Currently I use Weather Underground and CAIC forecasts to help judge conditions around here. As mentioned, keeping track of weather once it hits the mountains has always seemed very unreliable, storms always just seem to go their own way around here.
Maybe start down in SW Colorado and move to the north. Lots of people ride Wolf Creek, then maybe up to Grand Mesa, then the Vail Pass area, Then Kremling/Steamboat, Winter Park area, Grand Lake area...
Then maybe a row to the east like Monarch/Salida and north up around Leadville. Not sure where people ride the most over there though.
I always avoid ski town forecasts because they imbellish snow depths on a regular basis to increase business.
I need to check out your site, a one stop shop geared towards sledders is great idea. If CO is your target market maybe road and traffic conditions too for the city dwellers who need to drive 2-5 hrs into the hills.