The Biological Event Reconstruction Tool (BERT) is a fast-running code that performs source inversion using measurements of concentration and winds from a network of biological agent collectors and wind sensors. BERT was developed to aid a national program responsible for biological agent measurement networks. BERT determines bounds on release amounts and release locations when sensors register hits. The BERT uses a collector footprint scheme to achieve results quickly. In this presentation, we describe modifications made to the footprint scheme to account for uncertainties in the wind field that arise from measurement errors and wind model errors. Accounting for these errors results in a much higher probability of obtaining answers on release location and amount.