I usually cross reference the marine weather forecast with the wind forecast on weather.com... if they match up I usually say that they have a 70% chance of being remotely correct. If the marine says 10-20mph and weather.com says 5-10mph I usually say they have a 25% chance of being correct. For this weekend, I'd say if you have something better to do, do it. I have a 5.5 hr drive to the lake, but don't have anything better to do and enjoy hanging out at the docks with our fishing friends
Nick