Robert H. "Bob" Johns (October 30, 1942 - October 26, 2020) was an American meteorologist specializing in severe convective storms and tornadoes. Johns spent his career in forecasting and forecaster training. When he retired, he started working on a project reanalyzing the Tri-State Tornado. He furthered forecasting techniques and developed the modern conceptualization of the derecho following landmark work on “northwest flow” severe weather patterns. Johns also introduced the enhanced wording "Particularly Dangerous Situation" (PDS) for tornado watches during the April 2-3, 1982 tornado outbreak. Johns died on October 26, 2020.