Codex · Cloud
Mammatus
Pouch-shaped clouds hanging below the anvil of a thunderstorm. They are striking at sunset but are not a sign that a tornado is forming.
How to spot it
Smooth, rounded lobes dangling from the underside of the anvil, best seen when low sun lights them from the side.
On radar
Not detectable on radar.
Safety
They can follow severe weather but mean nothing on their own.
Related
Last reviewed 2 November 2026