The term "tornado preparedness" refers to safety precautions made before the arrival of and during a tornado. Historically, the steps taken have varied greatly, depending on location, or time remaining before a tornado was expected. For example, in rural areas, people might prepare to enter an external storm cellar, in case the main building collapses, and thereby allow exit without needing rescue from the main building as in urban areas. Because tropical storms have spawned many tornadoes, hurricane preparations also involve tornadoes. The term "tornado preparedness" has been used by government agencies, emergency response groups, schools,[1] insurance companies, and others.
Preparedness involves knowing the major dangers to avoid. Some tornadoes are the most violent storms in nature.[2] Tornadoes have varied in strength, and some tornadoes have been mostly invisible due to a lack of loose dirt or debris in the funnel cloud.[2] Spawned from severe thunderstorms, tornadoes have caused fatalities and devastated neighborhoods within seconds of arrival.
A tornado with no obvious funnel from the upper clouds, although the rotating dust cloud indicates strong winds at the surface.
A tornado operates as a rotating, funnel-shaped cloud that extends downward from a thunderstorm, to the ground, with swirling winds which have reached 300 miles per hour (480km/h).[2] The wind speed might be difficult to imagine: traveling the length of a U.S. football field within 1 second[3] (over 130 meters or 430 feet per second). Damage paths have been in excess of one-mile wide (1.6km) and 50 miles long (80km).[2]
Not all tornadoes are easily seen. A tornado funnel can be transparent until reaching an area with loose dirt and debris.[2] Also, some tornadoes have been seen against sunlit areas, but rain or nearby low-hanging clouds has obscured other tornadoes. Occasionally, tornadoes have developed so suddenly that little, if any, advance warning was possible.[2]
Before a tornado strikes an area, the wind has been known to die down and the air to become very still.[2][dubious–discuss] A cloud of debris has sometimes marked the bottom of a tornado even when the funnel was not visible. Tornadoes typically occur along the trailing edge of a thunderstorm.
The following is a summary of typical tornadoes:[2]
They may strike quickly, with little or no warning.
They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.
The average tornado moves Southwest to Northeast in the U.S., but tornadoes have been known to move in any direction.
The average forward speed of a tornado is 30 miles per hour (48km/h), but has varied from stationary to 70mph (110km/h).
Tornadoes can also accompany tropical storms and hurricanes as they move onto land.
a large, dark, low-lying cloud (particularly if rotating);
loud roar of wind, sounding similar to a freight train.
Upon seeing an approaching storm or noticing any of the danger signs, they were advised to prepare to take shelter immediately,[2] such as moving to a safe room, internal stairway, or other safe-haven area.
All individuals and families should have a disaster preparedness kit made prior to tornado. According to FEMA the kit should include items needed to shelter in place in the event of a disaster such as a tornado for up to 72 hours following impact.
Actions taken during tornadoes
National Weather Service employees take cover as an intense tornado tracks less than 1mi (1.6km) south of them
Generally accepted tips to minimize risk of injury or death during and after a tornado include wearing sturdy shoes or boots, a helmet, long sleeves, gloves, and a heavy quilt or coat. These can offer extra protection from shards of glass, splinters and other airborne objects.[5][6][7]
Ahead of an expected tornado outbreak, the Department of Homeland Security has outlined the following items as beneficial to have.
