A front is defined as the transition zone between two air masses of different density. The following symbols have been designated to represent various types of fronts on standardized weather maps.

Representation Line	Type of Front	Definition
	Cold Front	Transition zone where a cold air mass is replacing a warmer air mass.
	Warm Front	Transition zone where a warm air mass is replacing a cold air mass
	Stationary Front	When a warm or cold front stops moving, it becomes a stationary front
	Occluded Front	When a cold front catches up to a warm front.
	Instability (Squall) Line	Squall line storms consist of a line of storms with a continuous, well developed gust front at the leading edge of the line.
	Trough	When pressure height contours bend strongly to the south. Strong troughs are typically preceded by stormy weather and colder air at the surface.
	Ridge	When pressure height contours bend strongly to the north. Strong ridges are accompanied by warm and dry weather conditions at the surface.

A three digit frontal code is found along the side of the analyzed front. The first digit represents the type of front, the second the frontal intensity, and the third the frontal character. The three digits are preceded or followed by a bracket, [ ].