Hail Storms in The United States

Although hail storms may occur throughout the U. S. there is one geophysical area that has the dubious honor to be called “Hail Alley”. It is a name given to the region called”The Great Plains” which includes the following states:

Colorado Wyoming Texas
New Mexico Montana Oklahoma
Nebraska South Dakota Kansas

Severe Weather Oklahoma

Oklahoma City’s statistical area contains 621 square miles and the US 2007 census estimated population of 1,192,989. The metropolitan residents increase the estimated population to 1,262,027. Oklahoma City, the capital of the State of Oklahoma is the 31st ranked of cities in the United States.

Oklahoma City is high on the list as a most likely place to encounter a hailstorm in the United States. In Oklahoma City, Spring and Summer months, bring severe thunderstorms containing large hail, rain, winds, and on occasions tornadoes. Oklahoma City weather varies quite dramatically throughout the year. During the winter, the city averages nine inches of snow.

Lying in the heart of “Tornado Alley”, Oklahoma City weather can often be impacted by tornadic thunderstorms characterized by frequent interaction between cold and warm air masses producing the severe weather. An average of 54 tornadoes strike the state per year – one of the highest rates in the world. Many thunderstorms bring about these severe weather changes which are often accompanied by hailstorms causing damage to property and crops.

On May 3, 1999, Oklahoma City experienced an F5 Tornado that was the deadliest (36 killed), costliest ($1billion in damages) and most violent tornado on record in the immediate Oklahoma City area.

The second deadliest tornado occurred June 12, 1942 (35killed)

Nine violent tornadoes (eight F4 and one F5) have occurred on the Oklahoma City area.

Oklahoma City, because of its large area location near the heart of “Tornado Alley”, is known as one of the more Tornado prone cities in Unites States.

What Is Hail And How Does It Form?

Hail is defined as a precipitation in the form of balls or lumps usually called hailstones. With summer come thunderstorms. Tornadoes, flash floods, and hail are dramatic by-products of thunderstorms. Of the different types of inclement weather that summer can bring the most devastating though not the most dramatic is hail which results in an estimated 1- 2 billion dollars worth of damage per year.

Cumulonimbus clouds commonly known as thunderheads are where hail stones form. The ground is heated during the day by the sun and the air close to the ground is heated as well. Hot air is less dense and therefore lighter than cold air, therefore it rises and cools. As it cools, it loses the capacity to hold moisture. Water vapor then condenses, forming loose clouds reminiscent of cotton balls. This condensing moisture releases heat of its own into the surrounding air, causing the air to rise faster and release still more moisture. Cummulonimbus clouds contain vast amounts of energy in the form of updrafts and downdrafts. Hail grows in the storm cloud's main updraft, where most of the cloud is in the form of "supercooled" water. The term supercooled is a reference to the fact that this part of the cloud is composed of water that remains liquid although its temperature is at or below 0 degrees Celsius. A supercooled water drop needs something on which to freeze, or it remains liquid. Ice crystals, frozen raindrops, dust, and salt from the ocean are also present in the cloud. On collision, supercooled water will freeze onto any of these hosts, creating new hailstones or enlarging those that already exist.

Cross sections of hailstones often reveal layers, caused by the different rates of accumulation and freezing of supercooled water, as the hailstone forms. The more supercooled water a hailstone makes contact with, the larger and heavier the stone is likely to become. When the hailstone becomes so heavy that the updraft can no longer support it, it falls from the sky.

Hail Storm Damage

Hail falls along paths called hail swaths. These vary from a few square acres to large belts reaching sizes as large as 10 miles wide and 100 miles long. Swaths can leave hail piled so deep it has to be removed with a snow plow. Hail does a great deal of damage to crops. U.S. costs run into hundreds of millions of dollars annually. While hailstones have been found weighing as much as 0.75 kilograms (1.67 pounds), even much smaller hail can destroy crops, slicing corn and other plants to ribbons in a matter of minutes. Farmers cope with the hail hazard by purchasing insurance. Illinois farmers lead the United States in crop-hail insurance, spending more than $600 million annually.