Mobile, Ala. (WKRG) — During this spring severe weather season, our stretch of the Gulf Coast has seen multiple large hail events. Before we answer the question of why we saw so much large hail in the past couple of months, we have to first break down how hail forms.
In order to have a thunderstorm, you must have warm, moist, rising air. This is called an updraft. The updraft carries rain droplets into the cold parts of the atmosphere and they freeze into ice. The hail stones then collide with other pieces of ice and water droplets to grow in size. Once the hail gets too heavy for the updraft to hold up, it falls down to the ground.
In the month of April, we saw large hail several times. Most notably April 9 and 10, April 15, and April 24. April 10 brought the historic 4-inch hail in Baldwin County. But they the abnormal amount of large hail?
“The reason we have seen such large hail this year is we have seen a feature that we call and elevated mixed layer,” says Jason Beaman with the National Weather Service in Mobile.
An elevated mixed layer is just a fancy word for an area of warm and dry air in the mid-levels of the atmosphere that comes from higher elevations, like mountains, to our west.
“It’s very dry and very warm to begin with, but it’s also potentially very unstable if all of the other atmospheric ingredients are right. And it is situated right where the hail growth zone is. So really unstable air where the hail growth is can result in really significant hail. And this season, we have really seen the extreme side of that,” adds Beaman.
We typically do not get the atmospheric set-ups for large hail, but the steering patterns this season have brought more of this unstable warm, dry air from the west to our neighborhood and had aided in hail growth.