A balloon pilot participating in a Balloon Fest departed in VMC conditions and during climb at 1;200 FT became IMC. He declared an emergency; programmed his GPS for a known safe field and landed.

Narrative

At the balloon fest the participating pilots had a scheduled weather briefing early that morning. Visibility was less than 3 miles so we were put on a weather hold and a new briefing was scheduled for and held 45 minutes later. Visibility at that time was greater than 3 miles and since conditions were improving; a flight was planned. My crew and I drove to a launch field 4 miles southwest of the balloon field and visibility continued to improve. We launched under clear skies with 3 MPH surface winds from the northeast and winds aloft from the southwest. After ascending to 1;200 FT AGL at 2;000 FT per minute and heading northeast at 12 MPH; I noticed patchy fog starting to move in beneath me from the northeast. I effected a descent rate of 200 FT per minute and by the time I reached 800 FT AGL; I could not see the ground at all. At this time declared an emergency and ascended to an altitude and wind direction to fly to the balloon field because I knew it contained no obstacles and was a safe landing site. I had programmed this field into my GPS and the wind direction was such that I had no doubt this was my best course of action. I landed at the balloon field without incident.