“California cannot count on potential El Niño conditions to halt or reverse drought conditions. Historical weather data shows us that at best, there is a 50/50 chance of having a wetter winter. Unfortunately, due to shifting climate patterns, we cannot even be that sure.” State Climatologist Michael Anderson.
The current drought has resulted in observations of new, record-high temperatures and record low snowpack for California. Five of the lowest 10 snowpacks on record have occurred in the last decade, including the past four years. The seasonal snowpack is a key element to California’s water resources management, modulating winter precipitation into spring runoff for beneficial use through the dry summer.
As California heads into a new water year (October 1 to September 30) with a potential fifth year of drought and expectations of El Niño impacts in play during the winter, questions mount on what can be expected of winter temperatures, precipitation and snowpack for California.
Unfortunately, a historical look at past years with similar El Niño conditions as currently forecasted provide little guidance as to what California might expect this winter. Of the seven years since 1950 with similar ENSO signals (1958, 1966, 1973, 1983, 1988, 1992, and 1998) three were wet years, one was average and three were dry (with water year 1992 perpetuating a drought). Past years were cooler than the temperatures we are experiencing now which will impact the rain/snow boundary for any storms that materialize this winter.
For more detail and information on the unpredictable nature of the El Niño phenomenon, visit: http://water.ca.gov/waterconditions/docs/Drought_ENSO_handout4.pdf.