What is a MICROBURST?
Microbursts What Are They?
Dennis Mersereau explains
Microbursts, also called "downbursts," are a sudden downward burst of wind from the base of a thunderstorm. The air can rush towards the ground at speeds of 60 MPH before impacting the surface and spreading out in all directions. Winds at the surface can exceed 100 MPH in the strongest microbursts, often causing extensive tree and building damage.
As the name suggests, microbursts tend to affect a small area, no larger than a few square miles in most cases. The intense damage these wind events leave behind can cause residents to think they had a tornado. While weak tornadoes and microbursts can produce similar amounts of damage, there is a marked swirl in tornado debris on the ground when viewed from above, while microbursts produce damage in a starburst pattern, with straight-line winds radiating away from the point of impact.
Two Types of Microbursts
There are two types of microbursts—dry microbursts and wet microbursts—each native to certain parts of the United States.
Drier climates, such as Denver, experience dry microbursts. Dry microbursts hit the ground without any precipitation, making them virtually impossible to see unless they kick up dust and dirt at the surface. Dry air entrainment is basically the only process driving these wind events.
East of the Rockies, especially in the southeastern United States, wet microbursts are dominant. Wet microbursts form from both dry air entrainment (causing cold air to sink towards the ground) and water loading (weight of the rain dragging the air). Seen from a distance, wet microbursts look like an upside-down mushroom cloud—a narrow rainshaft extending from the cloud to the ground, with a large burst of wind-driven water and dirt puffing away from the point of impact at the surface.
To learn more about cleaning up after a storm, click here.