Weather: Severe thunderstorm warning for South Canterbury

South Canterbury is under a "top priority" weather warning, with the risk of tornadoes about to strike Ashburton and Timaru along with severe thunderstorms for the South Canterbury region.

"At 03:22pm, MetService weather radar detected severe thunderstorms near Carew, Peel Forest and Arundel," it warns.

"These severe thunderstorms are moving towards the eastnortheast, and are expected to lie near Carew and Arundel at 03:52pm and near Carew and Lismore at 04:22pm.

"These thunderstorms are expected to be accompanied by very heavy rain, large hail and possible tornadoes."

Tornadoes can blow out windows, lift roofs, break large branches off trees, generate dangerous flying debris and blow vehicles off the road.

The Ministry of Civil Defence and Emergency Management is warning residents that, as storms approach, they should:

  • Take shelter, preferably indoors away from windows
  • Avoid sheltering under trees, if outside
  • Move cars under cover or away from trees
  • Secure any loose objects around your property
  • Check that drains and gutters are clear
  • Be ready to slow down or stop, if driving

"Very heavy rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous," MetService says.

"Large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles, and make driving conditions hazardous."