Severe winds and tornadoes

Overview

A tornado is a narrow, violently rotating column of air that extends from a thunderstorm to the ground. They can destroy buildings, flip cars, and create deadly flying debris, causing extensive damages to infrastructure, homes, and businesses within minutes. Tornadoes occur in many parts of the world, including Australia, Europe, Africa, Asia, and South America; even New Zealand reports about 20 tornadoes each year. Two of the highest concentrations of tornadoes outside the U.S. are Argentina and Bangladesh. Readers can read more about tornadoes from many resources, including the NOAA Storm Prediction Center, NOAA National Severe Storm Laboratory website, and the wikipedia page of tornado.

The behavior and path of tornadoes has changed over the past few decades. In the United States, the number of tornado days per year has fallen since the 1970s, but the number of tornadoes occurring on those days has increased. This means that when tornadoes strike, they are more likely to occur in clusters or outbreaks, sometimes with 30 or more tornadoes in a single day. The extent of the season over which such tornado activity occurs is increasing as well -- they start earlier in the season. In addition, tornado outbreaks are becoming more geographically concentrated, with tornadoes occurring closer together, and their intensity has increased. Furthermore, the distribution of tornadoes has shifted eastward, placing new regions at greater risk of damage and financial loss.

Climate change is likely to amplify the observed trend in tornado activity. While current climate models are unable to directly simulate tornadoes due to their coarse resolution, researchers use metrics that assess the "environment" conducive to tornado formation based on large-scale variables like temperature, humidity, and wind. Consistent findings suggest that with future warming, the frequency of severe tornadoes is expected to increase, and the storms themselves will likely become stronger.

Implication for finance

The financial repercussions of tornadoes are far-reaching. They disrupt local economies, destroy supply chains, and result in substantial insured and uninsured losses. Tornadoes can be especially costly in regions with significant population density, such as the central and eastern United States, where large concentrations of assets are vulnerable. In fact, tornado is one of the highly costly severe weather phenomena in the US, being one of the Billion-dollar weather and climate disasters, together with other severe convective storms such as hailstorms and derechos. Between 1983 and 2024, severe storms, including tornadoes have caused over 500 billion dollars loss in the US, the second largest disaster in terms of loss. In 2023 alone, tornadoes caused over $1.5 billion loss across the United States.

Recent shifts in tornado behavior have amplified these financial risks -- the growing density of tornado clusters, the increasing strength of these storms, and an earlier start to tornado season are all contributing to rising insured and uninsured losses. Same is with projected future change in tornado behavior. Governments, insurers, and businesses must account for these risks in their financial planning, as the damages extend beyond immediate destruction. Business interruption, property repair, loss of inventory, and labor displacement often lead to prolonged recovery times and increased costs.

Data:

Historical Tornado data

Dataset	Description	Data Access
Severe weather events archive by NOAA	Organized severe thunderstorms archived by Storm Prediction Center of NOAA. The weather events covered include tornadoes, hail, and strong winds. The archive provides information on observation time, location (with detailed latitude and longitude), and estimated wind speed.	Access
Severe weather database by NOAA	Data for tornadoes, hail, and damaging wind, as compiled from NWS Storm Data. Tornado reports exist back to 1950 while hail and damaging wind events date from 1955. Information is provided on observation time, location, storm magnitude, as well as mortality, injuries, and estimated losses for property and crops. Please read the format specification for more information.	Access (Note: The CSV data files are located further down the webpage.)
Severe weather data inventory (SWDI) by NCEI of NOAA	An integrated database of U.S. severe weather records that provides access to data from a variety of sources in the NCEI archive. SWDI includes multiple search and access methods for records that cover particular time periods and geographic regions. Data are currently available in Shapefile (for GIS), KMZ (for Google Earth), CSV (comma-separated), and XML formats. Note that no additional quality control measures are taken beyond the processing that takes place during data archival.	Access

The Storm Prediction Center of NOAA contains a lot of useful resources, including climatology and statistics of tornadoes: https://www.spc.noaa.gov/wcm/#data

European Severe Weather Database https://eswd.eu/

Global Disaster Database (EM-DAT)

monthly tornado report

tornado count

wind speed averages: https://disgeoportal.egs.anl.gov/portal/apps/webappviewer/index.html?id=a69fcf899d91410799233f104b025552; https://climrr.anl.gov/mapexplorer;