Hail!
As we all know, hail is created inside thunderstorms. They begin life as tiny, ice-coated particles that are swept high into a thunderstorm on powerful updrafts and then plunge downward before they are lifted once again.
Some hail stones remain tiny and fall from the storm early in their development, but some ride up and down drafts inside the storm for much longer and eventually become quite large. This is what all weather people know about hail but there are a few things we might not yet have heard.
For instance: What part of the United States gets the most hail? About 4,800 hailstorms occur in the US every year. Of them, 500-700 produce hail large enough to do damage. One would think the thunderstorm capital of the US, Florida, would have the most hail, but it does not. While hail is pretty common in the High Plains, the Midwest and the Ohio Valley, none of those areas have the most hail either.
That distinction goes to “Hail Alley,” where the most hailstorms occur, which includes portions of eastern Colorado, Nebraska and Wyoming. Cheyenne, Wyoming is the US city with the greatest frequency of hailstorms and averages 10 days with hail per year. The US Pacific coast has the least hail in the country and what hail does occur is usually very small.
Since Florida is too warm to get much hail, are large hailstones even possible there? You bet! It takes a very deep mid-latitude winter or early spring storm to do it, but big hail can occur in the sunshine state. On March 25, 1992, Orlando suffered tens of millions of dollars in hail damage. Some of the hailstones were as large as large oranges. Drifts of hail reached several feet deep in some places.
What parts of the world are most prone to hail? Northern India has the highest frequency of large hail events and also suffers the most human fatalities from such storms. The world’s hail belts are generally in the midlatitudes and are often downwind of large mountain ranges.
The High Plains of the US and Canada, Central Europe eastward to the Ukraine, the Himalaya region, southern China, and parts of Argentina, South Africa, and southeastern Australia all get hail. Keriche, Kenya, which averages 132 hail days per year may be the world record holder. I’d bet everyone wears hard hats in that city!
What do the rings found in hailstones mean? All right, most of us know what it means; the hailstone has made multiple trips up into the thunderstorm and picked up layer after layer of ice over a central snow or ice core. As many as 25 rings have been counted in hailstones collected in the US. What was the biggest hailstone ever reported? Coffeyville, Kansas once played host to a hailstone that was 17.5 inches in circumference and weighed 1.67 pounds. A stone reported in Germany weighed about 4 pounds but is believed to actually be several stones frozen together.
How big are hailstorms anyhow? Hail often falls in swaths or streaks below the parent thunderstorms. These swaths are typically 5 miles long and 1/2 mile wide and the largest are 10 miles across and 100 miles long. In 1968, however, a superstorm over Illinois produced a swath of hail 19 miles wide and 51 miles long.
Some hailstorms can produce an amazing amount of hail too. In Colorado and Wyoming, it is not unusual to use snow plows to clear main highways of hail drifts. In August 1980 in Orient, Ohio, hail drifts reached a remarkable 6 feet deep and took several days to clear.
Okay, that is enough interesting stuff about hail. How are hailstones categorized? In the US, they are classified by size and are described by comparisons to everyday items everyone recognizes. The list below includes the most common sizes.
These are typically used in the US but other comparatives are used around the world.
| Size | Descriptive Term |
|---|---|
| 0.25 inch | pea |
| 0.50 inch | marble |
| 0.75 inch | penny/dime/large marble |
| 0.88 inch | mothball/nickel |
| 1 inch | quarter |
| 1.25 inch | half dollar |
| 1.50 inch | walnut |
| 1.75 inch | golfball |
| 2 inch | hen egg |
| 2.5 inch | tennis ball |
| 2.75 inch | baseball |
| 3 inch | teacup |
| 4 inch | grapefruit |
| 4.5 inch | softball |
| * Basketball-sized hail has also been reported, but the reports are highly suspect. | |
Hail mainly occurs in the spring in the US but it can occur at any time of the year when conditions are right for big, cold thunderstorms to develop. There is no place completely immune from hail but obviously some places are safer than others. Hail awareness is important for weather people and their customers, so be alert to the atmospheric conditions around you and learn to recognize the signs that hail is a possibility.
Written by Melody L. Higdon, 14 WS/DOPA