9.35am MetService advises that the the Severe Thunderstorm Warning has now been lifted for the Bay of Plenty radar area.

Earlier MetService reported that the MetService weather radar had detected severe thunderstorms near Waihi and Waihi Beach.

A tornado which went through Waihi Beach at around 8am has torn rooftops off houses, and caused powerlines to come down, resulting in over 900 properties affected by a power outage.

7.34am update: MetSerivce is reporting that at 7.15 am, the MetService weather radar detected severe thunderstorms near Waihi and Waihi Beach.

"These severe thunderstorms are moving towards the south, and are expected to lie near Waihi Beach and Katikati at 7.45am and near Katikati at 08:15 am," says a MetService spokesperson.

"These thunderstorms are expected to be accompanied by very heavy rain."

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

A Severe Thunderstorm Watch remains in force for Bay of Plenty and Hawke's Bay.

The National Emergency Management Agency advises that as storms approach you should:
- Take shelter, preferably indoors away from windows;
- Avoid sheltering under trees, if outside;
- Get back to land, if outdoors on the water;
- 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.

During and after the storm, you should also:
- Beware of fallen trees and power lines;
- Avoid streams and drains as you may be swept away in flash flooding.

Earlier, 7am: MetSerivce has issued a severe thunderstorm watch for both Bay of Plenty and Hawke's Bay.

A few heavy showers and/or thunderstorms are likely to affect parts of Bay of Plenty this morning, especially near the coast and Kaimai range.

Between 7am and 11am today, a few heavy showers or isolated thunderstorms may affect the area between Waihi and Opotiki, with localised downpours of 20-35mm per hour.

Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.

Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.

Hawke's Bay

Thunderstorms embedded within broader areas of rain are likely to affect Hawke's Bay until this evening, but may become more isolated after midday.

A few of the thunderstorms could be severe with localised downpours of 25 to 40 mm per hour, mainly south of Wairoa.

Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.

Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.

For information on preparing for and keeping safe during a storm, see the Civil Defence Get Ready website