The Worker Adjustment and Retraining Notification Act $($WARN$)$ notice requirements do not apply when:a plant closing will result in an employment loss for $50$ or more workers at one site within a $30-$day period.a plant closing will result in an employment loss for less than $25$ workers at one site within a $60-$day period.a mass layoff involves at least $33$ percent of the workforce $($minimum of $50$ employees$)$ within any $30-$day period.a mass layoff involves at least $500$ employees within any $30-$day period.