Cold Front - Characteristics of Boundaries Around An Extratropical Cyclone

Characteristics of Boundaries Around An Extratropical Cyclone

Cold fronts form when a cooler air mass moves into an area of warmer air in the wake of a developing extratropical cyclone. The warmer air interacts with the cooler air mass along the boundary, and usually produces precipitation. Cold fronts often follow a warm front or squall line. Very commonly, cold fronts have a warm front that is ahead of the cold front but with a perpendicular orientation. In areas where cold fronts catch up to the warm front, the occluded front develops. Occluded fronts have an area of warm air aloft. When such a feature forms poleward of an extratropical cyclone, it is known as a trowal, which is short for TRough Of Warm Air aLoft. A cold front is considered a warm front if it begins to retreat ahead of the next extratropical cyclone along the frontal boundary, and called a stationary front if it stalls.