Normally expect the shear line to lie parallel to the surface front as the air mass moves over the continents (particularly true over North America).  As the front moves into subtropical areas (generally north of 35S over South America, Gulf of Mexico over North America) the shear line races ahead of the front.
	Characteristics distinguishing a front include a pressure trough, a change in wind direction, moisture discontinuity, and certain characteristic cloud and precipitation forms.