"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. Policies that could reduce U.S. vulnerability to severe thunderstorms and tornadoes include improvements in the capability to accurately detect storms and to effectively warn those in harm's way. The National Weather Service (NWS) has the statutory authority to forecast weather and issue warnings. Some researchers suggest that there are limits to the effectiveness of improvements in forecasting ability and warning systems for reducing losses and saving lives from severe weather. The research suggests that, for example, social, behavioral, and demographic factors now play an increasingly important role in tornado-related fatalities."
CRS Report for Congress, R40097