On This Day in 1989: Rare January Tornado Strikes in Utah

A rare, first-ever recorded tornado touchdown in January was so brief it generated most of its damage in a 300-square foot area in Sandy, Utah, a suburb south of Salt Lake City.

Everything about this reported tornado touchdown to the National Weather Service office in Salt Lake City on January 10, 1989, at 9:15 a.m. MST by KSL radio was puzzling. From a meteorological standpoint, there hadn’t been support for thunderstorm development, never mind a tornado. Until this report, there had never been a documented tornado in Utah in January. A second call a couple minutes later from the same radio station, however, indicated there was damage to 10 homes. At this point, given the National Weather Service office was so close, a “survey team” was dispatched to look at the damage.

At about 11 a.m. MST, a group consisting of the meteorologist in-charge, deputy meteorologist in-charge, a lead forecaster and a meteorological intern left the office.

Geographically, the area the tornado occurred is just north of a low range of mountains but where a break exists through which the Jordan River flows into the Salt Lake Valley. Locally, the break is referred to as the “Point of the Mountain.” Often, southwesterly flow occurs here and can be enhanced, and that indeed is what was happening well ahead of a cold front that day.

A review of meteorological data from an early-morning balloon release didn’t support thunder. An ARTCC radar didn’t pick up any echoes and another radar, Hill AFB FPQ-21, picked up on activity to the north and west but ground clutter and terrain blocked echoes from being seen in the southeastern part of the Salt Lake Valley. While radar didn’t detect echo tops higher than 20,000 feet, 25 minutes after the event, observations taken while virga was within the Sandy, Utah, area had tops near 25,000 feet. This indicated the atmosphere might have briefly become moderately unstable. Lightning nor thunder still hadn’t been detected.

Complicating matters even more was the tornado debris pattern. A line of virga, channeled southwest to northeast, moved across the valley from northwest to southeast. A forecaster driving to work from the south reported the damage started over the southeast part of the valley. The survey team found that the damage pattern occurred from southeast to northwest, which was perpendicular to the southwesterly flow in the area.

It is theorized the tornado could have formed due to a mechanical or terrain-induced eddy, or possibly a convergence boundary associated with the line of virga. As the virga moved across this vortex, it’s possible it may have significantly strengthened briefly. This would also explain the northward movement in the low level flow rather than the way the line was moving, east or southeast. The short duration and link between vortex and cell would also seem to fit the non-supercell tornado theory remarkably well too.

Three roofs suffered structural damage and three more had sections of asphalt shingles ripped off. A camper bolted down on four sides was lifted off a driveway and deposited in the street. A corner of one roof was taken off a home. Another home had a 4-foot by 8-foot hole in its roof, and the prefabricated chimney of a third home was demolished. The main damage was limited to a block with the heaviest damage occurring in less than one-half block.
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Story Image: Tornado damage is seen. (via Shutterstock)