October 2, 2016 - SACRAMENTO – California’s 2016 Water Year draws to a close tomorrow, ending a fifth consecutive year marked by meager precipitation that fell more often as rain than snow.
(Left) Tule elk graze on the bottom of the 2 million acre-foot state-federal San Luis Reservoir on August 24, 2016, when the reservoir was at 13 percent of its capacity.
Record warm temperatures created an early and below-average runoff that was in large part absorbed by parched soil before ever reaching the State’s reservoirs. The water content of the California Sierra snowpack, often referred to as ‘the State’s largest reservoir,’ flows each spring into a series of above ground storage reservoirs that essentially serve as California’s water savings accounts in order to meet the growing demands of an uncertain climate future.
These all-too-familiar dry, warming conditions have led State water officials to describe the situation as a California ‘snow drought.’ The California Department of Water Resources (DWR) explains the term in its recently released Drought and Water Year 2016: Hot and Dry Conditions Continue, a water year wrap-up delivered with detailed historical context.
A ‘water year,’ a 12-month time period during which precipitation totals are measured, runs from October 1 to September 30 of the following year. The year is designated by the calendar year in which it ends.
Water Year 2016 is officially listed in the record books as ‘Dry’ statewide, even though parts of Northern California experienced average to slightly above average precipitation.
The forecast for Water Year 2017 is uncertain. The National Oceanic and Atmospheric Administration’s Climate Prediction Center currently sees slightly better than even odds that weak La Niña conditions will develop this fall and winter. La Niña refers to the periodic cooling of sea-surface temperatures across the east-central equatorial Pacific. It represents the cold phase of the El Niño/Southern Oscillation cycle, nature’s year-to-year variations in oceanic and atmospheric conditions. La Niña is the opposite phase of the warm, El Niño phase that California experienced this water year. There are no guarantees for substantial La Niña rainfall.
Water officials warn that making seasonal forecasts of precipitation – the ability to predict now if 2017 will be wet or dry (and how wet or dry) – is scientifically difficult, and the accuracy of such predictions is very low; much less than that of a seven-day weather forecast.
Historical records are the only source of facts to study for any indication of what California may see in the form of precipitation in coming months.
Of the 18 La Niña winters since 1950-51, 16 have provided below average precipitation for Southern California’s coastal region, and 15 winters have resulted in below average precipitation for Southern California’s interior region. Above average precipitation was recorded in 11 winters for the Northern Sierra and in eight years for the Central and Southern Sierra. Water year 2011 brought the only significantly wet La Niña event in this time period.
Sixty percent of the state currently remains in severe or extreme drought. While mandatory water restrictions today vary across California, making water conservation a California way of life remains a statewide goal and a top priority in Governor Edmund G. Brown Jr.’s State Water Action Plan. Furthermore, responding to climate change is vital to minimizing conditions that likely lead to more frequent, prolonged and severe droughts.
Source: DWR
