Hazards - Tornado
Tornadoes strike suddenly. With little time to react, advanced planning is a key to survival.
Tornadoes are one of nature's most violent storms. In an average year, about 1,000 tornadoes are reported across the United States, resulting in 80 deaths and over 1,500 injuries.
Tornadoes by Definition
A tornado is a violent windstorm characterized by a twisting funnel shaped cloud and spawned by a thunderstorm. In Florida, hurricanes often bring thunderstorms which precede tornadoes. Tornadoes are produced when cool air overrides a layer of warm air, forcing the warm air to rise rapidly. The damage from a tornado is a result of the high wind velocity and windblown debris.
Tornado season is generally March through August, although tornadoes can occur any time during the year. They tend to occur in the afternoons and evenings. Eight out of ten tornadoes occur between noon and midnight.
Tornado Watches and Warnings
A tornado watch is issued by the National Weather Service when conditions which can lead to the development of tornadoes are present in your area. Remind family members about safety precautions, such as using a "safe room" in your home if you have built one, and continue to listen to broadcast reports.
A tornado warning is issued by the National Weather Service when tornado has been sighted or observed on radar. Move the family to the pre-identified safe room or other secure location and stay tuned to a battery operated radio until the National Weather Service determines that the threat has passed
Enhanced Fujita Scale
From the National Weather Service: The Enhanced Fujita Scale or EF Scale, which became operational on February 1, 2007, is used to assign a tornado a 'rating' based on estimated wind speeds and related damage. When tornado-related damage is surveyed, it is compared to a list of Damage Indicators (DIs) and Degrees of Damage (DoD) which help estimate better the range of wind speeds the tornado likely produced. From that, a rating (from EF0 to EF5) is assigned.
The EF Scale was revised from the original Fujita Scale to reflect better examinations of tornado damage surveys so as to align wind speeds more closely with associated storm damage. The new scale has to do with how most structures are designed.
3 Second Gust (mph)
The EF scale still is a set of wind estimates (not measurements) based on damage. Its uses three-second gusts estimated at the point of damage. These estimates vary with height and exposure. Important: The 3 second gust is not the same wind as in standard surface observations. Standard measurements are taken by weather stations in open exposures, using a directly measured, "one minute mile" speed.
Tornado Danger Signs
A tornado is a violently rotating column of air extending from a cumuliform cloud, such as a thunderstorm, to the ground. Tornadoes may appear nearly transparent until dust and debris are picked up or a cloud forms within the funnel. The average tornado moves from southwest to northeast, but tornadoes can move in any direction and can suddenly change their direction of motion.
When conditions are warm, humid, and windy, or skies are threatening, monitor for severe weather watches and warnings by listening to NOAA Weather Radio, logging onto weather.gov or tuning into your favorite television or radio weather information source. The following are tornado danger signs:
- Dark, often greenish sky
- Wall cloud
- Large hail
- Loud roar, often described as sounding like a freight train
- Visible funnel, often with debris below it
- Rain or low lying clouds can often obscure the funnel
- The wind could die down and the air become very still just prior to the tornado hitting
- Approaching clouds of debris could be visible, even if the funnel is not
Tornadoes often following on the trailing edge of thunderstorms. It is not uncommon to see sunlit sky behind the tornado.
Before the Tornado
Advanced planning is the key to surviving a tornado. The entire family must be aware that there is little warning. Having planned their actions prior to the event is critical. Ensure you have built a disaster supply kit, made a disaster plan, and are staying informed. During tornado season, you may want to consider adding a helmet (per family member) to your disaster supply kit to protect yourself from falling debris.
Tornado Communications Plan
Families could be separated when the tornado occurs, and telephone service might be disrupted. A family communication plan should identify who your family members will call to exchange information about their location and condition. This might be a relative or friend of the family who is willing to take messages and coordinate information.
Your house or entire neighborhood might be destroyed or cordoned off by emergency workers. Have an alternate location selected where the family can assemble. Keep in mind the age of the younger members of your family when developing your communications plan. Keep it simple.
Conduct Tornado Drills
Designate an area in your home as a shelter. It should be a room which you feel is the strongest structurally and thus the most likely to withstand the tornado winds and flying debris.
The Federal Emergency Management Agency encourages people to have a "safe room "in their house. This room should be structurally enhanced to make it more secure than it was when originally built. Those families awaiting their home being constructed should consider talking with their contractor about building in extra strength for one of the rooms. It is less expensive to do this during construction than to modify the house later.
Keep your disaster supply kit in your tornado shelter. Your family should practice responding to the room as if there were an actual threat.
During the Tornado
IF YOU ARE AT HOME:
- Get to the lowest level or point in your home, such as a basement.
- If you home does not have a basement, go to some area without windows, such as an inner hallway or perhaps bathroom.
- Stay away from windows.
- Room corners attract debris, so stay in the center of the room.
- Use a helmet to protect your head and neck, and shoes to protect your feet.
- Seek shelter under a sturdy piece of furniture, such as a dining room table.
- If you are in a mobile or manufactured home, leave it and seek shelter elsewhere.
IF YOU ARE IN A MOBILE/MANUFACTURED HOME:
- Mobile/manufactured homes are not safe during tornadoes!
- Make a plan today to stay with a friend or family member when a tornado watch is issued for your area, and seek shelter in a sturdy building.
- Ensure you have a plan in place that identifies the closest sturdy building where you can shelter – remember by the time a tornado warning is issued, you will have mere minutes to take shelter.
IF YOU ARE AT WORK:
- If a basement exists: use it, otherwise seek an interior hall.
- Avoid facilities with wide span roofs, such as shopping malls, auditoriums and the like.
- Use a helmet to protect your neck and head.
IF YOU ARE OUTDOORS:
- If possible, seek shelter in a building.
- If you do not have time to get inside of a building, seek out low-lying ground or a ditch. In Florida, be mindful of the wildlife that may inhabit ditches, and areas which could flood.
- Crouch near a strong building.
IF YOU ARE IN A VEHICLE:
- You cannot out-drive a tornado. They can move upwards of three hundred miles per hour, change direction, and can lift up vehicles as large as a railroad car and toss it through the air.
- Leave the vehicle as quickly as possible and seek shelter in a building.
- If you cannot reach a building, seek shelter outdoors as indicated above.
After the Tornado
- Remain aware that tornadoes can change directions and return quickly to areas they just left.
- Give aid to the injured.
- Listen to local emergency officials to stay informed about relief support.
- Stay away from damaged buildings. If your neighborhood has been evacuated, return home only after authorities have permitted re-entry.
- Use telephones only for emergency calls, text messaging is preferred.
- Clean up spilled medicines, bleaches, gasoline and other hazardous substances.
- Leave any building in which you can smell gas or chemical fumes.
- Take photographs of damage to support your insurance claims.
- The average forward speed of a tornado is 30 mph but may vary from nearly stationary to 70 mph.
- The strongest tornadoes have rotating winds of more than 200 mph.
- Tornadoes can accompany tropical storms and hurricanes as they move onto land.
- Waterspouts are tornadoes that form over warm water. Water spouts can move onshore and cause damage to coastal areas.
- Tornadoes can occur at any time of day, any day of the year.