Sunrise light on a grove of tufa towers emerging from the water of Mono Lake with soft green and dusty-red wild grasses in the foreground, Canada geese in the shallow water with reflections of the rocky towers, and desert hills in the distance.

Precipitation has reached the seasonal average

Late afternoon sunshine lights up Mono Lake's islands. Photo by Elin Ljung.

It was a remarkable December for precipitation, as well as snowfall at the higher elevations. Following a rainy October and a snowy November, December 2010 brought most areas of the Mono Basin and Owens Valley very close to seasonal average precipitation and snowfall—with the majority of the wet season left to go!

Precipitation
Statewide, December precipitation was 214% of average. In Lee Vining (click here for monthly and annual weather summaries) we measured 8.01″ of precipitation in December—380% of average! Most of this fell during a remarkable storm on December 17–20. This is essentially a tie with the previous December record of 8.02″ in 2005. It was also the warmest December since 2005, meaning a lot of that precipitation fell as rain and wet snow below 7,500′—although in Lee Vining we still measured 29.7 inches of snow, more than double the December average snowfall. The October–December precipitation total was 13.85″, or 312% of average, the wettest year for those months since 14.19 inches of precipitation fell in October–December 1996. After adding in the New Year’s weekend storm in January, Lee Vining’s seasonal precipitation total since October 1st stands at 14.45 inches, or 105% of average. And most of the wet season is still ahead!

Five miles south of Lee Vining but farther from the Sierra and thus slightly drier, Cain Ranch had 239% of average December precipitation, which makes this the wettest December since 1977. Cain Ranch’s October–December precipitation total was 225% of average—the fourth wettest such period since 1931. This adds up to 74% of the annual total already measured with nine months left to go in the season.

Precipitation at Ellery Lake, ten miles west of Lee Vining and more representative of the upper watershed, was 164% of average for December. October–December precipitation was  181% of average to date and 59% of the annual average.

Mono Lake
Mono Lake rose 0.4 feet in December to 6381.9 feet above sea level, gaining back half of the elevation lost since August. This is a similar rise as seen in Decembers 1996 and 2005. On average, Mono Lake rises 0.6 feet between January 1 and April 1, which means when combined with the probable springtime rise, we are likely to see the lake reach the 6383-foot elevation next summer.  Click here for the current level.

Snowpack
Gem Pass snow water content is currently 30.17″ or 95% of the April 1st average. Snow water content at Mammoth Pass so far this winter is keeping up with the winter of 1982–83, the wettest year on record. Tuolumne Meadows is reporting over 80 inches of snow on the ground, and Tioga Pass is reporting 10 feet. Click here for the latest snow pillow reports.

What’s next?
For the first time since mid-November, we finally have a dry week ahead. The National Weather Service is even saying that any fog will be patchy, so we will hopefully see the sun most of the week. The Climate Prediction Center‘s 30 day outlook is for a slight chance of a wetter than average January. The three-month outlook is for equal chances of above- or below-average precipitation. It would have to be quite dry to end up with below-average snowpack on April 1st. We are almost assured of an above-average runoff year, and a rising Mono Lake!