Backdoor Cold Front

Source: Wikipedia

NOAA defines a backdoor cold front as "a cold front moving south or southwest along the Atlantic seaboard and Great Lakes; these are especially common during the spring months". However, the term is frequently used by meteorologists in the Southwest.

A cold front, typically, approaches from the north, northwest or west, and its wind direction will generally be from those directions (since most weather moves west to east). This does not happen with a backdoor cold front. Rather, a back door cold front arrives from an opposite direction, the east or northeast. The front is termed "backdoor" because it arrives from the east, meaning it originates from the opposite direction of a typical cold front and therefore comes through the region's "back door."

Below is a depiction of a regular cold front and a backdoor cold front.