Heavy snow leads to disruption
The Met Office has issued an amber weather warning across Yorkshire and said "significant snow accumulations" were likely on higher ground.
Heavy snow in South Yorkshire closed more than 30 schools and disrupted public transport.
There have been delays to bus services in Sheffield, and the A628 Woodhead Pass has been closed.
The weather could also disrupt the start of the flat racing season at Doncaster.
'Hard at work'
Course officials said they would carry out an inspection at 06:00 GMT on Saturday to decide whether the day's meeting, featuring the William Hill Lincoln, could go ahead.
Leeds Bradford Airport was open but said the weather was causing some disruption to flights. Robin Hood Airport said it was open as usual.
Sheffield City Council's highway contractor, Amey, said it was working "round the clock" to keep the city's routes clear.
Chris Morris, Amey operational director, said: "We've got snow ploughs fitted to our gritters and are using them on the high grounds where we have seen much greater snow fall than in the city centre.
"We've also diverted staff from other areas and they are hard at work clearing footpaths around shopping centres, hospitals and other busy pedestrian areas."