The Bureau had previously warned of damaging winds and large hailstones earlier in the afternoon.

"Weather Situation: A humid, unstable air mass lies over NSW, with a low pressure trough moving slowly eastwards across the State [on Friday]," the warning stated.

"Severe thunderstorms are likely to produce damaging winds, large hailstones and heavy rainfall that may lead to flash flooding over the next several hours in the South West Slopes and parts of the Central Tablelands, Southern Tablelands, Central West Slopes and Plains, Riverina and Upper Western districts.

"Locations which may be affected include Orange, Goulburn, Yass, Dubbo, Parkes and Wagga Wagga.

"Severe thunderstorms are likely to produce damaging, locally destructive winds, large, possibly giant hailstones and heavy rainfall that may lead to flash flooding over the next several hours in parts of the Central Tablelands and Southern Tablelands districts. Locations which may be affected include Crookwell and Taralga."

The State Emergency Service advises that people should:

Transport for NSW has closed the Olympic Highway at Yerong Creek on Friday in both directions after flooding on the roadway near Seeligers Lane.

Motorists have been advised to use the Hume and Sturt highways as an alternative route when travelling from north of Table Top or southbound from Wagga.

Lockhart Shire council has advised that French Park, Bullenbung, Hollies and Yerong Creek Mittagong roads are closed.

There is also water over the roadways on:

The Bureau of Meteorology has issued advice of possible minor flooding along the Tumut and Murrumbidgee rivers due to storms being forecast on Friday and Saturday.

Speed limits have been reduced on the highways to the west and south of Wagga following two days of severe weather that saw trees blown over, buildings damaged and cars smashed.

Lanes have been closed and the speed limit reduced to 40 kilometres per hour on the Sturt Highway around Galore with alternating start/slow traffic traffic conditions in place due to water on the road.

The speed limit on the Olympic Highway has been reduced to 60 kilometres per hour at various locations between Gerogery and Henty, also due to water being over the road.

The Bureau of Meteorology has forecast a very high chance of showers or thunderstorms, possibly severe with heavy rainfall possible in Wagga on Friday.

"A severe thunderstorm outbreak and rainfall is forecast over the coming days with widespread areas of risk through inland NSW during ... Friday, shifting to the coast into Saturday," the BOM Flood Watch alert stated.

"This rainfall has the potential to cause riverine flooding along the Orara River in the Mid North Coast, over inland parts of NSW in the Riverina and South West Slopes and the Murray River downstream of Hume Dam at Corowa.

"Catchments conditions are average to wet following rainfall in recent weeks."

In other news

The Flood Watch status means that people living or working along rivers and streams must monitor the latest weather forecasts and warnings and be ready to move to higher ground should flooding develop.

Flood Warnings will be issued if a minor flood level is expected to be exceeded at key sites along the Tumut and Murrumbidgee rivers.

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