The warning comes as some Dubbo residents are left without power following a storm earlier in the morning. 

The weather warning states Severe thunderstorms are likely to produce heavy rainfall that may lead to flash flooding, large hailstones and damaging winds in the warning area over the next several hours. Locations which may be affected include Newcastle, Gosford, Orange, Tamworth, Dubbo and Lightning Ridge.

The areas include the Hunter, Central Tablelands, Central West Slopes and Plains and parts of the Mid North Coast, North West Slopes and Plains and Upper Western Forecast Districts.

The State Emergency Service advises that people should: 

* Move your car under cover or away from trees. 

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

* Keep clear of fallen power lines. 

* 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. 

* Unplug computers and appliances. 

* Avoid using the phone during the storm. 

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

* For emergency help in floods and storms, ring the SES (NSW and ACT) on 132 500. 

The next warning is due to be issued by 3pm.