Nothing you can do about it at the moment. When it gets closer, if DL foresees an issue they will issue a weather waiver here:
http://www.delta.com/content/www/en_...dvisories.html
That weather waiver will detail the airports impacted and the rules for making changes (you can look at the current ones for example). If impacted, Delta will give you the opportunity to reschedule or cancel depending on the rules they put in place.
FWIW, minor amounts of snow / ice at DTW aren't going to cause much of an issue (maybe a delay due to de-icing). They have experience with that at DTW to handle that - of course if it's significant that could cause problems but I wouldn't make assumptions based on a 9 day forecast.