Presentation on theme: "A Safety Guide Oklahoma Department of Corrections, Training Administration Unit TORNADOES Photo: NOAA."— Presentation transcript:
A Safety Guide Oklahoma Department of Corrections, Training Administration Unit TORNADOES Photo: NOAA
Course Information Course Author: Lynne Presley Photos: All weather photos used with permission of the National Oceanic and Atmospheric Administration (NOAA) and the Federal Emergency Management Agency (FEMA) Course created: October 2002 ORACLE course code: SAFI790000 Training Credit: One hour Data Sources Thunderstorms, Tornadoes, Lightning- Nature’s Most Violent Storms, NOAA & American Red Cross, NOAA/PA 99050, ARC 1122. Tornado Information & Hazardous Weather, Copyright 2002 USA TODAY, Gannett Co. Inc. The Tornado Project Online, 2002.
Course Objectives At the end of this course, students will be able to : Understand how a tornado forms Define the difference between a tornado warning and alert, and know what to do in each case Understand the Fujita scale of tornado classification Plan and practice tornado safety procedures Understand the safety measures to take after a tornado strikes
Introduction Tornadoes have touched down in every U.S. state, in both metropolitan and urban areas. Many tornadoes strike within an area from central Texas north to Nebraska, in an area known as Tornado Alley. Oklahoma lies within this Alley, so it’s important that we understand tornadoes and the extreme damage they can inflict. Photo: FEMA
Tornado Facts From Nature’s Most Violent Storms, National Oceanic & Atmospheric Administration and the American Red Cross A tornado is a violently rotating column of air extending from a thunderstorm to the ground Tornadoes may be transparent or filled with dust & debris The average forward speed of a tornado is 30 mph The strongest tornadoes have rotating winds of more than 250 mph Tornadoes are most likely to occur between 3 and 9 pm, but can happen at any time The average yearly number of tornadoes in the U.S. is 1,200 Photo: NOAA
Tornado Myths and Truths From Nature’s Most Violent Storms, National Oceanic & Atmospheric Administration and the American Red Cross “Myth: Areas near lakes, rivers and mountains are safe from tornadoes. Truth: No place is safe from tornadoes. A tornado near Yellowstone National Park left a path of destruction up and down a 10,000 foot mountain. Myth: The low pressure with a tornado causes buildings to “explode” as the tornado passes overhead. Truth: Violent winds and debris slamming into buildings cause most structural damage.”
Tornado Myths and Truths, cont’d. From Nature’s Most Violent Storms, National Oceanic & Atmospheric Administration and the American Red Cross “Myth: Windows should be opened before a tornado approaches to equalize pressure and minimize damage. Truth: Leave the windows alone. The most important action is to go to a safe shelter. Myth: If you are driving and a tornado is sighted, you should turn and drive at right angles to the storm. Truth: The best thing to do is to seek the best available shelter. Many people are injured or killed when remaining in their vehicles.”
Classifying Tornadoes: The Fujita Scale University of Chicago meteorologist T. Theodore Fujita, known as “Mr. Tornado”, created a wind damage scale to classify tornadoes and other wind storms. His scale is called the “F” scale, and uses numbers from F-0 to F-5 to measure wind damage. The National Weather Service accepted the Fujita Scale for use in 1973. Photo: FEMA
Fujita Scale Damage Descriptions F-0: Gale tornado (40-72 mph) Some damage to chimneys; breaks branches off trees; pushes over shallow-rooted trees; damages sign boards. F-1: Moderate tornado (73-112 mph) The lower limit is the beginning of hurricane wind speed; peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off roads; attached garages may be destroyed. F-2: Significant tornado (113-157 mph) Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars pushed over; large trees snapped or uprooted; light object missiles generated. (continued on next slide)
Fujita Scale Damage Descriptions, continued F-3: Severe tornado (158-206 mph) Roof and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted. F-4: Devastating tornado: (207-260 mph) Well-constructed houses leveled; structures with weak foundations blown off some distance; cars thrown and large missiles generated. F-5: Incredible tornado: (261-318 mph) Strong frame houses lifted off foundations and carried considerable distances to disintegrate; automobile-sized missiles fly through the air in excess of 100 meters; trees debarked; steel-reinforced concrete structures badly damaged.
Conditions for Tornado Development Photo: NOAA A typical tornado outbreak often features an intense upper-level disturbance. This disturbance provides the strong vertical wind shear that gives an updraft its twisting motion, turning a normal thunderstorm into a potentially tornado spawning supercell cloud formation.
