Definition
A thunderstorm composed of a cluster of convective cells in different stages of development, where new cells continually form along the gust front of older cells, allowing the storm system as a whole to persist and travel for several hours even though each individual cell lasts only 20 to 30 minutes.
Plain English
A thunderstorm made up of several smaller storm cells grouped together. As old cells weaken, new ones build up next to them, so the overall storm keeps going much longer than any single cell.
Context Anchor
Pilots may hear or see this term in weather briefings, radar summaries, convective outlooks, or discussions of thunderstorm hazards along a route.
Derivation
Multi-cell literally means 'many cells.' In meteorology, a 'cell' is a single self-contained pocket of rising and falling air that drives one thunderstorm. Calling a storm multi-cell signals that it is not one isolated cell but a group acting together.
Why Pilots Care
Multi-cell thunderstorms can produce severe turbulence, hail, strong winds, and lightning, posing significant hazards to aircraft.
Grounding Statement
On radar, a multi-cell thunderstorm may show one intense area weakening while a nearby area grows stronger.
Intuition Check
Do not assume “multi-cell” means several unrelated thunderstorms. Here it means one thunderstorm group made of several connected storm cells.
Example Sentence 1
The briefer warned that a multi-cell thunderstorm complex was moving across the route, and recommended a wide deviation to the south.
Example Sentence 2
Multi-cell thunderstorms often form in lines ahead of a cold front, requiring careful route planning.