General guidelines won't be much of help. It has to be safe. That's general guideline :) Visibility should be at least 2 gates, track should be hard enough and clean enough. What is hard enough and clean enough, and even 2 gate visibility is discussable. If it's about Kitzbuhel race, you get safe enough conditions quite easy, as we all saw week ago. If it's about some other race, things are normally different. But there's no way to tell, until it's finally canceled, if race will be or not. Last week on super-g in Garmisch, I was standing for 2 hours next to Schmalzl (men speed event race director) and waiting. Sure we both knew race most likely won't get through, and there was whole lot of traffic on radios, but things weren't canceled until last possible moment. So it's impossible to tell now already, if you should do something else or not. Weather forecasts are not all that accurate to make decision based just on that.