History and Measurement of the Two Major Scottsbluff Tornadoes of 27 June 1955

Fairly complete tornado life histories have been synthesized from over 100 still photographs and eight strips of color movie film taken of two tornadoes near Scottsbluff, Nebraska, in June 1955. Funnel height and width measurements have been made from the still photographs, and translational speed has been determined at a few points and rotational speed at one point from the movies. Evidence of downward air motion in the vicinity of the second tornado was found, and in one instance cloud elements acting as air parcel tracers demonstrated the downward motion. Outline tracings of photographs illustrating significant size- and shape-changes are presented and measurements of interest are attached. All drawings are scaled to give the effect of observing the tornadoes from the same distance. Time lapse between the significant stages of each tornado has been estimated. Some definite relationships are shown to exist between the tornado height and width, and differences between the two tornadoes in time trends of the several dimensions are also shown. A model of tornado evolution is proposed.