MEMPHIS, Tenn. (WMC) -Our weather forecast has been rather unsettled and we have had this pattern before. The culprit for the wetter pattern is a stationary front. A stationary front forms when a cold front or warm front stops moving. This occurs when two air masses are pushing against each other but neither is powerful enough to move the other. In addition of the wind is blowing parallel to the front instead of perpendicular, this can also help a front stay parked across the area.
A stationary front may stay across an area for days. If the wind direction changes the front will start moving again, becoming either a cold or warm front. Or the front may break apart altogether.
Because a stationary front represents two air masses, there are often differences in air temperature and differences in wind on opposite sides of it. The weather is often cloudy along a stationary front and rain or snow often falls, especially if the front is in an area where the pressure is low
When you look at the weather map, a stationary front is represented as red semi-circles and blue triangles like on the map below. The blue triangles will point in one direction representative of the cold air and the warm front represented by the red semi-circles represents the warmer air.
Sometimes a stationary fronts could produce severe weather. There could be a band of thunderstorms or heavy rain may be pushed down from the front, which could lead to flooding. On occasion a derecho is a fast-moving area of strong straight-line winds that are sometimes produced along stationary fronts. Downdrafts from frontal thunderstorms may shunt high winds downward off the jet stream to birth derechos, often bowed outward and fast-advancing.