Severe Weather Notes What is Severe Weather? Severe weather is any dangerous atmospheric event that has the potential to do damage to human life or property. Some main types of severe weather include thunderstorms, snowstorms, ice storms, hurricanes, tornadoes, floods, and droughts. Severe weather can take the form of high winds, hail, heavy rain, lightning storms, tornadoes, hurricanes, or other events. Approaching severe weather patterns can sometimes be predicted from the thickness of low-altitude clouds. Severe weather happens on relatively short timescales and at particular locations. Thunderstorms A thunderstorm is a type of severe weather that brings hail, lightning, thunder, heavy rain, and strong winds. Thunderstorms can cause flooding, fires (from lightning), or downed power lines. In a thunderstorm, it is best to stay inside and not to stand under trees. Hurricanes A hurricane is a large storm that forms over the ocean. It is made up of very strong winds (over 74 mph), which spiral inward. The center of a hurricane, or the "eye," is usually the calmest part of the storm. Hurricanes produce strong winds, heavy rains, and large waves on land. These can all cause damage to buildings, habitats, and wildlife. If enough advance warning is provided before a severe hurricane, the best course of action for anyone in the immediate path of a hurricane is to gather loved ones, evacuate the home, and leave the city. It is also a good idea to shut off gas valves before leaving. Boarding up windows or positioning sandbags can help to minimize the damage done to a home, but should only be done if local authorities recommend it. Local authorities will notify an affected population if and when an evacuation should occur. Tornadoes A tornado is a type of severe weather known for its funnel-shaped cloud and high winds. Very violent tornadoes can reach wind speeds of up to 300 mph. Tornadoes can cause damage to buildings, cars, bridges, and trees. If a tornado is approaching, people should immediately take cover, stay away from windows, and stay in the lowest level of the building they are in. If a person is caught outside during a tornado, he or she should seek cover in a building or lay flat on the ground in a low area. It is generally not safe to be in an automobile during a tornado. Tornadoes are caused by updrafts of a thunderstorm that start to spiral. Floods A flood can happen when rivers rise up to flow over their banks or when there are many days of heavy rains or melting snow. Floods can harm plants and animals, destroy habitats, make driving difficult, damage homes, or even cause drowning. During a flood, it is important to get to higher ground. Do not attempt to drive during a flood. If told to leave the area or evacuate, do so immediately. Droughts A drought is an long period of time in which there is very little rain. During droughts, there can be a decrease in the supply of drinking water. Having a back-up method of obtaining water could help during times of drought. Droughts cause harm to land because topsoil can be easily blown away when the ground is very dry. When a lot of dry soil is blown by the wind, it can even result in a dust storm. Droughts can harm habitats and ecosystems. When there is not enough water, plants and animals can become dehydrated and die. Also, dry, brittle plant material can easily catch fire, and huge wildfires can burn the rest of the plants in the area. Without plants to eat, animals can become sick. Snow and Ice Storms Snow and ice storms take place when large amounts of snow, sleet, or hail fall during times of cold temperatures. When a severe snow or ice storm occurs, it is very important that people avoid traveling along roads or highways. Since snow and ice can make these surfaces very slippery, controlling an automobile can become quite difficult. This is why automobile accidents are very common during snow or ice storms.