Hail Storms

Hail is a weather phenomenon that can damage homes, vehicles and crops. It could even lead to death. On May 16, 2010, a devastating hail storm hit the Oklahoma City area causing approximately a billion dollars in damage. Fatalities from hail are rare in the U.S., the last recorded was a Colorado infant in 1979. Deaths from hail are more common in underdeveloped parts of the world where people live in poorly constructed buildings.

What to do in a Hail Storm

Hail is fairly common in Oklahoma in the spring and being prepared on what to do during a storm can help protect you and your property. If hail begins to fall, take cover. If you are driving, stop if possible because the momentum of the vehicle can make the damage worse. Remember; protect yourself first before trying to save your car from those pesky dents.

What is Hail?

Hail is spherical or irregular shaped chunks of ice produced by intense thunderstorms. It is considered to have a diameter of at least pea sized and can become very large.

How is hail formed?

Hail forms when strong currents of rising air, called updrafts, carry water droplets high enough in a thunderstorm for the water to freeze. More and more water freezes around the piece of ice, causing it to grow in size. Once the frozen pellet is too heavy for the updrafts to keep it within the cloud, it begins to fall. For the hail to grow, strong updrafts catch the falling hail and carry it upward again, adding new layers of ice

The stronger the updraft, the bigger the hailstones can grow with some updrafts over 100 mph.

Hail Facts

• In the U.S., hailstorms are most common in the Central Plains, especially just east of the Rockies.

• Hail is usually produced by cumulonimbus clouds, called thunderstorms.

• Hail forms from condensation nuclei like dust or ice crystals. Then supercooled water freezes on contact with the ice around the nuclei causing it to grow larger.

• Cut in half, a hailstone has concentric rings like an onion, which reveals the number of times it traveled to the top of the storm before falling to Earth.

• The largest hailstone ever reported was 18.75 inches around, 7 inches wide and 2 pounds. The hailstone fell on July 23, 2010, in Vivian, Nebraska.

• When hail falls to Earth, the larger ones can reach speeds over 100 mph right before impact.

• Hail tends to occur in warm weather because hot air rising from the ground creates the turbulent updrafts and tall clouds necessary to keep the ice particles aloft for a long enough time to form hail.

Three Forms of Hail

Hail can be classified into three stages of development: grauple, small hail and hailstones.

• Grauple: Soft, opaque hail with a snowflake-like structure that bounces off of hard surfaces, also referred to as snow pellets.

• Small hail: Has a higher density than grauple, and is usually semi-transparent and rounded, typically up to a 1/5 inch in diameter.

• Hailstones: Round stones of ice, with layers that look like an onion. The layers are formed while the hail is rising and falling in the updrafts.

Hail chart-with examples