16-05-2025
How does hail form? How big can it get? What to know when severe weather strikes in Nashville
When severe weather strikes in Tennessee, hail can pose a significant threat.
According to the National Oceanic and Atmospheric Administration, strong surface winds can make hail fall at an angle or even sideways, causing damage to houses, cars, and potentially injuring people and animals.
In some cases, hail can be deadly to livestock and people. Here's everything to know.
Hail is formed when raindrops are carried upward by thunderstorm updrafts into extremely cold areas of the atmosphere, causing them to freeze. Hailstones then grow cold by colliding with liquid water drops that freeze onto the hailstone's surface, according to the agency.
If the water freezes immediately when colliding with the hailstone, cloudy ice will form as air bubbles become trapped in the newly formed ice.
"However, if the water freezes slowly, the air bubbles can escape and the new ice will be clear," writes the administration online. "The hail falls when the thunderstorm's updraft can no longer support the weight of the hailstone, which can occur if the stone becomes large enough or the updraft weakens."
Hail falls when it gets too heavy for the thunderstorm's updraft to hold it up, and gravity pulls it down. Smaller hailstones can be blown away by horizontal winds, so larger hail usually falls closer to the updraft, writes the administration.
The speed at which hail falls depends on its size, air friction, wind conditions, and how much it melts.
Small hailstones (less than 1 inch) fall at 9-25 mph.
Medium hailstones (1-1.75 inches) fall at 25-40 mph.
Large hailstones (2-4 inches) fall at 44-72 mph.
There is some uncertainty in these speeds due to variations in hailstone shape, melting and environmental conditions. Very large hailstones (over 4 inches) can fall at over 100 mph.
While Florida experiences the most thunderstorms, Nebraska, Colorado and Wyoming typically see the most hailstorms. The region where these three states meet, known as "hail alley," averages seven to nine hail days annually.
As for the Nashville area, according to data from the National Centers for Environmental Information, 240 hail events were reported in Davidson County between Jan. 1, 1974 - Dec. 31, 2024. The recorded hail sizes range from 0.75 inches to 4.5 inches in diameter. No deaths or injuries from hail were reported within that time frame.
The largest hailstone, measuring 4.50 inches, fell during a thunderstorm on June 4, 1985. According to a Storm Data Publication from June 1985, hailstones ranging from baseball to grapefruit size fell in the Nashville area, causing damage to numerous vehicles and buildings.
The largest hailstone ever recovered in the U.S. was discovered in Vivian, South Dakota, on June 23, 2010, according to the administration. The hailstone had a diameter of 8 inches, a circumference of 18.62 inches and weighed 1 pound 15 ounces.
Hail size is typically estimated by comparing it to familiar objects. Most hailstorms contain a variety of hailstone sizes, but only the largest ones pose a significant threat to people caught outside.
Pea: 1/4 inch diameter
Mothball: 1/2 inch diameter
Penny: 3/4 inch diameter
Nickel: 7/8 inch
Quarter: 1 inch (quarter-sized hail or larger is considered severe)
Ping-pong ball: 1 1/2 inch
Golf ball: 1 3/4 inches
Tennis ball: 2 1/2 inches
Baseball: 2 3/4 inches
Tea cup: 3 inches
Softball: 4 inches
Grapefruit: 4 1/2 inches
Diana Leyva covers trending news and service journalism for The Tennessean. Contact her at Dleyva@ or follow her on X, the platform formerly known as Twitter, at @_leyvadiana
This article originally appeared on Nashville Tennessean: How big can hail get? What Tennesseans need to know about it
