Northern New South Wales is set to be battered by severe thunderstorms and hail on Sunday night as Sydneysiders prepare for a miserable and wet covid Christmas. The Bureau of Meteorology issued an emergency alert at 5.16pm on Sunday warning of damaging winds and large hailstones for the flood-soaked Northern Rivers region around Lismore, Tenterfield and Grafton. The region has already suffered through torrential rains after a 'once in 100 years' storm swept through last week. The weather bureau warned everyone in those areas to stay indoors, unplug their electrical equipment such as computers in case of lightning damage, and to move their cars away from trees or under cover.