CU Spaceflight Landing Predicton - Similar to wyoming however is quicker to run and has more variables such as ascent and drag factor so you can tailor make your predicted trajectory flight path.

University of Wyoming's Balloon Trajectory program - Assumes about a 270m/min (4.5m/sec) ascent rate and 4.9m/sec (low altitude) descent rate.

University of Southampton's Balloon Trajectory program - Can run Monte Carlo Simulation to give spread of likely landing area.