The chance of El Niño weather conditions developing this winter for the Northern Hemisphere increased to 65 percent, but any hopes for drought relief during California's three-year dry spell should be tempered.
The latest figure, released Thursday by the Climate Prediction Center, represents an increase from last month's estimate of 58 percent. The tropical Pacfic Ocean phenomenon affects weather patterns and can potentially usher moisture into California, which needs about 150 percent of its normal annual rainfall to recover from the historic drought, according to experts.
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If El Niño develops, forecasters said it is expected to be weak. A weak system probably would not generate enough rainfall this winter to significantly improve drought conditions in California, which recently marked its driest three years on record, the federal government's National Climatic Data Center said.
El Niño forecast updates are released on the first Thursday of every month.
Nearly 80 percent of the state is under extreme drought, the second most severe category listed by the U.S. Drought Monitor. One year ago, about 28 percent of the state was under the severe drought category.
Not all of the precipitation from this week's California storms could be included in the latest Drought Monitor report released Thursday. Along with rain and snow, drought monitors consider the water levels in reservoirs, rivers and streams, soil moisture, and dozens of other factors.
The past two months have brought several back-to-back rainstorms, and the rain in late November and early December was among the heaviest that some areas had seen in years. The system dropped widely varying amounts of rain, ranging from trace levels in some areas to 14.5 inches at Yucaipa Ridge in the San Bernardino Mountains.
San Francisco saw 4.3 inches, while 1.5 inches fell on downtown Los Angeles, according to the National Weather Service. The San Francisco Bay Area reached or exceeded normal annual rainfall totals for the first time in years.
The storm put downtown Los Angeles slightly above normal for the season to date. Since July 1, it has recorded 2.30 inches of rain compared with the normal average of 2.14 inches by Dec. 4.
Climatologists have stressed that California needs to see a consistent pattern of storms to move beyond its driest three years on record. Critically low reservoir levels and diminishing Sierra Nevada snowpack prompted Gov. Jerry Brown in January to declare a drought emergency and ask Californians to cut residential water use by 20 percent. California's reservoirs are at 39 percent to 60 percent of normal.
Before this week's storms, snowpack in the southern Sierra Nevada Mountains had received just 47 percent of its normal rain and snow so far, and the northern Sierra 79 percent. Springtime runoff from the melting snowpack supplies water for an estimated 25 million Californians.