Microburst Explained
A microburst can flatten a stand of trees or flip a plane on final approach in under five minutes, with wind speeds rivaling a tornado — and it can develop and strike almost too fast for radar to catch.
A Sudden, Localized Downdraft
A microburst is a concentrated column of sinking air that plunges out of a thunderstorm and slams into the ground, then spreads outward in every direction — unlike a tornado's rotating winds, a microburst's damage pattern is a straight-line "starburst" pattern radiating from a central point.
By definition, a microburst affects an area less than 2.5 miles across and lasts under 5 to 15 minutes, but winds inside one can exceed 100 mph — comparable to an EF1 tornado.
Wet vs. Dry Microbursts
Wet Microburst
Comes with heavy rain and is driven by evaporative cooling as rain falls through dry air below the cloud, chilling and accelerating the descending air. Common with ordinary thunderstorms in humid climates.
Dry Microburst
Produces little to no rain at the surface — the precipitation evaporates completely before reaching the ground (a virga cloud). Common in arid climates like the High Plains and Southwest, and especially dangerous because there's little visual warning.
Why Radar Can Miss It
Weather radar scans at an angle above the ground, and that angle increases with distance from the radar site — so a shallow, fast-developing microburst near the surface can form and collapse in the gap between radar sweeps, or below the lowest beam the radar can see at a given range. Meteorologists watch for specific radar signatures — like a rapidly descending reflectivity core or a "divergence signature" in Doppler velocity — but a microburst can still strike with only a minute or two of detectable warning.
Why It's an Aviation Hazard
Microbursts are especially dangerous to aircraft during takeoff and landing. A plane flying into the outflow first experiences a headwind (extra lift), then flies into the descending core and a tailwind on the other side — a rapid loss of lift and altitude that has caused fatal crashes. Modern airports use Doppler radar and wind shear detection systems specifically built to catch this signature in the final seconds before it matters.
A Real Case: Delta 191
Microburst risk to aviation isn't theoretical. In 1985, Delta Air Lines Flight 191 crashed on approach to Dallas/Fort Worth Airport after flying through a microburst, killing 137 people. The crash became a turning point for aviation weather safety — it directly led to the FAA mandating onboard wind shear detection systems and Doppler weather radar installations at major airports across the country, which is why airport-specific wind shear alerts exist today.
What to Do
Microbursts arrive with the same general warning as any severe thunderstorm — there's no separate "microburst warning." Treat any Severe Thunderstorm Warning as capable of producing damaging straight-line wind: secure loose outdoor items, stay away from windows, and don't shelter under large trees.
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