New York...7
- North Carolina...19
- North Dakota...22
- Ohio...15
- Oklahoma...57
- Oregon...2
- Pennsylvania...12
- Rhode Island...1
- South Carolina...14
- South Dakota...29
- Tennessee...15
- Texas...139
- Utah...2
- Vermont...1
- Virginia...10
- Washington...2
- West Virginia...2
- Wisconsin...20
- Wyoming...11
How Tornadoes Form
What causes tornadoes?
How do tornadoes form?
Why do some storms produce tornadoes and other do not?
These are common questions asked by weather watchers of all ages about tornadogenesis. With millions of dollars spent on weather research, these questions are still not easily answered.
Basics of Tornado Formation
Tornadoes are produced when two differing air masses meet. When cooler polar air masses meet warm and moist tropical air masses, the potential for severe weather is created.In tornado alley, air masses to the west are typically continental air masses meaning there is little moisture in the air. This warm, dry air meets the warm, moist air in the Central Plains creating a dryline. It is a well-known fact that tornadoes and severe thunderstorms often form along drylines.
Most tornadoes form during supercell thunderstorms from an intensely rotating updraft. It is believed that differences in vertical wind shear are contributors to the rotation of a tornado. The larger scale rotation inside the severe thunderstorm is known as a mesocyclone and a tornado is one extension of that mesocyclone. An excellent flash animation of tornado formation is available from USA Today.
Dorothy and Tornadoes
Was Dorothy from the movie Twister a real machine for studying tornadoes? Actually, the answer is Yes...sort of.
The Dorothy and DOT machines featured in the popular 1996 disaster movie Twister were based on a real project by the National Severe Storm Laboratory (NSSL). In the movie, Dorothy is placed in the path of a tornado as tiny sensors swirl up into the intense winds and take data from inside a tornado.
In real life, this would be nearly impossible.
The Totable Tornado Observatory, or TOTO for short, was a project created by the NSSL and used for several years with little success. The TOTO was large, bulky, and hard to place in the path of a tornado. Inside the TOTO were sensors that measured wind speed, dew point temperature, and other atmospheric conditions. The difference was the sensors did not fly up inside the tornado.
Newer projects were developed by the NSSL that were a big improvement on the TOTO platform. In the mid-1990's, VORTEX-1 was designed to deploy "turtles" to study tornadoes. First used in 1986, a turtle was like a flipped-over stainless steel salad bowl filled with tornado sensors. More on the turtles is available from the Tornado Project.
Today, the NSSL is working to deploy the VORTEX-2(Verification of the Origins of Rotation in Tornadoes Experiment-2, or V2) from May 10 - June 15 of 2009 and 2010. The V2 will target severe storms in the central plains with instruments including radars, mobile vehicles equipped with instruments, weather balloons, and unmanned aerial vehicles.
According to the NSSL, the project will focus on gaining new insight about how, when, and why tornadoes form, why some thunderstorms produce tornadoes and others do not, and the structure of tornadoes. Answers to these questions will help improve forecasts and provide better warning systems for potential tornado outbreaks.
Famous tornadoes are hard to describe. Does the death toll make a tornado famous? What about wind speed? Or the target of a tornado? Each and every natural disaster that occurs is infamous for a variety of reasons.
Tornadoes of the more distant past are hard to verify. Records of tornadoes exist, but the accuracy of those records remains a bit shaky. Part of the problem is that the existence of a tornado needed to be verified by sight in the past.
One of the oldest tornado photos was taken in South Dakota in 1884. Now imagine if no one was around to photograph the tornado. The unpredictability of tornadoes means they do not necessarily land where anyone will see them.
- The 1974 Super Outbreak
- The Waco Tornado
- The Flint Beecher Tornado
- The Palm Sunday Tornado
- The New Richmond Tornado
- The McConnell Air Force Base Tornado
- The Veterans Day Tornado
- The Tri-State Tornado
- The Super Tuesday Tornado
Tornado safety is vital to understand. There are key safety points to follow before, during, and after a severe thunderstorm threatens your area.
Before a Tornado
Long before a severe thunderstorm threatens your area, you should prepare a weather emergency kit. Severe weather can threaten at any moment and with little warning. You will not have time to prepare an emergency kit once the storm is brewing.Families need to practice a tornado safety drill.
Each family member needs to know exactly what to do in the event of a tornado.
Pay attention to all watches and warnings issued by the National Weather Service. Never, ever assume that the tornado is not in your area. A warning issued by the NWS means a tornado is either happening or very likely to happen in a short period of time.
During a Tornado
If a tornado has been spotted in your immediate area, seek shelter immediately. The best location for tornado safety is in a storm cellar or tornado shelter. The next best place for safety is to go to the center of your home or other sturdy building. Mobile homes can withstand only small amounts of wind making mobile homes unsafe in a tornado.If you are outside, you should seek shelter in a flat, low-lying area. Bridges and overpasses are not safe. Do the best you can to protect yourself from debris. A strong tornado can pick up cars, trucks, and even houses.
If you are in a car, never try to outrun the tornado. A car is no match for a strong tornado.
Not only is the wind speed in a tornado intense, the forward progression of a tornado can be extremely fast as well. Several of these videos of tornadoes show ways cars and tornadoes do not mix.