This executive briefing is a preliminary report of a larger study on demand-side barriers and drivers of cloud computing adoption for HPC. A more comprehensive report and analysis will be published later in 2016. From June to August 2016, the CloudLightning project surveyed over 170 HPC discrete end users worldwide in the academic, commercial and government sectors on their HPC use, perceived drivers and barriers to using cloud computing, and uses of cloud computing for HPC.