What can I do to help my dad with alcoholism?

My dad has developed a pretty serious case of alcoholism over the past year or so. I caught him at 4:00 in the morning drinking a triple shot vodka and orange juice before going to work. I asked him if he was drinking and he lied to my face and said no so I asked to taste it and sure enough it tasted like vodka with a splash of orange juice. He likes to stash vodka bottles in the garage and in his car and sneak out there at various times in the evening and morning. I snuck into the garage and took the bottles out of his car. I don't want him to get himself or others killed by driving drunk. I am worried that he is driving to work while intoxicated and then taking nips at lunch time. He has begun to look much older the past couple of years and has gained a lot of weight. Several people have commented that his personality has changed over the past couple of years. My family has encouraged him to get help about 3 times this year. He says he has a problem and should probably get help and then does nothing about it. It seems to be getting worse. I told him this morning that this was not normal behavior to be skipping breakfast and drinking 3 shots of vodka instead. I told him I loved him and that I don't want him to get hurt by this behavior. My family is going to try to talk to him about it as a group soon but I'm not sure how much good that will do. I am very worried about him and I am wondering what kind of action my family and I should take to address this problem. I want to be proactive about it and I am not afraid to confront him about his drinking.