SAN FRANCISCO (CBS SF) — An atmospheric river building in intensity out in the Pacific moved ever closer to the Northern California coast Thursday, carrying with it the promise of much-needed rain beginning Sunday and rolling into next week.

That’s welcome news for a region still in the grip of severe drought conditions and coming in the wake of an extremely dry November.

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There were light showers in the Bay Area early Thursday, but they were a mere table setter for the main weather event that will begin Sunday.

“This system continues to look more organized with better dynamics and better moisture,” National Weather Service forecasters said. “Latest Atmospheric River guidance continues to up the ante potential.”

The forecasters predicted precipitation totals for Sunday through Wednesday of 1″-3″ in many urban areas across the region with 3″-6″ in the coastal ranges.

“Rain could impact parts of the Bay Area Saturday night and continues through early Wednesday,” NWS forecasters said. “In fact, there are signs now that the Atmospheric River could stall Monday along the Central Coast.”

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In the Sierra, Thursday’s storm did pack a stronger punch. A winter weather advisory was in effect for the Tahoe area until 4 p.m.

“Total snow accumulations of 2 to 7 inches, except 6 to 12 inches above 7000 feet,” National Weather Service forecasters predicted. “Winds gusting 25 to 40 mph in the Basin with up to 60 mph along Sierra ridgelines.”

Chain controls are in effect for the mountain passes.

The snow was a welcome relief for the Sierra ski resorts who have been forced to use limit access to their runs after a dry November. But Thursday’s storm is merely setting the table for what’s in store beginning Sunday.

“A significant Sierra Winter Storm remains the focus in the extended forecast,” weather forecasters in Reno predicted. “Confidence is increasing in seeing a 2-3 day period where multiple waves of heavy snowfall are expected across the Sierra.”

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“Timing details will still need to be refined but the current window for storm impacts could be as early as Sunday and lasting through Wednesday morning. The peak snowfall rates look to target the Monday-Tuesday timeframe.”