A snowy December in Las Vegas, Nevada.(OUTSTANDING STORMS OF THE MONTH)(Report)

After one of the warmest autumns on record in the Mojave Desert, a drastic shift in the upper air pattern took place in mid-December 2008 as a deep, upper-level trough established itself across the western United States. A series of upper-level disturbances and storm systems moving through the base of the trough resulted in unusual low elevation snow in the Mojave Desert during a roughly two week period.

On December 14th, an upper-level disturbance moving across southern portions of California and Nevada spread moisture into a chilly air mass that was in place across the Mojave Desert. Precipitation began in the lower elevations of the Mojave Desert on the morning of the 15th with snow levels around 3000 feet, however, as precipitation continued and the atmosphere was able to cool, snow levels began to lower to around 2500 feet by the late morning hours. In Las Vegas, a mix of rain and snow occurred at McCarran International Airport, making it the first time snow had been officially observed here since December 22, 2006. Although snow only mixed with rain for about an hour at the airport and never did accumulate here, higher elevations on the west and northwest side of the city (generally above 2600 feet) saw accumulating snowfall for several hours. Between 2 and 5 inches of snow fell in these areas, with even some less traveled roads and bridges in these areas seeing snow stick to them. Over 20 inches of snow fell in the Spring Mountains just west of Las Vegas above 7600 feet in elevation.

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Just two days later, an upper-level low moving through the base of the trough tracked inland from southern California bringing another round of precipitation to the Mojave Desert on December 17th. Moisture associated with the low moved into a low-level cold air mass, resulting in snow falling once again in the lower elevations of the Mojave Desert, with snow levels around 2000 feet. This storm finally moved east allowing precipitation to end on the morning of the 18th. As the air mass ...