 The convection then moves east and equatorward into the warm sector, parallel to low-level thickness lines.When the convection is strong and linear or curved, the MCS is called a squall line, with the feature placed at the leading edge where the significant wind shifts and pressure rises.Even weaker and less organized areas of thunderstorms will lead to locally cooler air and higher pressures, and outflow boundaries exist ahead of this type of activity, "SQLN" or "SQUALL LINE", while outflow boundaries are depicted as troughs with a label of "OUTFLOW BOUNDARY" or "OUTFLOW BNDRY".