The first significant rainfall since mid-December brought improved drought conditions to parts of California, but the February storms did not bring much-needed snow in the Sierra Nevada Mountain range where snowpack figures suggest no relief from the dry spell, according to this week's U.S. Drought Monitor report.
Most of the precipitation from the subtropical storms that swept through northern California fell as rain. Snowfall was limited to higher elevations, generally above 8,000 feet. Improved conditions in California rely on snowpack in the Sierra Mountains, where melting snow in spring provides freshwater for an estimated 25 million residents.
"Overall, the storms had little impact on the well-below-normal snowpack conditions across the Sierra Nevada and Cascades ranges," according to the report.
California's statewide snowpack remains about 27 percent of normal for this time of year.
Water runoff from the northern California storms provided about 500,000 acre feet of water flow to four major reservoirs -- Folsom, Oroville, Shasta, and Trinity -- that have been at critically low levels. As a result of the storms, parts of northwestern California and areas between San Francisco and Santa Cruz saw improved drought conditions compared to a week ago.
An acre-foot is a commonly used unit of volume used to measure large-scale water resources, such as reservoirs. It refers to the volume of one acre to a depth of one foot.
Nearly 100 percent of California remains under some type of drought, the severity of which falls under four Drought Monitor categories -- moderate, severe, extreme and exceptional. Last week, 77 percent of the state was under extreme drought, but that figure improved to 67 percent in the report released Thursday.
State climatologists estimate the state would need at least 150 percent of normal precipitation by the end of the water year, which is Sept. 30, if California has any chance of significant drought improvement.
Gov. Jerry Brown declared a drought emergency in January 2014 and asked Californians to reduce water use by 20 percent. State records show its a figure residents have had difficulty meeting, except for in December when statewide figures showed a 22-percent water-use reduction.