Ever wonder how strong the updraft winds must be to keep large hailstones up in a cloud? The following table from the National Weather Service shows the estimated updraft windspeeds necessary to keep various hail sizes suspended in the air within a thunderstorm. Tennis ball size hail needs 77 mph updraft winds and softball size hail needs updraft winds exceeding 100 mph. No wonder jet aircraft must avoid these intense thunderstorms.
And speaking of jet aircraft, the typical transcontinental flight is around 32,000 feet above sea level . However, these intense hail producing thunderstorms can reach more than twice that height reaching levels exceeding 65,000 feet above sea level.
See the earlier post about a potential new record size hail stone in South Dakota in July 2010.