Basic Items
Water
Food
Tools / Emergency Supplies
First Aid Supplies
Clothing and Bedding
Special Needs Items
In addition, they advise to refill and properly store prescription medicines, get some extra cash for when credit cards do not work, fill automobiles with fuel, stock extension cords and power strips, and to consider making motel/hotel reservations (at a location that is more than 50 miles) for several nights starting after the time of the tornado strike.[8]
During August 2010, FEMA advised people to perform the following actions when a tornado struck.[9]
Location
Action taken
In a structure (e.g., residence, small building, school, nursing home, hospital, factory, shopping center, high-rise building, restaurant)
They were to enter a pre-designated shelter area such as a safe room, basement, storm cellar, or the lowest building level.[9] If there was no basement, then to the center of an interior room on the lowest level (closet, interior hallway) away from corners, windows, doors, and outside walls. The goal has been to put as many walls as possible between the safe room and the outside. They were advised to get under a sturdy table or other object and use arms to protect their head and neck, and not open windows.[9]
In a vehicle, trailer, or mobile home
They were advised to leave immediately and enter the lowest floor of a sturdy, nearby building or a storm shelter.[9] Mobile homes, even if tied down, offer little protection from tornadoes.[9] If a car is flipped by high winds, there is also the danger of broken glass.
On the outside with no shelter
They were advised to lie flat in a nearby ditch or depression and cover head with their hands.[9] Also, to beware of the potential for flooding there.
They were advised to not stay under an overpass or bridge (where winds or debris might be funneled). It was safer to be in a low, flat location.[9]
The advice was to never try to outrun a tornado in urban or congested areas in a car or truck, but instead, to leave the vehicle immediately for safe shelter.
Flying debris from tornadoes causes most fatalities and injuries.[9]
Because some preparations vary, depending on location, people have been advised to consult their local area preparedness plans, rather than assume the plans are similar for all areas, such as which local buildings have been designated as storm shelters.
A 2012 study of tornado injuries found that wearing a helmet such as those used for American football or bicycling, is an effective way to reduce injuries and deaths from head trauma.[10][11] As of 2012, the CDC endorsed only general head protection, but recommended that if helmets are to be used, they be kept close by to avoid wasting time searching for them.[12]
After the 2013 Moore tornado, it became apparent that thousands of people attempt to flee major tornadoes, and this has been credited with reducing the death toll. However, during this event some people were killed as the tornado passed over the traffic jam caused by the impromptu evacuation. In addition to urban traffic, evacuation can also be hampered by flash flooding produced by associated thunderstorms, and the need to be certain about the position and direction of the tornado. Others who did not flee the Moore tornado were also killed because the buildings they were hiding in were completely destroyed, highlighting the need for storm shelters and safe rooms constructed specifically to withstand very high winds.[13]
Actions taken after tornadoes
Wear thick-soled shoes (or boots), long pants, and work gloves during cleanup.
Avoid injury from electric shock, electrocution, debris (nails, broken glass, sharp ends of broken wood), contaminated water, and carbon monoxide poisoning.[14]
Long-term preparations
Depending on location, various safe-haven areas have been prepared. The goal has been to avoid outer walls which might collapse when a roof section becomes airborne and the walls below lose their upper support: many interior rooms resist collapse longer, due to smaller walls interconnected to each other, while outer walls deflect the force of the winds. Because mobile homes typically lack foundation anchors and present a large surface-area sail (to catch wind), the advice has been to seek a safe haven elsewhere, such as in a stronger nearby building.[9] When a mobile home begins to roll, people have been injured by hitting objects inside, or being crushed when a trailer suddenly hits the ground and begins to collapse around them.
In a multi-story building, an internal stairway (away from broken windows) often acts as a safe haven, due to the stairs reinforcing the walls and blocking any major debris falling from above. If a stairway is lined with windows, then there would be the danger of flying glass, so an interior stairway, or small inner room, would be preferable.
In private homes, some similar stairway rooms have been used, or an interior room/closet kept clear to quickly allow entry when a storm is seen or heard approaching (the wind roar intensifies, sounding like a swift "freight train" coming nearer, louder).[2] With weeks or months to prepare, an interior safe room can be constructed, with space for emergency water, food and flashlights, and a telephone to call for rescue if the exit becomes blocked by falling debris. Some above-ground safe rooms have been built with steel-rebar rods in cement-filled cinder blocks, to withstand winds of 250 miles per hour (400km/h). Rural homes might have an outside storm cellar, or other external bunker, to avoid being trapped within a collapsing house. In rural homes, generators are also helpful to maintain power with enough fuel for a few days.
