A MAJOR storm front is drifting east across the Hunter on Thursday afternoon just as the majority of workers begin their commute home.
The Bureau Of Meteorology has issued a severe storm warning for people in the Hunter, Central Tablelands, Central West Slopes and Plains and North West Slopes and Plains Forecast Districts.
The BOM expects the thunderstorms to produce heavy rainfall that may lead to flash flooding over the next several hours.
The locations which may be affected include Gosford, Scone, Cessnock, Merriwa, Kulnura and Dunedoo.
Heavy rain has already began falling in Cessnock, Maitland and the Central Coast and is expected to reach Newcastle before 5pm.
The NSW State Emergency Service (SES) is urging commuters not to take the risk of driving through flash flooding as heavy rain lashes Metropolitan Sydney, the Central Coast, North Coast and Blue Mountains.
NSW SES senior manager of state operations, chief superintendent Dallas Burnes, said flash flooding is dangerous and can happen anywhere there is localised heavy rainfall.
"If it's flooded, stop and find an alternative route. Flash flooding can be deeper than it appears and can contain sewage and poisons, as well as hidden debris," Mr Burnes said.
"If you live, work or regularly commute through a low lying area, there may be no official warning for flash flooding. It is critical you assess the conditions and also check live traffic before travelling."
The storm follows last Sunday's downpour which led to NSW SES crews from Cooranbong, Swansea-Catherine Hill Bay and Lake Macquarie receiving 26 calls for help.
A water spout was even recorded travelling across Lake Macquarie early on Sunday morning.
