Shearlines vs. Fronts
•Shear Lines: are associated with wind shifts (direction and speed).
–A line or narrow zone across which there is an abrupt change in the horizontal wind component parallel to this line
•A line of maximum horizontal wind shear.
•An area of directional wind confluence along the tail end of a surface front.
•Lacks the baroclinicity/density discontinuity of surface fronts
•Fronts:  The interface or transition zone between two air masses of different density.
–Density depends on temperature and moisture content
–Fronts either lie along shear lines or can lag behind them.
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.