There were no building codes requiring tornado shelters nor specifically designed to prevent tornado damage[15] until the 2011 Joplin tornado prompted a local ordinance requiring hurricane ties or similar fasteners. The state of Oklahoma adopted the minimum U.S. standard that year for the first time, but did not add high-wind protections like those in Florida designed to protect against hurricanes.[16][17] Other states in Tornado Alley have no statewide building codes. The National Association of Home Builders opposes even "safe rooms" on the basis of cost/reward.[18] The chance of any given location in Tornado Alley getting hit by an F-2 tornado (strong enough to do major structural damage and exceeding the 90mph guideline for straightline winds) is about 1 every 4,000-5,000 years; in other areas the annual probability is one in several million.[15][19] The most stringent building codes only require earthquake strengthening for a 1 in every 500-1,000 year probability.[15]
The U.S. Federal Emergency Management Agency has spent tens millions of dollars subsidizing the construction of shelters and safe rooms in both private and public buildings.[16] Many buildings in Tornado Alley do not have basements, because unlike in more northern areas, there is no need for a deep foundation to get below the frost line, in some places the water table is high, and expansion and contraction of clay-heavy soils can produce additional pressure on buildings that can cause leaks if not reinforced.[20]
North of the equator, tornado generally travel between a northerly and easterly direction and cause the most damage on the southwest corner of buildings and that the north side and northeast corner of buildings were safest. Professor Joseph Eagleman of the University of Kansas found that 75 percent of the homes hit were most damaged in the southwest corner. He found that the southwest corner and the south side were the least safe. South of the equator, the south side and the southeast corner were safest.[21][22][23]
Medical preparations
Having a first aid kit in the safe haven is advised to help victims recover from minor injuries. People needing prescription medications could have a medicine bag ready to take to shelter. Some people have reported their "ears popping" due to the change in air pressure, but those effects seem to be temporary. Covering people with mattresses or cushions has helped avoid injury from flying debris,[9] as walls collapsed nearby.
Injuries sustained during a tornado vary in nature and in severity. The most common injuries experienced during a tornado are complex contaminated soft tissue wounds and account for more than 50% of the cases seen by emergency rooms following a tornado. These wounds will most likely be contaminated with soil and foreign bodies due to high wind speeds caused by tornadoes. Fractures are the second most common injury obtained after a tornado strikes and account for up to 30% of total injuries. Head injuries are also commonly reported during a tornado, but severe head injuries only account for less than 10% of the total. Even though only 10% of reported head injuries are severe, they are the most common cause of death following a tornado. Blunt trauma to the chest and abdomen are also injuries obtained following a tornado, but only account for less than 10% of overall injuries.[24]
Tornado drills
Students participate in a tornado drill, lining up along an interior wall and covering their heads.
Tornado drills (also known as severe weather drills) are an important element in tornado preparedness. Like any other safety drills, they increase chances of correct response to a real tornado threat.
Most states in the midwestern and southern United States conduct a statewide tornado drill in late winter or early spring in preparation for the severe weather season. During these drills, the National Weather Service issues test tornado warnings, and local Emergency Alert Systems and/or NOAA Weather Radio (normally as a Required Weekly Test or Required Monthly Test; Live Tornado Warning Codes can only be used if a waiver from the FCC is granted since "Live Code Testing" is prohibited per regulations) are activated along with outdoor warning sirens. Schools and businesses may also conduct a tornado drill simultaneously.
A tornado drill is a procedure of practicing to take cover in a specified location in the event that a tornado strikes an area. This safety drill is an important element of tornado preparedness.[25]
Generally, a signal is given, such as a series of tones (ex. Continuous Tone), or a voice announcement. Upon receiving the signal, building occupants of schools, hospitals, factories, shopping centers, etc. proceed to a designated location, usually an interior room or corridor with no windows, and assume a protective position.[26][27]
In homes and small buildings one must go to the basement or an interior room on the lowest floor (closet, bathroom), to stay away from glass.
