Weather Window | Cats run on Tahoe snow |

Weather Window | Cats run on Tahoe snow

Courtesy Mark McLaughlin

Editor’s note: This is part two in a two part series. For the first installment, visit, click here.

Over-snow vehicles are ubiquitous today in Tahoe’s mountain country. They range from high powered “sleds,” as modern snowmobiles are commonly called, to sophisticated snow cats that level moguls and groom a resort’s snow surface into ribbons of corduroy. Today’s snowmobiles and snow cats are highly advanced, but their technology is still based on early prototype models that manufacturers spent decades developing, including vehicles built for deployment to some of the harshest climates in the world.

Some of the earliest over-snow vehicle testing took place in our own backyard at the Central Sierra Snow Laboratory in Soda Springs near Donner Pass. In 1943, the U.S. Weather Bureau assigned its lead physicist, Dr. Robert W. Gerdel, to work with Dr. James E. Church from the University of Nevada, Reno. Dr. Church was a UNR professor who had developed a snow surveying system in the Lake Tahoe Basin to measure snowpack water content in order to predict spring runoff and help avoid damaging floods on the Truckee River. The two men briefly worked side-by-side at the U.S. Weather Bureau/University of Nevada research station, a small cabin and garage near the Soda Springs Hotel, but orders came from Washington D.C. for Dr. Gerdel to establish a large, federally funded snow lab near Donner Pass where the country’s top scientists could conduct experiments and study snowpack hydrology.

Lucky Tucker

As luck would have it, Emmitt Tucker, inventor of the legendary Tucker Sno-Cat, had chosen Donner Pass to test the feasibility of his new snow-tractor machines. Dr. Church managed to purchase one of the first models for his work, a two-track runabout (Church did not ski). Powered by a small two-cycle, air-cooled engine, Tucker’s first vehicles relied on a dual steel track (later converted to four track) for propulsion with two wide ski-shaped blades up front for turning and maneuverability.

Once the new Central Sierra Snow Lab was built and staffed (1946), the scientists there, who previously had to pack in all their equipment on skis or snowshoes, were more than happy to put Tucker’s Sno-Cat to the test. The machines proved invaluable for hauling gear to remote locations and made snow surveying much easier and quicker. Early in World War II, the U.S. military had requested the development of over-snow vehicles for troop deployment and innovative snow cats were produced by various contractors, including the Weasel, which could carry up to six passengers. (In the 1940s, Squaw Valley developer Wayne Poulsen employed an Army surplus Weasel to pull friends, guests, and potential resort investors on skis across the valley floor.) Private companies as well as various college engineering departments contributed to this rapid development of these snow cats, with virtually all the machines propelled by steel-cleated belts.

Sno-Ball’s chance in Idaho

In Idaho during the 1950s, a Boise company began producing modified automobiles for snow surveying activities. Known as the KAM Sno-Ball, any conventional car could be converted to an over-snow vehicle by removing the running gear, mounting the chassis over the tracks, and connecting the drive line to the track assembly. Various models of Jeeps and Chevrolet pickups were converted to over-snow vehicles this way. The last models of the Sno-Ball machine were not converted automobiles at all, but were constructed as complete units with aluminum custom cabs and aluminum framing. These rigs were used extensively in Idaho for nearly a decade. Ultimately, the Soil Conservation Service in Idaho switched over to single-belt track vehicles (snowmobiles) for snow surveying activities, rigs which proved extremely economical and dependable in the backcountry.

Flying over land

Not all of the over-snow vehicles were based on a track design. In open untimbered or sparsely forested areas, the so-called Snow Plane became a common means of winter travel. Designs varied considerably, but all of these propeller-driven vehicles were powered by an airplane engine mounted behind the driver’s cab or cockpit and used propeller blades to push the machine forward. These prop-driven air sleds were very fast and worked well in open spaces like the upper Midwest, but they were ill-suited to steep slopes or densely forested areas such as are found in the Sierra Nevada.

By the late 1950s, government engineers moved their proving grounds to the inhospitable Arctic regions of Greenland and northern Canada to push the final frontier of over-snow transportation capabilities. Large wheeled vehicles were tried with tires filled with liquid fuel to avoid hauling heavy sleds behind with loaded with drums of diesel. Ultimately, aircraft were tested with skis instead of wheels, which opened up the farthest reaches of the Arctic hinterlands.

Snow tractor and snowmobile development has produced modern vehicles that barely resemble these earliest machines, but the mechanical concepts for today’s rigs are primarily based on the first efforts to develop powered over-snow transportation.

Tahoe historian Mark McLaughlin is a nationally published author and professional speaker. His award-winning books are available at local stores or at You can reach him at Check out Mark’s new blog at

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