The Bureau of Meteorology has issued a Severe Thunderstorm Warning for parts of the Northern Rivers.

At this stage, the warning borders Lismore, and includes Casino, Kyogle, Evans Head and Yamba. However, this can change quickly.

A very moist unstable airmass combined with a low-pressure trough lying close to the east coast, with a developing low-pressure system, is drawing in significant moisture and triggering severe thunderstorms in the northeast part of NSW this afternoon.

The severe thunderstorms are likely to produce large hailstones, damaging winds and heavy rainfall that may lead to flash flooding in the warning area over the next several hours.

(The BoM weather radar at 3:24pm)

Locations which may be affected include Casino, Kyogle, Grafton, Coffs Harbour, Kempsey, and Tabulam

Safety advice

The State Emergency Service advises that people should:

* Park your car under secure cover and away from trees, powerlines and drains.

* Secure or put away loose items around your house, yard and balcony.

* Keep at least 8 metres away from fallen power lines or objects that may be energised, such as fences.

* Report fallen power lines to either Ausgrid (131 388), Endeavour Energy (131 003), Essential Energy (132 080) or Evoenergy (131 093) as shown on your power bill.

* Keep clear of creeks and storm drains.

* Don't walk, ride your bike or drive through flood water.

* If you are trapped by flash flooding, seek refuge in the highest available place and ring 000 if you need rescue.

* Stay indoors away from windows, and keep children and pets indoors as well.

For emergency help in floods and storms, ring the SES on 132 500.

Stay updated on the Hazards Near Me NSW app or the ACT ESA website (https://esa.act.gov.au).

Check https://www.bom.gov.au/weather-and-climate/warnings-and-alerts. Warnings are also available through TV and Radio broadcasts or call 1300 659 210. The Bureau and State Emergency Service would appreciate warnings being broadcast regularly.

The next warning is due to be issued by 5:50 pm.