2007 could be the second-driest on record
With the snowpack at 4 percent of average as of Thursday and Lake Tahoe 2 feet lower than last year at this time, 2007 is in the running to be the second-driest winter for weather records.
However, weather in the Sierra always is a wild ride.
“We’re definitely way, way down. If December got zero precipitation, which would really be amazing in Tahoe, this would be the second-driest year in 70 years (for Reno),” said Jim Ashby, a climatologist with the Western Regional Climate Center at the Desert Research Institute in Reno.
The driest year was 1976, with 9.34 inches of precipitation recorded at Lake Tahoe’s only outlet, the Truckee River in Tahoe City. Right now, 14.71 inches have been recorded in Tahoe City for the year – the long-term average is 32.6 inches of precipitation.
But as weather watchers warn, you never know in the Sierra.
The average precipitation in Tahoe City for December is 5.66 inches; however, in 1989, there was none, and in 1964, there was 27.55 inches in the wettest month of Tahoe City data going back 94 years.
“The point is, it could happen; it could be a monster month,” Ashby said.
But his colleague at the Western Regional Climate Center, interim director Kelly Redmond, says it is not likely.
“The types of patterns we are in is not conducive to bringing moisture to the Sierra,” Redmond said.
A strong La Niña is sending moisture north of California, or spinning it inland toward Arizona. In La Niña years, Redmond said, the farther south one goes, the drier it gets.
“The guts of winter is December, January and February,” he said.
The National Oceanic and Atmospheric Administration released its three-month forecast for the western United States on Nov. 15, showing Southern California as drier than normal, with Tahoe about 33 percent drier than normal.
“It’s not looking good at the moment. There are no strong systems moving in to jolt us out of the doldrums,” Redmond said.
The start to the water year, which begins Oct. 1, was helped by storms in October, but only 17 percent of average precipitation fell in November.
“October contributed a little more than its share. November is falling down on the job. It may get its license revoked. We’re getting rid of it, and we’ll try again in December,” Redmond joked.
He said northern Nevada and California residents should be more worried about the lack of snowpack than precipitation, because that is drinking water for next summer.
Ashby said “there’s no doubt” we’re in a drought.
“As far as the numbers are concerned, yeah, but to me, we’re always in a drought, even in a normal year,” Ashby said, adding that Reno only averages 8 inches of rainfall per year and has only 2.86 inches of precipitation now.
However, drought is hard to quantify, Redmond explained.
“Drought is a touchy word in California. There’s drought with a little ‘d’ and drought with a big ‘D,’ which is declared by the California Department of Water Resources,” Redmond said. At that point, water is cut off to customers.
Jay Lund, a University of California, Davis, professor and expert in water systems, said that “a drought is if you’re not getting as much water as you like.”
“For this climate, you don’t know if you’re in a drought for a couple of years. People sometimes talk about it being a creeping disaster,” Lund said.
He said official droughts were in 1928-34, 1976-77 and 1988-92.
Lund will be speaking about water management at 5:30 p.m. Wednesday at the UC Davis Tahoe Environmental Research Center in Incline Village.
“I think people are starting to wonder if this is the beginning of a drought,” Lund said.
Last year was a dry year, but the impacts were not felt because the 2005-06 year was such a high water year. If this year is dry, the back-to-back dry years will make an impact.
Federal Watermaster Garry Stone said the reservoirs in the Truckee River water system are lower than normal, except for Stampede, and Lake Tahoe will continue to drop if no storms are in sight. This week, at 6,224.98 elevation feet, Lake Tahoe was 2.68 feet lower than last year at this time.
“We had a reserve and it got pretty well used up. (The reservoirs) are going into the winter in a diminished capacity,” Redmond said.
Yet, the Sierra’s reputation for the unpredictable could predictably bode well.
“With a La Niña, there is not a strong tendency to be wet or dry. But the only thing we can say with a little bit more certainty is that there is a somewhat higher chance of major events,” Redmond said. “The big floods in the Sierra are from La Niñas. Four out of the top five floods have been La Nina.”
Two of the more recent La Niña flooding events were 1985-86 and 1996-97.
There are some, however, who no longer wait for Mother Nature’s whims. Sierra ski resorts now rely on snowmaking for their winter coverage.
“We don’t get too worried for a drier winter, as long as the temperatures stay cool, we make snow,” said Kayla Anderson, marketing coordinator at Diamond Peak Ski Area.