Saturday's National Hunt meeting at Newcastle needs to survive an 8am inspection on Friday.
With the ground already heavy and waterlogged in places, more significant rain is forecast leaving clerk of the course James Armstrong with no choice but to call an inspection.
Another 15mm of rain is expected to hit the course this afternoon.
Armstrong said: "It's not looking too promising at the moment I'm afraid. "We had eight millimetres of rain overnight and we are waterlogged in places this morning.
"We could get anything up to another 20mm of rain today, it is due to be relatively dry on Friday but then there is more rain coming in on Saturday.
"We'll see where we are in the morning but if today's forecast is correct, I think it might be a formality unfortunately."
Moore said: "We've now hard just over 28 millimetres of rain in less than 24 hours and it's still raining.
"Some forecasts suggest it might stop at around 9pm tonight, but even if that is the case, the course has not got enough time to dry out enough for it to be sage ground.
"It's a big blow as it's a popular Christmas meeting, but we can't do anything about what nature throws at us and we don't want to mess people around.
"We've raced in some pretty testing conditions here of late but, unfortunately, the sponge is getting fuller."