What Determines Hail Size? - NBC 5 Dallas-Fort Worth
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Weather Connection

What Determines Hail Size?

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    NEWSLETTERS

    People in Plano are cleaning up from another hail storm that damaged cars and homes. (Published Saturday, April 22, 2017)

    Friday night there were several large hail reports in North Texas as severe thunderstorms rolled through.

    Parts of Prosper, Celina and McKinney saw golf ball-to-baseball-sized hail that damaged several vehicles. Stephenville and Dublin also got hit with golf ball-sized hail. Denton and Rockwall were hit with quarter-sized hail.

    Carrollton and West Plano only got pea-sized hail. Usually pea-sized hail isn't large enough to cause damage.

    Your Hail Photos - April 21, 2017Your Hail Photos - April 21, 2017

    Why did some communities see large, damaging hail while others saw small hail stones? It all has to do with the strength of the updraft in the thunderstorm.

    Updrafts are the winds going into a thunderstorm. Hail is formed when the updraft carries a raindrop up into the upper levels of the atmosphere where the air is very cold. The raindrops then freeze into balls of ice.

    Hailstones grow by colliding with super cooled water drops (water below the freezing point, but not frozen yet). Super cooled water will freeze on contact when it encounters the hail, making the hail stone bigger.

    The stronger the updraft, the higher the hail will travel giving it more time to collide with super cooled water droplets. Think of making a large snow ball, the longer you roll the ball in the snow, the larger it gets.

    The hail stone will continue to grow larger until it is so heavy the updraft winds can't support it. The hail will then fall to the ground.

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