Interpretation of Doppler Weather Radar Displays of Midlatitude Mesoscale Convective Systems

Abstract

The utility of color displays of Doppler-radar data in revealing real-time kinematic information has been demonstrated in past studies, especially for extratropical cyclones and severe thunderstorms. Such displays can also indicate aspects of the circulation within a certain type of mesoscale convective system—the squall line with trailing “stratiform” rain. Displays from a single Doppler radar collected in two squall-line storms observed during the Oklahoma-Kansas PRE-STORM project conducted in May and June 1985 reveal mesoscale-flow patterns in the stratiform rain region of the squall line, such as front-to-rear storm-relative flow at upper levels, a subsiding storm-relative rear inflow at middle and low levels, and low-level divergent flow associated with strong mesoscale subsidence. “Dual-Doppler” analysis further illustrates these mesoscale-flow features and, in addition, shows the structure of the convective region within the squall line and a mesoscale vortex in the “stratiform” region trailing the line. A refined conceptual model of this type of mesoscale convective system is presented based on previous studies and observations reported here. Recognition of “single-Doppler-radar” patterns of the type described in this paper, together with awareness of the conceptual model, should aid in the identification and interpretation of this type of mesoscale system at future NEXRAD sites. The dual-Doppler results presented here further indicate the utility of multiple-Doppler observations of mesoscale convective systems in the STORM program.