Are grapefruit-sized hailstones on the horizon? Climate change might lead to massive ice chunks
Research suggests an increase in hailstones over two inches, with smaller ones declining as they are more likely to melt before reaching the ground.
A recent study released this week may elicit groans from those who have suffered damages to their vehicles from large hailstones.
According to a study published in the Nature journal “npj Climate and Atmospheric Science,” we can expect an increase in both the size and number of hailstones in the future as global temperatures rise, particularly in the Eastern United States.
The research analyzed past hailstone data to forecast future patterns under two different scenarios for greenhouse gas emissions. The findings revealed that:
“Hailstones greater than two inches are predicted to grow larger,” stated Victor Gensini, a co-author of the study and a meteorology professor at Northern Illinois University, who is highly regarded for his expertise in storms and tornadoes. He explained that the higher the greenhouse gas emissions, the larger the expected hailstones, with the worst-case scenarios leading to the largest and most frequent occurrences.
The study indicates that as temperatures rise, we will witness an increase in the powerful updrafts that contribute to the formation of larger hailstones. Gensini noted that smaller hailstones are likely to decrease since they are more prone to melting before reaching the ground, while larger hailstones, which fall faster, are less affected by the warming atmosphere.
Gensini compared the phenomenon, saying, “Creating a large hailstone requires a very strong updraft. It’s similar to balancing a ping pong ball with a hair dryer – easy to do. Balancing a grapefruit, however, needs a much stronger force.”
The warming temperatures are forecasted to enhance environmental instability, which fuels stronger updrafts, leading to the formation of larger thunderstorms capable of producing hefty hailstones. These updrafts carry raindrops high into storms, enabling the growth of hail.
Moreover, increased temperatures permit more water vapor to accumulate in the atmosphere, intensifying storms and adding moisture.
The study predicts a decrease in the number of severe hailstorm days in the High Plains, but an increase in days with larger hailstones in areas outside the southern plains, particularly in regions like the Midwest, Ohio Valley, and Northeast. Gensini and his colleagues have also observed similar trends with severe thunderstorms and tornadoes, with more tornadoes occurring further east and beyond traditional tornado seasons.
How does hail form?
Hail originates when raindrops are lifted into colder parts of the atmosphere in a storm, where they freeze. However, experts are still piecing together the complete process that transforms raindrops into record-breaking hailstones, like the 8-inch hailstone that fell in Vivian, South Dakota, on June 3, 2010.
Matthew Kumjian, a meteorology professor at Penn State who was not involved in the study, explained that research continues on various factors essential for producing significant hail. For instance, he mentioned that understanding how supercooling works in storms and its interaction with particles in the cloud to form ice crystals is a key area of investigation.
Similar to baking a cake, Kumjian noted that certain conditions are necessary for producing large hail: robust updrafts, supercooled liquids, and adequate residence time, which refers to the conditions inside the storm that keep a hailstone in the cloud for longer periods.
How do hailstones grow?
Large rotating supercell thunderstorms are primarily responsible for producing significant hail, Gensini stated.
Supercells are powerful thunderstorms characterized by a rotating column of air that can extend tens of thousands of feet into the sky. Going forward, he noted that stronger thunderstorms with more vigorous upward motion will generate the conditions that lead to increased hail production.
A hailstone’s growth occurs when additional raindrops freeze onto its surface while it is caught in an updraft, resulting in layers of growth and that knobby look that big hailstones exhibit as they rotate in the clouds. The longer a hailstone remains within the storm, the larger it can become.
The factors influencing residence time in the storm are believed to be the strength of the updrafts and the speed and direction of the swirling winds inside the updraft.
Kumjian explained that once a hailstone loses support from the updraft, it begins to fall. However, it may continue to grow until it reaches a temperature above freezing.
What is the maximum size of hailstones?
“That’s a tough question,” Kumjian responded. The largest hailstone on record was discovered in Bangladesh in 1986, weighing just over 2 pounds.
The scientists are still trying to understand what influences the size of hailstones, but model simulations suggest that the heaviest hailstone could reach up to 3 pounds.
By utilizing a large collection of actual hailstone shapes to study the relationship between mass, shape, and size, researchers have identified that a typically rounded hailstone could grow to about 10 inches in diameter, which is just a bit larger than an NBA basketball.
The rising costs of hail damage
On average, hail occurs in the U.S. 158 days each year, but it has been regarded as a secondary risk by the insurance sector, according to Gensini.
With yearly losses from hail damage and severe storms reaching into the billions and being five times greater than in 2008, these weather phenomena are rapidly becoming a primary threat, he stated. “This year alone, we’re already facing at least $60 billion in insured losses from severe storms.”
However, it’s not just the size or frequency of hail that is concerning, emphasized Walker Ashley, a meteorologist and professor at Northern Illinois University and a co-author of the hail study. The impact depends on where the hail strikes.
“Our population is growing, and it’s not just about density,” Ashley noted. The expansion into previously rural areas contributes significantly to the increasing financial losses.
Damage from hail usually does not stem from single catastrophic events but rather accumulates; “It’s like dying from a thousand small injuries,” Ashley remarked. “It’s $2 million in damages here and $10 million there.”
The combination of greater risks from larger hail and the spreading population indicates that economic costs will continue to rise, he added.
Is the size of hailstones increasing?
It is still too early to confirm a clear trend.
“Many experts in the climate and severe weather sectors believe that we’ve noticed an eastward shift in severe weather incidents in recent years,” Gensini remarked.
In the first quarter of 2024, there were 93 reports of hail larger than 2 inches, compared to 57 last year and the 20-year average of 50, according to a report by Gallagher Re, a reinsurance company.
Further investigation is necessary to grasp the dynamics of hail storms, Kumjian stated. “We are still working to understand the conditions that affect hail size and storm behavior.”
What is the largest hailstone recorded in the U.S.?
The University Corporation for Atmospheric Research indicates that when ranked by diameter, the largest hailstones are in the following order: if ranked by circumference, the Nebraska hailstone would take the top spot.
- Vivian, South Dakota, July 23, 2010: 31 ounces, 8 inches in diameter, and 18.6 inches in circumference.
- Aurora, Nebraska, June 22, 2003: 7 inches in diameter and 18.75 inches in circumference. Weight not available.
- Coffeyville, Kansas, September 3, 1970: 27 ounces, 5.7 inches in diameter, and 17.5 inches in circumference.
- Potter, Nebraska, July 12, 1928: 24 ounces, 5.4 inches in diameter.
What are common comparisons to estimate hail size?
Here are the sizes measured in inches by diameter:
- Pea – 0.25
- Mothball – 0.5
- Penny – 0.75
- Nickel – 0.875
- Quarter – 1
- Ping pong ball – 1.5
- Golf ball – 1.75
- Tennis ball – 2.5
- Baseball – 2.75
- Tea cup – 3 inches
- Softball – 4 inches
- Grapefruit – 4.5 inches
