Thunderstorms/Lightning
Every thunderstorm produces lightning, which kills more people each year than tornadoes. Heavy rain from thunderstorms can lead to flash flooding. Strong winds, hail, and tornadoes are also dangers associated with some thunderstorms. Thunderstorms affect relatively small areas when compared with hurricanes and winter storms. The following are facts about thunderstorms:
- They may occur singly, in clusters, or in lines.
- The typical thunderstorm is 15 miles in diameter and lasts an average of 20 to 30 minutes.
- Warm, humid conditions are highly favorable for thunderstorm development.
- About 10 percent of thunderstorms are classified as severe—one that produces hail at least three-quarters of an inch in diameter, has winds of 58 miles per hour or higher, or produces a tornado.
Facts about lightning:
- Lightning's unpredictability increases the risk to individuals and property.
- Lightning often strikes outside of heavy rain and may occur as far as 10 miles away from any rainfall.
- "Heat lightning" is actually lightning from a thunderstorm too far away for thunder to be heard. However, the storm may be moving in your direction!
- Most lightning deaths and injuries occur when people are caught outdoors in the summer months during the afternoon and evening.
- Your chances of being struck by lightning are estimated to be 1 in 600,000, but could be reduced even further by following safety precautions.
- Lightning strike victims carry no electrical charge and should be attended to immediately.
Preparing for a Severe Thunderstorm
Before a severe thunderstorm affects your area, take the following precautions:
- Monitor a NOAA Weather Radio or a reliable media source for watches and warnings.
- Postpone outdoor activities if thunderstorms are imminent. Coaches of outdoor sports teams should have a NOAA Weather Radio with a tone-alert feature during practice sessions and games.
- Pay attention to weather clues around you that may warn of imminent danger. Look for darkening skies, flashes of lightning, or increasing wind, which may be signs of an approaching thunderstorm.
What to do during a Thunderstorm
Obviously the best thing to do during a thunderstorm is to remain inside a building. If you are inside during a thunderstorm, follow these guidelines:
- Draw blinds and shades over windows. If windows break due to objects blown by the wind or large hail, the shades will help prevent glass from shattering into your home.
- Unplug appliances. Avoid using the telephone or any electrical appliances. If lightning strikes, telephone lines and metal pipes can conduct electricity. Leaving electric lights on, however, does not increase the chances of your home being struck by lightning.
- Avoid taking a bath or shower, or running water for any other purpose. Metal pipes and plumbing can conduct electricity if struck by lightning.
If you are caught outside during a thunderstorm, follow these guidelines:
- Take shelter in substantial, permanent, enclosed structures, such as reinforced buildings. Sturdy buildings are the safest place to be.
- If there are no reinforced buildings in sight, take shelter in a car. Keep car windows closed and avoid convertibles. Rubber-soled shoes and rubber tires provide no protection from lightning.
- If you are in the woods, find an area protected by a low clump of trees. Never stand underneath a single large tree in the open.
- If you are in an open area go to a low place such as a ravine or valley. Be alert for flash floods.
- If you are anywhere you feel your hair stand on end (which indicates that lightning is about to strike), squat low to the ground on the balls of your feet. Place your hands over your ears and your head between your knees. Make yourself the smallest target possible and minimize your contact it the ground. DO NOT lie flat on the ground.
Avoid the following conditions:
- Natural lightning rods such as a tall, isolated tree in an open area.
- Hilltops, open fields, the beach, or a boat on the water.
- Isolated sheds or other small structures in open areas.
- Anything metal—tractors, farm equipment, motorcycles, golf carts, golf clubs, and bicycles.
Hurricane winds (>74 mph) blow in a large spiral around a relatively calm center known as the “eye.” The “eye” is generally 20 to 30 miles wide, and the storm can have a diameter of up to 400 miles. A hurricane can bring torrential rains, high winds, and storm surge as it nears land. Inland flooding is a common occurrence with hurricanes and tropical storms. torrential rains from decaying hurricanes and tropical storms can produce extensive urban and river flooding.
Tropical storms and hurricanes are easily tracked and have as long an advance warning period as any weather system. However, their intensity, and speed and direction of motion can quickly change. While R-MC is located inland it does not mean that we are not at risk from high winds, rains and flooding associated with tropical storms and hurricanes. It is important to take these storms seriously and to plan accordingly.
