If there is ANY precipitation more than a very light sprinkle then the track will close. Even if that very light sprinkle occurs for more than about 5 minutes then they will close also. It is too much of a safety issue for them to remain open with slick tracks when they have 1,000+ hp cars screaming down the 1/4. It looks like a good chance of rain/snow Saturday and if it is real cloudy then that might not dry up in time for Sunday. Sunday looks like 30% chance of precipitation and will be overcast by the time the track opens which would make for a gloomy track day. Just my thoughts, but it would probably be best to push this event back to a time that will allow for nicer weather.