Isolated cells are individual thunderstorms that are not connected with steadier lighter rainfall, and the storms are scattered fairly far apart, so that they do not appear to be in a line, and they do not appear to be clustered together in a group. People affected by IC systems may experience a sudden thunderstorm with heavy rain while friends not far away stay sunny and dry.

Cluster of cells are individual thunderstorms that are not connected by lighter steadier rain, but the individual cells seem to exist in a group as opposed to a line or being randomly scattered around. People experiencing CC systems may be hit by several separate storms over a period of a few hours, with noticeable dry breaks in the weather between the storms.

Broken line thunderstorm systems consist of individual thunderstorm cells that are not connected by lighter steadier rainfall, but the individual storms are loosely organized into a line. People experiencing BL systems might experience a sudden thunderstorm with heavy rain but friends not far away might miss the storm and have sunny, dry weather. However, since the storms are in a line, they would probably be able to see storm clouds in two opposite directions. Usually these lines extend SW-NE or S-N.

Bow echoes are systems where the line of strongest thunderstorms takes on the shape of a bow or the backwards letter C, because the middle of the line moves faster than the rest of the line. This curved shape is important in identifying bow echoes. Sometimes, but not always, there will be lighter, steadier rainfall behind the heavier storms, so this lighter rain would be on the SW, W or NW sides of the system, with the heavier storms on the SE, E or NE side.

Trailing stratiform squall lines are systems where there is usually a long line of strong thunderstorms followed by a broad area of lighter, steadier rain. The heavy storms are therefore usually on the E, SE, or S side of the system with the lighter rains to the W, NW or N. People who are affected by TS systems first are hit with strong thunderstorms, lots of lightning, and very heavy rain, but after a little time, usually less than an hour, they experience just a light or moderate rainfall with a few claps of thunder.

Leading stratiform squall lines are systems where the light or moderate rain, and maybe a few small embedded heavier thunderstorms, are out in front of the main line of strong thunderstorms. Thus, the lighter rains are usually more on the E or NE side of the system with the main line of thunderstorms on the W or SW side of the system. People experiencing LS systems would have light or moderate rain develop, with perhaps some bursts of heavier rain with lightning, and after a period of time, perhaps an hour or two, they would experience heavier thunderstorms with much more lightning and much heavier rain.

Parallel stratiform squall lines are systems where the broader area of light rain is at the opposite end of the system from the line of strong storms, so that people who are hit by the strong thunderstorms do not really have much light rain afterwards, and people who experience the light rain often do not experience much of a thunderstorm. The heavy thunderstorms will usually be more on the south side of the system, with the lighter rain at the north.

A squall line with no stratiform rain will consist of a long line of fairly heavy thunderstorms, but with very little or no lighter rain extending out ahead of it, or behind it, or off to the north end. People who are hit by NS systems basically just have an intense period of heavy thunderstorm rain, which begins quickly and usually ends fairly quickly.

A nonlinear system is a group of thunderstorms or sometimes multiple groups of storms, all connected by lighter rainfall. The heavier storms are not really organized well into long lines. These systems can be rather large. People affected by NL systems will have alternating periods with heavy thunderstorm rains and lighter steadier rain, both of which can keep happening over and over during a period of several hours.

Mixed complex thunderstorm systems are usually systems that are very difficult to classify, because at the same moment, parts of the system behave like one of the other types, while other parts of the system behave like a different type. One example might be a portion of the system having a line of thunderstorms but that portion is connected to a broad area of lighter rain that also has several different clusters of heavy storms in it. People experiencing this type of system would likely have weather conditions similar to those experiencing an NL system --- that is, periods of very heavy rain with lots of lightning, followed by steady lighter rainfall, and then maybe again much heavier rain with thunderstorms.