Commuters have been warned to expect surface water on all major Scottish roads as torrential rain affects rush hour this morning
A yellow weather warning start at midnight this morning and is in place until 6am on Sunday.
The A9 has been shut north of the Inveralmond roundabout near Perth following a road traffic collision.
The incident was reported just before 12:30pm.
Traffic is reported to be very slow in the area, with all lanes closed northbound for up to an hour.
Motorists were earlier warned of surface water on the M8 and A720 near Straiton.
Surface water was also building on the approach to the Queensferry Crossing near Ferrytoll, with traffic reported to be travelling as slow as 15mph along the M90.
There have been reports of a lot of surface water on the west-bound entry slip to the A720 at Dreghorn.
Ferry services were disrupted by high winds across Scotland.
It follows localised flooding earlier in the week, which led to the cancellation of some rail services between Edinburgh and Glasgow.
Neil Armstrong, chief meteorologist at the Met Office, said: "This low-pressure system will bring challenging conditions, including unseasonably strong winds and heavy rain, from the west during Friday and Saturday.
"Summer storms - compared with those in autumn and winter - always have the potential to create additional impacts because more people are likely to be outdoors, especially by the coast.
"Additionally, with trees in full leaf they are more vulnerable to being brought down by strong winds."
The Scottish Environment Protection Agency (Sepa) has put 14 flood alerts in place, with warnings for regions including Aberdeenshire, Argyll and Bute, Central, Dumfries and Galloway, Dundee and Angus, Edinburgh and Lothians, Fife, Scottish Borders, Tayside and West Central Scotland.
A band of heavy rain followed by heavy showers or thunderstorms, with the potential for disruption, has been forecast for today.
The Met Office has warned there is a small chance that homes and businesses could be flooded, causing damage to some buildings. There is also a small chance of fast flowing or deep floodwater causing danger to life
"Where flooding occurs, there is a slight chance of delays or cancellations to train and bus services," the Met Office said.
"Spray and flooding could lead to difficult driving conditions and some road closures."
A traffic collision close to Strone Point near Inveraray has affected travel in both directions, with warnings of lane restrictions for up to 45 minutes.
The main rail route between Glasgow and Edinburgh has reopened after flooding at Winchburgh tunnel trapped passengers on trains for several hours.
Engineers, assisted by firefighters, were able to clear 2ft of water which had gathered in the West Lothian tunnel.
ScotRail said this morning that services between Dunblane - Edinburgh and Glasgow Queen Street were running as normal after major disruption on Thursday.
The heavy rain had caused problems around Edinburgh Airport on Wednesday afternoon, with flooding temporarily closing off access to the transport hub.
Up to 40mm of rain is forecast to fall across Saturday over all of Scotland away from the Highlands and Islands.
Richard Brown, flood duty manager for the Scottish Environment Protection Agency said: “Further unsettled weather is expected across Scotland on Friday and Saturday which may result in flooding.We would encourage the public to remain vigilant, especially in areas susceptible to flooding.”