When Maggie Harrop stepped outside after a summer thunderstorm Saturday evening, she saw something spectacular over Laramie, Wyoming. An incredible burst of color seemed to be exploding from the cloud-filled sky.
"It had rained a few minutes before, and I just looked outside, and I saw these cool-looking clouds," she told Cowboy State Daily. "And then I saw red from the sunset. I was in awe, and I had to take a picture."
Harrop managed to get a few photos of the brilliantly colorful clouds before both the light and the clouds disappeared.
"It only lasted a minute, but It was kind of like a God moment seeing those clouds like that," she said.
Mammoth Mammatus
Cowboy State Daily meteorologist Don Day said Harrop's photos are "amazing," and that she was in the right place at the right time to capture photos of the post-storm clouds.
The clouds themselves weren't unusual, especially at this time of year, he said. What makes these photos awesome is the timing of the sunset reflecting off them at just the right time.
"Those are called mammatus clouds," he said. "If you look at those pictures, you'll see the anvil clouds, those high cirrus clouds on the top of that thunderstorm, and those bulbous clouds right underneath there. That's exactly where you expect to see mammatus clouds."
Mammatus clouds are formed by the sinking cold air at the bottom of a thunderstorm cloud. They usually appear as the bulbous, lumpy undersides of anvil clouds, the massive flat-topped cumulonimbus clouds formed by mature thunderstorms.
Mammatus clouds are often the harbingers of severe weather, such as heavy rain, hail and lightning. That explains why they loomed over Laramie after the Saturday evening thunderstorm.
Day said Harrop's photos captured the entire structure of a thunderstorm, from the anvil cloud at the top to the mammatus clouds below. The red light from that evening's sunset perfectly reflected off the storm's structure in a uniquely beautiful way.
"Sunset illuminated that cloud structure very well," he said. "It was a perfectly illuminated thunderstorm for that brief moment."
When Maggie Harrop stepped outside after a summer thunderstorm Saturday evening, she saw something spectacular over Laramie, Wyoming. An incredible burst of color seemed to be exploding from the cloud-filled sky. (Courtesy Maggie Harrop) 
When Maggie Harrop stepped outside after a summer thunderstorm Saturday evening, she saw something spectacular over Laramie, Wyoming. An incredible burst of color seemed to be exploding from the cloud-filled sky. (Courtesy Maggie Harrop)
Average August
Day said mammatus clouds should be a common sight across Wyoming in the evenings in the last couple of weeks of August. Hot days are followed by afternoon and evening thunderstorms is a day-to-day pattern that repeats as things warm up and cool down.
"Moisture can't do anything until it warms up," he said. "The heat of the day causes the air to rise, and when moist air gets warm enough, those clouds will form, and you get afternoon showers and storms."
When the sun sets, the atmosphere cools off and stops lifting and warming the moist air. Day said that's why Wyoming's thunderstorms dissipate overnight, and the cycle repeats as temperatures rise the next day.
Plenty of subtropical moisture is moving across Wyoming. Day said Wyomingites should expect more afternoon and evening thunderstorms through the rest of August and into September, so long as the days stay hot and the nights cool off.
"Because the air mass isn't changing very much, the same thing occurs the next day as you get to the mature part of summer," he said. "This is a very typical summer pattern."
Andrew Rossi can be reached at arossi@cowboystatedaily.com.
