Active weather pattern through Wednesday will bring additional snow to the foothills and mountains, and scattered showers elsewhere. A warmer storm system late this week into the weekend will bring higher elevation snow along with moderate to heavy rain with local flooding impacts of small creeks and streams possible.
Discussion
Cool and unsettled weather will persist today and Wednesday as short-waves continue to rotate through the large trough along the coast. One wave is currently moving across the region bringing an area of light showers to the valley, and it will add a few more inches of snow to the northern Sierra snowpack as it moves to the northeast.
An additional 1-2 ft of snow accumulation is likely across the NorCal mountains through Wednesday with lighter amounts down into the lower foothill elevations. Snow levels will generally be around 1500-2500 feet, locally lower.
A few late-day thunderstorms will be possible again across the north end of the Sacramento Valley, but less deep forecast instability will likely limit the amount of small hail compared to Monday.
A brief break in the weather is forecast for later Wednesday into early Thursday before the major late-week warmer storm moves in beginning Thursday afternoon.
The timing of this system has sped up a bit, so the window for potential freezing temperatures in the valley on Wednesday night and early Thursday appears to be closing as clouds and southerly breezes increase.
Rain and gusty southerly winds will pick up Thursday night along with rising snow levels (to around 7-8k ft on Friday). Several inches of rain along with some lower elevation snow melt may lead to rises on small rivers and creeks draining the foothills Friday.
Keep in touch with the latest forecasts as the details on this storm will continue to evolve.
Extended Discussion (Saturday through Tuesday)
Showers expected over the weekend with the bulk of the precipitation over the Sierra Nevada. WPC QPF for the period Thursday through Sunday night is around 1 to 3 inches in the Central Valley, and around 3 to 6 inches in the foothills and mountains with locally higher amounts.
Warmer system with higher snow levels will pose a threat of significant snow melt in the lower elevations with possible hydrologic concerns.
Another AR event possible early next week. but model differences lead to some forecast uncertainties at this time.