A thunderstorm cell is a single convective unit with its own updraft, downdraft, and precipitation core that goes through a recognizable growth, mature, and decay life cycle. On radar it shows up as a local maximum in reflectivity that grows and then dissipates.
The life cycle of a cell
NSSL describes three stages. In the developing stage, a towering cumulus is pushed upward by an updraft, with little rain and occasional lightning. In the mature stage, the updraft continues to feed the storm while precipitation drives a downdraft, producing a gust front and the peak in hail, wind, and lightning risk. In the dissipating stage, precipitation dominates, outflow cuts off the warm inflow, and the cell decays.
The AMS Glossary defines a cell as a local maximum in radar reflectivity that undergoes a life cycle of growth and decay, with the rising reflectivity indicating the updraft and the descending portion indicating the precipitation downdraft. Ordinary cells typically persist for 20 to 30 minutes.
How cells combine into larger storms
Individual cells rarely produce all the severe weather forecasters warn on. More often, cells combine into multicell clusters, squall lines, or mesoscale convective systems, each producing its own new cells along shared boundaries and outflow features.
In a supercell, the cell itself is unusually long-lived. Strong deep-layer vertical wind shear tilts the updraft away from the downdraft so the two do not interfere, and a single quasi-steady cell can persist for hours rather than tens of minutes.
How forecasters use it operationally
Cell tracking algorithms identify reflectivity maxima, track them from volume to volume, and estimate motion, growth rate, and echo-top height. Those tracks feed storm-attribute tables that forecasters use to prioritize which cells to interrogate first during a busy severe-weather event.
Because cell tracking depends on identifying a single core within a reflectivity field, mergers, splits, and closely spaced cores routinely challenge the algorithms. A newly split right-mover, for example, may briefly disappear from tracking before it is reidentified as its own cell. Interpretation of cell attributes therefore always benefits from a look at the raw radar and at neighboring cells.