'Moisture surge' from atmospheric river to drench Sacramento on Friday and Saturday

Northern California's wet season will run at least another week as an unseasonably strong storm hits the region heading into this weekend.

Late Thursday drizzles are expected to turn into strong rain and winds by Friday morning, which will hold steady until petering out Saturday afternoon.

The subtropic "pineapple express" atmospheric river could bring up to 3 inches of rain total to Sacramento, South Lake Tahoe and the Bay Area and maybe 2 to 4 inches of snow Sunday along the I-80 and I-50 corridors.

Four to 5 inches of rain are forecast for Grass Valley, which National Weather Service meteorologist Jim Mathews said would make it one of the four heaviest two-day storms to hit the town since records began being kept in 1966.

"This will be a rare event for April rainfall, because we're looking at this moisture surge from Hawaii," Mathews said. "From what we can tell here, it looks quite wet, quite anomalous ... usually April storms tend to be more showery and not as widespread."

A lighter, more typical spring system is forecast to shower Northern California next Tuesday, though no prediction totals have been set.

Sacramento saw 77 percent more rainfall than usual during March this year, but the added precipitation wasn't enough to make up for the wet season's dismal start. In the Sierra Nevada on Monday, Department of Water Resources higher-ups urged Californians to conserve in anticipation of future droughts and noted the mountain range's snowpack was only 52 percent of normal.

Highs in the mid-70s and lows around 50 degrees are expected Tuesday and Wednesday before the storm, at which point upper temperatures will top out in the mid-60s. A melting snowpack and warm rain could create flooding in the foothills and cause small rivers and streams in the Sacramento Valley's low-lying areas to rise.

Benjy Egel: (916) 321-1052,

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