From NOAA NWS:
One thing which has emerged is increasing agreement among both deterministic guidance and EC/GEFS ensemble members in slowing the progression of the AR along the Central Coast. This trend, should it persist, points towards potentially higher rain totals for the Santa Cruz and Santa Lucia ranges, in addition to coastal portions of Monterey County. Thus confidence for higher rain totals in these areas has increased. Please see below for more details on timing, amounts, and potential impacts from this AR event. Light warm advection rains which began late Saturday night should persist into Sunday morning for the North Bay, while spreading towards the San Mateo coast and the remainder of the greater San Francisco Bay area by Sunday afternoon. The system should then stall/weaken over the Bay area into Sunday evening before intensifying on Monday with the greatest rain focus for the Santa Cruz Mountains, Santa Lucia Range, and Monterey Bay areas. While rain chances may persist into Tuesday, it still appears that the best window for meaningful rainfall (along with possible moderate and/or heavy rain rates at times) should be from about midday Sunday into Monday afternoon. Given the previous mention of the slowing AR on Monday some adjustment to rain totals were made to reflect model trends and known topographic effects. This includes decreasing amounts for rain shadowed valleys while increasing them for the Santa Cruz and Santa Lucia ranges. With that said the latest thinking on storm total amounts is as follows: North Bay Valleys: 2-3" North Bay Mountains: 3-6" Greater San Francisco and East Bay: 2-3" South Bay valleys: 1-2" Santa Cruz/Santa Lucia Ranges: 3-6"; locally up to 10" Monterey Bay: 2-3" Inland Monterey and San Benito Counties: 1-2" Keep in mind that adjustments to these forecast amounts are possible with additional information as we head closer to this rain event. Stay current with the latest forecast information. With rain on the way now`s a good time to take proactive measures like clearing gutters and storm drains of debris.