Earlier this week, the National Weather Service in Memphis received this…”unique” hail report:
— NWS Memphis (@NWSMemphis) June 5, 2019
Other unusual hail reports that come into the National Weather Service and news stations across the country include:
- “Sonic Ice” hail
- “Hen Egg” hail
- “Tea Cup” hail
But I do think that “pinky toe size hail” takes first place for oddest hail size!!
How Hail Forms
As illustrated in the video above, hail forms when water vapor is transported into a thunderstorm, where it cools and condenses into liquid droplets — until a certain point. Once the water travels higher than the freezing point, it freezes into ice pellets.
Within a combination of gravity and downward moving air (also known as downdrafts), the ice pellets fall into above-freezing air — melting a little in the process and/or getting soaked in a layer of liquid rain.
Upward moving air (also known as updrafts) carry the ice/liquid pellet back into the freezing zone, where everything refreezes (with the new layer of liquid forming a “ring” around the original ice pellet). Eventually, gravity and downdrafts pull the sphere of ice toward the ground, where it gets caught in yet another updraft and the cycle continues.
The longer the hailstones go through the cycle, the bigger they become — and that means the stronger the updrafts. Severe weather research focusing on hail has shown that updrafts as strong as 49 mph can generate hail the size of a quarter (1 inch in diameter); softball-size hailstones (4 inches in diameter) remain aloft via 103 mph updrafts.
Eventually, the hailstones become too big to stay lofted in the storm cloud, and gravity pulls them back to the ground. This is when hail damage occurs to vehicles, homes and crops. In fact, hailstones 1 inch in diameter or greater is considered severe, and severe thunderstorm warnings are issued for thunderstorms that produce hail of this size or greater.
How to relay your hail report
Recall that the tweet above says the hail was “pinky toe size” — an oddly specific sized object with which to compare a hailstone, or is it? After all, not everyone has the same size pinky toe (and I can’t believe I just wrote this sentence in a scientific article).
But it is highly recommended that you compare any hailstones that you receive with a round object, like a coin or a ball. Avoid using the term “marble” because marbles come in all sizes, some bigger than others, and we really need to know the closest size of the hail due to its implications with warning criteria.
Be sure to include the following information with your hail report:
- Approximate time when the hail fell
- Approximate hail size (compare it to a *standard* object, like a coin or ball… No pinky toes, please!)
- Nearest town or road intersection (we can co-locate your hail report with the radar data of the time)
Your hail reports are very important to WHNT News 19 as well as the National Weather Service! You may not realize it, but if you relay to us that you received hail, you are improving our coverage of the weather as it affects the Tennessee Valley. Your report provides “ground truth” that corroborates the radar data we are analyzing — it’s not always perfect, after all!
Are thunderstorms in the forecast? Check the WHNT News 19 Forecast Discussion by clicking here or read it on the Live Alert 19 app!
— NWS Mobile (@NWSMobile) July 22, 2018