Severe thunderstorms and tornadoes affect communities across the United States every year, causing fatalities, destroying property and crops, and disrupting businesses. Tornadoes are the most destructive products of severe thunderstorms, and second only to flash flooding as the cause for most thunderstorm-related fatalities. Damages from violent tornadoes seem to be increasing, similar to the trend for other natural hazards, in part due to changing population demographics and more weather-sensitive infrastructure, and some analysts indicate that losses of $1 billion or more from single tornado events are becoming more frequent. This book discusses issues such as forecasting and issuing warnings for severe thunderstorms and tornadoes, the role of mitigation and the effect of climate change. The book also discusses the role of the National Weather Service in forecasting severe weather and communicating the risk to communities and individuals.