Just fire them, no severance, no retraining.
I don't know where you live, friend, but it really is possible to be trapped by snow.
Three feet of snow of snow fell in Denver in a very short time a couple of years ago. Those of us who parked in our alley driveways (no on street parking) were trapped. As were thousands of others who couldn't get from their driveways to a plowed thoroughfare.
Add to that the Governor declared a state of emergency and wanted everyone off the roads so plows could be more effective. Almost all private businesses closed that day. One inch of snow closing down D.C. is one thing, three feet of snow is something else.