Initiation and Development of a Long-Lived, High Plains Squall Line

摘要

A non-severe squall line that developed on 21 June 1993 along the northernfoothills of the Colorado Rocky Mountains is analyzed using a series of triple-Doppler analyses and compared to the conceptual model for a typical squall line with trailing stratiform rain area. Based on simulations, some modelers hypothesize that the observed features can be explained through a balance between the circulations induced by the low-level ambient vertical shear of the horizontal wind ahead of the line and that induced by the horizontal buoyancy gradient along the leading edge of the convectively generated cold pool. These circulations dictate the orientation of the updraft which is key to understanding the structure and longevity of squall lines. Although this balance may be significant in some cases, observations in this case suggest that in differing environments, the hypothesis may need to be expanded. (MM).