30 minutes parking sign covered with snow

Federal: 13 of us in 5 vehicles parked at a USFS ranger station while we went snowshoeing and each driver was cited and fined for violating a 30 minute parking limit. None of us saw the 2-3 signs and believe they were covered with fresh snow.

Is the covered sign considered an effective defense for appeal? Must the USFS employee be at the hearing? Can some of the drivers turn over their appeal to some of the other drivers?

Any other thoughts?

Thank you.

What is the name of your state (only U.S. law)? Washington, Federal

I guess all you have to do is prove that the signs were covered with snow...

Most states require drivers to be able to recognize signs by their shape. If the sign looks official under that snow you should have scraped the snow off to see what rules might govern the parking space(s). I don't think you will get much sympathy from the court on this...