Hail may be present in some areas, with hailstones up to 3cm thick. As much as 25 litres/m2 of rainfall is also possible.
The yellow alert, which was in place since Thursday, has now been upgraded to orange and is valid until 8.00pm.
At 12.45pm on Friday, the weather radar predicted wind speeds of up to 150km/h by around 4.00pm.
