ClearSky uses a meteorological forecast and emissions estimates to drive a plume dispersion model to obtain predictions of surface level smoke concentrations. The University of Washington, Department of Atmospheric Sciences, Mesoscale Modeling group MM5 forecast operation provides the requisite meteorological forecast. ClearSky uses a UW MM5 run with 4-km grid spacing that runs overnight and covers the next day. Smoke emissions are expressed as PM2.5 (PM of diameter 2.5m.) and are generated using ClearSky codes, based on the user-defined field-burning scenarios, generated by the user via a web application. The dispersion calculations are performed using CALPUFF. Hourly concentration fields resulting from CALPUFF are visualized using the PAVE tool. The resulting GIF files are animated for users via a web-application on the ClearSky website. Also, on the day of a scenario prediction, the website can show the CALPUFF hourly PM2.5 predictions at selected (instrumented) receptor locations; after monitoring results are available for these sites (one day later) and comparisons of the predictions and observations are made available on the website, replacing the prediction graphics.