Cars and mobile homes must be abandoned, if there is small chance to drive away.
In some jurisdictions, schools are required to conduct regular tornado drills, though generally less frequently than fire drills.
During school tornado drills students are required to huddle up against the walls (picture above) of the building usually the hallway to prevent harm to the students and sometimes staff (teachers, janitors, etc) will also huddle against the wall to prevent harm.
Tornado drills by state
This section needs expansion. You can help by adding to it. (February 2013)
In many states tornado drills are part of the Severe Weather Awareness Week.
A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 180 kilometers per hour, are about 80 meters across, and travel several kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 kilometers per hour (300 mph), can be more than 3 kilometers (2 mi) in diameter, and can stay on the ground for more than 100 km (62 mi).
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are sometimes called thundershowers. Thunderstorms occur in a type of cloud known as a cumulonimbus. They are usually accompanied by strong winds and often produce heavy rain and sometimes snow, sleet, or hail, but some thunderstorms produce little precipitation or no precipitation at all. Thunderstorms may line up in a series or become a rainband, known as a squall line. Strong or severe thunderstorms include some of the most dangerous weather phenomena, including large hail, strong winds, and tornadoes. Some of the most persistent severe thunderstorms, known as supercells, rotate as do cyclones. While most thunderstorms move with the mean wind flow through the layer of the troposphere that they occupy, vertical wind shear sometimes causes a deviation in their course at a right angle to the wind shear direction.
The Federal Emergency Management Agency (FEMA) is an agency of the United States Department of Homeland Security (DHS), initially created under President Jimmy Carter by Presidential Reorganization Plan No. 3 of 1978 and implemented by two Executive Orders on April 1, 1979. The agency's primary purpose is to coordinate the response to a disaster that has occurred in the United States and that overwhelms the resources of local and state authorities. The governor of the state in which the disaster occurs must declare a state of emergency and formally request from the President that FEMA and the federal government respond to the disaster. The only exception to the state's gubernatorial declaration requirement occurs when an emergency or disaster takes place on federal property or to a federal asset—for example, the 1995 bombing of the Alfred P. Murrah Federal Building in Oklahoma City, Oklahoma, or the Space Shuttle Columbia in the 2003 return-flight disaster.
A tornado warning is a public warning that is issued by weather forecasting agencies to an area in the direct path of a tornado, or a severe thunderstorm capable of producing one, and advises individuals in that area to take cover. Modern weather surveillance technology such as Doppler weather radar can detect rotation in a thunderstorm, allowing for early warning before a tornado develops. They are also commonly issued based on reported visual sighting of a tornado, funnel cloud, or wall cloud, typically from weather spotters or the public, but also law enforcement or local emergency management. When radar is unavailable or insufficient, such ground truth is crucial. In particular, a tornado can develop in a gap of radar coverage, of which there are several known in the United States.
A tornado watch is a statement issued by weather forecasting agencies to advise the public that atmospheric conditions in a given region may lead to the development of tornadoes within the region over a period of several hours. In addition to the potential for tornado development, thunderstorms that develop within the watch area may contain large hail, straight-line winds, intense rainfall and/or flooding that pose a similar damage risk as the attendant tornado threat.
A severe thunderstorm warning is a type of public warning for severe weather that is issued by weather forecasting agencies worldwide when one or more severe thunderstorms have been detected by Doppler weather radar, observed by weather spotters, or reported by an emergency management agency, law enforcement, or the general public. Unlike a watch, a warning is issued to areas in the direct path of active severe thunderstorms, that are expecting a direct impact typically within an hour. Severe thunderstorms can cause property damage and injury due to large hail, high winds, and flooding due to torrential rainfall. The exact criteria to issue a warning varies from country to country.
