* WHAT...Sub-freezing temperatures as low as 30 expected. * WHERE...In New Jersey, Salem, Gloucester, Camden and Cape May. In Pennsylvania, Eastern Montgomery and Lower Bucks. * WHEN...From midnight tonight to 9 AM EDT Friday. * IMPACTS...Frost and freeze conditions will kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing. PRECAUTIONARY/PREPAREDNESS ACTIONS... Take steps now to protect tender plants from the cold.