If it is a warm storm like these Pineapple Express ones, it's more likely that the Grapevine ( I-5) pass north of Los Angeles will experience flooding/ landslide/accident related closures rather than snow, however the risk is less than for the coastal routes.

"If US 101, CA 1 and I-5 "grapevine" are closed on 2/14 then the plan C or D would be to fly from San Jose or Sacramento to Las Vegas and rent a car to drive to Long Beach."

Just no. If the drive becomes too difficult or unappealing to your liking, fly from San Francisco to LAX. Looking today at fares on Feb. 14th... $44 one way, non-stop on Air Alaska/United.

But your drive is still more than a month away!!

I know! There are multiple airports available in the Bay Area and Southern California if you need to fly. The main issue as far as cost was mentioned, is that after about 21 days out, the best pricing disappears. If you can find a good airfare (which is refundable) I might book something now as a backup. Or as Plan A. And always the day before the cruise.

Southwest flies nonstop from San Jose to Long Beach, so why fly SJC to LAS and then drive if the weather is bad? There is a sale on Southwest Airlines ending today (southwest.com) with nonstop midday flights 2/14 from either OAK or SJC to LGB at $49 for future credit to your own account, or $129 straight refundable to original form of payment , including luggage. Seems like perfect trip insurance to me.