Environment & Science

Despite possible rains, drought likely to persist this winter

Drought conditions are expected to continue or intensify this winter, as most of the state is forecast to have equal chances of a wet, dry or average November, December and January.
Drought conditions are expected to continue or intensify this winter, as most of the state is forecast to have equal chances of a wet, dry or average November, December and January.
NOAA

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California’s drought is likely to persist or intensify for most of the state during the next three months, with 2014 on its way to being the warmest on record, according to the winter outlook issued on Thursday by the National Oceanic and Atmospheric Administration’s Climate Prediction Center.

“California is now exceptionally vulnerable to water shortages if precipitation continues to be low. The situation is unlikely to change even if we get an average precipitation year,” said Kevin Werner, Western regional climate services director with NOAA’s National Climatic Data Center. “It will take significantly above average amounts of precipitation to refill reservoirs and recharge groundwater in the state. This is unlikely under the forecast.”

While the southern part of the state has a slight probability of a wetter-than-average winter, the central and northern parts of the state are at equal chances of seeing average, below-average and above-average precipitation during November, December and January.

Drought conditions in some small regions in the southern and northwestern parts of the state are likely to improve but not until December or January.

"Complete drought recovery in California this winter is highly unlikely," said Mike Halpert, acting director of NOAA’s Climate Prediction Center.  "While we’re predicting at least a 2 in 3 chance that winter precipitation will be near or above normal throughout the state, with such widespread, extreme deficits, recovery will be slow."

Winter is typically the season during which most of the state’s precipitation falls, including snow in the Sierra Nevada mountains. About a third of the state’s water supply comes from meltwater runoff from the snowpack.

This year saw considerably less runoff than in typical years. In April, the amount of snow in the statewide snowpack was at 31 percent of average. That dropped to below 10 percent in May.

Reservoir levels are also low. Werner said that in August, the 154 largest reservoirs in California held about 13.5 million acre feet of water, only 36 percent of storage capacity.

A naggingly persistent ridge of high pressure over the Pacific kept many storms away from California last winter. Halpert said that the ridge is less likely to develop this year. Currently, the ridge is not in place.

Forecasters are still expecting an El Niño weather pattern to develop, with a 67 percent chance it will happen by the end of the year. However, it’s unlikely that the climate pattern will bring enough precipitation to end drought conditions. If it develops, it is expected to be a weak El Niño, which historically has brought equal numbers of dry, wet and average years.