Let it snow
Survey and sensors show snowpack below average
An overnight storm that ended Thursday morning brought one-tenth to twotenths of an inch of rain to the Mother Lode, while a snow survey this week showed snowpack and snow water equivalents were below average this winter season.
There are more weak storms on the way this weekend, and a potentially stronger storm coming Sunday and Monday, Craig Shoemaker, a National Weather Service meteorologist in Sacramento, said Thursday in a phone interview.
The storms forecast Friday night, then Saturday and Sunday, are expected to be most active north of Lake Tahoe and Interstate 80, which means rain and snow from those systems may be very light in Calaveras and Tuolumne counties, Shoemaker said.
“Sunday night and Monday is the bigger storm for Tuolumne County,” Shoemaker said. “That could be one of the bigger storms of the season. May as much as an inch of rain, a foot or two of snow. Monday especially.”
The approaching storms are coming off the eastern Pacific Ocean, not the Gulf of Alaska, and longer-term there appears to be more potential storm activity for the first two weeks of January, Shoemaker said.
Significant snowfall is possible over mountain passes Sunday evening into Monday when that stronger winter storm is expected. Another potentially strong winter storm is forecast for late Tuesday into Wednesday. Specific details are uncertain.
The storm that began late Wednesday and ended Thursday morning brought 0.13 inch of rain to Sonora, 0.17 inch to Columbia, about 0.09 inch to Angels Camp, 0.20 inch to New Melones, and 0.18 inch to Pinecrest, according to the California Nevada River Forecast Center.
As of Thursday, the Mother Lode’s primary watersheds had received 4.6 inches of precipitation since the current water year began Oct. 1. That’s 35% of average to date.
Meanwhile, snowpack for the Central Sierra and Southern Sierra is below normal so far this winter, according to snow sensors in both regions and a snow survey conducted Wednesday about 90 miles northeast of Sonora.
As of Thursday, Central Sierra snowpack data from 43 automated snow sensors showed an average snow water equivalent of 6.1 inches, which is 59% of normal to date. Southern Sierra snowpack data from 27 automated snow sensors showed an average snow water equivalent of 2.8 inches, which is 35% of normal to date.
Statewide, snow water equivalents averaged 5 inches, which is 52% of normal for the end of December.
California Department of Water Resources staff portrayed the latest snowpack observations with the headline “Late December Storms Not Enough to Offset California’s Dry Fall.”
The first manual snow survey of the 2020-21 winter season on Wednesday at Phillips Station off Highway 50 in El Dorado County showed 30.5 inches of snow depth, and a snow water equivalent of 10.5 inches, which is 93% of the Jan. 1 average at that location.
State water resources staff emphasized that while conditions were positive at Phillips Station, the statewide snowpack is just 52% of average for late December and early January.
“The snow survey results reflect California’s dry start to the water year and provide an important reminder that our state’s variable weather conditions are made more extreme by climate change,” Karla Nemeth, the state DWR director, said Wednesday. “We still have several months left to bring us up to average, but we should prepare now for extended dry conditions.”