* WHAT...Sub-freezing temperatures as low as 30 possible, especially at higher elevations. * WHERE...the mountains of western North Carolina * WHEN...From late Saturday night through Sunday morning. * IMPACTS...Frost and freeze conditions could kill crops and other sensitive vegetation, and possibly damage unprotected outdoor plumbing. Take steps now to protect tender plants from the cold. In-ground sprinkler systems should be drained. Remove hoses and cover above- ground pipes.