By Mary Lee

SAN FRANCISCO (CBS SF) — The first in a series of wet storm systems brought some rain to the Bay Area Friday, with much heavier precipitation forecast for next week.

Cold temperatures and even some light snowfall at higher elevations are possible over the next week, culminating in a potential atmospheric river by the middle of the week, according to the National Weather Service.

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The KPIX weather staff was tracking showers on doppler radar at around 12:30 p.m. Friday afternoon. There was light-to-moderate rain across the Golden Gate Bridge and stretching into the East Bay around lunchtime.

There were also showers further east into Contra Costa County over Martinez and Concord, across the Peninsula from Redwood City through Palo Alto as well as over the South Bay from Saratoga and Sunnyvale to parts of San Jose and east of Morgan Hill and Gilroy.

In addition to scattered showers into Friday afternoon, brief heavy downpours or isolated thunderstorms are a possibility, especially for inland locations of the far North Bay, the East Bay and the South Bay.

KPIX producer Sarah Brown shot video of hail falling in Walnut Creek at one point Friday.

Former KPIX meteorologist Roberta Gonzales posted a clip showing some serious runoff in Pleasanton.

Temperatures had dropped 5-10 degrees since Thursday to the low-to-mid 50s across the region and were forecast to continue dropping as the cold front pushes through. Friday evening, lows will be in the mid 40s and north winds will be 10 to 20 mph.

Late Friday night and into early Saturday morning, this system wraps up. The winter weather is likely to end up producing about a quarter-inch of rainfall over the next several days

Saturday will be sunny with highs in the 50s. Northeast winds will be 5 to 15 mph before switching to west winds in the afternoon.

The next weather system rolls in Sunday afternoon and is projected to last into Monday.

Another stronger storm system is behind that, arriving late Tuesday and bringing heavier rain into Wednesday and Thursday. That appears to be the strongest of the three storm systems forecast in the next week that could turn into a moderate atmospheric river by the middle part of next week.

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The system could drop up to 3 inches of rain in urban areas and double that amount at higher elevations.