Definition
A small-scale, intense downdraft of air descending from a thunderstorm or rain shower that strikes the ground and spreads outward in all directions, producing strong, rapidly changing winds. Microbursts are typically less than 2.5 miles across at the surface, last only 5 to 15 minutes, and can produce downdrafts exceeding 6,000 feet per minute and horizontal wind differences of 90 knots or more across the affected area.
Plain English
A short, powerful blast of air that drops out of a storm cloud, hits the ground, and spreads outward like water from a hose hitting pavement. It is small, brief, and extremely violent.
Context Anchor
Seen in weather briefings, thunderstorm avoidance, and takeoff or landing decisions when storms or heavy rain are near the airport.
Derivation
From 'micro' (Greek mikros, meaning small) plus 'burst' (a sudden release of energy). The name was chosen to distinguish these small, short-lived events from larger downburst phenomena.
Why Pilots Care
Microbursts produce severe low-level wind shear that can cause sudden loss of airspeed and altitude, requiring an immediate escape maneuver.
Analogy
Picture pouring a bucket of water straight down onto a table: when it hits, it spreads quickly in every direction. A microburst acts in a similar way, except the moving material is air.
Grounding Statement
Picture a column of cold, heavy air falling out of a storm cloud, slamming into the runway, and fanning out across it in every direction within a minute or two.
Intuition Check
Do not let “micro” suggest “minor.” A microburst affects a small area, but the wind inside it can be violent and dangerous.
Example Sentence 1
The tower reported a microburst alert on final approach, and the crew immediately executed a go-around.
Example Sentence 2
During the weather briefing the pilot noted microburst potential due to the building cumulus clouds near the airport.