Microburst
A microburst is a compact, intense thunderstorm downdraft that hits the ground and spreads outward as damaging straight-line wind.
What a microburst is
A microburst is a localized column of sinking air inside or near a thunderstorm. When that air reaches the ground, it spreads outward rapidly in many directions. The result can be a short-lived but powerful burst of straight-line wind that damages trees, roofs, power lines, aircraft, and vehicles.
How a downburst forms
Microbursts begin with a strong downdraft. Rain, hail, and evaporative cooling can make air denser, helping it accelerate downward. When the descending air hits the surface, it cannot keep moving down, so it surges outward as a gust front. The strongest winds often occur near the outward-spreading edge.
Wet and dry microbursts
A wet microburst reaches the ground with heavy rain, making it more visible. A dry microburst forms when much of the rain evaporates before reaching the surface, so the damaging wind may arrive with little visible warning. Dry microbursts are common in high-based storms and dry environments.
Straight-line damage
Microburst damage can be confused with tornado damage, but the patterns differ. Tornado winds rotate and often produce convergent or twisting damage. Microburst winds spread outward from a central impact area, sometimes leaving a starburst-like pattern of fallen trees or debris.
Aviation danger
Microbursts are especially hazardous for aircraft during takeoff and landing. A plane may first encounter a headwind, then a downdraft, then a tailwind, causing rapid changes in airspeed and lift. Modern radar, wind-shear detection systems, pilot training, and warning procedures were shaped partly by past microburst accidents.
Forecasting and detection
Forecasters watch thunderstorm structure, dry air, instability, rain loading, downdraft potential, radar velocity signatures, and surface observations. Microbursts can develop quickly, so warnings may emphasize severe thunderstorm winds rather than using the microburst label directly.
Microburst versus derecho
A microburst is small and short-lived. A derecho is a widespread, long-lived thunderstorm windstorm that produces a long swath of damage. Both involve damaging straight-line winds, and both can include downbursts, but they differ in scale, duration, and organization.
Why it matters
Microbursts matter because they are brief, localized, and easy to underestimate. A storm that does not look tornadic can still produce destructive wind. Understanding microbursts helps people take severe thunderstorm warnings seriously and helps explain why damaging wind reports may be sharply concentrated.