.[sanhedrin].The USC ski/snowboard club hits up mammoth on the regular. That would be the best case scenario but being a grad student may not afford you that luxury.
Snow Summit/Bear are still fun mountains but they are nothing like what you are used to being from CO. Nevertheless, it was still a ton of fun to get above the smog and shred up at the resort in Big Bear Lake. The traffic on a snow day is next level aweful. But it can pay dividends.
Definitely get Cali4nia pass. You will be seriously bummed on bear/summit for anything but park.
I went to UCSB for undergrad and was on the ski team there. USC has a similar situation, ski team condo once you join the team, which can have 20 people in it sometimes, and you don't have to race when you don't want to. I almost never raced, I drove 6 hours to ski the noids and hangman's, not to wait for a race, but over all it was a great deal. For around $300 you got access to a condo for the whole season where you could stay whenever you wanted. I don't know if that access is there for grad students, but you should at least contact the USC ski team and see if you can join as a grad student. Even if it is against the rules you might be able to pay them under the table. Our ski team house and carpooling made it easy for me to get about 30 days a year in college despite being 6 hours from Mammoth.
The other option is to get a ski lease if you have the money. I live in Orange County and ski Mammoth about 3 weekends a month. My wife and I have joined 5 other couples to rent a condo for the winter so that we can use it as much as we want. It is 385 a month, but you can usually find them for less. Given how much we use it it is a good deal, if we did not have it I would not ski nearly as much as I do.
You can also find people to go up with and Motel 6 it pretty regularly. If you get a couple of people it should not be that bad.
Regardless, get the Cali4nia pass. Mammoth is one of the best mountains in the U.S. And like I said, look into the USC ski team house. With some luck you should be able to make things work.
And congrats on USC, that is an excellent program. I have a number of friends who did MBA's there and it definitely paid dividends. You might like socal and become a Mammoth weekender like the rest of us. If you are willing to drive, and you can afford a ski lease, which you should be able to coming from that program, you can ski all winter and surf all summer.
You also might want to look into a Mt. Baldy pass. When it gets snow, and it doesn't always, it is by far the best mountain in socal. It has some reasonably legit steeps, nothing like the steepest stuff at Mammoth but still fun. When the runs to the lot are open you won't believe you are in socal. I always try to get in a day at Baldy on weekends when I don't hit Mammoth. Passes are cheap, like $150, so it is not a bad idea to buy one and hope they get snow. Baldy blows bear/summit's doors off mountain wise, although they don't have a park.
Good luck. With some careful planning and a Cali4nia pass you should be able to have a good season.