Yes. It's not fair, but nobody said life was fair. Pennsylvania is an at-will state in which you can be fired at any time for a good reason, bad reason, or no reason at all. So long as your termination did not violate "public policy," which our courts, for the most part, interpret as meaning "legislative enactment" (such as the Workers Compensation Act, or the Pennsylvania Human Relations Act, or other state or federal law), your termination will be upheld.
If, however, they do not fire *everyone* who calls out, discriminating on the basis of sex, race, national origin, age or disability, they may be liable for unlawful discrimination.
You failed to mention whether your employer has a 'points' system for attendance and your calling out took you over the maximum. If you have already been placed on notice of attendance issues, the fact that a snowstorm knocks you out won't make their termination unlawful.
Note that if you did not have an attendance issue, and you file for unemployment compensation, you should get it because you missed work for a cause which was necessitous and compelling.