I look at the National Weather Service and Weather.com (Weather Channel). My impression is that, around here, Weather.com is more precise. NWS seems to me to cover themselves for a large coverage area by spreading things like rain chances as alike over a large area. But neither beats a genuine certified and experienced broadcast meteorologist with very long experience in your region, if you have that kind in your area. They are not so common.
But I also look at the traditional weather map to see how seriously to take either forecast. NWS calls it the National Forecast Charts under their Analyses and Forecasts section. Wunderground (Weather Underground) has mixed surface analysis maps with both isobars and pressure areas and clouds and precipitation imaging and radar that can be animated.
