(Corrects original start time to 10:00 a.m., not 10.45 a.m., in third paragraph) TOKYO, July 30 (Reuters) - Heavy rain and thunder across Tokyo forced organisers to delay the start of the BMX racing semi-finals at the Tokyo Olympics on Friday morning, as they scrambled to remove water from the course. Although Tokyo avoided a direct hit from tropical storm Nepartak earlier this week, the capital has seen intermittent rains and on Friday the city was lashed with rain. Organisers delayed the start of the BMX event, originally scheduled for 10:00 a.m. (0100 GMT) by 45 minutes. Workers at the Ariake Urban Park used what looked like leaf blowers and giant brushes to scrape the racing course of water.