Source: Bureau of Meteorology

For people in parts of Blue Mountains/Hawkesbury, Gosford/Wyong and Sydney areas.

Issued at 2:33 pm Thursday, 9 November 2023.

The Bureau of Meteorology warns that, at 2:35 pm, severe thunderstorms were detected on the weather radar near Colo Heights and the Wollemi National Park north of Kurrajong.

These thunderstorms are moving towards the east.

They are forecast to affect Wilberforce, the Yengo National Park northwest of St Albans and Cattai by 3:05 pm and Glenorie, Maroota and Wisemans Ferry by 3:35 pm.

Heavy rainfall that may lead to flash flooding is likely.

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.