1955 Scottsbluff tornado

Tornado summary

The first confirmed sighting of the tornado on the ground was from a resident of Henry, who saw the tornado first form as a waterspout west of the town. The tornado picked up water as it crossed over the North Platte River, forming a visible condensation funnel made of water particles. At this point, the tornado was moving directly to the east, which was confirmed by at least one other observer who saw the tornado form. As it hit Henry, the tornado produced minor damage to cottonwood trees.

In an October 1955 Publication of the Monthly Weather Review, meteorologist Edgar L. Van Tassel wrote that "it appeared as though a giant hand had reached down grasping the tree tops and pulled upward until the roots were freed from the soil and then the trees were dropped", noting damage in Henry. For approximately 3 miles (4.8 km) to the east of Henry, the tornado produced no discernible ground damage, before deroofing a farmhouse as it moved into a valley. Two people were in the house, both of whom survived the event.

Shortly after impacting the farmhouse, it was noted that the tornado's damage path "skipped" and was discontinuous. Seven visible funnel clouds were observed as the tornado was in this phase, although the tornado itself lost the condensation funnel it had formed when moving over the river earlier along its path. The tornado curved to the southeast and then abruptly changed its direction, moving directly east. The tornado was observed firmly on the ground 2 miles (3.2 km) west of Mitchell, where it stayed on the ground until dissipating later.

Prior to reaching the ground, uncertainty existed around whether the tornado was on the ground due to the lack of a continuous path, although the path past Mitchell was confirmed by residents who observed and documented the tornado as it moved by. The tornado exhibited abrupt changes in direction as it neared the town of Scottsbluff, where it turned to the south and curved east several times. It tracked over rural areas for the majority of its life, although it directly hit one housing project containing seventeen units; both fatalities recorded from the tornado took place at this location. One death took place in a vehicle and the other occurred when a large vehicle landed on a boy as he was taking shelter in a ditch.

The tornado destroyed a total of 146 structures and injured 40 others, along a 40 mi (64 km) path spanning around two hours on the ground. Damage from the tornado received an F4 rating on the Fujita scale.

Documentation

At the time of the event, the tornado was the most well-documented in history. Over 90 black-and-white photos and ten videos were taken by witnesses along the tornado's path. Using photographs of the tornado, meteorologists were able to calculate precise measurements of the tornado's height and width. The tornado was also visible on modified AN/APS-2 radars that were used by the Weather Bureau Office (WBO), where eight photos were taken of the storm's structure. A defined hook echo is visible in the radar photographs taken by the WBO; the tornado passed less than 1 mile (1.6 kilometres) to the south of the radar site, cutting off power to the site and preventing further radar observations as it moved to the southeast.

Cycloidal marks

Northeast of Scottsbluff, near the end of the tornado's path, cycloidal debris marks were documented in aerial shots after the event. At the time, cycloidal marks were an unknown phenomenon, and the marks left by the Scottsbluff tornado were the subject of a detailed study. The cycloidal marks, in conjunction with radar, were used to determine the forward speed of the tornado and showed the tornado's abrupt movements.

Citations and sources