How far is your work from home and are there any large obstacles in that path? For example: River bridges or overpasses, that if they are fairly large will probably withstand a hit from a tornado with perhaps minimal damage that may render it not usable for vehicle traffic, but ok for people to walk across.

Also do you not have any family, friends or co-workers that live closer and whose homes may not be affected by whatever disaster occurs? I am sure that if you get along with co-workers, one of them may take you in for a short time until things calm down a bit.