Four key alerts are issued that relate specifically to tropical storms and hurricanes.
- Tropical Storm Watch: Tropical storm conditions with sustained winds from 39 to 73 mph are possible in your area within the next 36 hours.
- Tropical Storm Warning: Tropical storm conditions are expected in your area within the next 24 hours.
- Hurricane Watch: Hurricane conditions (sustained winds greater than 74 mph) are possible in your area within 36 hours.
- Hurricane Warning: Hurricane conditions are expected in your area in 24 hours or less.
What to do during a hurricane or tropical storm warning:
- Stay indoors, on the first floor away from windows, skylights and glass doors, even if they are covered. Stay on the floor least likely to be affected by strong winds and flood waters. A small interior room without windows on the first floor is usually the safest place. Have as many walls between you and the outside winds as possible. sometimes strong winds and projectiles may tear hurricane shutters off, so stay away from windows even if they are covered. Lie on the floor under a table or other sturdy object. Being under a sturdy object will offer greater protection from falling objects.
- Close all interior doors. Secure and brace external doors. Closed doors will help prevent damaging hurricane winds from entering additional rooms.
- Have a supply of flashlights and extra batteries handy. Avoid using open flames (candles and kerosene lamps) as a source of light.
- Be alert to flooding or tornadoes. Continue to listen to a NOAA Weather Radio for information.
A tornado is a violently rotating column of air extending from a thunderstorm to the ground. The most violent tornadoes have rotating winds of 250 miles per hour or more. They are capable of causing extreme destruction, including uprooting trees and well-made structures, and turning normally harmless objects into deadly missiles. Most tornadoes are just a few dozen yards wide and only briefly touch down, but highly destructive violent tornadoes may carve out paths over a mile wide and more than 50 miles long. Although violent tornadoes comprise only 2 percent of all tornadoes, they are responsible for nearly 70 percent of tornado-related fatalities. The following are facts about tornadoes:
- 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, but tornadoes have been known to move in any direction.
- The average forward speed of a tornado is 30 MPH, but may vary from stationary to 70 MPH.
- Tornadoes can accompany tropical storms and hurricanes as they move onto land.
- Waterspouts are tornadoes that form over water.
- Peak tornado season in the southern states is March through May.
- Tornadoes are most likely to occur between 3 p.m. and 9 p.m., but can occur at any time.
During a Tornado Watch
- Monitor a NOAA Weather Radio or a reliable media source for watches and warnings.
- Be aware of your surroundings, paying attention to these warning signs:
- Dark, often greenish sky. Sometimes one or more of the clouds turns greenish (a phenomenon caused by hail) indicating a tornado may develop.
- Wall cloud, an isolated lowering of the base of a thunderstorm. The wall cloud is particularly suspect if it is rotating.
- Large hail. Tornadoes are spawned from powerful thunderstorms and the most powerful thunderstorms produce large hail. Tornadoes frequently emerge from near the hail-producing portion of the storm.
- Cloud of debris. An approaching cloud of debris can mark the location of a tornado even if a funnel is not visible.
- Funnel cloud. A visible rotating extension of the cloud base is a sign that a tornado may develop.
- Roaring noise. The high winds of a tornado can cause a roar that is often compared with the sound of a freight train.
- Tornadoes may occur near the trailing edge of a thunderstorm and be quite visible. It is not uncommon to see clear, sunlit skies behind a tornado. They may also be embedded in rain and not visible at all.
During a Tornado Warning:
- During a Tornado Warning, a tornado has been sighted or indicated in this area by weather radar. Take shelter immediately!
- The best place to be in the event of a tornado is the interior of a building with no exterior windows. If possible get to the lowest point of the building such as the basement.
- If you are in a vehicle, do not try and outrun the tornado. Exit the vehicle as soon as possible and seek shelter in the interior of a building.
- If you are stuck outside in a tornado with no shelter, lie flat in a nearby ditch or depression and cover your head with your hands. Be aware of the potential for flooding. Do not get under an overpass or bridge. You are safer in a low, flat location. Watch out for flying debris. Flying debris from tornadoes causes most fatalities and injuries.
