Northern California spring storm to brings thunderstorms, heavy rain and Sierra snow

A spring storm system is bringing rounds of rain and thunderstorms to Northern California, with the most active weather expected Friday into the weekend, when the Sierra will get a dumping of more snow.

In the Sacramento region, storms will likely be ongoing Friday morning, but the strongest window for thunderstorm activity is expected from the afternoon into the evening. Pingpong ball-sized hail or lightning have already been reported in areas including Sacramento, Modesto, Elk Grove, Solano County and more.

If there is a period of sunshine early to mid-afternoon, conditions could become more favorable for stronger or even severe thunderstorms. If cloud cover persists, the region is more likely to see widespread rain with embedded thunderstorms, with isolated stronger cells.

Throughout Thursday, roughly 3,000 cloud-to-ground lightning strikes were recorded in Northern California.

Storm hazards across the valley include gusty winds, brief heavy downpours, lightning and small hail, along with the potential for slick roads and ponding on area roadways.

The unsettled pattern will continue into the weekend, when a more organized system is expected to move through Northern California.

The CBS News Sacramento First Alert Weather team says multiple squall lines are expected to push onshore, with Saturday evening shaping up as the main event. That system could bring periods of heavy rain, poor drainage, flooding and embedded strong thunderstorms across the Sacramento Valley and surrounding areas.

The same system is expected to bring rain and heavy winds across the San Francisco Bay Area, with roughly three-quarters of an inch of rain possible throughout Saturday evening.

Thunderstorms are also likely in the Bay Area during this time, but early Sunday morning will bring an increased chance of that as the center of the system moves east over the region.

As the system moves into the Sierra Nevada, conditions are expected to develop quickly. Snow levels are forecast to drop quickly, leading to significant winter weather impacts.

Around 2 feet of snow is likely near Donner Pass, with up to 4 feet possible at higher elevations. Snow could also accumulate at lower elevations, with 2 to 6 inches possible down to about 4,000 feet.

Up to two inches of rain is expected across the valley floor, while as much as five inches could drench areas of the foothills like Grass Valley.

Waves of heavy rain and mountain snow are expected to continue through Sunday, before conditions begin to improve as the storm system exits the region.