Thunderstorms that rolled through Texas this week erupted from an extreme weather phenomenon called a “dry line,” officials say.
A National Oceanic and Atmospheric Administration satellite captured the Monday storms quickly developing along a straight line easily visible from space.
Dry lines frequently develop in the Great Plains during spring and summer when moist air from the Gulf of Mexico and dry air from the Southwest converge, according to NOAA.
Here’s a look at the storms — including numerous flashes of lightning — as they developed.
“Severe and sometimes tornadic thunderstorms often develop along a dry line or in the moist air just to the east of it, especially when it begins moving eastward,” NOAA says.
On Monday, severe thunderstorms in North Texas dropped tornadoes near Blum, a small town in Hill County, and in Ellis County, south of Dallas, officials said. Dozens of homes and buildings were damaged and several people were injured.
Though a dry line is similar to a cold front, it doesn’t have a wide contrast in temperature, NOAA says. Instead, the contrast is in moisture and air density.
“Dry lines are often a key driver for severe thunderstorm formation, where they tend to form on the moisture-rich side of the line,” NOAA says.