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A unit measuring radar reflectivity — essentially how much energy bounces back to the radar off precipitation or debris. Higher dBZ generally means heavier precipitation or larger hail.

A rotating column of air within a supercell thunderstorm, typically several miles wide, that can sometimes tighten into a tornado.

A lowered, often rotating cloud beneath a storm's main base, marking the area of strongest inflow and rotation — frequently the area to watch for tornado development.

A hook-shaped appendage on radar reflectivity, associated with a supercell's rear-flank downdraft wrapping around the mesocyclone — a classic tornado-warning signature.

A downdraft that wraps around the back side of a mesocyclone, often playing a key role in tornado formation and intensification.

A bow-shaped line of thunderstorms on radar, associated with damaging straight-line winds and sometimes embedded rotation.

A widespread, long-lived windstorm associated with a fast-moving band of severe thunderstorms, capable of producing damage similar to a hurricane over a large area.

A wall of dust or sand kicked up by a thunderstorm's outflow, common in arid regions, that can dramatically reduce visibility in minutes.

A line of thunderstorms, often producing damaging straight-line winds along its leading edge.

A concentrated, intense downdraft affecting a small area, capable of producing winds as strong as a tornado but without rotation.

A broader version of a microburst — a strong, damaging downdraft covering a wider area.

The ring of intense thunderstorms surrounding the calm eye of a hurricane, typically home to the storm's strongest winds.

Abnormal rise in sea level during a storm, caused primarily by wind pushing water onshore — often a hurricane's deadliest hazard.

Precipitation that evaporates before reaching the ground, often visible as streaks beneath a cloud base.

A dome-like bulge above a thunderstorm's anvil, indicating a particularly strong updraft.

The flat, spread-out top of a mature thunderstorm, formed where the updraft hits the stable stratosphere and spreads horizontally.

The rising and sinking currents of air within a thunderstorm that drive its growth, precipitation, and eventual decay.

A measure of local spin in the atmosphere — the underlying ingredient that, under the right conditions, can be stretched and tightened into a tornado.