I work in a highrise in downtown Houston. The crackheads who run my company told us we won't shutdown until noon on Friday. I told them to remember what traffic will be like. Geez, anybody looking for a good IT guy out there?
Tell the crackheads that you are taking FMLA leave, and go. It will take a week of paperwork for them to attempt to deny the leave of absence.
I would tell them you are leaving now. You don't need to risk your life for a job. the key to evacuation is to do so EARLY or you cannot find a room for many states and highways are a mess.