If you are in area that is under a watch or warning (or both), if there is any type of law or special circumstance that would allow you to prepare your home no matter what the bosses say. I don't know of any, but you may be able to call your county EMA and ask them about this.
I wonder how many businesses in NO wishes they had closed two days earlier....I betcha if they had to do it all over again, they'd make a different decision.
If all else fails, you can just DO IT. I did during a snowstorm in Atlanta about 15 years ago. The snow began falling pretty heavily and I asked my boss if I could leave at noon since I didn't want to be stuck on the highway with people who don't get the concept of driving in the snow. He said no. It got worse as the morning progressed, and I asked him again and got the same reply. Told him I was going to leave at noon unless he wanted to pay any expenses I incurred in an accident. He told me he would fire me, I said "Go ahead, Frank. I don't care. You CANNOT forbid me from protecting myself in a dangerous situation and I highly doubt that a judge would agree with you if you fired me for this." He never did.
Of course, I realize this is not an easy step to take, but you are the only one looking out for you!