When severe thunderstorms occur, they can produce “gorilla hail”—an unofficial term for hailstones far larger and more destructive than typical ice pellets. These icy projectiles can cause widespread damage. Understanding this phenomenon is important for anyone living in hail-prone regions.
Defining Gorilla Hail
“Gorilla hail” is a colloquial term, not a scientific classification, used to describe hailstones of exceptional size and destructive potential. Coined by meteorologist and storm chaser Reed Timmer, this term refers to ice pellets significantly larger than average, often surpassing the size of golf balls, baseballs, or even grapefruits. While common hail might be pea-sized or nickel-sized, gorilla hail typically measures over two inches in diameter, with some reports exceeding four inches. The largest recorded hailstone, found in South Dakota, measured eight inches in diameter and weighed nearly two pounds.
These colossal hailstones can exhibit varied appearances depending on their formation. Some gorilla hailstones appear jagged and irregular, while others are surprisingly smooth. The texture and clarity are influenced by the atmospheric conditions during their growth; turbulent environments can lead to a spikier surface. If water freezes rapidly upon impact with the growing hailstone, trapped air bubbles can make the stone appear hazy or opaque. Conversely, slower freezing allows air bubbles to escape, resulting in a clearer, more transparent appearance.
The Formation of Giant Hailstones
The formation of giant hailstones requires specific atmospheric conditions within severe thunderstorms. These ice chunks typically develop within supercell thunderstorms, which are characterized by strong, rotating updrafts and downdrafts. The process begins when water droplets are carried upward by intense updrafts, reaching altitudes where temperatures are well below freezing. At these frigid heights, supercooled water droplets freeze, forming small ice pellets.
As these initial ice pellets fall within the storm, they are repeatedly caught by strong updrafts and lifted back into colder regions. During each ascent, more supercooled water droplets collide with the hailstone and freeze, adding successive layers of ice. This cyclical process of being lifted and falling allows the hailstones to grow considerably. Stronger, more sustained updrafts allow hailstones to remain suspended longer and accumulate more ice, leading to their immense size. Eventually, hailstones become too heavy for updrafts to support and plummet to the ground, sometimes at speeds exceeding 100 miles per hour.
Understanding the Risks and Impacts
The immense size and velocity of gorilla hail cause widespread destructive impacts. Property damage is extensive, affecting vehicles, homes, and agricultural lands. Vehicles can sustain severe dents, shattered windshields, and broken windows. Roofs, siding, and exterior building structures are also vulnerable to substantial damage.
Agricultural crops can be decimated, leading to financial losses for farmers. Beyond property, there is a risk of injury or fatality to people and animals caught outdoors. The impact of a baseball-sized hailstone can be comparable to blunt force trauma. When faced with gorilla hail, seek sturdy shelter immediately. Staying indoors, away from windows, and in an interior room or basement offers the best protection.