Not sure what you're getting at but:

121.613 No person may dispatch or release an aircraft unless the weather reports or forecasts or any combination thereof, indicate that the weather will be at or above the authorized minimums at the ETA.

I'll back pedal my original statement but it's still half true. If your flight is less than an hour, the METAR is controlling and if it's below landing mins you can't go. I've been called by dispatch numerous times to tell me not to go for this very reason.