San Diego County will get hit by the second storm of the week late Friday. But it will be weaker than Tuesday’s system and will do little to reduce the growing deficit in seasonal rainfall. The National Weather Service says the system is likely to drop about a half-inch of rain at the coast and twice as much across inland valleys and foothills by the time it moves east late Saturday. The system also could bring snow. But the storm is warmer, so the snow level will be at about 6,000 feet.