High resolution (Credit: NOAA)
Of all the dangers associated with severe thunderstorms, such as lightning, flooding, and tornadoes, hail may be the one taken most lightly. But, hail is much more than an oddly fascinating weather phenomenon — it can cause injuries and significant financial losses due to property and crop damage.
Small hail (up to about the size of a pea) can wipe out a field of ripening grain or tear a vegetable garden to shreds. Large hail (the size of a tennis ball or larger) can batter rooftops, shatter windows, and “total” automobiles.
Did you know that hail can fall in every state in the country at any time during the year? Although it rarely causes death or serious injury, hail can bring financial devastation to storm-battered areas.
According to NOAA records, hail was the main factor in two weather events since 1980 that caused $1 billion or more in damages to young crops, businesses, homes, cars, and trucks. A series of storms over six days in early April 2001 caused $1.9 billion in damages in 13 states, spanning from Texas to Pennsylvania. A three-day event in early April 2003 damaged $1.6 billion in property and agriculture in 10 states stretching from Texas to Tennessee.
Hail starts out as little chips of ice in large cumulonimbus (thunderstorm) clouds. These ice chips are kept aloft by updrafts or upward movements of air within a thunderstorm.
As they are blown through freezing thunderstorm clouds, the ice chips grow larger and freeze solid into hailstones. The updrafts keep the hailstones aloft until they become too heavy to remain in the clouds. The stronger the updraft, the larger the hailstone can grow before falling to Earth.
Small hail is created by short-lived, multi-cell thunderstorms common to the United States, China, Russia, India, and northern Italy. (The vast majority of hail remains relatively small, about the diameter of a pea.) The most hail-prone area of the United States, “Hail Alley,” includes southeastern Wyoming, northeastern Colorado, and the southern Nebraska Panhandle. Fortunately for roof shingles and sheet metal, most hailstorms do not cover large areas, nor do they last long.
High resolution (Credit: NOAA)
The sustained updrafts of violent supercell thunderstorms, which are common to the central United States and often result in tornadoes, can produce large hail ranging from about the size of a quarter to the record-setting size of a volleyball!
And, here’s another interesting fact: A hailstone the size of a baseball falls at the speed of about 100 miles per hour! That will seriously damage whatever it hits.
High resolution (Credit: UCAR)
Add hail to the other perils associated with a severe thunderstorm (e.g., damaging winds and threatening lightening strikes) and you have a dangerous combination that shouldn’t be taken lightly.
When a thunderstorm producing large hail — generally ¾ to 1 inch in diameter —is detected by National Weather Service radar or storm spotters, meteorologists at the local National Weather Service office will issue a “Severe Thunderstorm Warning,” which includes hail ¾ inch and larger, to alert the public to in advance of the coming threat.