From May 2 to 8, 1999, a large tornado outbreak took place across much of the Central and parts of the Eastern United States, as well as southern Canada. During this week-long event, 152 tornadoes touched down in these areas. The most dramatic events unfolded during the afternoon of May 3 through the early morning hours of May 4 when more than half of these storms occurred. Oklahoma experienced its largest tornado outbreak on record, with 70 confirmed. The most notable of these was the F5 Bridge Creek–Moore tornado which devastated Oklahoma City and suburban communities. The tornado killed 36 people and injured 583 others; losses amounted to $1 billion, making it the first billion-dollar tornado in history. Overall, 50 people lost their lives during the outbreak and damage amounted to $1.4 billion. For these reasons, the outbreak is known in Oklahoma as the May 3rd outbreak or the Oklahoma tornado outbreak of 1999.
A storm shelter or storm cellar is a type of underground bunker designed to protect the occupants from severe weather, particularly tornadoes. They are most frequently seen in the Midwest and Southeastern United States where tornadoes are generally frequent and the low water table permits underground livings.
Tornado myths are incorrect beliefs about tornadoes, which can be attributed to many factors, including stories and news reports told by people unfamiliar with tornadoes, sensationalism by news media, and the presentation of incorrect information in popular entertainment. Common myths cover various aspects of the tornado, and include ideas about tornado safety, the minimization of tornado damage, and false assumptions about the size, shape, power, and path of the tornado itself.
Emergency evacuation is an immediate egress or escape of people away from an area that contains an imminent threat, an ongoing threat or a hazard to lives or property.
Cyclone mitigation encompasses the actions and planning taken before a tropical cyclone strikes to mitigate damage and injury from the storm. Knowledge of tropical cyclone impacts on an area help plan for future possibilities. Preparedness may involve preparations made by individuals as well as centralized efforts by governments or other organizations. Tracking storms during the tropical cyclone season helps individuals know current threats. Regional Specialized Meteorological Centers and Tropical Cyclone Warning Centers provide current information and forecasts to help individuals make the best decision possible.
A safe room or panic room is a fortified room that is installed in a private residence or business to provide a safe shelter, or hiding place, for the inhabitants in the event of a break in, home invasion, tornado, terror attack, or other threat. Safe rooms usually contain communications equipment, so that law enforcement authorities can be contacted.
The effects of Hurricane Isabel in Virginia proved to be the costliest disaster in the history of Virginia. Hurricane Isabel formed from a tropical wave on September 6, 2003, in the tropical Atlantic Ocean. It moved northwestward, and within an environment of light wind shear and warm waters it steadily strengthened to reach peak winds of 265 km/h (165 mph) on September 11. After fluctuating in intensity for four days, Isabel gradually weakened and made landfall on the Outer Banks of North Carolina with winds of 165 km/h (103 mph) on September 18. It quickly weakened over land as it passed through central Virginia, and Isabel became extratropical over western Pennsylvania on September 19.
In weather forecasting in the United States, "particularly dangerous situation" (PDS) is enhanced wording used by the National Weather Service to convey special urgency in some watch or warning messages for unusually extreme and life-threatening severe weather events, above and beyond the average severity for the type of event. It is used in the format "This is a particularly dangerous situation..." at the discretion of the issuing forecaster. A watch or warning bearing the phrase is referred to as a PDS watch or PDS warning as shorthand jargon.
A tornado emergency is an enhanced version of a tornado warning, which is used by the National Weather Service (NWS) in the United States during imminent, significant tornado occurrences in highly populated areas. Although it is not a new warning type from the NWS, issued instead within a severe weather statement or in the initial tornado warning, a tornado emergency generally means that significant, widespread damage is expected to occur and a high likelihood of numerous fatalities is expected with a large, strong to violent tornado.
