Narrow streaks of "straight-line" wind damage: Do tornadoes or microbursts produce them?

Straight-line wind damage is commonly produced by severe storms ranging from isolated supercell storms to squall lines. It is not uncommon for damage patterns from these phenomena to exhibit large length-to-width aspect ratios, in which the width is on the order of several hundred meters or less. This paper examines this question from several viewpoints. First we document a subset of such cases appearing in storm data that are classified as damaging wind. Second, several case studies of such storms are presented which show that such damage is associated with mesocyclones, suggesting that damage streaks in those cases were most likely produced by relatively weak tornadoes embedded within fast-moving parent storm cells and squall lines. Third, we support the hypothesis that such damage patterns are tornadic using theoretical arguments based on measurements of the storm environment in the cases with adequate documentation. Finally, we examine this problem with a very simple model of a vortex embedded within a background uniform flow field. The sum of translational and rotational motions in such cases may produce a narrow swath of damage in the narrow regions where these two components are additive. One implication is that short-lived vortices (i.e. weak tornadoes) are more common than the SPC tornado data base would suggest. It is proposed that the aspect ratio of the damage pattern be used as a strong constraint in differentiating the classification of damage between straight-line and tornadic.