Hail, Lightning, and Strong Wind: The Hidden Toll of Severe Thunderstorms

While hurricanes and tornadoes command headlines, severe convective storms - the thunderstorms that produce hail, lightning, and damaging winds - collectively cause more annual property damage in the United States than any other natural hazard. Understanding these threats is essential for homeowners, businesses, and outdoor workers.

Hail: Ice Falling at Terminal Velocity

Hail forms within powerful thunderstorm updrafts that carry supercooled water droplets high into the atmosphere where they freeze into ice pellets. As the pellets circulate within the storm's updraft, they accumulate layers of ice, growing until they become too heavy for the updraft to support and fall to the ground. Hailstone size can range from pea-sized to softball-sized or larger. The largest hailstone on record in the United States, recovered in Vivian, South Dakota in 2010, measured 8 inches in diameter and weighed nearly 2 pounds.

Hail causes an estimated $8-14 billion in property damage annually in the United States, with vehicle and roof damage representing the majority of losses. The region known as 'Hail Alley' - centered on eastern Colorado, Nebraska, and Wyoming - experiences the highest frequency of large hail events globally. However, damaging hail can occur virtually anywhere in the country when conditions are favorable.

Lightning: A Geophysical Force

Lightning is an electrical discharge produced by the charge separation that occurs within thunderstorms. A typical lightning bolt carries roughly 300 million volts and 30,000 amperes of electricity, and can heat the surrounding air to approximately 30,000 Kelvin - roughly five times the surface temperature of the sun. Despite this extraordinary energy, modern lightning protection systems and public education have reduced U.S. lightning fatalities significantly since the mid-20th century, from several hundred deaths per year in the 1940s to fewer than 30 in recent years.

Lightning poses risks not only through direct strikes but through ground current (electrical current spreading outward through the ground from a strike point), side flash (electrical current jumping from a struck object to a nearby person), and contact voltage (current transmitted through a conductive object a person is touching). Open fields, bodies of water, golf courses, and tall isolated trees are particularly high-risk locations.

Strong Wind: Derecho Events and Straight-Line Wind Damage

Not all damaging wind events are tornadoes. Straight-line winds from severe thunderstorms can reach speeds of 80-100 mph or more, causing damage easily confused with tornado damage. Particularly significant are derechos - long-lived, widespread straight-line wind events associated with bands of rapidly moving thunderstorms. Derechos can affect areas hundreds of miles long and wide, causing extensive tree damage, power outages, and structural damage over vast regions. The August 2020 Midwest derecho tracked approximately 770 miles across Iowa, Illinois, and Indiana, causing an estimated $11 billion in agricultural and property damage.

Protecting Yourself and Your Property

• Hail: Monitor severe thunderstorm warnings and seek shelter for vehicles and people when large hail is possible. Consider impact-resistant roofing materials if you live in a high-hail-frequency area.
• Lightning: Follow the 30-30 rule - if the time between lightning flash and thunder is 30 seconds or less, seek shelter immediately and stay inside until 30 minutes after the last thunder. No outdoor location is safe during a thunderstorm.
• Strong wind: Secure outdoor furniture, decorations, and equipment before a severe storm season. Know the difference between a Watch (conditions are favorable) and a Warning (severe weather is occurring or imminent).