It’s not every day you see a textbook microburst like this one caught on camera, but Toddy Jack managed to get this insane photo on Sunday afternoon. At the time, Dallas was getting drenched with heavy rain as this nearly stationary storm sat over the area. Then it finally and literally unloaded all of its precipitation in a giant “rain bomb” — right over downtown.
A microburst is a sudden but powerful area of sinking air, associated with the downdraft area of a thunderstorm. While microbursts are typically small, and 2.5 miles in diameter or smaller, they can do incredible damage. Microbursts can have wind speeds in excess of 100 mph, and have been known to do so much harm that the destruction left behind can be mistaken for tornado damage.
A microburst occurs when a thunderstorm simply can no longer “hold” its precipitation. Think of it as being like a brown paper grocery bag. When the bottom of the bag can no longer support the weight of the groceries within, it breaks and all your apples, oranges, etc. fall and spread out all over the floor. Microbursts behave the same way.
When an updraft is strong, it can hold and suspend large amounts of rain droplets as well as hail within the cloud. When the updraft weakens, as is especially typical with a vertically stacked summertime storm, it can no longer hold that rain and hail within. Eventually, the updraft collapses, and all the precipitation crashes to the ground and spreads out in all directions.
While microbursts can do extreme damage to buildings and landscapes such as forests and croplands, they are especially dangerous for aircraft. It is impossible to predict when and exactly where a microburst may occur during a thunderstorm, which makes planes that are either taking off and especially landing (times when the planes are closest to the ground) susceptible if caught in one of these powerful downdrafts. Unfortunately, several fatal airline crashes in history can be attributed to microbursts.
There are actually two types of microbursts: wet and dry. Wet microbursts are most common in the Southeast during the summer months, while dry microbursts are more common over the West. The storm over Dallas on Monday was a wet microburst, as seen by the dark rain curtain spilling out of the cloud.
Microbursts are also known for the visual feature called “rain foots” (think Elf Shoes) that occur when the rain and/or dust hits the ground, then curls back upward as it spreads out horizontally on each side.
Just for fun, here’s an enhanced photo of the same microburst, also shared by Toddy Jack.
Weather is awesome. #cwgpicoftheweek