The 1999 Bridge Creek–Moore tornado was a large, long-lived and exceptionally powerful F5 tornado in which the highest wind speed ever measured globally was recorded at 321 miles per hour (517 km/h) by a Doppler on Wheels (DOW) radar. Considered the strongest tornado ever recorded to have affected the Oklahoma City metropolitan area, the tornado devastated southern portions of Oklahoma City, Oklahoma, United States while near peak intensity, along with surrounding suburbs and towns to the south and southwest of the city during the early evening of Monday, May 3, 1999. Parts of Bridge Creek were rendered unrecognizable. The tornado covered 38 miles (61 km) during its 85-minute existence, destroying thousands of homes, killing 36 people, and leaving US$1 billion in damage, ranking it as the fifth-costliest on record not accounting for inflation. Its severity prompted the first-ever use of the tornado emergency statement by the National Weather Service.
The 2013 El Reno tornado was an extremely large, powerful, and erratic tornado that occurred over rural areas of Central Oklahoma during the early evening of Friday, May 31, 2013. This rain-wrapped, multiple-vortex tornado was the widest tornado ever recorded and was part of a larger weather system that produced dozens of tornadoes over the preceding days. The tornado initially touched down at 6:03 p.m. Central Daylight Time (2303 UTC) about 8.3 miles (13.4 km) west-southwest of El Reno, rapidly growing in size and becoming more violent as it tracked through central portions of Canadian County. Remaining over mostly open terrain, the tornado did not impact many structures; however, measurements from mobile weather radars revealed extreme winds in excess of 313 mph (504 km/h) within the vortex. These are among the highest observed wind speeds on Earth, just slightly lower than the wind speeds of the 1999 Bridge Creek–Moore tornado. As it crossed U.S. 81, it had grown to a record-breaking width of 2.6 miles (4.2 km), beating the previous width record set in 2004. Turning northeastward, the tornado soon weakened. Upon crossing Interstate 40, the tornado dissipated around 6:43 p.m. CDT (2343 UTC), after tracking for 16.2 miles (26.1 km), it avoided affecting the more densely populated areas near and within the Oklahoma City metropolitan area.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.
The 2011 El Reno–Piedmont tornado was a long-tracked and deadly EF5 tornado that struck central Oklahoma on the evening of May 24, 2011. The tornado impacted areas near or within the communities of El Reno, Piedmont, and Guthrie, killing nine and injuring 181. After producing incredible damage in several locations along a path of more than 60 miles (97 km), the El Reno–Piedmont tornado was given a rating of EF5, the highest category on the Enhanced Fujita scale, as well as being the highest rated tornado on the scale since its implementation in 2007, with estimated peak winds >210 mph (337 km/h). It was also the first tornado rated EF5 or F5 to strike Oklahoma since the 1999 Bridge Creek–Moore tornado. A mobile radar found that the tornado possessed possible wind speeds of up to 295 mph (475 km/h).
The 2013 Washington, Illinois, tornado was an unusually powerful and violent tornado that caused catastrophic damage to the city of Washington and several farmsteads in rural central Illinois during the early afternoon of November 17, 2013. The tornado resulted in three fatalities and injured 125 people. This tornado was one of the two violent tornadoes in the tornado outbreak of November 17, 2013, and was the strongest, costliest, and longest-tracked tornado. It was tied for the deadliest tornado of the outbreak, tied with another intense tornado that went through Brookport, Illinois. The tornado was the eighth violent tornado of the below-average yet destructive year of 2013.
References
↑ "Tornado Preparedness Tips for School Administrators", NOAA.gov, 2010, web: NOAA-sch. This article incorporates text from this source, which is in the public domain.
↑ A speed of 300 miles per hour is 300*5280 = 1,584,000 feet per hour, or 440 feet (134 m) per second.
↑ "What to do Before a Tornado", FEMA.gov, August 2010, web: FEMA-toArchived 2011-05-02 at the Wayback Machine . This article incorporates text from this source, which is in the public domain.
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