An overnight storm forced organizers to delay spectator entry to Augusta National on Wednesday as course staff cleared up debris for the practice rounds at the Masters.

The Augusta area received thunder and lightning, heavy rain and hail around midnight and while damage appeared limited, the gusty winds had blown twigs and pine needles on to the course.

Spectators were allowed into the course after a 40 minute delay.

Tiger Woods, the bookmakers' favorite for the title, had to walk through some of the debris as he undertook an early practice session.

The weather forecast for Thursday's opening round predicts a 70 percent chance of rain with thunderstorms likely especially in the afternoon and evening.