GENERAL GUIDELINES FOR HAZARDOUS WEATHER PREPARATIONS AT R-MC:
Residence Halls: R-MC's number one priority during a hazardous weather event is the protection of our students. R-MC Campus Safety, EH&S, and Office of Residence Life maintain detailed emergency procedures for many foreseeable situations. The following guidelines will help students prepare for hazardous weather events:
- Residence hall staff will provide necessary instructions for emergency procedures. Please act quickly when advised by staff to evacuate to other parts of the building, or make emergency preparations in your room.
- Remain in the Residence Hall unless advised otherwise by staff. In immediate danger, staff will instruct you to move to lower floors, the basement, hallways, or to evacuate the building.
- Keep a flashlight and replacement batteries. Do not use candles or any open flame lantern, etc. These are highly dangerous in a power outage.
- Electrical equipment should be unplugged and placed off the floor, preferably in a closet or as far away from windows as possible.
- Since the floors can get wet, all articles such as shoes, rugs, clothes, bags, suitcases, etc., should be placed on closet shelves, in dresser drawers, or on a bed.
- All loose objects should be placed in drawers or closets. Papers, books, etc. , should not be left on top of desks or dressers.
- Valuables should be placed in a theft secure place (or securable location). All doors should be locked when the occupants are not in the room or apartment.
- All windows and drapes/curtains must be closed tightly.
- Due to heavy rain and wind, move all personal belongings away from the outside wall(s) in your room.
- Have a container with some fresh water in case water supply is affected. Three gallons per person per day is advised.
- If caught outside, avoid contact with dangling or loose wires, likewise, do not touch trees or other items outside, because they may conduct electricity.
- Emergency shelters may be set up at various campus locations. Residence hall students will be instructed of locations should the need to evacuate arise.
Office Environment: It is essential to make preparations for personal safety during a hazardous weather event, but it is also quite important to ensure the protection of work areas and the equipment and data necessary to continue operations during the event and/or resume operations after the event. The following guidelines should help most work areas prepare for hazardous weather:
- Move and secure valuable items in your office away from exterior windows.
- Lock windows and draw drapes or lower the blinds.
- Back up personal computer data and software then shut down computers and printers.
- Store the software and data disks in a dry place off the ground, such as the top drawer of a file cabinet.
- Unplug electrical equipment such as computers, printers, clocks, radios etc. from outlets.
- Cover large valuables, such as computers and printers, with plastic or some other material for protection.
- If your office is below ground, store all your valuables well above the floor.
- If caught in a building during the hurricane, stay inside away from windows and near the center of the building.
Laboratory Environment: Hazardous weather can threaten the safety and operation of research laboratories. Plans should be developed well in advance of a severe weather event to ensure the protection of valuable research equipment, specimens and data. Once a hazardous weather watch is issued, these plans should be implemented in each research area in preparation for the hurricane. Even with backup generators available, researchers should protect their valuable materials in case power, water and climate control go out of service for an extended period of time. Special arrangements may need to be planned to protect and prevent release of hazardous chemicals. Here are some tips to help laboratories prepare for hazardous weather:
- When a hazardous weather watch is issued, make necessary preparations to suspend ongoing experiments involving biological cultures, radioactive agents and hazardous chemicals.
- When a hazardous weather warning is issued, implement activities to suspend operations in the laboratory. Plan to shut operations down within three hours of initial hurricane warning.
- Remember, don't count on the availability of power, water, climate control, or fume hood exhaust systems.
- Always keep chemical/radioactive materials in your inventory to a minimum.
- Reorganize and dispose of old materials routinely to keep chemicals from becoming outdated.
- Due to the possibility of power outages, materials that are volitile, toxic, or pose a respiratory hazard should not be stored in fume hoods or refrigerators but in tightly sealed, impervious and impact-resistant containers.
- Laboratories with outside windows should develop a secure area for the storage of water reactive chemicals, radioactive materials and biological agents. These secure areas should be waterproof and heavy enough to not be affected by the wind.
- Hazardous chemicals should not be stored below ground level during a hurricane. Find a secure area above the ground floor levels to secure these materials in case of flooding.
- Any radioactive materials must be returned to the radiation storage room. See Physics Dept. Chair for details.
- Keep plastic waterproof containers on hand to store reactive chemicals, lab notes, research documentation, computer disks, and any other materials that you cannot afford to have damaged.
- Keep plenty of warning labels appropriate for the hazards of the materials you work with on hand. These may be needed after the weather event.
(partially excerpted from the American Red Cross Disaster Services site http://www.redcross.org/disaster/safety/guide.html)