What Is Hail?
Hail causes over 1 billion dollars in damages a year. Learn what hail is and when it's most likely to visit your neighborhood.
WHAT IS HAIL?
Hail is defined as "precipitation of balls or pieces of ice." Most commonly, hail ranges in size from .2"-4" in diameter, and is most often less than 2" in diameter. Large hailstones are spherical in shape and composed of alternate hard and soft layers of ice.
HOW DOES HAIL FORM?
Hailstones form when raindrops are blown up to a high, cold area in the clouds. Because the air temperature is below 32-degrees farenheit, the raindrops freeze. As they fall, they are coated with other water drops and blown back up into the clouds, adding more layers ice. This process continues until the wind currents are no longer able to support the weight of the hailstone, and they fall to the ground. The speed at which hail travels can reach as high as 120MPH.
WHEN DOES HAIL FALL?
Because the formation of hail usually requires convective and cumulonimbus clouds with strong updrafts, hail most often accompanies a thunderstorm. Very often, large hail is observed immediately north of a tornado track. The presence of hail however, doesn't necessarily mean a tornado is approaching, just as the absence of hail doesn't mean there is no risk of tornado. A typical hailstorm lasts approximately 15 minutes.
WHERE DOES HAIL FALL?
Hail can fall practically anywhere, at any time of the year. Hailstorms are most common in the middle United States, and most often accompany a thunderstorm. Hail is also most likely to occur in late afternoon.
WHAT SHOULD I DO DURING A HAILSTORM?
The National Weather Service urges all to move to an area of shelter during a storm. Because of the speed and angle at which hail falls, it is extremely dangerous.
HAIL CAN easily encourage a flash flood situation. Because hail floats on water, it often clogs drainage paths, culverts and grates, making a bad situation even worse.
Storms that produce both high winds and hail are often responsible for thousands of dollars in damage to car windows, car hoods and roofs, homes and crops.
The National Weather Service often broadcasts storm information by the estimated size of hail. Though it's difficult to accurately measure hail while it's falling, these numbers represent the average diameters followed by the NWS:
Pea sized hail: 1/4 inch
Marble sized: 1/2 inch
Dime sized: 3/4 inch
Ping-pong sized:1-1/2 inch
Golfball sized: 1-3/4 inch
Baseball sized: 2-3/4 inch
Grapefruit sized:4 inch
Softball sized: 4-1/2 inch
Hail causes $1 billion in damages to crops and property each year.
The largest hailstone ever recorded fell in Coffeyville, Kansas in 1970. It measured approximately 17.5" in circumference, 5.6" in diameter, and weight almost 2 pounds.
The most damaging hailstorm ever was in Denver, CO, in July of 1990. Estimated damages from the brief hailstorm reached upwards of $625 million.
Hail often falls 30, 000 feet during a storm.