Stationary front

Stationary fronts[1] may also change into a cold or warm front and may form one or more extratropical or mid-latitude cyclone[2] s at the surface when atmospheric waves aloft are fiercer, cold or warm air masses advance fast enough into other air masses at the surface.

A warm front may bring persistent precipitation, fog, and cloudy skies, signaling the start of wet weather.

Sleet forms when a warm front meets an extremely cold air mass.

When a cold front moves into an area, it brings with it a drop in temperatures, which can lead to thunderstorms.

If one or both air masses are humid enough, cloudy skies and prolonged precipitation are recurring, with storm trains or mesocyclone systems.