A severe weather warning for thunderstorms and heavy rainfall has been issued by the Bureau of Meteorology for people in the Southern Tablelands, South West Slopes, Riverina, Snowy Mountains and parts of the Illawarra, South Coast, Central Tablelands, Central West Slopes and Plains, Lower Western, Upper Western and Australian Capital Territory Forecast Districts.

Severe thunderstorms are likely to produce heavy rainfall that may lead to flash flooding in the warning area over the next several hours. Locations which may be affected include Nowra, Bowral, Goulburn, Cooma, Yass, Wagga Wagga, Albury, Deniliquin, Griffith, Hay, Wilcannia and Ivanhoe. 

30mm of rainfall in 60 minutes to 2:00pm at Cabramurra AWS.

21mm of rainfall in 15 minutes to 3:10pm at Yalwal in the Illawarra.

The State Emergency Service advises that people should: 

* 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 6:20 pm.

If severe thunderstorms develop in Sydney Newcastle Wollongong or surrounding areas or Canberra and Queanbeyan, a more detailed Severe Thunderstorm Warning will be issued to people in these areas.

Warnings are also available through TV and Radio broadcasts, the Bureau's website at www.bom.gov.au or call 1300 659 218. The Bureau and State Emergency Service would appreciate warnings being broadcast regularly.