Reply to Silverman Comments on WMA Journal Paper entitled “30+ Winter Seasons of Operational Cloud Seeding in Utah”, Griffith et al. 2009

North American Weather Consultants (NAWC) published a peer-reviewed paper in the WMA 2009 Journal of Weather Modification entitled “30+ Winter Seasons of Operational Cloud Seeding in Utah”, Griffith et al. 2009. That overview paper describes several operational winter cloud seeding programs being conducted in Utah (Griffith et al. 2009), hereafter referred to as Griffith. The paper included estimations of seeding effects using an historical target/control method to assess the ongoing nonrandomized seeding projects. Silverman (2010) has submitted comments to the Editor of the WMA Journal of Weather Modification questioning the basis and accuracy of estimates of seeding effectiveness summarized in the Griffith paper.