A Tornado Forms The rising air’s rotation within the thunderstorm updraft creates pressure that tilts the rotating air from horizontal to vertical. The area of rotation now extends through much of the storm. Most tornadoes form within this area of strong rotation. Photo: NOAA From Nature’s Most Violent Storms, National Oceanic & Atmospheric Administration and the American Red Cross
Tornado Signs According to the Tornado Project Online, here are some things that people describe when they tell about a tornado experience: “A sickly greenish or greenish black color to the sky. The fall of hail during a tornado watch or warning. A strange quiet during or shortly after a thunderstorm. Clouds moving very fast, especially in a rotating pattern or converging towards one area in the sky. A sound a little like a waterfall or rushing air at first, then turning into a roar as it comes closer. The sound of a tornado has been likened to that of both railroad trains and jets.”
Weather Radar Photo: NOAA The National Weather Service uses Doppler radars across the United States for detection of severe weather. These radar units are capable of detecting air rotation patterns that can develop into tornadoes, so that life-saving warnings may be broadcast to citizens.
Tornado Alerts National Weather Service tornado alerts are announced on radio and television. Alerts are defined as either of the two categories below: Tornado Watch: Atmospheric conditions are favorable for severe thunderstorms to produce tornadoes. Listen for updated forecasts and possible warnings. Tornado Warning: A tornado has been spotted on the ground or is indicated by radar. Take cover immediately! Photo: NOAA
Tornado Safety Guide “When a tornado is coming, you have only a short amount of time to make life-or-death decisions. Advance planning and quick response are the keys to surviving a tornado.” (FEMA) Photo: NOAA
Tornado Safety Guide: Planning Planning and practice will help you and your family to avoid panic during an emergency. Here are some ways to be prepared: Designate an area in the home as a storm shelter, and practice having everyone in the family go there. Make sure everyone in your family understands the difference between a tornado “watch” and tornado “warning.” Have disaster supplies on hand (flashlights & batteries, portable radio & batteries, first aid kit & manual, emergency food and water, non-electric can opener, and essential medicines). Data source: FEMA
Tornado Safety Guide: Storm Shelters At home: Go at once to an official storm shelter. If this isn’t possible, go to your storm cellar or basement. If you don’t have a basement or storm cellar, go to an inner hallway or a small inner windowless room, such as a bathroom or closet. Assume the position shown below. It’s important to select a safe shelter during a tornado. You can increase your odds of surviving a tornado if you follow these shelter guidelines: Use your arms to protect your head and neck. Data source: FEMA
Tornado Safety Guide: Storm Shelters, cont’d. At home, continued: If you live in a mobile home, be aware that they are vulnerable to storm damage. A mobile home can overturn easily during a storm, even if it’s tied down. If a tornado warning is issued, leave the mobile home and go to an official storm shelter. If an official shelter or other permanent structure is not available, lie in a ditch or other low- lying area a safe distance away from the mobile home. Data source: FEMA
Tornado Safety Guide: Storm Shelters, cont’d. At work or school: Go at once to an official storm shelter. If this isn’t possible, go to the basement or to an inside hallway at the lowest level. Avoid places with wide-span roofs such as auditoriums, cafeterias, large hallways, or shopping malls. If outdoors: If possible, get into a building. If shelter is not available or there isn’t time to get into a building, lie in a ditch or low-lying area or crouch near a strong building. Use your arms to protect your head and neck (as shown in a previous slide). Data source: FEMA
Tornado Safety Guide: Storm Shelters, cont’d. If in a car: Never try to outdrive a tornado. Tornadoes can change direction quickly and can lift and throw a vehicle through the air. Get out of the vehicle immediately and seek shelter in a nearby building. If there’s no time to find a building, get out of the vehicle and lie in a ditch or low-lying area. Use your arms to protect your head and neck (as shown in a previous slide). Data source: FEMA. Photo: NOAA
Tornado Safety Guide: During the Storm Stay in your shelter until the tornado passes. Even though the tornado may not strike your area, it can throw debris for miles around. Don’t leave your shelter until the storm is over! (Photo: NOAA)
Tornado Safety Guide: After the Storm Listen for emergency announcements on the radio and television Stay away from downed power lines Check for gas leaks and turn the valve(s) off if there is a leak Use a flashlight, NOT LIT CANDLES, to check for damage Turn off electricity if you see sparks Watch for loose debris that may fall on you Check on the elderly and your pets Check yourself and your family for injuries. Administer first aid as necessary while you wait for rescue workers. Data: USA Today Photo: NOAA
Conclusion Tornadoes are a serious business. We hope the information you’ve viewed in this course will help should you experience the awesome power of a tornado. Learn more about it… To learn more about the fascinating subject of severe weather, visit the National Weather Service Storm Prediction Center at: http://www.spc.noaa.gov Exit This Course