| description abstract | The development of mesoscale lines of nonsevere convection in Oklahoma during the spring is discussed. This documentation complements the study by Bluestein and Jain of severe, mesoscale convective-fine development. Three major classes of squall line formation,broken line, back building. and broken areal, are identified from analyses of an 11-year period of reflectivity data from the National Severe Storms Laboratory's 10-cm radar in Norman, Oklahoma. The environment for each of the types of squall-line development was determined from data store the standard National Weather Service surface and upper-air networks and from special rawinsonde launches. The convective available potential energy for, each type of nonsevere squall-line development is significantly less than that for severe squall-line development, while the convective inhibition is greater. Cells within nonsevere squall lines are characterized by low relative helicity. The environmental vertical shear associated with all types of nonsevere squall-line development is less than that associated with supercells and severe, back-building squall lines. Most fines were oriented approximately 50° to the left of the pressure-weighted vertical shear vector in the troposphere, along the shear vector in the lowest 0.6 km, and normal to the shear in the lower portion of the middle troposphere. | |
