Truckee one of nation’s coldest towns in 1998 | SierraSun.com

Truckee one of nation’s coldest towns in 1998

MARK McLAUGHLIN, Special to the Sun

After a four-year hiatus, the town of Truckee is back in the race.In the annual battle to determine America’s coldest city, Truckee ranked fourth in 1998. Despite last year’s powerful El Nino which helped make 1998 one of the warmest years of record throughout the United States, Truckee recorded the nation’s chilliest daily temperature 20 times.Truckee hasn’t placed in the top five cold spot rankings since 1994, when it took the gold with an impressive 63 registered national lows. The data are compiled by Professor David Hickcox, a geographer at Ohio Wesleyan University. Utilizing National Weather Service reports, Dr. Hickcox only counts stations in permanently inhabited villages, towns and cities.Alaska and Hawaii are excluded, as well as extreme locations such as Death Valley.Altitude and topography are two primary factors in Truckee’s status as one of the coldest cities in the nation. Located at the Truckee-Tahoe Airport, the official thermometer is situated at 5,900 feet above sea level. Since the atmosphere cools at an average rate of 3.3 degrees for every 1,000 feet gained in elevation, Truckee’s averagelow temperatures are nearly 20 degrees cooler than sea level locations.Topography also plays a vital role in this equation. The mountain slopes surrounding the airport are often snow-covered, and as air comes into contact with the snow, it cools and sinks. This dense air mass settles down into the airport basin, creating a chilled micro-climate. The fact that the airport thermometer is located within this cold air drainage definitely contributes to Truckee’s nippy weather.These factors contribute to Truckee’s consistently lower temperatures during spring and fall seasons when the area records the bulk of its “coldest in the nation” readings. High pressure tends to dominate West Coast weather during the summer and autumn months. This large semi-stationary air mass forces vigorous cold fronts to track far to the north, providing California with a sunny, dry climate. The air pressing down on the Sierra Nevada during these dry summer months contains very little moisture. Without much humidity in the air, there is nothing to trap and hold the sun’s heat. As soon as the sun sets, temperatures plummet.The same principle applies to deserts, known for scorching heat during the day followed by frigid nights. This high pressure cell also fosters calm, windless evenings in the Sierra, which inhibits atmospheric mixing. Without breezes to stir up the night air, the dense cooler air settles to the ground with warmer air above. This nocturnal inversion, known as such because air aloft is normally colder than at the surface, keeps Truckee’s average minimal summer temperatures hovering in the upper thirties.In addition, Truckee’s typical cloud-free evening sky allow accumulated daytime heat to escape rapidly back into the atmosphere, a dynamic known as radiational cooling. Another component that contributes to extreme temperature fluctuations is distance from any large body of water. Oceans and large lakes, like Tahoe, heat up and cool off slowly, while land surfaces gain and lose heat much more rapidly. Truckee’s afternoon temperatures are usually much higher than those recorded near Lake Tahoe, but at night plunge quickly, and are often 10 to 15 degrees colder by sunrise. According to Hickcox it is common for Arizona, California, and Nevada to record both national highs and lows.Truckee’s temperature bottomed out at 30 degrees last July 14th , rather mild but still the lowest recorded in the nation for the whole month. Just 72 hours later the thermometer at Death Valley spiked at a sweltering 129 degrees, the highest recorded anywhere last year.In 1998 California had both the national high and low on the same day five times. Just for the record, out of the last 15 years, Truckee has made the top five rankings 11 times.And three of those years, 1991,1993 and 1994, Truckee claimed the dubious honor of coldest spot in the nation, excluding Alaska. Weather Historian Mark McLaughlin’s books Sierra Stories: True Tales of Tahoe, Vol. 1 & 2 are available at local bookstores.