Observations of the Formation and Early Evolution of Bow Echoes

Bow echoes addressed in the literature have been observed to develop from a number of different convective structures; most commonly squall lines and supercells. However, no quantitative investigations have been performed to determine the frequency of convective morphologies from which bow echoes most frequently form, or the atmospheric conditions which favor the development of bows within each type. In this study, almost 100 bow echoes (primarily from the Northern High Plains and the Mid-Mississippi Valley) are examined to determine and characterize the primary modes of bow echo development, and compare the modes of development between two climatologically different areas.

From the bow echoes which have been examined in detail so far (65), three distinct modes of bow echo development have been identified:

43% of the bows evolved from unorganized areas, or groups of cells. 32% of the bows evolved from squall lines. 25% of the bows evolved from supercells.

Close examination of the evolution of the bow echoes illustrated that 35% of all bow echoes were closely associated with a cell or storm merger, an observation not significantly addressed in current bow echo literature. For this presentation, the results of the analyses of bow echo evolution over the Northern High Plains and the Mid-Mississippi Valley will be summarized through conceptual models, with pertinent differences between these areas highlighted.