Weather and Climate Systems

Comparing Characteristics of the 2011-2016 California Drought with Climatology

Veronica Fall

School of Meteorology

07 December 2016, 3:00 PM

National Weather Center, Room 5930
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

The ongoing California drought has persisted for the last five years since beginning in 2011. After reaching a peak severity in 2013-2014, there has been some relief over the last year due to increased precipitation and snowfall that may be attributed to the strong El Niño of last winter. Previous studies have shown that while precipitation has been low over the past five years, precipitation alone has not made this drought record breaking. Record-setting warm temperatures have exacerbated low precipitation and snowfall. Additionally, previous studies have only used a framework analyzing one year of the drought or the three years of 2012-2014 against climatology, but there has yet to be an analysis performed to see how the past five years of drought, 2011-2016, compare to the climatological record. Emphasis will be placed on snowfall changes, since the snowfall and associated springtime runoff that fills California’s reservoirs is crucial to management of the state’s water resources.

Using permutation tests, maximum temperature, minimum temperature, precipitation and snowfall for 2011-2016 are analyzed against other five-year periods starting in 1950 to determine how the recent period has differed. Results show that the maximum temperature of 2011-2016 is the highest on record and that snowfall from 2011-2016 is the lowest in the observational record. The minimum temperature during the drought is one of the highest, but not absolute warmest on record, while precipitation is low but not the lowest. In the Sierra Nevada Mountains, snowfall is the lowest on record, with a mean value nearly twice as low as the second lowest five years on record. After five years of drought, California may hope for more precipitation and snowfall, but as temperatures continue to increase, drought conditions may become more normal.