NSW cops soaking, flood warning out

A SEVERE weather warning has been issued for parts of NSW where heavy rain is expected to cause flash flooding.

The Bureau of Meteorology says the downpour is affecting the northwest slopes and northern tablelands as a cold front and low pressure trough move across the state.

Flash flooding is predicted for these areas.

A flood warning has also been issued for the Castlereagh River, which is likely to peak at Mendooran in the early hours of Saturday.

A flood watch is current for the Peel Valley, which takes in the towns of Nundle and Tamworth.

The BoM says 19mm of rain has fallen in Tamworth since 9am (AEST) on Friday and rain is still soaking the region.

The Namoi and Lower Gwydir Valleys are also on alert.

Emergency services are advising people to stay away from creeks, storm drains and causeways.

Conditions are expected to ease on Saturday morning but light rain is forecast to continue throughout the weekend, the BoM says.