HOT AIR BALLOON FLT; VFR IN IMC.

Narrative

AFTER RECEIVING A WX BRIEFING FROM THE ST PETERSBURG FSS; WHICH FORECASTED 1500 SCATTERED; 12000 SCATTERED WITH OCCASIONAL 1 MI AND FOG; AND OBSERVING AT THE LAUNCH SITE 2 MI VISIBILITY AND A HIGH SCATTERED LAYER JUST PRIOR TO LIFTOFF; ALL BALLOON PLTS AND CREWS DETERMINED A SAFE FLT WOULD BE CONDUCTED WITH OBSERVED AND FORECAST CONDITIONS. APPROX 10 MINS INTO THE FLT; WX CONDITIONS RAPIDLY DETERIORATED DUE TO FOG. APPROX 1/2 MI VISIBILITY WAS OBSERVED WHILE AT AN ALT OF 200 FT. FLT AT 200 FT WITH 1/2 MI VISIBILITY COULD NOT BE CONTINUED AND NO SAFE LNDG AREA WAS OBSERVED. THEREFORE; A CLB THROUGH A 100 FT THICK LAYER OF FOG WAS INITIATED AND THE FLT WAS CONTINUED UNDER VFR ON TOP UNTIL A HOLE THROUGH THE FOG WAS FOUND AND A LNDG WAS MADE SAFELY IN A VACANT LOT AT WILLOW POND SUBDIVISION IN LUTZ; FL. CONSIDERING FUEL LIMITS AND DENSITY OF FOG AHEAD AND FAMILIARITY WITH SUBDIVISION; I CHOSE THE LNDG AREA AS THE SAFEST OPTION. CAUSE: INACCURATE WX FORECAST. RECOMMENDATION: INCREASE MARGIN FOR ERROR IN FORECASTS.