A High Plains Squall Line Associated with Severe Surface Winds

The characteristics of a severe squall line are examined using data acquired from the 1981 Cooperative Convective Precipitation Experiment (CCOPE). The case is unusual in that the squall line was decoupled from an immediate, surface-based inflow source due to a mesoβ-scale (20–200 km) outflow pool produced by a separate mesoscale convective system. Both systems participated in the development of a mesoscale convective complex which subsequently produced sustained, severe surface winds throughout its entire life cycle. Despite the absolutely stable, presquall atmospheric boundary layer, the squall line produced radar reflectivity values of 70 dBZ and storm-induced outflow of 30 m s−1. Aircraft soundings in the presquall environment suggest the storm was sustained by an elevated layer of high-valued θc air overriding the cold dome produced by the developing MCC. The strongest surface winds were located upshear from the convective line and consisted of a northerly (alongline) component. Because the ...