A stationary front, also known as a quasi-stationary front, is a weather front or transition zone between two air masses, such as cold and warm air masses, when neither air mass is advancing into the other at a speed exceeding 5 knots at the ground surface
. It forms when a cold or warm front slows down or grows over time from underlying surface temperature differences, like a coastal front
. Key features of a stationary front include:
- Position : A stationary front usually remains in the same area for hours to days and may undulate as it transitions into a cold or warm front
- Winds : Winds on the cold air and warm air sides often flow nearly parallel to the stationary front and often in opposite directions along either side of the front
- Weather : A wide variety of weather may occur along a stationary front. If one or both air masses are humid enough, cloudy skies and prolonged precipitation are recurring, with storm trains or mesocyclone systems. When the warmer air mass is very moist, heavy or extreme rain or snow can occur
- Formation : A stationary front may form when a cold or warm front slows down or grows over time from underlying surface temperature differences when there is little air, like a coastal front
- Dissipation : Stationary fronts may dissipate after several days or devolve into shear lines
A stationary front is similar to a warm front, with warm air present behind it (to its south) and cool air ahead of it (to its north)
. However, while a warm front shows movement, a stationary front shows little or no movement as the cooler, more dense air remains in tact and does not retreat
